Note: Descriptions are shown in the official language in which they were submitted.
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PROCESS FOR THE CONVERSION OF OXYGENATES TO OLEFINS
The present invention relates to a process for converting ethers to olefins
using a catalyst in the
form of a coated support substrate and using a catalyst for conversion of
ethers to olefins which
is obtainable according to the present invention.
INTRODUCTION
In view of increasing scarcity of mineral oil deposits which serve as starting
material for
preparation of lower hydrocarbons and derivatives thereof, alternative
processes for preparing
such commodity chemicals are becoming increasingly important. In alternative
processes for
obtaining lower hydrocarbons and derivatives thereof, specific catalysts are
frequently used in
order to obtain lower hydrocarbons and derivatives thereof, such as
unsaturated lower
hydrocarbons in particular, with maximum selectivity from other raw materials
and/or chemicals.
In this context, important processes include those in which methanol as a
starting chemical is
subjected to a catalytic conversion, which generally gives rise to a mixture
of olefins, paraffins
and aromatics.
In the case of such catalytic conversions, the challenge is to refine the
catalysts used therein,
and also the process regime and parameters thereof, in such a way that a few
very specific
products form with maximum selectivity in the catalytic conversion. Thus,
these processes are
named particularly according to the products which are obtained in the main.
In the past few
decades, particular significance has been gained by those processes which
enable the
conversion of methanol to olefins and are accordingly characterized as
methanol-to-olefin
processes (MTO process for methanol to olefins). For this purpose, there has
been
development particularly of catalysts and processes which convert methanol via
the dimethyl
ether intermediate to mixtures whose main constituents are ethene and propene.
Antia et al. in Ind. Eng. Chem. Res. 1995, 34, pages 140-147 describes the
coating of a support
substrate with ZSM-5 and the use thereof in a methanol-to-gasoline process
(MTG process).
US 4,692,423 relates to a process for preparing a supported zeolitic catalyst
by applying a
mixture of a zeolite in a polymerizable solvent, for example tetrahydrofuran,
to a porous support
substrate, and the latter may consist of organic or inorganic material.
lvanova et al. in J. Phys. Chem. C 2007, 111, pages 4368-4374 relates to a
foamed molding
and to an extrudate composed of 3-silicon carbide, to each of which a ZSM-5
coating is applied,
and to the use of such a coated foam body and extrudate in methanol-to-olefin
processes (MTO
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processes). Compared to the use of the pulverulent zeolite per se, an
improvement in the
catalytic activity/selectivity is observed here, the coated catalysts having a
higher stability with
respect to deactivation by coking.
Patcas, F. C. in Journal of Catalysis 2005, 231, pages 194-200, describes
ceramic foams
coated with ZSM-5 zeolite and the use thereof in methanol-to-olefin processes.
More
particularly, it is stated that, in comparison to zeolitic pellets, such
coated ceramic foams should
exhibit an improvement in activity and selectivity. At relatively low
temperatures and relatively
high space velocities, however, lower space-time yields are described compared
to the zeolitic
pellets.
WO 98/29519 Al describes nonzeolitic molecular sieves and especially SAPO
supported on
inorganic materials, and the use thereof in methanol-to-olefin processes.
WO 94/25151 Al describes zeolites and especially ZSM-5 supported on monoliths,
and the use
thereof as a molecular sieve in separation processes.
Hammon et al. in Applied Catalysis 1988, 37, pages 155-174 relates to
processes for producing
zeolite extrudates with little to no binder and the use thereof in methanol-to-
olefin processes.
However, Hammon et al. describes the use of extrudates shaped to monoliths as
catalysts as
being particularly disadvantageous due to rapid coking and correspondingly
short service lives.
Li et al. in Catal. Lett. 2009, 129, pages 408-415 relates to a foamed ZSM-5
monolith and to the
use thereof in a methanol-to-olefin process.
US 4,049,573 relates to a catalytic process for conversion of lower alcohols
and ethers thereof,
and especially methanol and dimethyl ether, selectively to a hydrocarbon
mixture with a high
proportion of C2-C3 olefins and monocyclic aromatics and especially para-
xylene.
Goryainova etal. in Petroleum Chemistry 2011, vol. 51, no. 3, p. 169-173
describes the catalytic
conversion of dimethyl ether to lower olefins using magnesium-containing
zeolites.
Even though some advances have been achieved in the prior art with regard to
the selectivities
and/or activities of the catalysts by alterations to their composition and/or
their configuration,
especially also in methanol-to-olefin processes, there is still a considerable
need for new
catalysts and processes which, as well as new and/or improved selectivities,
also have better
resistance to any deactivation in such processes. This is especially true of
those improvements
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which can lead to lower coking of the catalyst, in order thus to be able to
enable a higher
efficiency of existing and new processes.
DETAILED DESCRIPTION
It was thus an object of the present invention to provide an improved
catalyst, especially for the
conversion of oxygenates to olefins, which enables a longer service life of
the catalyst with
comparable space velocity and conversion of oxygenates. In this context, it
was a particular
object of the present invention to bring about improvements with regard to the
coking of the
catalyst which, for example in methanol-to-olefin processes, decides the
service lives of a
catalyst before regeneration of the catalyst is required, in order to achieve
the desired selectivity
and/or an adequate space-time yield.
It has been found that, surprisingly, through the combined use of a gas stream
comprising one
or more ethers with a catalyst comprising a support substrate and a layer
applied to the
substrate, the catalytically active layer comprising one or more zeolites of
the MFI, MEL and/or
MWW structure type, it is possible to provide a process for preparing olefins
which enables
considerably longer service lives of the catalyst. More particularly, it has
been found that,
unexpectedly, in a process for preparing olefins, an unexpected improvement in
the resistance
of the catalyst with respect to deactivation can be achieved during the use
thereof in the case of
use of such a coated support substrate as a catalyst when the reactant stream
comprises one
or more ethers.
Thus, the present invention relates to processes for converting ethers to
olefins, comprising
(1) providing a gas stream comprising one or more ethers;
(2) contacting the gas stream provided in (1) with a catalyst,
the catalyst comprising
- a support substrate and
- a layer applied to the substrate,
the layer comprising one or more zeolites of the MFI, MEL and/or MWW structure
type.
With regard to the support substrate used in the process according to the
invention, there is in
principle no restriction whatsoever with regard to the form thereof. It is
thus possible in principle
to select any conceivably possible form for the support substrate, provided
that it is suitable for
being at least partially coated with a layer of the one or more zeolites of
the MFI, MEL and/or
MWW structure type. According to the present invention, however, it is
preferred that the form of
the support substrate is selected from the group consisting of granules,
pellets, meshes, rings,
spheres, cylinders, hollow cylinders, monoliths and mixtures and/or
combinations of two or more
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thereof. With respect to the preferred mixtures, these relate preferably to
those forms of the
support substrate which are commonly used for production of beds, this
relating especially to
the preferred forms of the support substrate selected from the group of the
granules, pellets,
meshes, rings, spheres, cylinders and hollow cylinders. On the other hand,
with respect to the
combinations of forms of the support substrate according to the present
invention, preference is
given to those combinations of beds and monoliths where the beds preferably
comprise support
substrates selected from the group consisting of granules, pellets, meshes,
rings, spheres,
cylinders, hollow cylinders and mixtures of two or more thereof. More
particularly, such
combinations of beds and monoliths relate to preferred forms of the catalyst
in which a
sequence of one or more monoliths and one or more beds is present, in which
the bed(s) and
monolith(s) form individual zones of the catalyst. Alternatively, however,
preference is also given
to embodiments of the inventive catalyst which comprise combinations of
monoliths as the form
of the support substrate, especially combinations of monoliths according to
the particular or
preferred embodiments as described in the present application. In particularly
preferred
embodiments of the present invention, the support substrate consists of one or
more monoliths,
and, in the case of use of a plurality of monoliths, a sequence and/or a
succession of individual
monoliths or plural monoliths arranged alongside one another at least in pairs
is present in the
catalyst.
Thus, according to the present invention, preference is given to embodiments
of the
process for converting ethers to olefins in which the form of the support
substrate is
selected from the group consisting of granules, pellets, meshes, rings,
spheres, cylinders,
hollow cylinders, monoliths and mixtures and/or combinations of two or more
thereof, the
support substrate preferably being one or more monoliths.
With regard to the one or more monoliths which are preferably present as the
support substrate
in the catalyst of the process according to the invention, there is again in
principle no restriction
with respect to the form that the one or more monoliths may take. According to
the present
invention, preference is given to monoliths selected from the group consisting
of honeycombs,
braids, foams and combinations of two or more thereof, and the one or more
monoliths further
preferably comprise one or more honeycombs and/or braids. More preferably,
according to the
present invention, the one or more monoliths which are preferably used as the
support substrate
are in honeycomb form.
Thus, according to the present invention, preference is given to embodiments
of the
process for converting ethers to olefins in which the one or more monoliths as
the preferred
support substrate are selected from the group consisting of honeycombs,
braids, foams and
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combinations of two or more thereof, the one or more monoliths preferably
being in honeycomb
form.
