Note: Descriptions are shown in the official language in which they were submitted.
~98S2
Docket 937
IMPROVED RESIN CATALYSTS
AND METHOD OF PREPARATION
This invention was made with Government support
under Contract No. DE-FC07-80CS40454 awarded by the
Department of Energy. The Government has certain rights in
this invention.
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to acid cation
exchange resins which have been modified to form
substantially neutral metal salts thereof, which have been
found to be superior catalysts for several processes.
Related Art
~219~52
The acid cation exchange resins are well known and
have a wide variety of uses. The resins are cation
exchangers, which contain sulfonic acid groups, and which
may be obtained by polymerization or copolymerization of
aromatic vinyl compounds followed by sulfonation. Examples
of aromatic vinyl compounds suitable for preparing polymers
or copolymers are: styrene, vinyl toluene, vinyl
naphthalene, vinyl ethylbenzene, methyl st~rene vinyl
chlorobenzene and vinyl xylene. A large variety of methods
may be used for preparing these polymers; for example,
polymerization alone or in admixture with other monovinyl
compounds, or by crosslinking with polyvinyl compounds; for
example, with divinyl benzene, divinyl toluene,
divinylphenylether and others. The polymers may be prepared
in the presence or absence of solvents or dispersing agents,
and various polymerization initiators may be used, e.g~.,
inorganic or organic peroxides, persulfates, etc.
The sulfonic acid group may be introduced into these
vinyl aromatic polymers by various known methods; for
example, by sulfating the polymers with concentrated
sulfuric and chlorosulfonic acid, or by copolymerizing
aromatic compounds which contain sulfonic acid groups (see
e.g., US Pat. No. 2,366,007). Further sulfonic acid groups
may be introduced into the polymers which already contain
sulfonic acid groups; for example, by treatment with fuming
sulfuric acid, i.e., sulfuric acid which contains sulfur
1219~l52
1 trioxide. The treatment with fuming sulfuric acid is
preferably carried out at 0 to 150 degrees C. and the
sulfuric acid should contain sufficient sulfur trioxide so
that it still contains 10 to 50% free sulfur trioxide after
the reaction. The resulting products preferably contain an
average of 1.3 to 1.8 sulfonic acid groups per aromatic
nucleus. Particularly, suitable polymers which contain
sulfonic acid groups are copolymers of aromatic monovinyl
compounds with aromatic polyvinyl compounds, particularly,
divinyl compounds, in which the polyvinyl benzene content is
preferably 1 to 20% by weight of the copolymer (see, for
example, German Patent Specification 908,247).
The ion exchange resin is generally used in a
granular size of about 0.25 to 1 mm, although particles from
0.15 mm up to about 2 mm may be employed. The finer
catalysts provide high surface area, but also result in high
pressure drops through the reactor. The macroreticular form
of these catalysts have much larger surface area exposed and
limited swelling which all of these resins undergo in a
non-aqueous hydrocarbon medium compared to the gelular
catalysts.
The acid cation exchange resins have been widely
used in etherifications and have recently been found to be
useful for deetherifications and transetherifications.
Other reactions known to be carried out with the aid of
cation exchange resins include dimerizations, hydration of
olefins, esterifications and expoxidations.
1219852
1 The modified cation exchange resin catalyst of the
present invention have been found particularly useful for
deetherifications, dehydration and hydration of organic
compounds.
The modified catalysts of the present invention
exhibit substantial improvement in thermal stability
compared to the base resin, however, the catalysts continue
to exhibit the properties of acid catalysts. Furthermore,
the present catalysts have been observed to be morç
selective in reactions.
The simplicity and safety of the present process
which produces the present high temperature, active resin
type catalysts is an advantage over other types of
stabilizations wherein the resins are chlorinated or
brominated.
lZl9~SZ
~UMMARY OF THE INVENTION
In its broader aspects the present invention relates
to improved catalysts compositions which are nuclear
sulfonic acid solid resins which have at least 50% of the
sulfonic acid groups neutralized with metal ions of Group
4b, 5b, 6b, 7b, 8, lb or 2b, and of the Periodic Table of
elements, the rare earth metals or mixtures thereof, and the
balance of the sulfonic acid groups neutralized with an
alkali metal or alkaline earth metal, ammonium or mixtures
thereof. The sulfonic acid may be attached to any polymeric
backbone. The preferred metals are Ti, V, Cr, Mn, Fe, Co,
Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Ta, W, Re, Pl,
Ce, Nd, Sm, and Eu.
