Note: Descriptions are shown in the official language in which they were submitted.
i~9339
TWO STAGE PROCESS FOR CATALYTIC CONVERSION OF
OLEFINS TO HIGHER HYDROCARBONS
TECHNICAL FIELD
This invention relates to a method of
catalytically converting olefins into higher hydro-
carbons. This invention more particularly relates to
a method for converting feedstocks containing
ethylene and C3~ olefins to higher hydrocarbons by
contact with siliceous crystalline molecular sieves.
BACKGROUND ART
Conversion of various hydrocarbon fractions
with acidic catalysts generally and more particularly
~ith siliceous crystalline molecular sieves is well
known in the art. The conversions for which such
catalysts have been used include cracking, isomeriza-
tion, hydrocracking, etc. Molecular sieves have also
been used for the conversion of hydrocarbon feeds
consisting essentially of C2-C5 olefins, mixtures
thereof, and mixtures thereof with paraffins to
higher mol~cular weight products.
U.S. Patent 3,325,465 teaches a process for
polymerizing olefinic hydrocarbons over zeolites, the
initially present cations of which have been
partially exchanged with cations selected Erom the
group consisting Co,Ni and rare earth cations.
Ethylene polymerization at atmospheric pressure is
described in Examples 3~8 of the paten~. At column
6, lines 41-47, the patent teaches that use of atmos-
pheric pressure is preferred, although pressures up
to 1000 atmospheres may be used. Higher pressures
are said to increase throughput but increase the risk
of catalyst cleactivation. Operating temperatures oE
25 to 400C and space velocities of 50 to 1000 hr.-l
VHSV (volume hourly space velocity), preferably less
~;9339
than 300 hr.~l VHSV, are taught. Hydrocar~on
diluents such as para~ins and/or cycloparaffins may
be present in the olefinic feedstoc~, but the patent
does not indicate what efect such presence may have
on selection of operating par~meters for the process.
U.S. Patent 3,760,024 teaches preparation
o~ aromatic compounds by contacting Cz-C4 paraffins
and/or olefins with a ZS~-5 type zeolite. Operating
temperatures of 100-700C, ooerating pressuras of
0-1000 psig ~preferably 0-500 psig), and s~ace
velocities of 0~5-40 hr.~l W~SV (weight hourly space
velocity) are taught. The particular combination of
operating parameters employed is selected to producs
a significant yield of liquid product from a given
feedstoc~, which product is substantially aromatic in
nature.
U.S. P~tsnt 3,827,968 discloses an aromati-
zation process wherein the olefin content of a C2-Cs
olefincontaining feed is first oligomerized to
produce higher molecular weight olefins over a ZS~I-5
type zeolite and then contacting the liquid, higher
molecular oleflns with a zeolite catalyst in a second
stage to produce aromatic liquids. The first step of
the '968 proc~ss differs from the '024 patent in that
less severe operating conditions are used to produce
a product having a liquid portion consisting princi-
pally of Cs-Cg olefins. Attempting direct aromatiza-
tion of certain fesdstoc~s--~specially those contain-
ing large amounts of paraffins--~as apparsntly found
to cause rapid catalyst aging and/or deactivation.
Operating conditions employed in the first step of
the '968 patent include temperatures of 290-450C,
pressures up to 800 psig and 0.5-50 hr.~l r.~SV. The
first stage oligomerization e~fluent, in addition to
. j
.,~.~, ~,,
* Trade Mark
~ S.~3~
olefinic liquids, contains a gas product consisting
of a highly paraffinic C4- stream. In addition, the
second stage o~ the '968 process produces an effluent
which may contain up to 50~ C4- paraffins. The C4-
paraffin streams are, according to the '968 patent,
preferably recycled to a pyrolysis unit.
U.S. Patent 3,960,978 discloses the conve~-
sion of gaseous C2-C5 olefins, either alone or in
admixture with paraffins, to a gasoline fraction
having no more than about 20 wt. % aromatics by con-
tacting the olefin feed with a ZSM-5 type zeolite
having a controlled acid activity (i.e., alpha value)
of about 0.1-120. Other oligomerization conditions
include temperatures of 260-480C ~preferably 290-
]5 450C), WHSV of 0.1-25 hr.~l (preferably 0.5-20), and
hydrocarbon partial pressures of ~.5 to 40 atmos-
pheres (preferably 0.5-20 atmospheres). An advantage
of the process is said to be improved catalyst
stability~ Example 1 of the patent shows oligomeriz-
ation of propylene according to the method of the
'378 patent. The gaseous product produced was
primarily ~4 olefins. The patent suggests recycle of
the gaseous C4 olefin byproduct to extinction.