In the preferred embodiments of the process in which the catalyst comprises
one or more
monoliths in honeycomb form, there are no particular restrictions whatsoever
with regard to the
honeycomb form, provided that it is suitable for being at least partially
coated with the one or
more zeolites of the MFI, MEL and/or MVVW structure type. In particularly
preferred
embodiments, the honeycomb consists of a multitude of channels which run
parallel to one
another and which are divided from one another by the walls of the monolith,
and the shape of
the channels and/or preferably the thickness of the walls of the monolith
which divide the
channels from one another, up to a certain tolerance, are the same both in
terms of the shape of
the channels and with regard to the wall thickness, the latter typically
resulting from the material
used for production of the monolith or from the mode of production of the
honeycomb or the
honeycomb form. For example, preference is given to channels which have an
angular shape,
preferably the shape of a regular polyhedron having three or more vertices,
preferably having
three, four or six vertices and more preferably having four vertices. With
regard to the
dimensions of the channels in the preferred embodiments of the monoliths in
honeycomb form,
there is no restriction in principle, provided that the selected dimensions
allow at least partial
coating of the monolith in honeycomb form as the support substrate in the
inventive catalyst with
the one or more zeolites of the MFI, MEL and/or MWW structure type. Thus,
according to the
present invention, it is possible to use, for example, monoliths in honeycomb
form having 62 to
186 channels per square centimeter (400 to 1200 cpsi = cells per square inch),
preference
being given to monoliths in honeycomb form having 78 to 171 channels per
square centimeter
(500 to 1100 cpsi), further preference to those having 93 to 163 (600 to 1050
cpsi), further
preference to those having 109 to 155 (700 to 1000 cpsi), further preference
to those having
124 to 147 (800 to 950 cpsi) and further preference to those having 132 to 144
(850 to 930
cpsi). In particularly preferred embodiments of the present invention,
according to which the
support substrate comprises one or more monoliths in honeycomb form, those
having 136 to
141 channels per square centimeter (880 to 910 cpsi) are used.
In alternative embodiments of the present invention which use one or more
monoliths as the
support substrate in the catalyst, no substrate foams are present therein.
Thus, preference is
likewise given to embodiments of the catalyst used in the process in which the
support substrate
does not comprise any foams and more particularly does not comprise any foams
as a monolith.
With regard to the substance of which the support substrate consists, and
especially the beds
and/or monoliths present therein, according to the present invention, there
are no restrictions
whatsoever in this regard, provided that it is suitable for being at least
partially coated with the
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one or more zeolites of the MFI, MEL and/or MWW structure type. Thus, it is
possible in
principle to use any suitable material and/or any material composite as the
substance for the
support substrate, preference being given to using those materials which have
high thermal
stability and/or are inert to a high degree with regard to the chemical
reactivity thereof. Thus,
preference is given to using ceramic and/or metallic substances and composite
materials of
ceramic and/or metallic substances as the support substrate in the inventive
catalyst,
preference being given to using ceramic substances as the support substrate.
With regard to
the preferred ceramic substances, preference is given to using one or more of
these substances
selected from the group consisting of alumina, silica, silicates,
aluminosilicates, silicon carbide,
cordierite, mullite, zirconium, spinels, magnesia, titania and mixtures of two
or more thereof. In a
particularly preferred embodiment of the present invention, the ceramic
substances preferably
used for the support substrate are selected from the group consisting of a-
alumina, silicon
carbide, cordierite and mixtures of two or more thereof. In particularly
preferred embodiments,
the support substrate comprises cordierite, the support substrate further
preferably being a
cordierite substrate.
Thus, according to the present invention, preference is given to embodiments
of the
process for converting ethers to olefins in which the support substrate
comprises ceramic
and/or metallic substances, preferably ceramic substances, further preferably
one or more
substances selected from the group consisting of alumina, silica, silicates,
aluminosilicates,
silicon carbide, cordierite, mullite, zirconium, spinels, magnesia, titania
and mixtures of two
or more thereof, preferably from the group consisting of alpha-alumina,
silicon carbide,
cordierite and mixtures of two or more thereof, the support substrate more
preferably being
a cordierite substrate.
With regard to the one or more zeolites present in the catalyst, according to
the present
invention, there are no restrictions whatsoever either with respect to the
type or with respect to
the number of zeolites which can be used herein, provided that they are
zeolites of one or more
of the MFI, MEL and MWW structure types. If one or more of the zeolites
present in the catalyst
are of the MWW structure type, there is again no restriction whatsoever with
respect to the type
and/or number of MWW zeolites which can be used according to the present
invention. Thus,
these may be selected, for example, from the group of zeolites of the MWW
structure type
consisting of MCM-22, MCM-36, [Ga-Si-0]-MWW, [Ti-Si-0]-MWW, ERB-1, ITQ-1, PSH-
3, SSZ-
25 and mixtures of two or more thereof, preference being given to the use of
zeolites of the
MWW structure type which are suitable for the conversion of ethers to olefins,
especially MCM-
22 and/or MCM-36.
7
The same applies correspondingly to the zeolites of the MEL structure type
which can be used
according to the present invention in the catalyst, these being selected, for
example, from the
group consisting of ZSM-11, [Si-B-0]-MEL, boron-D (MFI/MEL mixed crystal),
boralite D, SSZ-
46, silicalite 2, TS-2 and mixtures of two or more thereof. Here too,
preference is given to using
those zeolites of the MEL structure type which are suitable for the conversion
of ethers to
olefins, especially [Si-B-0]-MEL.
According to the present invention, however, especially zeolites of the MFI
structure type are
used in the catalyst of the process according to the invention for converting
ethers to olefins.
With regard to these preferred embodiments of the present invention, there is
likewise no
restriction whatsoever with respect to the type and/or number of the zeolites
of this structure
type which are used, the one or more zeolites of the MFI structure type which
are used in the
inventive catalyst preferably being selected from the group consisting of ZSM-
5, ZBM-10, [As-Si-
[Fe-Si-0]-MFI, [Ga-Si-0]-MFI,' AMS-1B, AZ-1, boron-C, boralite C, encilite, FZ-
1, LZ-
105, monoclinic H-ZSM-5, mutinaite, NU-4, NU-5, silicalite, TS-1, TSZ, TSZ-
III, TZ-01, USC-4,
USI-108, ZBH, ZKQ-1B, ZMQ-TB and mixtures of two or more thereof. Further
preferably,
according to the present invention, the catalyst comprises ZSM-5 and/or ZBM-10
as the zeolite
of the MFI structure type, particular preference being given to using ZSM-5 as
the zeolite. With
regard to the zeolitic material ZBM-10 and the preparation thereof, reference
is made, for
example, to EP 0 007 081 Al and to EP 0 034 727 A2, particularly with regard
to the preparation
and characterization of the material.
Thus, according to the present invention, preference is given to embodiments
of the process for
converting ethers to olefins in which the one or more zeolites are of the MFI
structure type, and
are preferably selected from the group consisting of ZSM-5, ZBM-10, [As-Si-0]-
MFI, [Fe-Si-O]-
MFI, [Ga-Si-0]-MFI, AMS-1B, AZ-1, boron-C, boralite C, encilite, FZ-1, LZ-105,
monoclinic H-
ZSM-5, mutinaite, NU-4, NU-5, silicalite, TS-1, TSZ, TSZ-III, TZ-01, USC-4,
USI-108, ZBH, ZKQ-
1B, ZMQ-TB and mixtures of two or more thereof, further preferably from the
group consisting of
ZSM-5, ZBM-10 and mixtures thereof, the zeolite of the MFI structure type
preferably being
ZSM-5.
In a preferred embodiment of the present invention, the catalyst does not
comprise any
significant amounts of one or more nonzeolitic materials and especially does
not comprise any
significant amounts of one or more aluminosilicophosphates (SAP0s). In the
context of the
present invention, the catalyst is essentially free of or does not comprise
any significant amounts
of a specific material in cases in which this specific material is present in
the catalyst in an
amount of 0.1% by weight or less based on 100% by weight of the total amount
of the one or
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more zeolites of the MFI, MEL and/or MVVVV structure type, preferably in an
amount of 0.05% by
weight or less, further preferably of 0.001% by weight or less, further
preferably of 0.0005% by
weight or less and further preferably in an amount of 0.0001% by weight or
less. A specific
material in the context of the present invention particularly denotes a
particular element or a
particular combination of elements, a particular substance or a particular
substance mixture,
and also combinations and/or mixtures of two or more thereof.
The aluminosilicophosphates (SAP0s) in the context of the present invention
include especially
the SAPO materials SAPO-11, SAPO-47, SAPO-40, SAPO-43, SAPO-5, SAPO-31, SAPO-
34,
SAPO-37, SAPO-35, SAPO-42, SAPO-56, SAPO-18, SAPO-41, SAPO-39 and CFSAPO-1A.
With regard to the form in which the one or more zeolites of the MFI, MEL
and/or MWW
structure type is used in the catalyst of the process according to the
invention for converting
ethers to olefins, there is no restriction whatsoever in principle, especially
with respect to the
further elements or compounds which may be present therein. Thus, there are
generally no
restrictions whatsoever with regard to the ions and compounds which may be
present in the
micropores of the one or more zeolites, especially with respect to the
counterions to the possibly
negatively charged zeolite skeleton which are present in the micropores.