The present invention includes the method of
preparing cation resin catalysts, cation resin catalysts,
and the processes using the catalysts.
In a preferred embodiment the present catalyst is
prepared by contacting a macroporous matrix containing a
sulfonic acid group with aqueous solution of metal salts and
solutions of alkali metal salts, alkaline earth metal salts
and/or ammonium salts to neutralize the acid groups. Alkali
metal and alkalineearth metal ions are preferred for the
neutralization.
In a preferred procedure the present catalysts are
prepared by contacting a sulfonic acid cation exchange resin
comprising a macroporous matrix of a polyvinyl aromatic
lZ1913SZ
1 compound crosslinked with a divinyl compound and having
thereon from about 3 to 5 milli equivalents of sulfonic acid
groups per gram of dry resin (1) with an aqueous solution of
a soluble compound of an alkali metal or alkaline earth
metal of Group la or 2a of the Periodic Table of elements or
mixtures thereof in an amount to neutraIize all of the
available sulfonic acid groups and (2) thereafter contacting
said neutralized resin with an aqueous solution of a soluble
salt of a metal as described and preferably a soluble salt
of Al, Fe, Zn, Cu, Ni or mixtures thereof to replace at
least 50% of the alkali metal, alkali earth metal or
mixtures thereof associated with said sulfonic acid groups
with said metal.
- In an alternate procedure the present cation resin
catalyst composition is prepared by contacting, a sulfonic
acid cation.exchange resin comprising a macroporous matrix
of a polyvinyl aromatic compound crosslinked with a divinyl
compound and having thereon from about 3 to 5 milli
equivalents of sulfonic acid groups per gram of dry resin,
(1) with an aqueous solution of a soluble metal salt as
described and preferably of Al, Fe, Zn, Cu, Ni or mixtures
thereof to neutralize at least 50% to less than 100% of the
available sulfonic acid groups with said metal ions to
produce a partially neutralized resin and (2) thereafter
contacting said partially neutralized resin with an aqueous
solution containing a soluble compound of an alkali or
alkaline earth metal of Group la or 2a, of the Periodic
~z~9~s~
1 Table of elements or mixture thereof to neutralize the
remaining sulfonic acid groups.
Following either procedure substantially equivalent
catalysts which are fully neutralized are obtained.
The resin catalyst composition is a solid comprising
a macroporous matrix of polyvinyl aromatic compound
crosslinked with a divinyl compound and having thereon from
about 3 to 5 milli equivalents of sulfonic acid groups per
gram of dry resin, wherein at least 50% to less than 100%
preferably at least 59% and more preferably 70 to 90% of
said sulfonic acid groups are neutralized with a metal ion
as described and preferably Al, Fe, Zn, Cu, Ni or mixtures
thereof and said sulfonic ac d groups not neutralized with
said metal ion are neutralized preferably with alkali or
alkaline earth mètal ions of Group la or 2a of the Periodic
Table of elements, ammonium ions or mixtures thereof.
The modified acidic cation exchange resins, i.e.,
the neutralized resins of the present invention have been
found to be stable at fairly high temperatures (for resin
type catalysts), e.g., temperatures of 150-200C may be used
for operations with good time trend for catalyst activity
and structural integrity. The catalyst are suitable for
both liquid phase and vapor phase (or mixed phase) organic
reactions.
The catalysts are preferably employed in a fixed
bed, in any of the conventional configurations, such as
tubular reactors, packed in a single continuous bed or in
:12~91~5Z
1 supported structures as described in US Pat. No's.
4,250,052; 4,215,011 and 4,302,356.