U.S. Patent 3,972,832 discloses conversion
of aliphatic compounds over phosphorus-containing
zeolites. Example 8 of the patent shows that when
ethylene is contacted with the phosphorus-containing
zeolite at 500C and a r~HSV of about 1.5, ethylene is
converted into propylene and Cs hydrocarbons as the
major products. As compared to a zeolite without
phosphorus, the olefin/paraffin ratios of the product
obtained over the phosphorus-containing zeolite were
much higher and the quantity of aromatics produced
much less. Also see U.S. Patent 4,044,065 at column
.
~Z~9339
9, lines 32-48.
U.S. Patent 4 ,021,502 discloses the conver-
sion of gasesous C2-C; olefins or mixtures thereof
with Cl-C5 paraffins to higher molecular weight
olefins, over ZSL~-4, ZS~-12, ZS~-18, chabazate or
zeolite be a~ The process is operated under condi-
tions selected to give low yields of aromatics.
Te.mperatures are a~out 230-650C (preferably 290-
5aooC)~ WHSV is about 0.2-50 (preferably 1-25).
Hydrocarbon partial pressures are about O.l-5n atmos-
pheres (prefera~ly 0.3-20 atmospheres). An advantage
of the process is said to be the stability of the
zeolite under the conditions employed.
U.S. Patent 4,070,411 discloses the conver-
sion of lower olefins (e.g., ethylene or propylene)
over HZSL~-11 catalyst to produce a product having a
significant isobutane content. The conversion is
effected at temperatures of 300-500~C and at space
velocities of 0.5-100 '.~SV.
9~ U.S. Patent 4,100,218 discloses a process
for converting ethane to LPG and gasoline and/or
aromatic concentrate by passing olefin effluent from
the thermal cracking of ethane over a ZS-~-S type
zeolite.
2~ U.S. Patent 4 ,150 ,062 discloses the conver-
sion of C2-C~ olefins over ZS.~-5 type zeolites in the
presence of co-fed water. Temperatures are about
230-430C ~pref~aDly 290-400C). Press~res range
from atmospheric to 1000 psig preferaoly fr,m atmos-
pheric to 450 psig). The ~S~ is
about 0.2-20 hr.-l.
U.S. Patent 4,211,6~0 teaches conversion of
olefinic gasoline Lractions over ZSLI-~ type zeolit-s
to produce gasoline (having enhanced gum sta~ilit~)
~ * Trade Mark
~5~33~
and fuel oil.
U.S. Patent 4,227,992 discloses a process
for selectively reacting C3 and higher olefins from a
mixture of the same with ethylene to produce products
comprising fuel oil and gasoline. ~perating condi-
tions are selected such that the C3 and higher
olefins are substantially converted to products com-
prising fuel oil and gasoline but such that substan-
tially no ethylene will be converted. Generally,
operating pressures are within the range of about
100-1000 psig, temperatures are within the range of
about 150-315C, and space velocities are within the
range of about 0.1-10 WHSV (based on the C3 and
higher olefins).
U.S. Patent 4,451,685 teaches conversion of
lower olefins to gasoline blending stocks over boro-
silicate catalysts~
U.S. Patent 4,423,268 teaches oligomeriza-
tion of normally gaseous olefins over essentially
alumina-free molecular sieves (e.g., silicalite).
As noted, conversion of oleEins to gasoline
and/or distillate products over a ZSM-5 type catalyst
is known. See the description of U.S. Patent Nos.