Accordingly, the one or
more zeolites may be in a form in which the possibly negative charge of the
zeolite skeleton is
compensated for by one or more different cationic elements and/or compounds,
this preferably
being accomplished at least partly by means of one or more cationic elements
and/or
compounds selected from the group consisting of H+, NH4, Li+, Na, K+ and
combinations of two
or more thereof, further preferably from the group consisting of H+, Na, K+
and combinations of
two or more thereof. In particularly preferred embodiments of the present
invention, the one or
more zeolites of the MFI, MEL and/or MWW structure type optionally comprise H+
and/or Na+,
and preferably H+ as the counterion to the negatively charged zeolite
skeleton, which means
that the one or more zeolites of the MFI, MEL and/or MWW structure type are
more preferably
used in the respective H form thereof in the catalyst of the process according
to the invention.
With regard to the amount in which the one or more zeolites of the MFI, MEL
and/or MWW
structure type has been applied to the support substrate in the catalyst
according to the present
invention, there is in principle no restriction whatsoever, provided that a
layer comprising the
one or more zeolites can be formed at least partially on the support
substrate. Thus, the
inventive catalysts comprise, for example, the one or more zeolites of the
MFI, MEL and/or
MVVVV structure type in a total loading of 0.005-1 g/cm3. The volume relates
here to the volume
of the coated support substrate, and this in the case of bodies and forms
comprising hollow
bodies and/or recesses also comprises those cavities and recesses. In an
alternative definition
according to the present invention, the volume in the case of the loading of
the support
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substrate, in embodiments comprising beds, is based on the respective volume
of the bed
including the intermediate spaces and cavities present therein. In preferred
embodiments of the
present invention, the catalyst comprises the one or more zeolites of the MFI,
MEL and/or
MVVW structure type in a total loading of 0.01-0.5 g/cm3 based on the volume
of the coated
support substrate and especially on the volume thereof according to the
aforementioned
particular and preferred definitions, further preferably in a total loading of
0.02-0.2 g/cm3, further
preferably of 0.04-0.1 g/cm3, further preferably of 0.055-0.08 g/cm3 and
further preferably of
0.065-0.075 g/cm3. In particularly preferred embodiments of the present
invention, the catalyst
comprises the one or more zeolites of the MFI, MEL and/or M1NW structure type
in a total
loading of 0.07-0.072 g/cm3 based on the volume of the coated support
substrate according to
the particular and preferred definitions of the present invention.
Thus, according to the present invention, preference is given to embodiments
of the
process for converting ethers to olefins in which the catalyst comprises the
one or more
zeolites of the MFI, MEL and/or MVVW structure type in a total loading of
0.005 to 1 g/cm3 based
on the volume of the coated support substrate, preferably in a total loading
of 0.01 to 0.5 g/cm3,
further preferably of 0.02 to 0.2 g/cm3, further preferably of 0.04 to 0.1
g/cm3, further preferably
of 0.055 to 0.08 g/cm3, further preferably of 0.065 to 0.075 g/cm3, and
further preferably in a
total loading of 0.07 to 0.072 g/cm3.
The same applies correspondingly to the one or more ethers present in the gas
stream
according to (1), and so there is no restriction here whatsoever in principle
in the process
according to the invention, provided that the one or more ethers present in
the gas stream
according to (1) can be converted by one of the catalysts according to the
present invention and
especially according to the particular and preferred embodiments thereof to at
least one olefin
when contacted according to (2). According to the present invention, however,
it is preferable
that the one or more ethers present in the gas stream according to (1) is
selected from the
group consisting of di(C1-C3)alkyl ethers and mixtures of two or more thereof.
Further preferably,
the one or more ethers are selected from the group consisting of dimethyl
ether, diethyl ether,
ethyl methyl ether, diisopropyl ether, di-n-propyl ether and mixtures of two
or more thereof, the
one or more ethers further preferably being selected from the group consisting
of dimethyl ether,
diethyl ether, ethyl methyl ether and mixtures of two or more thereof. In
particularly preferred
embodiments of the process according to the invention for converting ethers to
olefins, the gas
stream according to (1) comprises dimethyl ether as the one or more ethers,
and dimethyl ether
is more preferably the ether present in the gas stream according to (1).
Thus, according to the present invention, preference is given to embodiments
of the process for
converting ethers to olefins in which the gas stream according to (1)
comprises one or more
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di(Ci-C3)alkyl ethers, preferably one or more ether compounds selected from
the group
consisting of dimethyl ether, diethyl ether, ethyl methyl ether, di-n-propyl
ether, diisopropyl
ether, and mixtures of two or more thereof, further preferably from the group
consisting of
dimethyl ether, diethyl ether, ethyl methyl ether and mixtures of two or more
thereof, the gas
stream according to (1) further preferably comprising dimethyl ether.
On the other hand, with regard to the content of ethers in the gas stream
according to (1) in the
process according to the invention for converting ethers to olefins, there is
no restriction
whatsoever according to the present invention here either, provided that, when
the gas stream
is contacted in (2) with a catalyst according to the present invention, at
least one ether can be
converted to at least one olefin. In preferred embodiments, the content of
ethers in the gas
stream according to (1) is in the range from 30 to 100% by volume based on the
total volume,
the content especially being based on a gas stream at a temperature in the
range from 200 to
700 C and at a pressure of 101.3 kPa, preferably at a temperature in the range
from 250 to
650 C, further preferably from of 300 to 600 C, further preferably from 350 to
560 C, further
preferably from 400 to 540 C, further preferably from 430 to 520 C, and
further preferably in the
range from 450 to 500 C and at a pressure of 101.3 kPa. According to the
present invention, it
is further preferred that the content of ethers in the gas stream according to
(1) is in the range
from 30 to 99% by volume, further preferably from 30 to 95% by volume, further
preferably from
30 to 90% by volume, further preferably from 30 to 80% by volume, further
preferably from 30 to
70% by volume, further preferably from 30 to 60% by volume and further
preferably from 30 to
50% by volume. In particularly preferred embodiments of the process according
to the invention
for converting ethers to olefins, the content of ethers in the gas stream
according to (1) is in the
range from 30 to 45% by volume.
Thus, according to the present invention, preference is given to embodiments
of the
process for converting ethers to olefins in which the content of ethers in the
gas stream
according to (1) is in the range from 30 to 100% by volume based on the total
volume,
preferably from 30 to 99% by volume, further preferably from 30 to 95% by
volume, further
preferably from 30 to 90% by volume, further preferably from 30 to 80% by
volume, further
preferably from 30 to 70% by volume, further preferably from 30 to 60% by
volume, further
preferably from 30 to 50% by volume, and further preferably from 30 to 45% by
volume.
According to the present invention, there is no restriction whatsoever in
principle with respect to
the composition of the gas stream in (1), provided that at least one of the
ethers present in the
gas stream can be converted to at least one olefin in the process according to
the invention.
Thus, there is also no restriction whatsoever with respect to the origin of
the gas stream
provided in (1), provided that the aforementioned condition of the conversion
of at least one
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ether to at least one olefin has been correspondingly fulfilled. Accordingly,
the gas stream may
in principle be composed of one or more ethers and one or more additional
compounds to give
a gas stream. In particularly preferred embodiments of the process according
to the invention
for chemically converting ethers to olefins, the gas stream provided in (1)
originates from at
least one preliminary reaction, preferably from the chemical conversion of one
or more alcohols
to one or more ethers, the one or more alcohols preferably being selected from
the group of the
aliphatic aliphatic alcohols. In further preferred embodiments, at least a
portion of the gas
stream provided in (1) originates from the chemical conversion of one or more
aliphatic (Ci-C6)
alcohols and mixtures of two or more thereof, further preferably from the
conversion of one or
more aliphatic (Ci-C4) alcohols and mixtures of two or more thereof, further
preferably from the
chemical conversion of one or more aliphatic alcohols selected from the group
consisting of
methanol, ethanol, n-propanol, isopropanol, butanol and mixtures of two or
more thereof, further
preferably from the group consisting of methanol, ethanol, n-propanol and
mixtures of two or
more thereof, the gas stream provided in (1) more preferably originating from
a preliminary
reaction of methanol and/or ethanol and methanol further preferably being at
least partly
converted to one or more di(Ci-C2)alkyl ethers, preferably to one or more
di(Ci-C2)alkyl ethers
selected from the group consisting of dimethyl ether, diethyl ether, ethyl
methyl ether and
mixtures of two or more thereof. For instance, the gas stream provided in (1),
in a particularly
preferred embodiment, originates from a preliminary reaction of conversion of
methanol to
dimethyl ether.
In the particularly preferred embodiments of the process according to the
invention in which the
gas stream provided in (1) originates from a preliminary reaction of one or
more alcohols, there
is no particular restriction whatsoever in principle with respect to the
reaction and hence the
reaction product of the conversion of one or more alcohols, provided that this
leads to a gas
stream comprising one or more ethers which, when contacted in (2) with a
catalyst according to
the present invention, enables the conversion of at least one of the ethers to
at least one olefin.
