Note: Descriptions are shown in the official language in which they were submitted.
2~4~g~
W094/02~3 PCT/US93/06712
--1--
r~v~ .~WIS A~Tn PRO~IO~ T~ANSITION ~rT~T~A
~A~AT.ysTs AND ISOP~AFFIN AT,~yT.~ION PROCESSES USING
THOS~ ~AT~TYSTS
Field of the Invention
This invention is to: a) a catalyst system,
b) an improved catalyst system cont~;ning specified
amounts of water, c) a compo~nt of that system
comprising certain transition aluminas promoted with a
Lewis acid (preferably BF3), and d) a catalytic process
for the alkylation of isoparaffin with olefins. The
catalyst component is proAt~ by contacting the
transition alumina with the Lewis acid at relatively
low temperatures. The catalyst system comprises that
component and an additional amount of free Lewis acid.
The process entails olefin/isoparaffin alkylation using
the catalyst comr~n~nt and its allied catalyst system.
BACKGROUND OF ~F I NV~:N'l'lON
The preparation of high octane bl~n~i ng
components for motor fuels using strong acid alkylation
processes (notably where the acid is hydrofluoric acid
or sulfuric acid) is well-known. Alkylation is the
reaction in which an alkyl group is added to an organic
molecule, typically an aromatic or olefinic molecule.
For production of gasoline blenA;~g stocks, the
reaction is beiween an isoparaffin and an olefin.
Alkylation pro~C~es have been in wide use since World
War II when high octane gasolines were needed to
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W094/02~3 PCT/US93/06712
~ -2-
satisfy demands from high compression ratio or
supercharged aircraft engines. The early alkylation
units were built in conjunction with fluid catalytic
cracking units to take advantage of the light end by-
products of the cracking units: isoparaffins andolefins. Fluidized catalytic cracking units still
constitute the major source of feedstocks for gasoline
alkylation units. In spite of the mature state of
strong acid alkylation technology, existing problems
with the hydrofluoric and sulfuric acid technologies
continue to be severe: disposal of the used acid,
unintentional emission of the acids during use or
storage, substantial corrosivity of the acid catalyst
systems, and other environmental concPrns.
Although a practical alkylation process using
solid acid catalysts having little or no co~o~ive
components has long been a goal, commercially viable
processes do not exist.
The open literature shows several systems
used to alkylate various hydrocarbon feedstocks.
The American Oil Company obtained a series of
patents in the mid-1950's on alkylation pro~e-cr^c
involving C2-CI2 (preferably C2 or C3) olefins and C4-C8
isoparaffins. The catalysts used were BF3-treated
solids and the catalyst system (as used in the
alkylation process) also cont~; nP~ free BF3. A summary
of those patents is found in the following list:
BF3-Treated Catalyst
Patçnt No. Inventor (with free BF3)
2,804,491 May et al. SiO2 stabilized Al2O3
(10%-60% by weight BF3)
2,824,146 Kelly et al. metal pyrophosphate
hydrate
2,824,150 Knight et al. metal sulfate hydrate
2~ 4~3~
.
W094/02~3 PCT/US93/06712
--3--
2,824,151 Kelly et al. metal stannate hydrate
2,824,152 Knight et al. metal silicate hydrate
2,824,153 Kelly et al. metal orthophosphate
hydrate
2,824,154 Knight et al. metal tripolyphosphate
hydrate
2,824,155 Knight et al. metal pyroarsenate
hydrate
2,824,156 Kelly et al. Co or Mg arsenate
hydrate
2,824,157 Knight et al. Co, Al, or Ni borate
hydrate
2,824,158 Kelly et al. metal pyroantimonate
hydrate salt
2,824,159 Kelly et al. Co or Fe molybdate
hydrate
2,824,160 Knight et al. Al, Co, or Ni tungstate
hydrate
2,824,161 Knight et al. LG~O~U~YX~iC acid
hydrate
or Ni or Cd
borotungstate
hydrate
2,824,162 Knight et al. phosphomolybdic acid
hydrate
2,945,907 Knight et al. solid gel alumina (5%-
100% by weight of Zn or
Cu fluoborate,
preferably
anhydrous)
May be supported on Al203
None of the above patents disclose a process for
alkylating olefins and isoparaffins using neat alumina
treated with BF3.
Related catalysts have been used to
oligomerize olefins. U.S. Patent No. 2,748,090 to
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--4--
Watkins suggests the use of a catalyst made up of a
Group VIII metal (preferably nickel), a phosphoric acid
(preferably cont~; ni ng phosphorus pentox;~P), all
placed on an alumina adsorbent, and pretreated with
BF3. Alkylation of aromatics is suggested.
U.S. Patent No. 2,976,338 to Thomas suggests
a polymerization catalyst comprising a complex of BF3
or H3PO4 optionally on an adsorbent (such as activated
carbon) or a molecular sieve optionally contAi~ing
potassium acid fluoride.
Certain references suggest the use of
alumina-cont~;n;ng catalysts for alkylation of aromatic
compounds. U.S. Patent No. 3,068,301 to Hervert et al.
suggests a catalyst for alkylating aromatics using
"olefin-acting compounds". The catalyst is a solid,
silica-stabilized alumina contAin;ng up to 10% SiO2,
all of which has been modified with up to 100% by
weight of BF3. None of these prior references suggest
either the process or the material used in the
processes as is disclosed here.
Other BF3-treated aluminas are known. For
instance, U.S. Patent No. 3,114,785 to Hervert et al.
suggests the use of a BF3-modified, substantially
anhydrous alumina to shift the double bond of 1-butene
to produce 2-butene. The preferred alumina is
substantially anhydrous gamma-alumina, eta-alumina, or
theta-alumina. The various al~r; n~ will adsorb or
complex with up to about 19% by weight fluorine
~PpPn~ing upon the type of alumina and the temperature
of treatment. The all~ri~c are treated with BF3 at
elevated temperatures. Hervert et al. does not suggest
using these catalysts in alkylation reactions.
In addition, TJ~So P~tent No. 3,131,~0 to
Hervert et al. describes a process for the alkylation
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W094/02243 PCT/US93/06712
of aromatic compounds which utilizes a catalyst
comprising boron trifluoride and boron trifluoride
modified, substantially anhydrous alumina. This
reference teaches that the activity of the catalyst is
maintained by introducing water in an amount up to 400
parts per million molal and boron trifluoride in an
amount up to 3200 parts per million molal in the
hydrocarbon feed. Although this reference teaches that
the modification of the alumina with the boron
trifluoride gas may be carried out in a range between
room temperature and up to about 300C, it is noted
that this step is highly exothermic. For example, when
the modification is carried out at room temperature, a
temperature wave will travel through the alumina
causing the temperature to increase up to about 150C
or more.
In U.S. Patent No. 4,407,731 to Imai, a high
surface area metal oxide such as alumina (particularly
gamma-alumina, eta-alumina, theta-alumina, silica, or a
silica-alumina) is used as a base or ~u~po~L for BF3.