3,960,978 and 4,021,502, supra. U.S. Patent
4,227,992 discloses operating conditions for selec-
tive conversion of C3-~ olefins and no more than 20%
ethylene converslon. Closely related is U.S. Patent
4,150,062 which discloses a process of converting
olefins to gasoline components. In such processes
for oligomerizing olefins using acidic crystalline
zeolites, it is known that process conditions may be
varied to favor the formation of either gasoline or
distillate range products, At moderate temperatures
(i.e., 190-315C) and relatively high pressures
J~ZS~339
(i.e,, 42-70 atmospheres) the conversion conditions
favor distillate range product having a normal point
of at least 165C. At moderate temperature and
relatively lower pressures (i.e., 7-42 atmospheres),
the conversion conditions favor gasoline and distil
late range products. See U,S. Patent 4,211,640,
supra. The distillate mode conditions do not convert
a major fraction of ethylene. At hiyher temperatures
(i.e., 285-370C) and moderate pressures (i~e., 4-30
atmospheres) the conversion conditions favGr produc-
tion of an olefinic gasoline comprising hexane,
heptene~ octene and other C6+ hydrocarbons in good
yield. The gasoline mode conditions convert a major
fraction of ethylene,
U.S. Patent 4,433,185 discloses a process
for converting an olefinic feedstock containing
ethylene and C3+ olefins to produce a heavier hydro-
carbon product rich in distillate by contacting the
feedstock with an oligornerization catalyst bed at
elevated pressure and temperature conditions in an
operating mode favorable to the formation of heavy
distillate product by selective conversion of C3+
alkenes. The distillate mode e~fluent stream
contains substantially unconverted ethylene which is
recovered from -the distillate mode effluent stream
and further converted to olefinic gasoline in a
second oligomerization catalyst bed at reduced
moderate pressure and elevated temperature conditions
in an operating mode favorable to the formation of
C6~ olefinic gasoline. At least a portion of the
olefinic gasoline is recycled for conversion with the
feedstock in the distillate mode catalyst bed.
U.S. Patent 4,414,423 discloses a process
for preparing high boiling hydrocarbons from normally
33~
gaseous olefins which comprising contacting a feed
comprising normally gaseous olefins with an interme-
diate pore size siliceous crystalline molecular sieve
to produce a first effluent comprising normally
liquid olefins and contacting at least a part of the
normally liquid olefins contained in the first
effluent with a second catalyst comprising an inter-
mediate pore size siliceous molecular sieve under
oligomerization conditions to produce a second
effluent comprising oligomers of the normally liquid
olefins and wherein at least some of said oligomers
are liquids under the oligomerization conditions.
One object of the present invention is an
improved method for converting ethylene and C3~
olefins to high yields o~ heavier hydrocarbons. A
more particular object is the production of high
yields of normally liquid hydrocarbons from such a
feedstock, employing a siliceous crystalline mole-
cular sieve catalyst which is relatively stable under
the conditions employed. other objects, aspects and
the several advantages of the presen~ invention will
be apparent to those skilled in the art upon consi-
deration of the following description of this inven-
tion and of the appended claims.
DISCLOSURE OF THE INVENTION
In accordance with the present invention
there is provided a process for producing normally
liquid hydrocarbons which process comprises: contac-
ting a feedstock containing ethylene and C3~ olefins
in a first catalyst reactor z~ne with a siliceous
crystalline molecular sieve at elevated temperature
and relatively low ethylene partial pressures under
conditions which maximize: (1) ethylene conversion
and (2~ selectivity to propylene, butylenes, and
~2S~33~
normally liquid C5~ hydrocar~ons; separating the
first reactor zone effluent to form at least one
normally liquid C5+ hydrocarbon fraction and at least
one fraction comprising C3-C4 olefins; and contacting
said C3-C~ olefinic Eraction in a second reactor zone
with a siliceous crystalline molecular sieve at
moderate temperature under conditions favorable for
conversion oE C3-C4 olefins to a second reactor
effluent stream rich in heavier hydrocarbons in the
gasoline or distillate boiling range.
In addition to lower olefins, the hydro-
carbon feed may contain other hydrocarbons such as
paraffins (e.g., methane and higher alkanes) as well
as inorganic components such as water, COx and N2.
In such an embodiment of this invention, it has been
further found desirable to maintain the pressure in
the second reactor zone such that the ethylene
partial pressure in the feed contacted with the
catalyst in that zone is maintained within the ran~e
of about 0.5 to 5 atmospheres.
Oligomerization of olefins according to the
method of this invention has been found to allow the
catalyst activity to be maintained at a relatively
stable level for extended periods of time. Further-
more, the oligomerization process is capable of
quantitative conversions of gaseous C2+ olefins to
liquid hydrocarbon products with minimal recovery and
recycle of process streams to the oligomerization
reactors.
BRIEF DESCRIPTION OF THE FIGURES
Figure 1 is a plot of results of run time
vs. productivity for catalysts prepared in accordance
with Examples I and II.
Figure 2 is a plot o~ results of
~S93~9
temperature vs. ethylene conversion and wt. % select-
ivity to propylene, butylenes and C5+ hydrocarbons
for catalysts prepared in accordance with Example II.