In these particular embodiments, it is further preferable that the preliminary
reaction leads to
conversion of at least one alcohol to at least one ether and especially to at
least one dialkyl
ether, the preliminary reaction more preferably being a dehydration in which
water is obtained
as a coproduct to one or more dialkyl ethers. In the particular and preferred
embodiments of the
present invention in which the gas stream provided in (1) originates from a
preliminary reaction,
it is particularly preferred in the process according to the invention that
such a gas stream
originating from a preliminary reaction is supplied directly and without
workup to the process
according to the invention in step (1).
Thus, according to the present invention, preference is given to embodiments
of the
process for converting ethers to olefins in which the gas stream according to
(1) is obtainable
CA 02877576 2014-12-22
12
from a preliminary stage, preferably from a preliminary stage of the
dehydration of one or more
aliphatic alcohols, preferably of one or more (C1-05) alcohols, further
preferably of one or more
(C1-C4) alcohols, further preferably of one or more aliphatic alcohols
selected from the group
consisting of methanol, ethanol, n-propanol, isopropanol, butanol and mixtures
of two or more
thereof, further preferably from a preliminary stage of the dehydration of
methanol and/or
ethanol, preferably of methanol.
With regard to the dehydration which is preferably performed in the
preliminary stage for
providing the gas stream in (1), according to particularly preferred
embodiments of the process
according to the invention, there are again no restrictions whatsoever with
respect to the
manner in which this is performed, provided that at least one alcohol and
preferably at least one
aliphatic alcohol is chemically converted to at least one ether. In preferred
embodiments, the
dehydration is at least partly a catalytic dehydration, and there is in
principle no restriction
whatsoever with respect to the catalyst used for this purpose, provided that
it is capable under
the selected conditions of the preliminary reaction of catalytically
converting at least one alcohol
and preferably at least one aliphatic alcohol to at least one ether,
preferably with simultaneous
formation of water. In particularly preferred embodiments of the process
according to the
invention, a heterogeneous catalyst is used for the preferred dehydration as
the preliminary
reaction, the catalyst preferably being in solid form and preferably having
acidic sites, at least
some of these preferably being in the form of Lewis-acidic sites. Thus, in
these particularly
preferred embodiments of the process according to the invention, for example,
alumina is used
as the heterogeneous catalyst for the preliminary reaction, and, in a
particularly preferred
embodiment, gamma-alumina is used as the heterogeneous catalyst for the
dehydration.
With respect to the reaction conditions which are selected for the dehydration
in the preferred
embodiments of the process according to the invention, there are no
restrictions in principle in
this respect either, provided that at least one alcohol and preferably at
least one aliphatic
alcohol can be chemically converted to at least one ether. With regard to the
temperature
selected for the dehydration, it is thus possible to set any temperature
suitable for this purpose,
and, in the case of the dehydration according to the particular or preferred
embodiments in
which a heterogeneous catalyst is used, the temperature for the preliminary
reaction is
preferably in the range from 100 to 600 C, further preferably from 150 to 500
C, further
preferably from 200 to 400 C, further preferably from 230 to 350 C, further
preferably from 250
to 300 C, and further preferably from 270 to 280 C.
With regard to the other components in the gas stream according to (1) in the
process according
to the invention, there is in principle no restriction whatsoever, provided
that the gas stream is
suitable overall for conversion of at least one of the ethers to at least one
olefin in step (2) when
CA 02877576 2014-12-22
13
contacted with a catalyst according to the present invention. In addition, for
example, as well as
the one or more ethers in the gas stream according to (1), one or more inert
gases may also be
present therein, for example one or more noble gases, nitrogen, water and
mixtures of two or
more thereof. In particular embodiments of the present invention, the gas
stream according to
(1) of the process according to the invention, as well as the one or more
ethers, comprises
water, this being especially true of the particular and preferred embodiments
of the present
invention in which the gas stream according to (1) is obtained from a
preliminary stage of
dehydration.
With respect to those preferred embodiments in which, as well as the one or
more ethers, water
is present in the gas stream according to (1), there is no restriction in
principle with respect to
the water content which may be present therein, provided that the conversion
of at least one
ether in the gas stream to at least one olefin in step (2) of the contacting
of the gas stream can
be effected with a catalyst according to the present invention. In those
preferred embodiments,
however, it is preferable that the water content in the gas stream is in the
range from 5 to 60%
by volume based on the total volume, the water content more preferably being
in the range from
to 55% by volume, further preferably from 20 to 50% by volume and further
preferably from
30 to 45% by volume.
Thus, according to the present invention, preference is given to embodiments
of the
process for converting ethers to olefins in which water is present in the gas
stream according to
(1), preferably in the range from 5 to 60% by volume based on the total
volume, preferably from
10 to 55% by volume, further preferably from 20 to 50% by volume, and further
preferably from
30 to 45% by volume.
With respect to the manner of contacting the gas stream with a catalyst
according to the present
invention in step (2) of the process according to the invention for converting
ethers to olefins,
there is in principle no restriction whatsoever, provided that the conversion
of at least one ether
to at least one olefin can be implemented. This applies, for example, to the
temperature at
which the contacting (2) takes place. Thus, for example, the contacting in
step (2) of the process
according to the invention can take place at a temperature in the range from
200 to 700 C,
preference being given to selecting temperatures in the range from 250 to 650
C, further
preferably from 300 to 600 C, further preferably from 350 to 560 C, further
preferably from 400
to 540 C and further preferably from 430 to 520 C. In particularly preferred
embodiments of the
present invention, the contacting according to (2) of the process according to
the invention is
performed at a temperature in the range from 450 to 500 C.
CA 02877576 2014-12-22
14
Thus, according to the present invention, preference is given to embodiments
of the
process for converting ethers to olefins in which the contacting according to
(2) is effected at a
temperature in the range from 200 to 700 C, preferably from 250 to 650 C,
further preferably
from 300 to 600 C, further preferably from 350 to 560 C, further preferably
from 400 to 540 C,
further preferably from 430 to 520 C, and further preferably from 450 to 500
C.
The same applies correspondingly to the pressure at which the gas stream is
contacted in step
(2) of the process according to the invention with the catalyst according to
the present invention.
Thus, the contacting can in principle take place at any desired pressure,
provided that this
allows the conversion of at least one ether to at least one olefin by virtue
of the contacting of the
gas stream with the catalyst. Thus, the pressure, for example in the
contacting in step (2), may
be in the range from 0.1 to 10 bar, the pressure according to the present
application indicating
the absolute pressure, such that a pressure of 1 bar in the contacting
accordingly corresponds
to the standard pressure of 1.03 kPa. According to the present invention, the
contacting in step
(2) takes place preferably at a pressure from 0.3 to 7 bar, further preferably
from 0.5 to 5 bar,
further preferably from 0.7 to 3 bar, further preferably from 0.8 to 2.5 bar
and further preferably
from 0.9 to 2.2 bar. In particularly preferred embodiments of the process
according to the
invention for converting ethers to olefins, the contacting in step (2) takes
place at a pressure of
1 to 2 bar.
Thus, according to the present invention, preference is given to embodiments
of the
process for converting ethers to olefins in which the contacting according to
(2) is effected
at a pressure in the range from 0.1 to 10 bar, preferably from 0.3 to 7 bar,
further preferably
from 0.5 to 5 bar, further preferably from 0.7 to 3 bar, further preferably
from 0.8 to 2.5 bar,
further preferably from 0.9 to 2.2 bar, and further preferably from 1 to 2
bar.
In addition, there are no particular restrictions with respect to the manner
of performance of the
process according to the invention for converting ethers to olefins, and so it
is possible to use
either a continuous or a noncontinuous process, the noncontinuous process
being performable,
for example, in the form of a batch process. According to the present
invention, however, it is
preferable to conduct the process according to the invention for the
conversion of ethers as a
continuous process. Thus, according to the present invention, preference is
given to
embodiments of the process for converting ethers to olefins in which the
process is a
continuous process.
With respect to these preferred embodiments of a continuous process, there are
no restrictions
whatsoever with respect to the space velocity selected, provided that the
conversion of an ether
to an olefin can be effected. Thus, it is possible to select, for example,
space velocities in the
CA 02877576 2014-12-22
contacting in step (2) which are in the range from 0,5 to 50 h-1, preference
being given to
selecting space velocities (VVHSV = weight hourly space velocity is calculated
as the ratio of
oxygenate reactant stream in kg/h to the amount of zeolite in the reactor in
kg) from 1 to 30 h-1,
further preferably from 3 to 25 h-1, further preferably from 5 to 20 h-1,
further preferably from 7 to
15 h-1 and further preferably from 8 to 12 h-1. In particularly preferred
embodiments of the
process according to the invention for converting ethers, space velocities for
the contacting of
the gas stream in step (2) in the range from 9 to 11 h-1 are selected.
Thus, according to the present invention, preference is given to embodiments
of the
process for converting ethers to olefins in which the space velocity in the
course of contacting
according to (2) is in the range from 0.5 to 50 h-1, preferably from 1 to 30 h-
1, further preferably
from 3 to 25 h-1, further preferably from 5 to 20 h-1, further preferably from
7 to 15 h-1, further
preferably from 8 to 12 h-1, and further preferably from 9 to 11 h-1.