The BF3 treated metal oxide is used for generic
oligomerization and alkylation reactions. The metal
oxide is treated in a complicated fashion prior to
being treated with BF3. The first step entails
treating the metal oxide with an acid solution and with
a basic aqueous solution. The support is washed with
an aqueous decomposable salt such as ammonium nitrate.
The support is washed using deionized H20 until the
wash water shows no alkali or alkaline earth metal
cations in the filtrate. The support is dried and
calcined. The disclosure suggests generically that BF3
is then introduced to the treated metal oxide ~u~orL.
The examples show introduction of the BF3 at elevated
temperatures, e.g, 300C or 350C.
2 1 ~
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--6--
Similarly, U.S. Patent No. 4,427,791 to Miale
et al. suggests the enhancement of the acid catalytic
activity of inorganic oxide materials (such as alumina
or gallia) by contactingL~he material with ammonium
fluoride or boron fluorlde, contacting the treated
inorganic oxide with an aqueous ammonium hydroxide or
salt solution, and calcining the resulting material.
The inorganic oxides treated in this way are said to
exhibit enhanced Bronsted acidity and, therefore, are
said to have improved acid activity towards the
catalysis of numerous reactions (such as alkylation and
isomerization of various hydrocarbon compounds). A
specific suggested use for the treated inorganic oxide
is as a matrix or support for various zeolite materials
ultimately used in acid catalyzed organic compound
conversion proceR-^c.
U.S. Patent No. 4,751,341 to Rodewald shows a
process for treating a ZSM-5 type zeolite with BF3 to
reduce its pore size, enhance its shape selectivity,
and increase its activity towards the reaction of
oligomerizing olefins. The patent also suggests using
these materials for alkylation of aromatic compounds.
Certain Soviet publications suggest the use
of Al203 catalysts for alkylation processes. Benzene
alkylation using those catalysts (with 3 ppm to 5 ppm
water and periodic additions of BF3) is shown in
Yagubov, Kh. M. et al., Azerb. Khim. Zh., 1984, (5) p.
58. Similarly, Kozorezov, Yu and Levitskii, E.A., Zh.
Print. Khim. (Lenin~rad), 1984, 57 (12), p. 2681, show
the use of alumina which has been heated at relatively
high temperatures and modified with BF3 at 100C.
There are no indications that BF3 is maintained in
excess. Isobutane alkylation using Al203/BF3 catalysts
is suggested in Neftekhimiya, 1977, 17 (3), p. 396;
1979, 19 (3), p. 385. The olefin is ethylene. There
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W094/02~3 PCT/US93/06712
-7-
is no indication that BF3 is maint~;ne~ in excess
during the reaction. The crystalline form of the
alumina is not described.
U.S. Patent No. 4,918,255 to Chou et al.
suggests a process for the alkylation of isoparaffins
and olefins using a composite described as "comprising
a Lewis acid and a large pore zeolite and/or a non-
zeolitic inorganic oxide". The process disclosed
requires isomerization of the olefin feed to reduce
substantially the content of alpha-olefin and further
suggests that water addition to the alkylation process
improves the operation of the process. The best
Research Octane Number (RON) product made using the
inorganic oxides (in particular SiO2) is shown by Table
6 therein to be 94Ø
Similarly, PCT published applications WO
90/00533 and 90/00534 (which are based in part on the
U.S. patent to Chou et al. noted above) suggest the
same process as does Chou et al. WO 90/00534 is
specific to a process using boron trifluoride-treated
inorganic oxides including "alumina, silica, boria,
oxides of phosphorus, titanium oxide, zirconium oxide,
chromia, zinc oxide, magnesia, calcium oxide, silica-
alumina-zirconia, chromia-alumina, alumina-boria,
silica-zirconia, and the various naturally occurring
inorganic oxides of various states of purity such as
bauxite, clay and diatomaceous earth". Of special note
is the statement that the "preferred inorganic oxides
are amorphous silicon dioxide and aluminum oxide". The
examples show the use of amorphous silica (and BF3) to
produce alkylates having an RON of no greater than 94.
None of these disclosures shows crystalline
transition aluminas which were promoted with Lewis
acids at lower temperatures nor any effect upon the NMR
spectrum because of such a treatment. Nor do these
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W094/02243 PCT/US93/06712
--8--
~'r
disclosures show their~use in isoparaffin/olefin
alkylation. These disclosures further do not show any
benefit to the alkylation of isoparaffins and olefins
using these specifically treated aluminas.
BRIEF DESCRIPTION OF THE DRAWINGS
Figures lA-lD are nuclear magnetic reso~n~e
(NMR) plots of certain transition aluminas treated with
BF3 at a range of temperatures.
10Figure 2 is a three-~im~ncional graph showing
octane sensitivity for the inventive process as a
function of olefin feed content.
Figure 3 is an FTIR spectrum showing the
effect of the thermal treatment on the free water
15content (1500-1650 cm~~ band) and hydroxyl content
(3300-3800 cm~l) of gamma alumina as a function of
temperature.
Figures 4A and 4B are graphs showing the
effect of specific amounts of free water on the alumina
surface on catalyst life (amount of olefin procesc~ or
aged) and formula octane number (FON or R+M/2) achieved
in the alkylation of a isobutene and mixed butene feed
stream.
Figure 5 is a graph showing the effect of
initial water and performance in alkylation in terms of
~C8 of alkylate product, RON of alkylate in the
mixture, catalyst life (amount of olefin proc~sse~ or
age) and the total amount of olefin pro~c~ed prior to
significant C8 yield decline.
SUMMARY OF THE I~v~NllON
This invention is variously a catalyst
component comprising one or more transitional aluminas
which are treated with one or more Lewis acids
(preferably BF3) at a fairly low temperature desirably
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W094/02~3 PCT/US93/06712
so low that the component exhibits æpecific NMR
spectra, an improved catalyst system cont~i n i ~g
transition alumina and one or more Lewis acids and a
limited amount of water, a catalyst system comprising
that catalyst component with free Lewis acid, and an
olefin/isoparaffin alkylation process step using these
catalyst systems.
Use of the catalyst systems, i.e., the
catalyst component in conjunction with free Lewis acid,
produces high octane alkylate from isobutane and butene
at a variety of reaction temperatures between -30C and
40OC. The catalyst's high activity can result in low
operating costs because of its ability to operate at
high space velocities as well as enh~nce~ alkylate
production.
D~SCRIPTION OF THE INV~NTION
This invention is:
A) a catalyst comronent comprising certain
Lewis acid treated transition aluminas,
B) a catalyst system comprising the catalyst
component in combination with at least a minor amount
of free Lewis acid,
C) a catalyst component (A) or system (B)
cont~; n; ~g limited amounts of water, and
D) an alkylation process for producing
branched paraffinic products from olefins and
isoparaffins using that catalyst system.