BEST_MODES FOR_CARRYING OUT THE INVENTION
In the following description of the present
invention, the term "WHSV7' reEers to weight hourly
space velocity, esp., weight of ethylene or olefin
feed per weight of molecular sieve per hour. WHSV is
calculated on the basis of the weight of active
catalyst (i.e~, molecular sieve) excluding any
binders, matrix materials or other inert solid
diluents.
The feedstock converted to normal liquid
hydrocarbons according to this invention contains
ethylene and may also contain C3+ olefins. In
addition, the feedstock may contain other hydrocarbon
or non-hydrocarbon components. Examples of other
hydrocarbon components include the lower alkanes,
especially Cl-C5 alkanes. Examples of non-hydrocar-
bon components include water, carbon oxides (i.e., CO
and/or CO2), N2 and the like. Ths presence of steam
in the catalyst reactors ~ones under the temperature
conditions employed is not presently believed to
substantially effect the aging and/or the deactiva~
tion characteristics of the catalyst. Preferably,
the olefins are converted in the substantial absence
of hydrogen.
One distinct aspect of the present inven-
tion involves the use of highly dilute olefinic feed-
stocksO More particularly, according to this aspect
of the present invention, it has been found that
desirable results may be obtained even thou~h the
feedstock contains major amounts (i.e., more than 50
vol. ~) of lower alkanes. It has further been found
~;z5933~
--10--
that desirable results may be obtained even though
the feedstock contains major amounts (i.e., more than
50 vol. %) of methane. When employing such highly
dilute olefinic feedstocks in the process of this
invention, it has been found advantageous to maintain
the ethylene partial pressure in the feed contacted
with the catalyst in the first reactor zone within
the range of about 0.5 to 5 atmospheres, preferably
within the range of about 1 to ~.5 atmospheres.
Total operating pressure in the first reactor zone is
thus determined by the ethylene content of the feed
to the first reactor zone. According to this aspect
of the present invention such ethylene content may
vary broadly, e.g., within the range of about less
than 10 vol. % to 50 vol. ~.
As will be apparent to those skilled in the
art, the sele~tion of whether to employ such highly
dilute, olefinic feedstocks or to first isolate an
olefinic eraction of such feedstock prior to oligo-
merization according to this invention, will be
dependent on the cost of processing the highly dilute
feedstock via oligomerization relative to the cost of
isolating an olefinic fraction therefrom. In general,
it will noted that alkane recovery from oligomeriza-
tion effluents (particularly the second catalyst
rector zone effluent of the process of this inven-
tion) is much easier than isolation before oligomer-
ization.
The process of this invention, wh~ e not
limited thereto in its broader aspects, is particu-
larly suited to oligomerizing feedstocks comprising
an olefinic fraction which contains a major amount
(i.e., greater than 50 vol. %, preferably greater
than 80 vol. %) of ethylene. One observation that
F
~2S933~
led to the present invention was that operating modes
favoring direct production of normally liquid hydro-
carbons from gaseous olefins (especially from
ethylene) also favor the formation of additional
gaseous hydrocarbons. For example, the direct con-
version of ethylene to normally liquid hydrocarbons
also produces substantial amounts of gaseous C3+
hydrocarbons ~oth olefinic and paraffinic hydrocar-
bons). Thus, in those sequential processes previ-
ously suggested wherein higher olefin oligomerization
precedes lower olefin oligomerization, the final
effluent will contain significant amounts of lower
hydrocarbons which, to optim ze yields, must be
recovered and recycled through the prior oligomeri-
zation steps. ~ne advantage of the present invention
is that it minimizes the need for such recovery and
recyle.
A related observation is that the formation
of additional gaseous hydrocarbon increases as oligo-
merization severity increases. Thus, direct conver-
sion of propylene to distillate products or aromatic-
rich products produces more byproduct gaseous hydro-
carbons than direct conversion of propylene to
olefinic gasoline products, the former conversion
requiring higher severity conditions than the latter
conversion.
Considering the foregoing observations in
the context of the present invention, it has been
found desirable to select operating severities for
the first catalyst reactor zone that maximize the
conversion of ethylene to C3-C4 olefins and Cs+
hydrocarbons. Selection of more severe operating
severities--e.g., those that maximize formation of
gasoline or distillate products- is not always
~;25;~3339
-12-
desirable in the context of this invention. Rather
than selecting operating severities to effect conver-
sion of ethylene to a particular product, it is pre-
ferable to select operating severities which effect
substantiall~ quantitative conversion of ethylene,
without rigorous attention to whether, or to what
extent, normally liquid hydrocarbons are produced.