As described above and shown in the examples of the present application, it is
possible to
achieve particularly long service lives with the inventive catalyst in a
process for converting
ethers as described in the present application, especially with respect to the
particular and
preferred embodiments of the process according to the invention. It has thus
been found that,
surprisingly, the use of a catalyst according to the present invention can
considerably increase
the service life of the catalyst before the process has to be interrupted for
regeneration of the
catalyst, at least with respect to the use of this catalyst batch compared to
the use of catalysts
according to the prior art. It is thus particularly preferable according to
the present invention to
select long service lives for the performance of the process for converting
ethers to olefins at
one of the particular or preferred space velocities, as described in the
present application.
Thus, preference is given to service lives in the range from 15 to 200 h,
further preferably in the
range from 20 to 150 h, further preferably from 25 to 100 h, further
preferably from 30 to 80 h,
further preferably from 35 to 70 h, further preferably from 40 to 65 h,
further preferably from 45
to 60 h and further preferably from 50 to 55 h. More particularly, based on
the particular and
preferred space velocities at which the process according to the invention is
performed,
preference is thus given, for example, to service lives of 15 to 200 h at a
space velocity in the
range from 0.5 to 50 h-1. Preference is further given to a service life from
20 to 150 h at a space
velocity of 1 to 30 h-1, further preference to a service life from 25 to 100 h
at a space velocity of
1 to 30 h-1, further preference to a service life from 30 to 80 h at a space
velocity of 3 to 25 h-1,
further preference to a service life from 35 to 70 h at a space velocity in
the range from 5 to 20
h-1, further preference to a service life from 40 to 65 h at a space velocity
in the range from 7 to
15 h-1 and further preferably from 45 to 60 h at a space velocity of 8 to 12 h-
1. In a particularly
preferred embodiment of the process according to the invention, a service life
of the catalyst,
CA 02877576 2014-12-22
16
during which the continuous process is performed without interruption, in the
range from 50 to
55 h at a space velocity of 9 to 11 h-' is selected. According to the present
invention, the
particular and preferred embodiments with respect to the service life selected
and especially the
service lives selected in combination with particular space velocities
preferably relate to a
minimum conversion of the one or more ethers present in the gas stream
according to (1) of the
process according to the invention, sustained conversion below this value
leading to
subsequent performance of the regeneration of the catalyst. According to the
present invention,
there is no particular restriction with respect to the minimum conversion
selected, this preferably
allowing full conversion of the one or more ethers present in the gas stream
according to (1) of
the process according to the invention during the service life of the
catalyst. Thus, in preferred
embodiments of the present invention, a minimum conversion of 60% of the one
or more ethers
present in the gas stream according to (1) of the process according to the
invention is selected,
sustained conversion below this value leading to performance of the
regeneration of the
catalyst, preferably a minimum conversion of 70% or more, further preferably
of 80% or more,
further preferably of 85% or more, further preferably of 90% or more, further
preferably of 95%
or more, further preferably of 97% or more, further preferably of 98% or more,
and further
preferably of 99% or more of the one or more ethers present in the gas stream
according to (1)
of the process according to the invention.
Thus, according to the present invention, further preference is given to
embodiments of the
process for converting ethers to olefins in which the service life of the
coated support substrate
as a catalyst, during which the continuous process is performed without
interruption, is in the
range from 15 to 200 h, preferably from 20 to 150 h, further preferably from
25 to 100 h, further
preferably from 30 to 80 h, further preferably from 35 to 70 h, further
preferably from 40 to 65 h,
further preferably from 45 to 60 h, and still further preferably from 50 to 55
h.
According to the present invention, the catalyst can be regenerated in
principle in order to be
reused in the process according to the invention. With regard to the
regeneration of the catalyst,
there are no restrictions whatsoever, provided that this leads to the
regeneration to an at least
partial re-establishment of the original activity thereof in the conversion of
oxygenates to olefins.
In a particularly preferred embodiment of the process according to the
invention, the catalyst is
regenerated by thermal treatment and especially by calcination and reused in
the process.
Thus, according to the present invention, preference is given to embodiments
of the process for
converting ethers to olefins in which the process comprises the further steps
of
(3) calcining the catalyst for regeneration;
(4) providing a gas stream comprising one or more ethers;
(5) contacting the gas stream provided in (4) with the regenerated
catalyst.
CA 02877576 2014-12-22
17
With regard to the calcination of the catalyst in (3), there are no
restrictions whatsoever in
principle, either with regard to the duration or with regard to the
temperature for calcination,
provided that it contributes to an at least partial re-establishment of the
original catalytic activity
in the conversion of oxygenates to olefins. For example, the calcination can
be performed at a
temperature in the range from 200 to 1100 C, preference being given to
temperatures in the
range from 250 to 900 C, and further preferably in the range from 300 to 800
C, further
preferably in the range from 350 to 700 C, further preferably in the range
from 400 to 600 C,
further preferably in the range from 450 to 550 C, and further preferably in
the range from 475
to 525 C. With regard to the duration of the calcination, this can be
performed, for example, for
a period of 0.25 to 30 h, the duration calcination preferably being in the
region of 0.5 to 20 h,
further preferably from 1 to 15 h, further preferably from 1.5 to 12 h,
further preferably from 2 to
h, further preferably from 3 to 8 h, further preferably from 3.5 to 7 h,
further preferably from 4
to 6 h, and further preferably from 4.5 to 5.5 h.
The calcination in (3) for regeneration of the catalyst can in principle be
performed in any
suitable atmosphere, provided that at least partial re-establishment of the
original activity can be
achieved. Thus, the calcination can be performed, for example, in oxygen or in
an oxygen-
comprising atmosphere such as air or in a mixture of oxygen and an inert gas
such as nitrogen
and/or one or more noble gases. In preferred embodiments, the calcination in
(3) is performed
in air or in a mixture of oxygen and an inert gas, the calcination in (3) more
preferably being
effected in air atmosphere.
In principle, the catalyst can be regenerated by the preferred embodiments by
which it is
regenerated (3) at any suitable time in the process, provided that this leads
to at least partial re-
establishment of the original activity when the catalyst used had yet to be
used in the
conversion of oxygenates to olefins and more particularly when it was still
fresh or freshly
regenerated. Thus, the calcination in (3) for regeneration of the catalyst can
be performed, for
example, when the methanol conversion in the process for conversion of
oxygenates to olefins
falls below 70%, the regeneration preferably being performed when the methanol
conversion in
the reaction falls to 70%, and further preferably to 75%, further preferably
to 80%, further
preferably to 85%, further preferably to 90%, further preferably to 95%, and
further preferably to
97%.
With regard to the step, which follows the calcination in (3), of providing a
gas stream
comprising one or more ethers in (4) and of contacting the gas stream with the
regenerated
catalyst in (5), these steps are in principle performed analogously to steps
(1) and (2) of the
process according to the invention, and more particularly according to the
particular and
CA 02877576 2014-12-22
18
preferred embodiments of steps (1) and (2) as defined in the present
application. Thus, all
particular and preferred embodiments for step (1) apply in the same way to
step (4) and,
independently of this, all particular and preferred embodiments for step (2)
also apply in the
same way to step (5).
With regard to the preferred embodiments of the process according to the
invention in which the
catalyst is subjected to a calcination for regeneration of the catalyst, it
has been found in an
entirely surprising manner that the regeneration led to a further improvement
in the service life
of the catalyst, even though the opposite effect would be expected in the case
of an already
used catalyst. Given that, the additional effect that it was possible to
distinctly enhance the
selectivities of the catalyst for 03 and 04 olefins through the calcination
was all the more
surprising. Thus, the preferred calcination of the catalyst in (3) serves not
just for the
regeneration thereof but also leads unexpectedly to an enhancement both of the
service life and
of the selectivity of the catalyst for C3 and 04 olefins as products of the
conversion of
oxygenates, especially in the particular and preferred embodiments of the
process according to
the invention.
Finally, steps (3) to (5) of the preferred embodiments of the process
according to the invention
can be repeated as desired, and so they can be repeated, for example, once to
1000 times.
According to the present invention, it is preferable, however, that steps (3)
to (5) are repeated 5
to 800 times, further preferably 10 to 700 times, more preferably 15 to 600
times, further
preferably 20 to 500 times, further preferably 25 to 400 times, and further
preferably 30 to
300 times.
The catalyst used in the process according to the present invention can in
principle be prepared
in any suitable manner, provided that it comprises one or more zeolites of the
MFI, MEL and/or
MWW structure type which are present in a layer applied to a support substrate
according to the
present invention and especially according to one of the particular and
preferred embodiments
of the invention as described in the present application. According to the
present invention, the
catalyst for use in the process according to the invention is preferably
obtainable by one of the
processes described in the present application for preparation thereof,
preferably by one of the
particular or preferred processes for preparation thereof, and, in
particularly preferred
embodiments of the present invention, it is obtained by one of the processes
described in the
present application, preferably by one of the particular or preferred
processes for preparation
thereof.