The Catalvst Component
The catalyst component of this invention
comprises or consists essentially of a major amount of
t~ansition aluminas (preferably eta- or gamma-alumina)
which has been treated with a Lewis acid, preferably
BF3. The catalyst component preferably does not
W094/02243 2 1 ~ 0 3 ~ ~ PCT/US93/06712 ~
--10--
contain any metals (except, of course, aluminum and any
metal associated with the Lewis acid such as the semi-
metal boron) in catalytic amounts.capable of
hydrogenating the hydrocarbons.present in the feeds
except those impurity metals which may be present in
trace amounts in the Lewis acid or the alumina.
Alumina
Aluminum oxide (alumina) occurs abundantly in
nature, usually in the form of a hydroxide in the
mineral bauxite, along with other oxidic impurities
such as TiO2, Fe2O3, and SiO2. The Bayer process is used
to produce a reasonably pure Al2O3 having a minor amount
of Na2O. The Bayer process may be used to produce a
variety of alumina hydroxides:
2~03~
WO 94/02243 PCr/US93/06712
--11--
s~
z ~
0 ~ ~ N m N
~J N N o
C.
O
--~ O O O O O
~1: . . . . .
O ~ ~ --I N
t'~ ~i N
~D ~
2 0 0 ~ ~ ,~
~ s ) _, s
5 o
U ~ C
2 5 .c s~
'D Q)
,r
3 a .c ~ '' o
c
a ~ o .c
W094/02243 PCT/US93/06712
-12-
The aluminum hydroxides may then be treated
by heating to produce various activated or transition
aluminas. For instance, the aluminum hydroxide known
as boehmite may be heated to form a sequence of
transition phase aluminas: gamma, delta, theta, and
finally, alpha (see Wefers et al., "Oxides and
Hydroxides of Alumina", Technical Paper No. 19,
Aluminum Company of America, Pittsburgh, PA, 1972,
pp.1-51).
Transition aluminas (and their crystalline
forms) include:
gamma tetragonal
delta orthorhombic/tetragonal
eta cubic
theta monoclinic
chi cubic/hexagonal
kappa hexagonal
lambda orthorhombic
Activated aluminas and aluminum hydroxides are used in
various chemical processes as catalyst and adsorbents.
The aluminas suitable for use in this process
include the noted transition aluminas: gamma, delta,
eta, theta, chi, kappa, rho, or lambda. Especially
preferred are gamma- and eta-aluminas. Nixtures of the
two are also desireable.
Since it is difficult to produce a
substantially pure single phase transition alumina,
mixtures of various aluminas are tolerable so long as a
major amount of the specified alumina, e.g., an amount
greater than about 50% by weight of the alumina present
in the catalyst, is present in the catalyst. For
instance, in the production of eta-alumina, gamma-
alumina is often concurrently present in the resulting
product. Tn~P~, x-ray diffraction analysis can only
21~3~
W094/02~3 PCT/US93/06712
-13-
difficultly detect the difference between the two
phases. Aluminum hydroxides (boehmite, gibbsite, etc.)
may be present in the predominately transition phase
product in more than trivial amounts so long as they do
not substantially affect the desired alkylation
reaction.
While the surface area of the alumina may
suitably vary over a wide range dependent on the
specific type of transition alumina employed, best
results in the alkylation process of the invention are
associated with the use of aluminas having surface
areas in ~cess of about 160 m2/g. Accordingly,
transition aluminas having surface areas above 160 m2/g
are preferred with aluminas having surface areas in the
range of about 200 to about 400 m2/g being most
preferred.
The alumina may be produced in any
appropriate form such as pellet, granules, bead,
sphere, powder, or other shape to facilitate its use in
fixed bed, moving bed, slurry, or fluidized bed
reactors.
TPwis Acids
The catalyst component of this invention
contains one or more Lewis acids in conjunction with
the alumina noted above. A Lewis acid is a molecule
which can form another molecule or an ion by forming a
complex in which it accepts two electrons from a second
molecule or ion. Typical strong Lewis acids include
boron halides such as BF3, BCl3, BBr3, and BI3; antimony
- pentafluoride (SbF5); aluminum halides (AlCl3 and
AlBr3); titanium halides such as TiBr4, TiCl~, and TiCl3;
zirconium tetrachloride (ZrCl4); phosphorus
pentafluoride (PF5); iron halides such as FeCl3 and
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W094/n2243 -14- PCT/U593/06712
FeBr3; and the like. Weaker Lewis acids such as tin,
indium, bismuth, zinc, or mercury halides are also
acceptable. Preferred Lewis~acids are boron contA; n; ng
materials (BF3, Bc13, Bbr3,-~and BI3), SbF5, and AlCl3;
most preferred is BF3.
It is believed that the Lewis acid forms
complexes or surface compounds with the alumina
substrate. In particular, we believe that BF3 strongly
adsorbs in the vicinity of the hydroxyl groups found on
the alumina surface and additionally is physi-sorbed at
the alumina surface.
The total amount of Lewis acid in the alumina
surface is between 0.5% and 40% by weight of the
catalyst dep~n~;~g in large measure on two factors: the
Lewis acid chosen and the susceptibility of the alumina
surface to accepting the Lewis acid by chemisorption or
by physisorption. In the case of BF3, we believe that
5-20% of the weight of the alumina catalyst component
is attributable to BF3 products (e.g., the production
of aluminum fluoroborate or similar compounds) and the
remainder is physi-sorbed BF3. Preferably, the total
amount of BF3 (as BF3 products) added is in ~YC~5 of 7%
by weight of the alumina catalyst component and, most
preferably, from about 10% to about 20% by weight of
the alumina catalyst component.
To maintain the presence of sufficient Lewis
acid on the catalyst composition, we have found it
desirable to maintain at least a minor amount of the
Lewis acid in the proximity of the alumina surface,
preferably in the reaction fluid. This amount is an
amount at least sufficient to maintain the
concentration of the Lewis acid specified above on the
alumina. At the WHSV ranges specified below with
regard to the alkylation reaction, we have found that
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PCT/US93/06712
~ W094/02243 -15-
generally an amount of at least 0.5% of Lewis acid (by
weight based on the hydrocarbon) is suf f icient to
maintain the Lewis acid level on the alumina. For BF3
it is preferred to use BF3 concentrations of about 0.8%
to about 15% (by weight based on hydrocarbon) with BF3
amounts in the range of about l.5% to about 6.0% by
weight being most preferred. On an alumina basis, the
ratio of free Lewis acid (that is, Lewis acid in the
proximity of the alumina but not associated with the
alumina by chemisorption or physisorption) to alumina
is in the range of 0.05 to 30 g Lewis acid/g Al2O3. For
BF3, the preferred range is 0.08 to l0 g BF3/g Al2O3, and
more preferably in the range of 0.l0 to 8 g BF3/g Al2O3.