Having formed a C3+ olefinic, intermediate product in
the first reac~oc ~one, the further conversion to
normally liquid products may be accomplished with
relative ease~
The broad concept of contacting olefins--
including mixtures of ethylene with higher hydrocar-
bons-~with a siliceous crystalline molecular sieve to
oligomerize the olefins is not novel. A key to one
inventive concept of this invention resides in selec-
ting within a limited range of operating conditions
such that the following objective will be accom-
plished in the first catalyst reactor zone: ethylene
will be substantially converted to C3-C4 olefins and
Cs+ hydrocarbons. Such objective is meant to connote
several correlative objectives. For example,
ethylene conversion to aromatics in the first
catalyst reactor zone will be minimized. Moreover,
no attempt is made to maximize conversion of ethylene
to normally liquid hydrocarbons in the first reaction
zone. ~,~hile liquids will be formed at operating
conditions providing a severity sufficient to maxi-
mi7e ethylene conversion and selectivities to C3-C4
olefins and C5+ hydrocarbons, hydrocarbon liquid
formation is not the principle object to be accompli-
shed in that zone. Furthermore, selecting operating
severities for the first reactor zone according to
the method of this invention minimizes the formation
9~
of Cl-C4 alkanes. Thus, the gaseous fraction of the
first zone effluent is more amenable for further
processing to produce normally liquid hydrocarbon
products.
The general operating parameters for the
first, ethylene oligomerization step of this inven-
tion can be defined by stating that the conversion is
effected at elevated temperatures and relatively low
ethylene partial pressure. sy "elevated temperature"
is meant a temperature selected within the range of
about 285-425C, preferably within the range of about
325-375C. By "relatively low ethylene partial
pressure" is meant a partial pressure within the
range of about 0.5 to 5 atmospheres. The space
velocity will be one selected within the range of
about 9.1 -to 20 WHsV~ based on ethylene. These
ranges of pressure, temperature, and space velocity
are not intended to be construed as meaning that all
operations with these limits will accomplish the
desired results of this invention. Furthermore, as
noted previously, use of highly dilute olefinic feed-
stocks may require rela~ively high overall pressures
to maintain the desired ethylene partial pres~ure o~
0.5 to 5 atmospheres.
What is meant by the foregoing limits is
best expressed in a negative way. Operation outside
the ranges set forth will not accomplish the desired
results of the process of this invention. A well-
known correlation exists between temperature,
pressure anA space velocity with respect to the
severity of the reaction. Stated simply, the first
step of the present method is concerned with the
conversion of ethylene at a severity such that
ethylene will be substantially converted to C3 C4
~tt?,5~339
olefins and C5~ hydrocarbons. The examples below
illustrate such a severity.
To further illustrate, it is known that if
the pressure remains constant and space velocity is
increased, then a higher temperature is necessary to
achieve the desired severity. Conversely, if the
space velocity would remain constant and the pressure
increased, then a lower temperature is necessary to
achieve the desired severity. The precise space
velocity and pressure for any given temperature
within the broad range previously stated can be
easily obtained by routine experimentation following
the guidelines and illustrations set forth herein.
The effluent from the first reactor zone
comprises C3-C4 olefins and C5+ hydrocarbons. This
effluent is separated by means known to those skilled
in the art to produce a normally liquid C5~ hydrocar-
bon fraction and a C3-C4 olefin fraction. For
example, the first stage effluent may be cooled and
reduced in pressure by ~lashing into a phase separa-
tion zone to provide a vapor phase rich in C3-C4
olefins and liquid stream rich in Cs+ hydrocarbons.
The liquid s~ream may be further processed according
to means known in the art. For example, the liquid
2S stream ma~ be upgraded to improve gum stability or
may be hydrotreated or may be further converted to
form additional distillate products such as diesel
and fuel oils. The C3-C4 olefinic fraction which
may contain other components, esp. Cl-C4 alkanes,
is then passed to the second catalytic reactor zone~
Regarding selection of operating conditions
to be employed in the second catalyst reactor zone of
this invention, the general operating parameters for
converting C3-C4 olefins to heavier hydrocarbons in
~;~S~33~
- 15 -
the gasoline and/or distillate boiling range can be
defined broadly by stating that the conversion is
effected at moderate temperature. By "Moderate
temperature" is meant a temperature selected within
the range of about 150-330C. The pressure employed in
the second catalyst reactor zone may be vary widely,
preferably within the range of about 1 to 70
atmospheres. Similarly, the space velocity may vary
widely, generally within the range of about 0.1 to 20
W~SV, based on olefin. Several alternative objectives
are within the scope of operation of the second
reactor zone oE this invention: (1) substantial
conversion of C3-C4 olefins to normally liquid hydro-
carbons; (2) substantial conversion of C3-C4 olefins
to gasoline boiling range hydrocarbons; or (3)
substantial conversion of C3-C4 olefins to distillate
boiling range hydrocarbons. By "substantial
conversion" is meant the conversion of at least 80 wt.