Thus, according to the present invention, preference is further given to
embodiments of the
process for converting ethers to olefins in which the catalyst, and especially
the catalyst
CA 02877576 2014-12-22
19
obtainable by one of the particular or preferred embodiments of the process
according to the
invention, is obtainable by a process comprising
(i) providing the support substrate and the one or more zeolites of the MFI,
MEL and/or
MVVW structure type;
(ii) preparing a mixture comprising the one or more zeolites of the MFI, MEL
and/or
MWW structure type and one or more solvents;
(iii) homogenizing the mixture obtained in (ii);
(iv) coating the support substrate with the homogenized mixture obtained in
(iii);
(v) optionally drying the coated support substrate obtained in (iv);
(vi) optionally calcining the coated support substrate obtained in (iv) or
(v).
With regard to the process for preparing the catalyst used in the process
according to the
invention, especially in the particular and preferred embodiments described in
the present
application, there is in principle no restriction whatsoever with respect to
the properties and
especially the particle sizes and morphologies of the one or more zeolites of
the MFI, MEL
and/or MWW structure type provided in step (i). According to the particle size
of the zeolites
provided in step (i), however, one or more steps are optionally performed
during the process
according to the invention, preferably prior to the provision of the one or
more zeolites in (i) or
after the preparation of the mixture in step (ii), in order to bring the one
or more zeolites to a
preferred particle size. In this connection, there is at first no particular
restriction with regard to
the particle size of the one or more zeolites, provided that this is suitable
for the performance of
the further steps in the process according to the invention, especially
according to the particular
and preferred embodiments of the present invention, and the particle size
should especially be
suitable for performance of the coating in step (iv), more particularly
depending on the nature
and form of the support substrate used according to the present invention and
especially
according to the particular or preferred embodiments of the support substrate
as described in
the present application. Thus, in particular embodiments of the process
according to the
invention, one or more steps are performed prior to the provision of the one
or more zeolites in
(i) or after the preparation of the mixture in step (ii), preferably after the
preparation of the
mixture in step (ii) and more preferably in step (iii) of the homogenizing of
the mixture obtained
in (ii), in order to bring the one or more zeolites of the MFI, MEL and/or MWW
structure type to a
particle size D50 in the range from 0.01 to 200 pm. In further preferred
embodiments of the
process according to the invention, the one or more zeolites are brought after
one or more of
the aforementioned steps, in one or more steps, to a particle size D50 in the
range from 0.03 to
150 pm, further preferably from 0.05 to 100 pm, further preferably from 0.1 to
50 pm, further
preferably from 0.3 to 30 pm and even further preferably from 0.4 to 20 pm. In
yet further
preferred embodiments of the process according to the invention, the one or
more zeolites, after
CA 02877576 2014-12-22
the preparation of the mixtures in step (ii) and preferably in step (iii) of
the homogenizing of the
mixture obtained in (ii), is brought in one or more steps to a particle size
D50 in the range from
0.5 to 15 pm. With regard to the number of steps and the manner in which the
one or more
zeolites are brought to a particular or preferred particle size D50, according
to the present
invention, there are no restrictions whatsoever, and so it is possible in
principle to use any
suitable process for this purpose. According to the present invention, the one
or more zeolites,
however, are preferably subjected to one or more grinding steps prior to the
provision of the one
or more zeolites in (i) or after the preparation of the mixture in step (ii),
preferably after the
preparation of the mixture in step (ii), and the one or more zeolites are more
preferably brought
to one of the particular or preferred particle sizes 050 by the operation of
homogenizing in step
(iii), especially according to the particular and preferred embodiments of the
present invention.
Thus, according to the present invention, preference is given to embodiments
of the process
for preparing the catalyst, and especially the catalyst according to one of
the particular or
preferred embodiments thereof, in which the provision of the one or more
zeolites in (i) is
preceded or the preparation of the mixture in step (ii) is followed,
preferably the preparation of
the mixture in step (ii) and more preferably in step (iii) of the homogenizing
of the mixture
obtained in (ii) is followed, by bringing of the one or more zeolites of the
MFI, MEL and/or MWW
structure type to a particle size D50 in the range from 0.01 to 200 pm,
further preferably from
0.03 to 150 pm, further preferably from 0.05 to 100 pm, further preferably
from 0.1 to 50 pm,
further preferably from 0.3 to 30 pm, further preferably from 0.4 to 20 pm,
even further
preferably from 0.5 to 15 pm.
According to the present invention, in the preferred process for preparing the
catalyst, a drying
step according to step (v) is optionally performed. With regard to the manner
in which the
optional drying is achieved, there is no restriction whatsoever in principle,
and so the drying can
be performed at any suitable temperature and in any suitable atmosphere. Thus,
the optional
drying can be effected under a protective gas atmosphere or in air, the
optional drying
preferably being effected in air. With regard to the temperature at which the
drying is effected, it
is possible, for example, to select a temperature in the range from 50 to 220
C. According to the
present invention, the optional drying according to step (v) is effected at a
temperature in the
range from 70 to 180 C, further preferably from 80 to 150 C, further
preferably from 90 to 130 C
and further preferably in the range from 100 to 120 C. In particularly
preferred embodiments of
the process according to the invention, the drying according to step (v) is
effected at a
temperature in the range from 105 to 115 C. With regard to the duration of the
one or more
optional drying steps, especially in particular and preferred embodiments of
the process
according to the invention, there is no particular restriction, provided that
drying suitable for the
further process steps can be achieved, for example after a drying step having
a duration of 0.1
CA 02877576 2014-12-22
21
to 20 hours. In particular embodiments of the process according to the
invention, the optional
drying is performed for a period of 0.3 to 10 h, further preferably of 0.5 to
5 h, further preferably
of 0.8 to 2 h and still further preferably of 0.9 to 1.5 h.
Thus, according to the present invention, preference is given to embodiments
of the process
for preparing the catalyst, and especially the catalyst according to one of
the particular or
preferred embodiments thereof, in which the drying in (v) is effected at a
temperature in the
range from 50 to 220 C, preferably from 70 to 180 C, further preferably from
80 to 150 C,
further preferably from 90 to 130 C, further preferably from 100 to 120 C, and
further preferably
from 105 to 115 C.
With regard to the optional calcining according to the present invention, the
same applies in
principle as with regard to the optional drying step, and so no particular
restriction whatsoever
exists here either, either with regard to the temperature or with regard to
the atmosphere in
which the calcination is performed, and finally also not with regard to the
duration of a
calcination according to the particular and preferred embodiments of the
present invention,
provided that the product of the calcination is an intermediate suitable for
being processed in the
further steps of the process according to the invention to give a catalyst
according to the present
invention. Thus, for example, with regard to the temperature of the optional
calcining in step (vi),
a temperature in the range from 300 to 850 C may be selected, preference being
given to
selecting a temperature in the range from 400 to 750 C, further preferably
from 450 to 700 C,
further preferably from 500 to 650 C and even further preferably from 530 to
600 C. In yet
further preferred embodiments of the present invention, the calcination in the
optional step (vi) is
performed at a temperature of 540 to 560 C. With respect to the atmosphere in
which the
optional calcination according to one or more of the aforementioned steps of
the process
according to the invention is performed, this may be either an inert
atmosphere or air, the
optional calcination in step (vi) preferably being performed in air. Finally,
there is also no
restriction whatsoever with regard to the duration of the calcination step in
the optional step (vi).
Thus, the duration of the calcination in the optional calcination step in (vi)
may, for example, be
0.5 to 20 hours, preference being given to a duration of 1 to 15 h, further
preferably of 2 to 10 h,
further preferably of 3 to 7 h, and particular preference to a duration of 4
to 5 h.
Thus, according to the present invention, preference is given to embodiments
of the process
for preparing the catalyst, and especially the catalyst according to one of
the particular or
preferred embodiments thereof, in which the calcining in (vi) is effected at a
temperature in the
range from 300 to 850 C, preferably from 400 to 750 C, further preferably from
450 to 700 C,
further preferably from 500 to 650 C, further preferably from 530 to 600 C,
and further
preferably from 540 to 560 C.
CA 02877576 2014-12-22
22
In step (ii) of the preferred process for preparing the catalyst, the one or
more zeolites of the
MFI, MEL and/or MWW structure type are first mixed with one or more solvents.
According to
the present invention, there is no restriction whatsoever in step (ii) with
regard to the type and/or
number of solvents used for this purpose. Thus, it is possible in principle to
use any suitable
solvent or solvent mixture in step (ii), provided that it is suitable for
enabling homogenization in
step (iii) and the coating in step (iv). For example, it is possible in step
(ii) to use one or more
solvents selected from the group consisting of alcohols, water, mixtures of
two or more alcohols
and mixtures of water and one or more alcohols. In preferred embodiments of
the present
invention, the one or more solvents used in (ii) are selected from the group
consisting of
(Ci-C6)-alcohols, water, mixtures of two or more (Ci-C6)-alcohols and mixtures
of water and one
or more (Ci-C6)-alcohols, the one or more solvents further preferably being
selected from the
group consisting of (Ci-C4)-alcohols, water, mixtures of two or more (Ci-C4)-
alcohols and
mixtures of water and one or more (Ci-C4)-alcohols. In further preferred
embodiments, the one
or more solvents in step (ii) are selected from the group consisting of
methanol, ethanol,
n-propanol, isopropanol, water and mixtures of two or more thereof, further
preferably from the
group consisting of methanol, ethanol, water and mixtures of two or more
thereof, the solvent
even further preferably being water, preferably distilled water.