The catalyst may be used in processes by passing the
reactants in vapor phase or liquid phase (as indicated by
equilibrium considerations) through the fixed bed.
Similarly, the catalyst in supported structures as described
in US Pat. No's 4,250,052: 4~215,011 and 4,302,356 may be
used as both a catalyst contact and distillation structure
ro where the reaction products are conveniently concurrently
made and separated by distillation.
The deetherification to produce an olefin and an
alcohol is most conveniently carried out in a fixed bed with
`the feed in vapor phase at temperature in the range of
150C.-190C. preferably below 180C., i.e., about 160C. to
170C., at LHSV (liquid hourly space velocity) preferably of
about 1 to 10 and more preferably about 3 to 6. The ethers
which may be easily dissociated are those of the general
formula
Rl-O-R2
wherein R1 is a hydrocarbon radical having 4 or 5 carbon
atoms and R2 is a hydrocarbon radical having 1 to 6
carbon atoms. The hydrocarbon radicals may be straight
chain or branches. Some illustrative ethers are methyl
tertiary butyl ether, ethyl tertiary butyl ether, propyl
tertiary butyl ether, butyl tertiary butyl ether, tertiary
butyl tertiary butyl ether, pentyl tertiary butyl ether,
!hexyl tertiary butyl ether, methyl 2-methyl butyl ether,
~Z19852
1 methyl 3-methyl butyl ether, ethyl n-amyl ether, methyl
isoamyl ether and the like.
The dissociation of the ethers is favored at higher
temperatures, that is, the equilibrium constant shifts
toward dissociation at the higher temperatures recited. It
is an advantage that the higher temperature allow higher
pressures of 4 to 40 atmospheres, preferably about 5 to 10
atmospheres of operation in the vapor phase and the
hydrocarbon, i.e., C4 or C5 olefin, dissociation
product can be condensed at the higher pressure without
refrigeration, i.e., condensation water at ambient
temperatures can be used.
The use of the present catalyst rather than
conventional acidic cation exchange resins for
deetherification is advantageous since the reaction is more
selective to the production of the olefin at high
conversions. In addition, the present catalysts
substantially eliminate the formation of ether by-products
and acetals.
Dehydration of alcohols such as tertiary butyl
alcohol can also be carried out at high temperatures and
pressure in vapor phase, e.g., 130C.-150C. at LHSV in the
range 1 to 10 using the present catalyst in a fixed bed
usually with pressure drops through the bed of about 1 to 30
psig, preferably about 5 to 15 psig.
Hydration of unsaturated hydrocarbons such as
tertiary butene to form alcohols is preferably carried out
~219~5Z
1 in liquid phase at temperatures in the range of 100C to
130C at LHSV in the range of 1 to 10 using the present
catalyst in a fixed bed with sufficient pressure to maintain
the liquid phase.
` lZ19852
1 DETAILED DESCRIPTION OF THE INVENTION
Any of the acidic cation exchange resins known to
the art and described above, preferably the macroporous form
may be employed in the present modification procedure,
however, polystyrene crosslinked with diYinyl benzene is
preferred. The macroporous resins are frequently referred
to as macroreticular. This type of resin structure has been
described in the art since the early 1960's, for example, by
K. A. Kun, and R. Kuninr "J. Poly Sci", A-l Vol 6, page ~64
(1968) and R. Kunin, E. Meitzner, N. Bortnick, "J.Am. Chem.
Soc.",~Vol. 84, page 305 (1962) and US Pat. No. 3,037,052 to
Bortnick.
The macroporous resins have heterogenous structures,
and consist of agglomerates of very small gelular
microspheres. Each microsphere has a microporous matrîx
structure identical to that of common gelular resins but
much smaller than the gelular resin beads. Thus, the
macroporous resins are formed of areas of microporous cell
matrix interspersed with macropores. A common example of
this material is Rohm and Haas Amberlyst 15. Those
macroreticular sulfonic acid cation exchange resins having a
specific pore volume of at least about 0.01 cc./gm. and
preferably in excess of 0.03 cc./gm. are suitable for the
present invention.