CatalYst Component Prepa~ation
The catalyst component may be prepared in a
variety of ways including preparation in situ in, e.g.,
an alkylation reactor by passing the Lewis acid in
gaseous form through the vessel cont~;ni~g the
transition alumina. Alternatively, the alumina may be
contacted with the Lewis acid and later ilLLLoduced into
the reactor.
In any case, the alumina may be substantially
dry or anhydrous prior to contact with the Lewis acid
and maintained in a state of dryness, i.e., maintAine~
at a very low free H2O content. The alumina phase
chosen in conjunction with proper treatment of the
alumina to maintain the presence of hydroxyl ~LVU~
(usually by maintaining the alumina at temperatures
below 450C during pretreatment) allows the presence of
about 4-l0 hydroxyl groups per l00 A2 of alumina
surface area. Preferred is 6-l0 hydroxyl groups per
100 A2 of alumina surface area. The alumina is
- preferably completely hydroxylated since that
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W094/02~3 PCT/US93/06712
-16-
hydroxylation, in turn, permits the formation of the
maximum amount of the Al-OH-Lewis acid complex,
believed to be one element of the active alkylation
catalyst at the alumina sur~ace. The alumina may be
partially or substantially dehydroxylated but the
catalyst is not as efficacious.
Alumina, as received from the manufacturer or
exposed to the atmosphere for appreciable periods of
time, picks or adsorbs substantial water. Careful
heating and control of the atmosphere surrounding the
alumina is consequently desirable. Suitably, the
alumina is heated at a temperature below 500C and
preferably at a temperature in the range of about 50C
to about 400C prior to treatment with the Lewis acid.
Additionally, free water (in distinction to
the water which may be identified as hydroxyl groups on
the alumina surface) may be present in limited amounts
in the alumina. The free water content in the alumina
is suitably less than about 15% by weight but
preferably is less than about 8.0% by weight. Most
preferably the free water content of the alumina is
between 0.5 and 6.0% by weight. Higher amounts of
water appear both to degrade the catalyst and to impair
the effectiveness of the catalyst in the practice of
the alkylation reaction. Higher amounts of water also
tend to form compounds, such as BF3 hydrates, which are
corrosive and therefore undesirable.
The use of Lewis acid promoted transition
aluminas having the limited free water content as set
forth above in a process of alkylating lower olefin
with isobutane has several surprising benefits. This
catalyst component or catalyst composition improves the
octane number of the resulting alkylate, t~e p~rcent2ge
of C8 in alkylate, and the effective life of the
catalyst before regeneration. We have not observed
~ 21~0~
W094/02~3 PCT/US93/06712
-17-
these advantages when water is added to the alkylation
process feedstock.
Lewis acid-alumina, contact temperatures
between -25C and less than abou~ 150C are acceptable;
a temperature between -25C and 100C is desirable; a
temperature between -30C and 30C is preferred. The
partial pressure of gaseous Lewis acid added to the
alumina is not particularly important so long as a
sufficient amount of Lewis acid is added to the
alumina. We have found that treatment of the alumina
with BF3 at the noted temperatures will result in an
alumina-BF3 complex contA;n;ng BF3 sufficient to carry
out the alkylation. The alumina contains between 0.5
and 30% by weight of BF3. We have observed that æolid
state boron-nuclear magnetic re~QnAnce (lIB-NMR)
analysis of the catal~st component provides evidence (a
pronounced peak at about -21.27 ppm relative to boric
acid) of tetragonal boron in the catalyst composite
produced at the lower temperatures. Aluminas treated
with BF3 at temperatures of 150C and higher show
spectra which are indicative of the presence of
trigonal symmetry about the boron. We prefer catalysts
in which the relative amounts of trigonal
boron:tetragonal boron (as calculated by the
integration of the respective llB-NMR spectra) are in
the range of 0:1 to 1:1. More preferred is the range
of 0:1 to 0.25:1; most preferred is 0:1 to 0.1:1.
Obviously, the alumina may be inco~o~ated
into a binder prior to its treatment with Lewis acid.
The binders may be clays (such as montmorillonite and
kaolin) or silica hAc~A materials (such as gels or
other gelatinous precipi~ates). Other binder materials
include carbon and metal oxides such as alumina,
silica, titania, zirconia, and mixtures of those metal
oxides. The composition of the binders is not
:
21~03~ ~
W094/02243 PCT/US93/06712
-18-
particularly critical but care must be taken that they
not substantially interfere with the operation of the
alkylation reaction.
The preferred method for incorporating the
catalytic alumina into the bind y is by mixing an
aluminum hydroxide precursor (sùch as boehmite) with
the binder precursor, forming the desired shape, and
calcining at a tPmrPrature which both converts the
aluminum hydroxide precursor into the appropriate
transition phase and causes the binder precursor to
bind the alumina particles. The absolute upper
temperature limit for this calcination is about 1150C.
Temperatures below abou~ 1000C may be ap~o~Liate.
Alkylation Process
The inventive catalyst component and the
allied catalyst composition are especially suitable for
use in alkylation processes involving the contact of an
isoparaffin with an olefin. The catalyst component
should be used in conjunction with an amount of free
Lewis acid.
Specifically, the catalyst system (the
inventive catalyst component in combination with a free
Lewis acid) is active in alkylation reactions at low
temperatures (as low as -30C) as well as at higher
temperatures (nearing 50C). Lower temperatures (-5C
to 15C) are preferred because of the ~nhAnC~ octane
of the alkylate produced and are particularly preferred
if the feedstream contains more than about 1%
isobutylene. Higher temperatures also tend to produce
larger amounts of polymeric materials.
The pressure used in this process may be
between atmospheric pressure and about 750 psig.
Higher pressures within the range allow ~ecovery of
excess reactants by flashing after the product stream
2140~63
W094/02~3 PCT/US93/06712
--19--
leaves the alkylation reactor. The amount of catalyst
used in this process depPn~c upon a wide variety of
disparate variables. Nevertheless, the Weight Hourly
Space Velocity ("WHSV" - weight of olefin feed/hour .
weight of catalyst) may effectively be between 0.1 and
120, especially between 0.5 and 30. The overall molar
ratio of isoparaffin to olefin may be between about 1:1
to 50:1. With recycle reactors the paraffin to olefin
ratio could be substantially higher and could PYcee~
1000:1. The preferred range is between 2:1 to 25:1;
the more preferred range is between 3:1 to 15:1.
The feedstreams intro~llcP~ to the catalyst
are desirably chiefly isoparaffins having from four to
ten carbon atoms and, most preferably, four to six
carbon atoms. Isobutane is most preferred because of
its ability to make high octane alkylate. The olefins
desirably contain from three to twelve and preferably
from three to five carbon atoms, i.e., propylene, cis-
and trans-butene-2, butene-1, and amylene(s).