Thus, according to the present invention, preference is given to embodiments
of the process
for preparing the catalyst, and especially the catalyst according to one of
the particular or
preferred embodiments thereof, in which the mixture prepared in (ii) comprises
one or more
solvents selected from the group consisting of alcohols, water, mixtures of
two or more alcohols,
and mixtures of water and one or more alcohols, preferably from the group
consisting of (Ci-C6)
alcohols, water, mixtures of two or more (C1-C6) alcohols, and mixtures of
water and one or
more (01-C6) alcohols, further preferably (C1-C4) alcohols, water, mixtures of
two or more
(Ci-C4) alcohols, and mixtures of water of one or more (C1-C4) alcohols,
further preferably
consisting of methanol, ethanol, n-propanol, isopropanol, water and mixtures
of two or more
thereof, further preferably consisting of methanol, ethanol, water and
mixtures of two or more
thereof, the solvent further preferably being water, preferably distilled
water.
With respect to the solids concentration of the mixture provided in (ii),
according to the present
invention, there are no particular restrictions whatsoever, provided that
homogenizing of the
mixture in step (iii) and the use of the homogenized mixture obtained in (vi)
for the coating in (iv)
are possible. Thus, the solids concentration of the mixture provided in (ii)
may, for example, be
in the range of 10-75% by weight, the solids concentration according to the
present invention
preferably being in the range of 15-65% by weight and further preferably in
the range of 20-60%
by weight and further preferably being in the range of 25-55% by weight and
further preferably
CA 02877576 2014-12-22
23
in the range of 30-50% by weight. In particularly preferred embodiments of the
process
according to the invention for preparing a catalyst, the solids concentration
of the mixture
provided in (v) is in the range of 35-45% by weight.
Thus, according to the present invention, preference is given to embodiments
of the process
for preparing the catalyst, and especially the catalyst according to one of
the particular or
preferred embodiments thereof, in which the solids concentration of the
mixture prepared in (ii)
is in the range from 10 to 75% by weight, preferably from 15 to 65% by weight,
further
preferably from 20 to 60% by weight, further preferably from 25 to 55% by
weight, further
preferably from 30 to 50% by weight, and further preferably from 35 to 45% by
weight.
With regard to the homogenizing in step (iii) too, according to the present
invention, there is no
particular restriction whatsoever, and so it is possible to select any
conceivable procedure in
order to obtain a homogeneous mixture of the mixture prepared in step (ii),
for which purpose it
is possible to use, for example, one or more processes selected from the group
consisting of
stirring, kneading, agitating, vibration, or a combination of two or more
thereof. According to the
present invention, the mixture prepared in step (ii) is preferably homogenized
by stirring and/or
by vibration in step (iii), the homogenization in step (iii) further
preferably being effected by
vibration, preferably by means of ultrasound, for example by use of an
ultrasound bath into
which the mixture to be homogenized is introduced.
Thus, according to the present invention, preference is given to embodiments
of the process
for preparing the catalyst, and especially the catalyst according to one of
the particular or
preferred embodiments thereof, in which the homogenizing in (iii) is effected
by stirring,
kneading, agitating, vibration or combinations of two or more thereof,
preferably by stirring
and/or vibration, further preferably by vibration, and further preferably by
means of ultrasound.
With regard to the coating of the support substrate in step (iv) of the
process according to the
invention, there is in principle no restriction whatsoever with respect to the
performance thereof,
provided that a corresponding layer is formed thereby at least partially on
the support substrate.
Thus, any suitable form of coating or of layer formation can be employed in
the process
according to the invention for preparing the inventive catalyst, the coating
in step (iv) preferably
being effected by spray coating and/or wash coating. In particularly preferred
embodiments of
the process according to the invention, the coating in step (iv) is effected
by wash coating, the
wash coating preferably being effected by dip coating. Such a preferred dip
coating operation is
effected, for example, by dipping the support substrate once or more than once
into the mixture
prepared in step (ii) and homogenized in step (iii), and, according to the
present invention, the
dip coating is preferably followed by a treatment to remove excess mixture
from the support
CA 02877576 2014-12-22
24
substrate. In preferred embodiments of dip coating, in which the substrate is
dipped repeatedly
into the mixture prepared in step (ii) and homogenized in step (iii), the
further preferred
treatment for removal of excess mixture can in principle be effected after the
repeated dipping
and/or between two or more dipping steps, each dipping step preferably being
followed by
removal of excess mixture by a suitable treatment of the coated support
substrate. More
preferably, however, according to the present invention, one dipping step into
the mixture
prepared in step (ii) and homogenized in step (iii) is performed, followed by
a corresponding
treatment for removal of excess mixture. With regard to the particularly
preferred removal of
excess mixture according to the particular embodiments of the present process,
in which dip
coating is performed in step (iv), there is in principle no restriction
whatsoever with respect to
the way in which excess mixture is removed. Thus, a removal can be achieved,
for example, by
suitable hanging of the coated support substrate and/or leaving it to stand,
and/or directly or
indirectly by mechanical or other action, for example by mechanical stripping
and/or by removal
with a suitable gas blower and/or by suitable application of centripetal
forces, for example by
means of centrifugal forces directed in a suitable manner. According to the
present invention,
however, particular preference is given to removing excess mixture by means of
a gas blower,
more preferably with the aid of compressed air by suitable extractive blowing
of the excess
mixture.
Thus, according to the present invention, preference is given to embodiments
of the
process for preparing the catalyst, and especially the catalyst according to
one of the particular
or preferred embodiments thereof, in which the coating in (iv) is effected by
spray coating and/or
wash coating, preferably by wash coating, the wash coating preferably being
effected by dip
coating, which is preferably followed by a treatment for removal of excess
mixture, the removal
of excess mixture preferably being effected at least partly with compressed
air.
In the process according to the invention, according to the present invention,
it is possible in
principle to provide the support substrate with a plurality of layers of the
same and/or different
composition, especially with respect to the one or more zeolites of the MFI,
MEL and/or MWW
structure type. Thus, preference is given to embodiments of the process
according to the
invention for preparing a catalyst according to the present invention in which
step (iv) is
repeated once or more than once, step (v) and/or step (vi) and preferably both
step (v) and step
(vi) preferably being executed between the repetitions. In such preferred
embodiments of the
process according to the invention in which two or more layers of different
composition,
especially with respect to the one or more zeolites, are applied to the
support substrate, steps
(ii) and (iii) are also repeated correspondingly in the case of preparation of
the different
compositions of the mixture in step (ii), and this may relate not just to the
chemical composition
but also to further properties of the mixture, for example the average
particle size of the one or
CA 02877576 2014-12-22
more zeolites of the MFI, MEL and/or MWW structure type. In particularly
preferred
embodiments of the process according to the invention, steps (iv) and (v)
and/or (vi), preferably
steps (iv)-(vi), are repeated once or more than once, in order to achieve
multiple coating of the
support substrate with a mixture prepared in step (ii) and homogenized in step
(iii).
With regard to the number of repetitions which, in the preferred embodiments
of the process
according to the invention for preparing a catalyst according to the present
invention, there is no
restriction in principle, and the steps in the repetitions of the particular
and preferred
embodiments of the process according to the invention are preferably repeated
once to five
times, further preferably once to four times, further preferably once to three
times and further
preferably once or twice.
Thus, according to the present invention, preference is given to embodiments
of the
process for preparing the catalyst, and especially the catalyst according to
one of the particular
or preferred embodiments thereof, in which step (iv) is repeated once or more
than once,
preferably steps (iv) and (v), further preferably steps (iv) to (vi), and the
steps are preferably
repeated once to five times, further preferably once to four times, further
preferably once to
three times and further preferably once or twice.
According to the particularly preferred embodiments of the present invention
in which the one or
more zeolites of the MFI, MEL and/or MWW structure type may each be present in
the catalyst
in the H form thereof, these may, in correspondingly preferred embodiments of
the process for
preparing the catalyst, either be provided in the H form in step (i) and/or
converted to the H form
during the process by suitable treatment and especially by ion exchange. In
the preferred
embodiments of the process for preparing the catalyst according to which the
one or more
zeolites are converted to the H form during the preparation, there are no
particular restrictions in
principle with respect to the manner in which this is conducted, the
conversion of the one or
more zeolites preferably being effected by ion exchange. The one or more
zeolites can thus
also be converted to the H form at any suitable point in the process, this
preferably being
performed after the preparation of the mixture in (ii) or after the coating
and optional drying
and/or calcining, preferably after the drying of the coated support substrate
in (v) and more
preferably after the calcining of the coated support substrate in (vi), the
conversion to the H form
preferably being effected on the dried and calcined coated support substrate.