These matrixes (matrices) are sulfonated as
described earlier in order to introduce sulfonic acid groups
1%198~2
1 (-S03H) into the matrix to form strongly acidic
catalysts. It should be noted that anion forms of the
resins are also known and prepared by the introduction of
amine groups into the matrix. Hence, generally acidic or
basic catalyst are known and used.
The catalysts of the present invention are
substantially neutral (although all of the sulfonic acid
sites are neutralized, on hydrolysis the present catalyst
will exhibit a sli`ghtly acidic pH) having been neutralized
with specific metal ions and preferably alkali and/or
alkaline earth metal ions to obtain specific catalytic
properties.
As described earlier a nuclear sulfonic acid resin,
for example, macroreticular resin catalyst, preferably
polyvinyl styrene crosslinked with divinyl benzene and
sulfonated to contain from 3 to 5 milli equivalents of
sulfonic acid is contacted with a solution of a water
soluble salts, as described and in a one embodiment, a salt
of Al, Fe, Zn, Cu, Ni or mixtures thereof and a salt of an
alkali or alkaline earth metal. Soluble salts of the metals
described are known, but some examples are aluminum
chloride, iron (Fe+3) chloride, nickel chloride, copper
(Cu+2) chloride, zinc chloride, copper (Cu+2)
sulfate, iron (Fe+3) sulfate, zinc sulfate, and the
like. The mixtures of metal ions may include any two or
more of the metals disclosed.
Preferred alkali and alkaline earth metals are Li,
~219~52
1 Na, K, Mg, Ca, Sr, Ba, or mixtures thereof. The mixtures of
alkali metal ions or alkaline earth metal ions may comprise
any two or more of the elements from Periodic Table group la
and 2a. 5uitable soluble salts include sodium chloride,
potassium chloride, lithium sulfide, magnesium acetate,
calcium bromide, strontium bromide, barium bromide and the
like. Ammonium chloride, for example, is illustrative of
the soluble salts suitable for use in the present process
Preferred Procedure
The preferred method of catalyst preparation is
advantageous since it is the metal ion which is the active
species and it is simpler to replace the alkali or alkaline
ion (or ammonium ion) to the desired extent than avoid
removing the metal ion in the alternate procedure. The
neutralization of the sulfonic acid sites with the alkali or
alkaline earth metal salt solution (or ammonium salt) can be
easily and quickly carried out using a brine, e.g., NaC1 in
a saturated solution.
The displacement of alkali, alkaline earth or
ammonium ions with the metal ion may be controlled by using
the metal salt solution in portions containing metal ion in
theoretical amounts to displace the alkali, alkaline or
ammonium ions in stages or in a single solution of a
theoretical amount. Analysis of a portion of the catalyst
can readily determine if the desired displacement has taken
place and if not, further treatment and analysis can be
121985Z
1 carried to arrive at the desired level of metal ion
concentration in the catalyst.
Of course, a continuous stream contact of a specific
concentration of the metal salt can be plotted for specific
rates, temperature, and the like and an accurate and
reproduced synthesis established.
The solutions are normally at ambient room
temperature and atmospheric pressure, although temperatures
in the range of 10C. to 80C., are suitable and both sub-
and super atmosphere pressure could be used for both
procedures.
As a final step in both disclosed processes the
catalyst is preferably washed with a water substantially
free of electrolytes, i.e., deionized water or distilled
water, to remove any residual contact solution. The
catalyst may be dried in air or in various known driers or
washed with methanol then heated. In some utilizations the
catalyst may be loaded in the reactor wet and dried as part
of the start up process.
Alternate Procedure
The amount of soluble metal salt present is that
amount which will react with (neutralize) at least 50% of
the active sulfonic acid sites present in the resin being
contacted and preferably an excess of salt is present. In
no event will there be a 100% neutralization of the sulfonic
active sites with metal ions even if an excess of the salt
14
~Z198SZ
1 beyond 100% is present, since these salts form acidic
solutions, and an equilibrium is established, depending on
the acidity, between the hydrogen ion on the sulfonic acid
group and the metal ion. It can be expected that one
Fe+3 ion will neutralize three sulfonic acid sites as
will the aluminum ion, whereas metals of +2 valence will
neutralize two sites per ion.