Preferably, the olefin stream contains little (if any)
isobutylene. Similarly, for the inventive catalysts
the process works better in producing high octane
alkylate if the feedstream contains little or no
butadiene (preferably less than 0.2% to 0.3% molar of
the total olefins) and a minimal amount of isobutylene,
e.g., less than about 2.5% molar based on the olefins.
Although the catalyst alkylates butene-1, it is
preferred to operate with a minimum of butene-l, e.g.,
less than about 10% by mol, since it lowers the octane
values of the resulting alkylate. Of course, if it is
desired to operate a process with high throughput
rather than with highest octane, a higher level of
butene-l is tolerable. An excellent source of a
feedstock containing a low level of isobutylene is the
2~3~3 ~
W094/02~3 PCT/US93/06712
-20-
raffinate from a process which produces methyl-t-
butylether (MTBE).
The water content of the feedstocks may vary
within wide limits, but preferably is at a low level.
The water content should be less than about 200 ppm (by
weight) and most prefera~ly less than about 50 ppm (by
weight). Higher levels of water content tend to lower
the octane value of the resulting alkylate and form
corrosive hydrates or reaction products with the Lewis
acids. Because the sources of most alkylation unit
feedstocks tend to introduce water into those feeds, we
prefer to dry one or more of the feedstocks to achieve
the preferred water content.
The feedstocks should contain a minimum of
oxygenates such as ethers and alcohols. Oxygenates
appear to lessen substantially the effectiveness of the
catalyst system.
The process of this invention includes
increasing the effective catalyst life by con~llcting
the alkylation process with isobutane and lower olefins
using catalyst components and catalyst compositions
having the limited free water content specified above
in the discussion of preparation of the transition
alumina catalyst compound and catalyst composition.
The products of all variations of this
alkylation process typically contain a complex mixture
of highly brAnch~A alkanes. For instance, when using
isobutane as the alkane and n-butylene as the olefin, a
mixture of 2,2,3-; 2,2,4-; 2,3,3-; and 2,3,4-
trimethylpentane (TMP) will result often with minor
amounts of other isomeric or polymeric products. ~he
2,3,4-TMP isomer is the lowest octane isomer of the
noted set. The 2,2,3- and 2,2,4-TMP isomers are higher
octane components. Calculated average octane values
(the average of the Research Octane Number (RON) and
21~03~
W094/02~3 PCT/US93/06712
-21-
the Motor Octane Number (MON), as denoted by (R + M)/2)of the various C8 isomers are:
-
Isomer Octane (R + M)/2
2,2,3- 104.8
2,2,4- 100.0
2,3,3- 102.8
2,3,4- 99.3
The process may be carried out in the liquid,
vapor, or mixed liquid and vapor phase. Liquid phase
operation is preferred.
The invention has been disclosed by direct
description. Below may be found a number of examples
showing various aspects of the invention. The examples
are only examples of the invention and are not to be
used to limit the scope of the invention in any way.
EXAMPLES
Example 1
CatalYst Testinq
This example shows the preparation of a
number of alumina-based catalysts in situ and their
subsequent use in an alkylation reaction using model
feeds. It is used to evaluate catalyst activity and
selectivity.
The alumina samples were dried at 110C
overnight and charged to a semi-batch reactor having an
internal volume of about 500 cc. The reactor
temperature was controllable over the range of -50C to
40C. For initial catalyst treatment, the reactor
contA; n; ng the catalyst was purged with an inert gas
and cooled to about 0C. About 275 cc of isobutane was
21403~9 ' : ~
W094/02~3 PCT/US93/06712
-22-
added to the reactor. After a brief degassing, BF3 was
added batchwise. After BF3 is added, the temperature
of the reactor rises and the pressure typically drops
as the alumina adsorbs or reacts with the BF3.
Additional infusions of BF3 are made until the pressure
in the reactor no longer drops. The BF3 saturation
equilibrium pressure was about 40 psig. The liquid
phase concentration of BF3 was about 1.5%. At that
point the alumina had adsorbed or reacted with all of
the BF3 possible at that temperature and the catalyst
was in its most active form.
A 4/1 molar mixture of isobutane and trans-2-
butene was added to the reactor at a WHSV of 3.5 until
the paraffin to olefin ratio reached 25.
The product alkylate was then removed from
the reactor vessel and analyzed using gas-liquid
chromatography.
The results of those runs are shown in Table
1.
Table 1
~C~ in
Alumina TYpeSurface Area Alkylate
Product
gamma 180 m2/gm 95.4
gamma 116 m2/gm 82.07
delta 118 m2/gm 94.3
pseudoboehmite352 m2/gm 74.2
bayerite 40 m2/gm 69.1
pseudoboehmite250 m2/gm 59.6
boehmite 150 m2/gm 59.8
It is clear from these pr~l iri~ry scre~ning
data that the transition ~gamma and delta) aluminas
produce significantly higher percentages of C8 in the
product alkylate than do the other aluminum hydroxide
2~.~036g~
W094/02243 PCT/US93/06712
-23-
catalysts. The result did not appear to correlate to
the specific surface area of the catalyst.
~Ample 2
Catalyst Screening
This example compares the performance of eta-
alumina (a preferred form of the inventive catalyst)
with representative samples of other acidic oxides each
combined with BF3 for the reaction of isobutane with
butylenes to produce alkylate.
The eta-alumina sample was prepared by a
controlled thermal treatment of bayerite (Versal B from
LaRoche Chemical) for 15 hours at 250C and 24 hours at
500OC under a N2 atmosphere.
The comparative oxidic materials were:
silica-alumina, synthetic mordenite zeolite, and fumed
silica. The silica-alumina (obtained from Davison
Chemical) contAine~ 86.5~ sio2 and had a surface area
of 392 m2/gm. It was used without further treatment.
The mordenite was a hydrogen form zeolite and
was obtained from Toyo Soda. It was prepared from Na-
mordenite and subjected to ion exchange, steam
treatment, and calcination to achieve a Si/Al ratio of
28:1.
Each of the samples was dried at 110C
overnight and introduced into the semi-batch reactor
described in Example 1. The samples were purged with a
dry inert gas and cooled to 0C. Isobutane was added
to the reactor to an initial volume of 100 cc. BF3 was
added with stirring until an equilibrium pressure of 30
psig was obtained.
A mixture of isobutane/t-2-butene was fed to
the reactor. At the completion of the reaction,
alkylate was removed and analyzed by gas-liquid
chromatography. The RON were calculated from the gas-
-
214~3.~
W094/02243 PCT/US93/06712
-24-
liquid chromatography data using the well-known
correlations in Hutson and Logan, "Estimate Alky Yield
and Quality", Hydrocarbon Processing, September, 1975,
pp. 107-108. The summary of the experiments and
results is shown in the following Table 2:
~ 21~36b
WO 94/02243 PCI'/US93/06712
--25--
Oa~ D~ O _I
. . -
O ~ O~ O ~ O
_I
a~
5 0 r a~ ~ o ~ ~ o , a~ o o
d ~ ~ O O In ~ co ~ o ,i ~i ~ o
d
Cl
1` C~ O ~ t~l CO O N 1
I ~ ~ o o ~ ~ ~ o o ~ u~ a~ ~i _i
~ ~ ~ o
r
Q
~ n ~1 l` ~ o o ~ a~
E~ .. . . . . . . .. . .