With respect to the preferred embodiments of the process for preparing the
catalyst according to
which the conversion of the one or more zeolites of the MFI, MEL and/or MWW
structure type to
the H form is effected over one or more ion exchange steps, there are again no
particular
restrictions with respect to the manner in which this is conducted, provided
that at least some of
CA 02877576 2014-12-22
26
the counterions to the zeolite skeleton are exchanged by H+ ions. In preferred
embodiments, for
the purpose of ion exchange, the one or more zeolites are contacted with a
solution of a
protonated volatile base, preferably of a protonated volatile amine, more
preferably with an
ammonium salt solution, or alternatively with an acid and preferably with an
aqueous acid
solution, preferably with an aqueous solution of a mineral acid. With respect
to the ammonium
salts which are preferably used, there is no general restriction, provided
that the exchange of at
least some of the counterions present in the one or more zeolites for ammonium
can be
accomplished. For example, it is possible for this purpose to use one or more
ammonium salts
selected from the group consisting of NI-141\103, NH4CI, (N1-14)2SO4 and
mixtures of two or more
thereof. The same applies correspondingly with respect to the acids and
especially the mineral
acids which can be used for the purpose of ion exchange, provided that the
exchange of at least
some of the counterions present in the one or more zeolites for H+ can be
accomplished. Thus,
it is possible to use, for example, solutions of the mineral acids HNO3, HCI,
H2SO4, and also
mixtures of two or more thereof for the ion exchange. With respect to the
concentration of the
solutions of protonated volatile bases or of acids used for the preferred ion
exchange, there is
no particular restriction whatsoever, provided that at least some of the
counterions of the zeolite
skeleton can be exchanged, and, in the case of use of one or more acids, that
the pH of the
solution does not lead to any significant dissolution of the zeolite skeleton.
Thus, it is possible to
use, for example, solutions of the salts or of the acids having a
concentration of 1 to 50% by
weight, preference being given to using concentrations of 5 to 30% by weight
and more
preferably of 10 to 25% by weight for the ion exchange. The same applies
correspondingly with
respect to the weight ratio of salt or acid solution to the one or more
zeolites which are ion-
exchanged. Thus, the weight ratio of the solution used for the ion exchange to
the one or more
zeolites may, for example, be in the range from 1 to 20, the weight ratio
preferably being in the
range from 2 to 10 and further preferably in the range from 4 to 7.
The ion exchange may in principle here precede the provision of the one or
more zeolites in
step (i), or follow one or more of the steps of the preferred process for
preparing the catalyst, an
ion exchange preferably being performed prior to the provision in step (i)
and/or after the coating
and optional drying and/or calcining, preferably after the drying of the
coated support substrate
in (v) and more preferably after the calcining of the coated support substrate
in (vi). In the
preferred embodiments of the preparation of the catalyst used in the process
according to the
invention in which a step of ion exchange with a protonated volatile base, and
preferably with a
protonated volatile amine, more preferably with ammonium, is performed after
the calcining in
(vi), it is further preferred that, after the ion exchange and an optional
wash step and/or after an
optional drying step, a further calcining step is performed in order to remove
the volatile base
and more preferably ammonia completely from the ion-exchanged zeolite.
CA 02877576 2014-12-22
27
EXAMPLES
Comparative example 1: Preparation of an extrudate comprising ZSM-5
380 g of H-ZSM-5 (ZEO-cat PZ2-100 H from Zeochem) with Si/AI = 50 were mixed
with 329 g of
pseudoboehmite (Pural SB; Sasol), admixed with 10 g of formic acid in 50 ml of
water and
processed with 300 ml of water in a kneader to give a homogeneous material.
The starting
weights were selected such that the zeolite/binder ratio in the calcined
extrudate corresponds to
60:40. This kneaded material was pushed with the aid of an extrudate press at
approx. 100 bar
through a 2.5 mm die. The extrudates were subsequently dried in a drying
cabinet at 120 C for
16 h and (after heating time 4 h) calcined in a muffle furnace at 500 C for 4
h. Thereafter, the
extrudates were processed in a sieving machine with 2 steel balls (diameter
approx. 2 cm,
258 g/ball) to give 1.6-2.0 mm spall.
Example 1: Preparation of a support coated with ZSM-5
An aqueous suspension having a solids concentration of 40% by weight of H-ZSM-
5 zeolite
(ZEO-cat PZ2-100 H from Zeochem) with Si/AI = 50 was prepared and homogenized
in an
ultrasound bath. Cylindrical honeycomb pieces of cordierite (900 cpsi,
diameter 0.9 cm, length =
11 cm) were dipped into this suspension and then blown dry with compressed
air. The coated
supports were then dried at 110 C for 1 h and subsequently calcined at 550 C
for 3 h. The
coating step was repeated until a loading of 0.5 g of zeolite per honeycomb
piece (0.071 g/cm3)
was attained.
Example 2: Methanol-to-olefin process with preceding conversion of methanol to
dimethyl ether
2 g of the catalyst prepared according to comparative example 1 were mixed
with 24 g of silicon
carbide and installed in a continuous, electrically heated tubular reactor,
such that the bed in the
reactor has a length of 30 cm and a diameter of 12 mm. For the tests using the
catalyst
prepared according to example 1, two of the coated honeycomb bodies were
installed in the
reactor and sealed at the tube wall with glass fiber cord.
Upstream of the test reactor, methanol vapor was produced to give a gas stream
comprising
75% by volume of methanol and 25% by volume of N2, which was converted to
dimethyl ether
by means of a preliminary reactor charged with 34 ml of alumina spall at 275 C
and an
(absolute) pressure of 1-2 bar. The stream comprising dimethyl ether was then
passed into the
tubular reactor, and converted therein at a temperature of 450 to 500 C, a
WHSV (= weight
CA 02877576 2014-12-22
28
hourly space velocity, is calculated as the ratio of oxygenate reactant stream
in kg/h to the
amount of zeolite in the reactor in kg) of 7 or 10 h-1 based on methanol and
an (absolute)
pressure of 1 to 2 bar, and the reaction parameters were maintained over the
entire run time.
Downstream of the tubular reactor, the gaseous product mixture was analyzed by
on-line
chromatography.
On completion of one cycle with the catalyst according to example 1, the
catalyst was
deinstalled and calcined in a muffle furnace at 500 C in an air atmosphere for
5 h, in the course
of which the coke was almost completely incinerated. The regenerated catalyst
was
subsequently used again in the test reactor under the same conditions as the
fresh catalyst from
example 1.
The results achieved in the NATO process for the catalysts according to
comparative example 1
and according to example 1 (before and after the regeneration of the catalyst)
with respect to
the selectivities are shown in table 1, these reproducing the average
selectivities during the run
time of the catalyst in which the conversion of methanol was 95% or more.
Table 1: Average selectivities of a cycle (methanol conversion of >95%).
Example 1 after
Comparative example 1 Example 1
regeneration
Service life [h] 33 53 68
WHSV [h-1] 10 7 7
Me0H load per
cycle [kgmeohl = 330 371 476
kg zeolite-1]
Selectivity [%]:
ethylene 9 8 8
propylene 24 19 25
butylene 15 17 20
Ca paraffins 10 12 9
C5+ (mixture) 16 18 20
aromatics 19 18 13
01-C3 paraffins 7 8 5
As can be inferred from the values in table 1, it has been found that,
surprisingly, the specific
use of a zeolite which has been applied to a support substrate in an MTO
process with a
preliminary reaction of methanol to give dimethyl ether enables a surprisingly
long service life or
an unexpectedly high methanol load per cycle of the catalyst at which a
methanol conversion of
CA 02877576 2014-12-22
29
more than 95% can be maintained. All the more surprising is the fact that the
regeneration of
the catalyst by calcination led to a further considerable gain in service life
(see example 1 after
regeneration in table 1). Furthermore, the results of the reaction for the
regenerated catalyst
show that the latter also has a further gain in selectivity for butylene
compared to the fresh
catalyst, and also exhibits a selectivity for propylene which is higher than
the selectivity
achieved for the comparative example. Thus, the present invention provides a
process for the
conversion of ethers to olefins which, as shown by the test results in the MTO
process using the
catalyst according to example 1, enables much longer service lives compared to
such a process
which uses a catalyst in the form of an extrudate (see results with the
catalyst from comparative
example 1). Furthermore, the process surprisingly achieves an additional gain
toward longer
service lives, and also unexpectedly higher C3 and C4 selectivities compared
to the comparative
example after the regeneration of the catalyst by calcination.
CA 02877576 2014-12-22
Prior art documents cited
¨ Antia et al. in Ind. Eng. Chem. Res. 1995, 34, pages 140-147
¨ US 4,692,423
¨ lvanova et al. in J. Phys. Chem, C 2007, 111, pages 4368-4374
¨ Patcas, F. C. in Journal of Catalysis 2005, 231, pages 194-200
¨ WO 98/29519 Al
¨ WO 94/25151 Al
¨ Hammon et al. in Applied Catalysis 1988, 37, pages 155-174
¨ Li et al. in Catal. Lett. 2009, 129, pages 408-415
¨ US 4,049,573
¨ Goryainova et al. in Petroleum Chemistry 2011, vol. 51, no. 3, p. 169-173