Hence, after the contact with the metal salt
solution, there will still be some active sulfonic acid
sites. These residual sulfonic acid sites are neutralized
by contacting the resin with a solution of an alkali or
alkaline earth metal salt or ammonium salt. These solutions
will neutralize the residual sulfonic acid sites, such that
the final resin product is a fully neutralized material, or
in practice very weakly acidic.
In the final alkali neutralization step under the
alternate procedure, care must be exercised not to contact
the partially neutralized resin with a large excess of
alkali or alkaline earth metal ions, (a slight excess up to
about 20% may be used, beyond that required to neutralize the
residual sulfonic acid groups) since they appear to form
`double salts or possibly elute the metal ions, which may
reduce the catalytic activity of the catalyst. An empirical
technique of the manner to produce highly active fully
neutralized resins is the use of ordinary tap water which is
slightly alkaline, e.g. pH 8, which normally contains
dissolved alkali and alkaline earth salts. Generally an
1%1985Z
l amount over about 10 ml of such tap water per ml of
partially neutralized catalyst would be excessive.
The minimum amount of the alkali, alkaline earth or
ammonium salt is dependent on the extent of neutralization
in the first step. For example, a salt solution of copper
sulfate has a high pH (3.5) and obtained a high degree of
copper ion exchange, hence only 3 ml of tap water wash per
ml of resin produced an excellent catalyst, whereas 10 ml of
tap water wash per ml of resin would be excessive for this
catalyst. For an iron sulfate solution, pH 1, the ion
exchange equilibrium is lower and a 10 ml tap water wash is
reasonable.
Because different metal salts ~first stage
neutralization) have different pH's and the ion exchange
equilibrium is affected by pH, some experimentation will be
_ desirable, initially with the amount of alkali, alkaline
earth or ammonium salt solution to determine acceptable wash
amounts. However, once having determined equilibrium
constants for each solution, the amount necessary can be
calculated such that an excess may be readily avoided.
It should also be appreciated that the catalytic
activity varies for the different metal ions and the
activity of one metal ion modifier in one process may not be
similar when the catalyst is used in a different process.
In regard to deetherification, it has been observed that the
activity of the catalyst increases Ni <Zn <Cu <Fe and Al.
The modification of the acidic cation exchange
16
1219852
l resins according to the present invention as noted above,
substantially changes the characteristic of the resins,
namely, the high temperature properties are substantially
improved and the activity of the catalyst is changed. One
S particular benefit of the change of activity in regard to
deetherification is the greater selectivity of the
deetherified product to the olefin corresponding to the
ether, for example, deetherification of methyl tertiary
butyl ether using an unmodified resin produces small but
detectable amounts of isobutane, dimethyl ether and acetal,
whereas the modified catalysts substantially reduce these
side reactions.
The deetherifcation process using the present
catalyst is carried out in vapor phase, since the
dissociation is favored by higher temperatures and vapor
phase (less molecular contact for the reverse reaction).
Temperatures up to about 200C. may be used, but
temperatures up to 160C. to 170C. are preferred. Pressure
may range from atmospheric up to the pressure at which the
reactants and products are reduced to the liquid phase.
Generally, as a desirable expedient the system is operated
at a pressure at which the desired olefin product is
condensed with the least cooling, e.g., in MTBE
dissociation, isobutene can be condensed with available
ambient temperature cooling water at 70-100 psig, preferably
80-g0 psig.
The hydration of olefins, particularly, tertiary
~21~t35Z
1 olefins, such as isobutene or isoamylene is carried in
liquid phase at lower temperature, e.g., around 100C. to
130C. and sufficient pressure to maintain the liquid phase.
The dehydration of alcohols, particularly tertiary
alcohols such as tertiary butanol (TBA) lS carried out
either in vapor phase or liquid phase (vapor phase is
preferred because lower pressure may be used) at temperature
of 130C. to 150C. Very high conversion is obtained at
relatively good space rates (LHSV 1 to 10).