2 n C~ ~ ~ o t~ o ~ 1~ ~1
V _ 0~ ~ ~ o ~ ~ a~ a~
d
IY
2 5 -- ~,
tJ` C ~: -- C 3
,, ~ æ a~
~ U~ ~ r ,~
~ G
c L., ~ _ L 1 ~J r = c
u u ~ c c- ~ o ~ a z ~ .
U E~ O
21~36g.".~
W094/02243 PCT/US93/06712
-26-
Clearly, for the eta-alumina catalyst, the
yield of C8's was significantly higher; the overall
yield and RON were much better.
~m~le 3
This example shows that the addition of
either water or methanol produces no appreciable
improvement on the alkylation of butene-2 with
isobutane using the inventive alumina catalyst.
Indeed, water and methanol appear to be detrimental.
Three separate semi-batch reactors were dried
and flushed with nitrogen. A sample of 2.5 gm of a
gamma-alumina (LaRoche VGL) was loaded into each
bottle. The alumina samples had been previously dried
at 110C overnight. An amount of 0.278 gms of
deionized water was added dropwise to one reactor. An
amount of 0.988 gms of methanol was added to another
reactor. These amounts were calculated to be 10% of
the catalyst plus water equivalent. The rem~; n; n~
reactor was used as a control reactor. Isobutane (246
cc) was added to each bottle; BF3 was added (with
stirring) until the pressure reached a constant 30
psig. A feedstock of isobutane and 2-butene was
continuously added in a ratio of 2:1 and at a rate of
1.6 cc/minute. The reaction continued for about 75
minutes after which samples of the reactor liquids were
removed and analyzed using a gas-liquid chromatograph.
The conversion of olefin was more than 99% in each
case. Other reaction conditions and a summary of
reaction results are shown in Table 3:
21~0369 `` i
WO 94/02243 PCI'/us93/06712
--27--
O o o ~
~, ..
.¢
~ d~
~ ~ o ~
OU~ I O
;~ . . . . . .. .
oou~ o ~a~ ~o~ ~OD
,.
Q d ~., ~ ~ d~ ~
~- ~ O ~ ~ t~ O ~'7
E- ~ I~ ~ o 01
'I ~ ~1 a~ a~ o a~
-
C~
o
-
Q~
U
C
~ ~5
.
.,1 ) ~
~, ,1 _
U~ ~Q
0 3 ~ 3
C O
~ ~ ~n, 3 ~ ~ ~ v ~ ~
0 ~ ~ _ S'~ IV~ OD ~ ~ O ~
4 ~ 4 V C.) C.) ~ ~ p; _
2 1 ~ 036 9 i ; i i ~ ~ ~
W094/02243 PCT/US93/06712
-28-
It is clear that neither water nor methanol
created any advantage in the operation of the process
in producing a gasoline alkylate. The gross amounts of
C8 pro~llc~ were smaller than for the inventive
alumina; the amount of undesirable C,2+ were two to four
times higher than for the inventive alumina. The
yields were lower and, probably most importantly, the
octane values of the comparative products were
significantly lower.
T~Y~mple 4
This example shows the suitability of the
inventive catalyst (gamma-alumina, T~T~och~ GL) for a
variety of olefin feedstocks. The following reaction
conditions were used for the test series:
Temperature 0C
Total pressure 30 psig
WHSV 4
2 A semi-batch reactor was utilized in each run.
The olefin feedstocks were mixtures which
were chosen to allow us to identify desirable and
undesirable combinations of feed materials. The
mixtures are shown in Table 4:
21~0389
--WO 94/02243 PCI/US93/06712
--29--
o 1,1~
U
X ~ o ~ ~ o ~ o o
~ a
~ ~
~r 0
U
ll o o o ~ u~
c~ N N N N O O O O
c,~ Irt O O Ul In o o
E~l I N N ~1 _I N N _I ~i
~
U In o ~ o ~ o ~ o
N _I N ~I N _~ N ~
z
~i N ~ ~ In ~O t` CD
3 0 ~:
21~L03~9
W094/02243 PCT/US93/06712 -
-30-
The products made were analyzed using gas-
liquid chromatography and their respective octane
numbers are shown in Table 5:
. .
~ 214036~
WO 94/02243 PCI'/US93/06712
--31--
~ o OD a~ o ,i
Z ' ~ ~ a~
~o ~o oo o a~ a~ N
+ ~ a~ ~ o ~ ~ ~
_ , ~ o t~ t~ ~ ~
S
2 0 o a'
2 5 C) ,, U~ ts) ~ o ,~
.
.
z
0
X
'~:
21~0~
W094/02~3 PCT/US93/06712 -
-32-
This data shows that increa es in isobutene and
propylene feed concentrations directionally cause the
inventive alkylation process to produce lower alkylate
C8 content. As shown in Figu~é,2, smaller amounts of
either C3- or i- C4~ cause no more harm to alkylate
quality but are generally undesirable if extremely high
octane alkylates are nececc~ry.
~x~m~le 5
This example demonstrates the performance of
the transition alumina/BF3 catalysts in reacting
isobutane with butenes to form high octane product
under conditions of high space velocity and low
paraffin/olefin feed ratios.
A sample of gamma-alumina (VGL, LaRoche) was
dried overnight at 110C and loaded into the semi-
continuous reactor unit described in Example 1. The
catalyst was purged with dry inert gas and cooled to
ooc. Isobutane was added to the reactor and then the
system was exposed to BF3 under stirring conditions
until an equilibrium pressure of 30 psig was achieved.
A feed comprising pure trans-2-butene was then pumped
into the reactor under vigorous stirring conditions
over a period of 60 minutes; samples were obt~i n~
periodically during the run (at 30 and 60 minutes).