%, preferably 90 wt. %, of the C3+ olefins to said
products.
Selection of operating parameters suitable to
accomplish any of the foregoing objectives have
previously been described in the particular context of
oligomerization using ZSM-5 typezeolites. See, for
example, U.S. Patent 3,760,024 (describes conversion
of C2-C4 paraffins and/or olefins); U.S. Patent
3~960,978 (describes conversion of C2-C5 of olefins to
a gasoline fraction containing no more than about 20
wt. & aromatics): U.S. Patent 4,021,502 (describes
conversion of gaseous olefins to higher molecular
weight olefins over ZSM-4, ZSM-12, ZSM-18 chabazite or
zeolite beta); and U.S. Patent 4,227,992 (describes
selective oligomerization of C3~ olefins to produce
fuel oil and gasoline products).
`,.~
~ZS9339
- 16 -
The comments made above concerning the effect
of varying operating temperature, pressure, and space
velocity on severity of the first reaction zone apply
generally to the effect of such operating conditions
on severity in the second reaction zone.
Furthermore1 the foregoing descriptions of how
to use ZSM-5 type zeolites in the process of this
invention also apply to the similar use of other
siliceous crystalline molecular sieves. Moreover, the
use of borosilicate catalyst and the use of silicalite
catalyst in the present process are considered to be
distinct aspects of the broader invention generally
described herein.
The catalyst employed in the method of this
invention are siliceous crystalline molecular sieves.
Such silica-containing crystalline materials include
materials which contain, in addition to silica,
materials which contain, in addition to silica,
significant amounts of alumina. These crystalline
materials are frequently named "zeolites", i.e.,
crystalline aluminosilicates. However, the use of
materials exempliEied by silicoaluminophosphates (see
U.S. Patent 4,440,871) are also within the scope o
this invention. Silica-containing crystalline
materials also include essentially aluminum-free
silicates. These crystalline materials are
exemplified by crystalline silica polymorphs (e.g./
silica silicalite, disclosed in U.S. Patent 4,061/724
and organosilicates disclosed in U.S. Patent RE.
29948)/ chromiasilicates (e.g./ CZ~)/ ferrosilicates
and galliosilicates (see U.S. Patent 4,238,318)~ and
borosilicates (see U.S. Patent Nos. 4/226/420;
4/269/813 and 4/327/236.
~`
.~
~l2~33~
-17-
The term l'essentially aluminum-free"
silicates i5 not intended to totally exclude the
presence of aluminum from the catalyst composition.
For example, it has been suggested that silicates
containing less than 100 ppm. by weight of aluminum
may not be effective for the oligomerization oE
olefins. ~ee U.S. Patent 4,331,6~1, especially see
column 9, lines 49-52 of that patent.
Crystalline aluminosilicate zeolites are
best exemplified by ZSM-5 (see U.S. Patent Nos.
3,702,886 and 3,770,614), ZSM-ll (see U.S. Patent No.
3,709,979) ZSM-12 (see U.S. Patent 3,832,449), ZSM~21
and ZSM-38 (see U.S. Patent 3,948,758), ZSM-23 (see
U.S. Patent 4,076,842), and ZSM-35 (see. U.~S. Patent
4,016,246).
The acidic crystalline aluminosilicates are
desirably in the hydrogen form, although they may
also be stabilized or their performance otherwise
enhanced by ion exchange with rare earth or other
metal cation.
The molecular sieves can be composited with
inorganic matrix materials, or they can be used with
an or~anic binder. It is preferred to use an
inor~anic matrix since the molecular sieves, because
of their large internal pore volumes, ten~ to be
fra~ile, and to be subject to physical collapse and
attrition in normal loading and unloading of the
reaction zones as well as during oligomerization
processes.
Preferred siliceous crystalline molecular
sieves to be employed in the process of this inven-
tion are ZSM-5 type zeolites, borosilicates,
silicoalu~inophosphates and silicalite. ZSM-5 and
borosilicate are particularly preferred.
~25~339
-18-
The present invention is further
illustrated by reference to the following e~amples.
E~AMPLE 1
A crystalline borosilicate catalyst was
prepared by dissolving ~3B03 and N20~ in distilled
H2O~ Then tetran-proplyammonium bromide (TPAB) was
added and dissolved. Finally, Ludox AS-30(30%
solids) was added with vigorous stirring. The
addition of Ludox gave a curdy, gelatinous, milky
~0 solutionO This solution was placed in a vessel and
sealed. The vessel was heated to 329F. (165C) for
7 days. At the end of this time, it was opened and
its contents were filtered. The recovered crystal-
line material was washed with co~ious quantities of
H2O and was then dried at 329F (165C) in a forced
air oven.
The material was calcined at 1,100F.
(593C) in air for 4 hours to remove the organic
base. The calcined sieve was e~changed one time with
an aqueous solution of NH4NO3 and then a second time
with an aqueous ammonium acetate solution at 190C.
(88C) for 2 hours. The e~changed borosilicate was
dried and c~lcined in air by heating it to 900F
(482C) in 4 hours, maintaining the borosilicate at
900C (482C) for 4 hours and then cooling to 100F
(38C) in 4 hours.
- The X-ray diffraction pattern is presented
in T~ble I below.
3~
* Trade Mark
S~33353
--19--
TABLE I
Inter~anar Spacin~(A) Relative Lntensity_SPacin~
3.34 9
3.30 10
3.24 5
3.04 14
2.g7 15
2.93 7
2.72 5
2.60 7
2.48 8
2.00 15
1 ~9 17
l.91 6
1.86 5
1.66 5
An aluminosilicate catalyst was prepared by
dissolving 400 grams of N-Brand sodium silicate in
300 ml. of water. Then 150 grams of NaCl, 14.2
grams of A12(So4)3.H2o~ and 32.9 grams of H2SO4 was
dissolved in 680 ml of H2O. Tetrapropyl ammonium
bromide (50 grams) was dissolved in 200 ml of H2O.
The sodium silicate solution was mixed with the
sodium chloride solution to form a thick, semi-solid
mass which was mixed well. The bromide solution was
then added to the mixture. The mixture (250 ml.) was
charged to an autoclave and was maintained with
stirring at 300F for 16 hours.
The mixture had a pH of about 12. The
solids were washed and decanted until no positive
Cl-test was shown with A~NO3. The solids were
calcined at 500C to produce a white solid.
The material was identified by x-ray
.
- ' '
~2S~339
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diffraction as having the typical ZSM-5 pattern. The
x-ray diffraction pattern is presented in Table 2.
TABLE 2
Interplanar SPacing(A) Relative Intensity
11.~7 21
10.16 18
6.80 3
6.41 6
6.02 12
5.64 10
5.03 6
4.64 5
4.29 9
3.86 100
3.74 5g
3.67 38
3 45 12
3.35 12
3.07 18
3.00 18
2.75 6
2.61 9
2.50 9
2.41 9
2.01 20
1.88 5
1.67 7
Example III
The physical characteristics of t~e
materials of Examples I and II were tested and are
presented in Table 3 below.
~Z~ 33~
-21-
TABLE 3
Bulk Acidity
Density Al content, wt~ meq~ NH~/gm
Example I 0.662 0.14 0.4
Example II 0.214 1.5 0.5
EXAMPLE IV
Olefin-conversion runs were made at atmos-
pheric pressur* and at temperatures between 300-369C
in a stainless steel tube reactor packed with 5 ml.
of catalyst. The reactors were brought up to temper-
ature under a flow of heated nitro~en which was
switched to olefin feed at the start of the run. The
olefin-contact runs described had a duration of one
hour for Group ~ 5 hours for Group B and 50 hours
for Group C.
Samples were taken during the run. The gas
effluent was collected and measured and analyzed from
which a cumulative sample was generated. At the end
of each olefin-contact run, the reactor was flushed
with nitrogen to cool the reactor and catalyst~
Space velocities are reported as weight
hourly space velocities (hr.~l) ~WHSV). The resi-
dence or contact time is also reported. The cumula-
tive results are shown in Tables 4-6 below, the
instantaneous results for Run #3 of Table 5 and for
the run described in Table 6 are plotted in Figure 1.
Referring to Figure 1, it can be seen that the
oligomerization catalyst is remarkably stable during
ethylene conversion accordin~ to the first step of
the method of this invention.