The results are summarized in Table 6 below:
2 1 ~
W094/02~3 PCT/US93/06712
-33-
Table 6
Catalyst charge (g) 2.5
Temperature (C) 0
i-C4 initial charge (ml) 300
Olefin feed Trans-2-butene
Space velocity (WHSV) 26.4
Run time (minutes) 30 60
Equivalent external i-C4/C4 5.4 2.6
Butene conversion (%) 100 100
Product analysis (weight %):
C5-C7 3.2 4.7
C8 saturates 91.1 81.9
0 C9+ 5.7 13.4
TMP/C8 total (%) 97.6 96.6
RON 99.0 96.8
Octane, R+M/2 97.0 95.3
~m~le 6
This example shows the utility of the
catalyst system on a feed obt~ine~ from a refinery MTBE
unit. The feed, containing minor amounts of butadiene
and isobutene, was introduced into a bed of a
commercial hydroisomerization catalyst (0.3% Pd on
Al2O3) at 400 cc/hr, 80C, and 350 psig along with 14
sccm H2. The molar ratio of H2:butadiene was 6:1. The
thusly treated feed, cont~ g no butadiene and 0.52 %
(molar) of isobutene, was mixed with an appropriate
amount of isobutane. The mixture had an approximate
composition as shown in Table 7 below:
21~0~9
W094/02~3 PCT/US93/06712
-34-
Table 7
ComPonent ~; mole %
propylene ,;~ 0.02
propane 0.13
isobutane 80.14
isobutene 0.52
1-butene 0.75
butadiene ---
n-butane 3.84
t-butene-2 8.23
c-butene-2 4.05
3-methyl-1-butene 0.01
isopentane 1.73
1-pentene 0.01
2-methyl-1-butene 0.03
n-pentane 0.08
t-2-pentene 0.18
c-2-pentene 0.06
2-methyl-2-butene 0.23
This mixture had an isoparaffin to olefin
ratio of 5.8:1 and an isobutane/olefin ratio of 5.7:1.
The mixture was then admitted to a pair of
continuous laboratory reactors each con~in;ng 280 cc
of liquid and con~in;ng 5.04 g of catalyst. The
temperature was maint~;ne~ at 0F. The WHSV for the
reactor was 4.3 hr-l and the LHSV was 1.07 hr~~. The
catalyst was a gamma alumina (~o~he VGL) and was
prepared by adding the proper amount to the reactors
along with a small amount of isobutane, pressuring the
reactor to about 40 psig of BF3, and maint~;n;ng that
pressure for the duration of the test. The test
was run for 41 hours total time. The catalyst was
regenerated four times during the run by rinsing the
catalyst in 200cc of trimethyl pentane, heating to
150C in air for 45 minutes to volatilize a portion of
the reaction product on the catalyst, and heating the
catalyst to 600C in air for 60 minutes to oxidize the
remaining hydrocarbonaceous materials. Small amounts
of the catalyst were added as necesC~ry with the
21~0359
W094/02243 PCT/US93/06712
-35-
regenerated catalyst to restore the catalyst to its
proper amount upon return to the reactor (0.41 g @
cycle 2, 0.97 g @ cycle 3, 0.0 g @ cycle 4, and 0.47 g
~ cycle 5). About 4.5 liters (3.2 kg) of stripped Cs+
alkylate was collected having about 7.6% C~7, 81.2% C8,
4.4% C~ll, and 6.8% Cl2 (all by weight). Using the
Hutson method disc~ P~ above, the octanes were
calculated to be: RON = 96.6, MON = 93.3, and the
(R+M)/2 = 94.95. The product was then engine-tested
using API methodology and the octanes were measured to
be: RON = 98.7, MON = 93.85. The resulting (R+M)/2 =
96.28. The Hutson method clearly underestimated the
RON octane values for this process.
T~YAmple 7
This example shows the preparation of a
number of BF3/alumina-based catalyst components. One
is made in accord with this invention and three are
comparative samples. Each of the samples was then
tested in an alkylation reaction using model feeds and
isobutane and butenes.
All four gamma-alumina samples (TARo~hP-
Versal GL) were infused with BF3 in a Cahn hAl~nce.
Use of a Cahn hAl~nc~ allowed close control of the
temperature at which the alumina contacted the BF3 and
further allowed the weight gain to be measured during
the treatment. The four samples were treated with BF3
respectively at 25C, 150C, 250C, and 350C. A
sample of each of the catalyst components was removed
and analyzed using llB- MAS-NMR. The results of these
analyses are shown in the figures: Figure lA shows the
treated alumina at 25C; Figures lB, lC, and lD show
the respective da~a from the 150C, 250C, and 350C
treated alllm; n~ . In Figure lA, there is a pronounced
21~3~
W094/02243 PCT/US93/06712
-36-
sharp peak at about -21.27 ppm (relative to boric acid)
suggesting significant tetragonal boron content. The
other three NMR plots do not show such a sharp peak.
Instead, the data suggest the presence of substantial
trigonal boron.
The four gamma-alumi,n,a~samples (LaRoche-
Versal GL) were then charged to a semi-batch reactor
having an internal volume of about 500 cc. The reactor
temperature was controllable over the range of -5C to
40C. For initial catalyst treatment, the reactor
cont~ining the catalyst was purged with an inert gas
and cooled to about 0C. About 275 cc of isobutane
were added to the reactor. After a brief degassing,
BF3 was added batchwise. Additional infusions of BF3
are made until the pressure in the reactor no longer
drops. The BF3 saturation equilibrium pressure was
about 40 psig. The liquid phase concentration of BF3
was about 1.5%.
A mixture of isobutane/trans-2-butene was fed
to the reactor. At the completion of the reaction,
alkylate was removed and analyzed by gas-liquid
chromatography. The RON's were calculated from the
gas-liquid chromatography data using the well-known
correlations in Hutson and Logan, "Estimate Alky Yield
and Quality", Hydrocarbon Processing, September, 1975,
pp. 107-108. The summary of the experiments and
results is shown in Tables 8 and 9 below:
2~03~9
WO 94/02243 PCr/US93/06712
--37--
c; _I ~ o
O ~ a~ ~D
O ~ 0 ~ 1~
o _1
~1 ~ _I
O ~ a~
1 0 ~ ~ ,i o o ~ 0 ~ u~
~o o_I
,~ ~ In
o O ~ a~
~ O O ~ 0~O In
.~ ,~ ~ ~ o ~1
u
a~
oo ~ ,~ qo ~o
~ r 0
_I ~ ~ o o u~
.4 ~ ~ ~ ~D O_I
E~ )
o
~ u
2 5 z
D~ J ~ ;~ _
c a c~ t)
~ ~ U ~cn
H H ~1 3
w w ~
Table 9
Product Summary c~
Rample No. 1 2 3 ~ c~
Total alkylate 27.63% 19.97% 11.48% 5.62%
Butene conversion 100.0% 86.15% 69.09% 67.03%
Cs7 hydrocarbon 1.51% 2.53% 2.55% 0.83%
C8 hydrocarbon 93.33% 87.58% 85.14% 70.56%
C9 ll hydrocarbon 0.49% 3.12% 6.45% 13.90%
Cl2+ hydrocarbon 4.67% 6.77% 5.86~ 14.72%
TMP/C8 97.54% 98.27% 96.70% 97.55% w
Yield (w/w) 1.94 1.40 0.80 0.39 -
RON 99.26 98.09 97.57 92.23
MON 94.88 93.73 93.16 90.07
(R + M)/2 97.07 95.91 95.36 91.15
2,2,4/2,3,4 0.81 0.54 0.48 0.33
21~0~
W094/02~3 PCT/US93/06712
It is ~lear from the data that the catalyst component
treated with BF3 at the lower temperature is superior
in operation in most practical aspects (conversion, C8
production, alkylate yield, RON, MON, etc.) than the
other materials.
F~mple 8
This example compares the results of a
variety of catalyst components and compositions
(comprising a transition alumina and BF3 and a variety
of water contents) when used in an alkylation process.
The intent was to compare the water content--whether
the water was in the form of surface hydroxyl content
or in the form of "free" or surface-adsorbed water--in
the catalyst to the octane number and C~ content of the
resulting alkylate.
A large batch of commercial alumina (LaRoche-
V-GL-Versal-250- a gamma alumina apparently made by
calcination of pseudo-boehmite) was transferred from
the as-received can into glass evaporating dishes. The
glass evaporating dishes are maintained in a drying
oven at 110C.
This alumina is believed to be fully
hydroxylated as it is received from LaRoche. By "fully
hydroxylated" is meant that substantially each surface
octahedral aluminum is terminated by an "-OH" group.
In addition, there likely is some surface bound H2O (or
"free water" as was ~iccl~ssed above) dep~n~;ng upon
the temperature, relative humidity, and h~n~l ing
history of the material.
We determined the temperature at which the
surface water was removed (without substantial
dehydroxylationj by placing an alumina sample taken
from the drying oven in a Fourier Transform Infra-Red
(FTIR) analyzer and made a series of scans at
214036~
W094/02~3 PCT/US93/06712
-40-
,~.
progressively higher temperatures (25C, 80C, 125C,
175C, and 225C) under a dry helium purge stream.
By following the progression of the H-O-H
h~n~i~g band of line A in Figure 3 at 1640 cm~', it may
be observed that dehydration is essentially complete
between 175C and 225C. Although some small amount of
dehydroxylation likely would occur as a result of the
rise to this temperature, to a good approximation, the
loss in weight occurring up to 200C is equal to the
amount of surface bound or "free" water on the surface
of the alumina sample.
Samples of the alumina were then subjected to
treatment with water vapor so to load specific amounts
of water onto the alumina surface. This was done by
placing the alumina samples in a closed vessel with
distilled water held at a specific temperature. The
liquid water was not placed in contact with the alumina
but instead was susp~n~e~ in the vessel creating an
atmosphere cont~ining water in equilibrium at the
chosen temperature. The samples were held in the
vessel for two hours each to allow equilibration
between the alumina and the water vapor. The
temperatures of treatment were variously at 0C, 18C,
and 30C. These three samples and a sample taken
directly from the drying oven were each placed in a
microbalance boat and the weight loss to 200C
determined.
In addition, each of the samples was heated
in the microbalance to 1075C, a temperature at which
substantially complete hydroxylation is achieved. At
temperatures above about 200C, the samples continue to
lose weight. This is thought to be due to the
condensation of Al-OH to form HzC, Al+, alld O~.
The results of these runs are shown in Table
10 below:
21~g3~
WO 94/02243 -4 1- PCI~/US93/06712
N ~ ~ i O O O ~
~ X
O
0 ~D O ~1 ~O
oooooo
o
O ~
--I ~It~U~ I OOOOOO
~J o
,r P~
E~
o~ ov V
O OD O
O O O ~
U U V C~ ov
O ., c~ O ., c ,~ In
o~ o~ o~ ~~
.
W094/02243 2 ~ 3 ~ g -42- PCT/US93/06712 -
Several catalyst samples, after treatment
with the temperature and water vapor treatments
specified above, were then subjected to an alkylation
reaction to check the cv~ L eOpondence between the
products proA~lc~ and the respective water contents.
Care was taken to prevent evaporative water
from being introduced into the catalyst. The seven
catalysts contained: 18% ~0, 6% H2O, 3% H2O (i.e.,
after removal from drying oven), fully dehydrated at
2.1 meq Al-OH/gm (after 200C pretreatment).
The alkylation reaction utilized a model feed
of isobutane and mixed butenes (I/O=6:1; where the
butenes were trans-2-butene=94%, 1-butene=5~, and
isobutene=1%). The feed had been twice dried using
freshly regenerated 3A zeolite beds to lower the water
content of the feed to less than 10 ppm. Commercial
C~'s purchased from vendors typically contain 20-40 ppm
of H2O. The BF3 co~s~ntration was held at about 1.8
wt.% of the total liquid weight. The reaction pressure
was 45 psig; residence time was 56 minutes; the
catalyst concentration was 1.5%; and the reaction
temperature was 0C.
The results of these runs are shown in
Figures 4A and 4B. The catalyst having full
hydroxylation and 3% free (or surface) water clearly is
superior both in %C8 produced and in the octane of the
resulting alkylate.
~mple 9
This example shows the interrelated effects
of water BF3/transition alumina catalysts on the age of
that catalyst and C8's in alkylate product.
In thi example, four cataiysts h~ on the
transition alumina utilized in Example 8 (gamma-phase
alumina - LaRoche VGL) were treated also as ~;~C11RSe~
21~0~
W094/02~3 PCT/US93/0671
-43-
in Example 8 to produce aluminas having 1 to 1.5% H2O,
3~ H2O, and 7% H2O (two batches).
The reactor was a Hastelloy autoclave
operated in CSTR mode, with continuous addition of
feed and BF3 and with continuous withdrawal of
product alkylate along with isobutane and BF3. The
feed was treated both with 3A and 13X mol~c~ r
sieves to remove water and other impurities.
Each of the catalysts was used in an
alkylation process operated in the following procedure:
The alumina was loaded into a tube and
pretreated with humidified nitrogen at a temperature
necessary to achieve a desired water content in the
alumina. At the start-up of the CSTR reactor, an
equilibrium mixture of isobutane and alkylate was
cooled to 0C and pressurized with BF3 to 50 pounds
pressure (gauge). The pretreated alumina was
introduced into the reactor through a port using liquid
isobutane to carry the alumina. The reaction was
initiated by introducing the 6:1 isobutene/olefin feed
derived from a hydroisomerized MTBE raffinate. The
olefin composition was:
butene-2 92.0%
butene-1 4.8%
isobutene 3.2%
The reaction conditions were: 0C, 3%
catalyst slurry co~cDntration and a WHSV of 8.7 to 9.
Samples were taken at several times
throughout the course of the reaction. The reaction
was run until a clear pattern of deactivation was
cbserved.
As is shown in Figure 5, the catalyst
cont~;ning 3% H2O maintained its ability to produce C8's
~14~36~
W094/02243 PCT/US93/06712
-44-
for a much longer period of time or catalyst age. In a
qualitative side, the optimization of moisture content
of the catalyst produced an alkylate having a specific
C8 content for about 50% longer~than catalysts
cont~in;ng either l.5% or 7S H2O.
It should be clear that one having ordinary
skill in this art would envision equivalents to the
processes found in the claims that follow and that
these equivalents would be within the scope and spirit
of the claimed invention.