~S~33~
-22-
TABLE 4
Group A
Feed Ethylene
Catalyst Example II
Run Time (hr)
Temp(C) 350
Pressure(psig) 0
Contact Time (sec) 0.51
I~SV( hr~l~ 8.1
C2= Conv(~) 99.3
Wt.% Selectivity
CH4 1.4
C2 1.0
C3= 1.7
c3 8.1
C4= 10.1
C4 3.7
C5+ 75.2
Coke 0.1
Productivity
(~Liquid/#Cat-hr) 5.g
~Z~9339
-23-
TABLE 5
Group B
Run# l 2 3 4
Feed Propylene Propylene Ethylene Ethylene
CatalystExampleExample Example Example
II I I II
Run
Time(hr) 5 5 5 5
Temp(C)300-8 300-6 350-351 350-355
WHSV
(hr~l)4.9 1.6 0.7 2.0
Pressure
(psig) 0 0 0 0
C2=
Conversion(%) ---- ---- ~9.3 99.5
c3=
Conversion(%) 99.2 98.9 -~
Wt.% Selectivity
CH4 <0.01 <O.Ol 0.03 0.04
c2= 0.2 0.1 ---- ____
C2 <0~01 <0.01 0.5 0.6
C3 ---- ____ 1.2 0.7
C3 0.8 0.2 4.9 5.9
c4~ 1.4 0.4 6.9 9.1
C4 0.5 0.2 2.8 3.0
C5+ 96.9 98.9 80.5 80.5
Coke o,l 0.2 0.2 0.1
~ ~ ~J~ ~ ~
-24-
TABLE 6
Feed Ethylene
Catalyst Example II
Run Time(hr) 50
Temp(C) 350-369
Press.(psig) 0
Contact Time (sec)2.1
WHSV(hr~l) 2.0
Cumulative C2~Conv(%) 83.4
Wt.% Selectivity
C~4 0.2
C2 o.~
C3= 4.3
c3 3.1
C4= 11.4
C4 4~6
C5~ 76~1
Coke 0.02
Productivity 1.3
~#liq/~cat-hr) 1.3
(~m liq/cm3cat-hr) 0.3
A PONA analysi.s was conducted on the
liquids produced in the run described in Table VI.
Results are shown below in Table 7.
33~
-25-
TABLE 7
COMPONENT WT. %
PROPANE 0.1
PROPYLENE 0.1
BUTENES 4-4
i-BUTANE 2.4
n-BUTANE 1.3
PENTENES 10.7
i-PENTANF. 5.6
n-PENTANE 2.2
TOTAL LIGHT END 26.8
.
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-27-
EXAMPLE V
The material prepared in Exa~ple I was run
under the conditions of Example IV at the tempera-
tures and contact times shown in Table 8. The cumu-
lative run results (obtained during 1 hr. runs) are
also shown in Table 8. The total cumulative results
ohtained as a function of temperature is shown in
Figure 2. Selectivity is reported as the sum of C3=,
C4= and Cs+ hydrocarbon in the effluent. Note that
as conditions reach the point where significant
amounts of ethyl~n~ dre converted, further increases
in severity (i.e., temperature), resulted in a rapid
rise of the ~ ethylene converted to quantitative
levels. Further increases in severity had the effect
of marginally lowering ethylene conversion. At about
the same level of severity where ethylene conversion
was quantitative, the wt. % selectivity to
C3=/C4=/Cs+ hydrocarbon products also reached a
maximum and the wt. % selectivity to Cl-C4 alkanes
reached a minimum. As severity was further increased,
the wt. ~ selectivity to C3=/C4=/C5+ hydrocarbon
products rapidly decreased and the wt. ~ selectivity
to Cl-C4 alkanes rapidly increased. Selection of
operating conditions to be employed in the ethylene
conversion step o~ the process of the present inven-
tion is preferably such that ethylene is substan-
tially quantitatively converted, yielding large
quantities of C3=, C4= and C5+ hydrocarbon products.
The yield (i.e., conversion multiplied by selectivity)
of these products in the first stage effluent will be
greater than about 70 wt. %. The C3= and C4= hydro-
carbons (i.e., propylene and butylenes) are then
converted to normally liquid hydrocarbons in the
second stage of this present process. The Cs+
'
33~3
-28-
hydrocarbons in the first stage effluent are
separated prior to t:ne second stage conversion.
~,'2S~3~9
--29--
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