The following examples will illustrate the invention
but are not intended to limit the scope thereof.
18
~Z19852
1 EXAMPLES 1-8
In the following examples, example 1 is a control.
The catalyst is ordinary Amberlyst 15 purchased from Rohm
and Haas. The modified catalyst are the same Amberlyst 15
treated with the various salt solutions and water as
indicated. Each catalyst was dried prior to use by washing
with methanol and heating. Each catalyst was placed in the
same reactor and the same feed was fed through under the
same conditions.
The reactor was a bench scale tubular reactor (3/8"
OD copper tubing) containing 60 ml of the dry catalyst and
heated with a steam jacket. The column was positioned
vertically and a stainless steel mesh screen used to support
the catalyst bed. The feed to each run was a 50/50
isobutanol/isobutyl tertiary butyl ether stream. The
temperature was held at 150C.-160C. for examples 2-8 and
100C. for example 1. The LHSV was between 3.5-5 for each
run and pressure was 65-90 psig bed exit pressure.
Each of the metal salt solutions used in the first
stage treatment were 20~ concentration. The metal salt
solution was contacted with the resin at ambient room
temperature (about 25C.). After the contact with the metal
salt each sample was washed with deionized water then as
indicated in TABLE I the sample was washed with tap water
and in some cases with deionized water. A final pH, which
is the pH of the final wash water through the catalyst is
19
1219~52
1 reported. This pH reflects the pH of the modified resin at
the time.
In TABLE I the treatment steps and solutions are set
~ out followed by the results of the deetherification run.
TABLE II is a typical analysis of the tap water used to
neutralize the remaining sulfonic acid groups.
EXAMPLE 9
The catalyst of example 6 was used for a dehydration
of tertiary butyl alcohol at 140C, LHSV 3. The conversion
of TBA to isobutene was 90 mole %.
EXAMPLE 10
Using the same catalyst as example 9, the
temperature was lowered to 125C. and water and isobutene
fed through the catalyst bed in liquid phase (325 psig) at
LHSV 3. The isobutene comprised 15% of a C4 stream.
Five % of isobutene was converted to TBA.
EXAMPLE 11
Using the same catalyst and reactor as example 4
methanol was dehydrated to produce dimethyl ether. The
reactor was heated with high pressyre steam (43 lbs.
pressure) through the jacket. The conditions and results
1219~52
1 are reported in TABLE III.
EXAMPLE 12
A catalyst was prepared by contacting macroreticular
sulfonated resin (Amberlyst 15) with a 20% solution of NaCl
until the acid sites were neutralized by washing three
volumes of resin three times with two volumes of the 20%
NaCl each time (total six volumes of NaCl). Following this
the resin was washed twice with one-half volume deionized
water. The neutralized catalyst was then washed three times
with two volumes of a 20% solution of zinc sulfate (total
six volumes). Following this the resin was washed twice
with one-half volume of deionized water. Analysis of the
final catalyst showed 7.6 wt. % Zn and 2.6 wt% Na.
Sixty ml. of this catalyst was dried with methanol
and placed in the reactor described in the prior examples.
A feed of 99.9+ % MTBE was passed (downflow) through the
catalyst with a jacket temperature of 371F. (160 pound
steam) at LHSV of 3-4. Average conversion of MTBE was 91.6
wt. %. The selectivity to isobutene was 99.9 wt % and
selectivity to methanol was 99.7 wt % (GC). The MTBE was
fed as a liquid to the reactor and vaporized in the reactor.
The back pressure on the reactor was 80 psig.
~ fr~lt n1
121985Z
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121985Z
TABLE II
Arsenic 0.01 mg. per liter
Barium 0 50 n n
Chromium 0 02 " "
Copper . 0 02 ~ n
Iron 0 02 " "
Lead 0 02 " "
Manganese 0 02 " "
Seleni~m 0 002 " . "
Silver 0.01 " "
Zinc 0.02 " "
PORTABLE WATER ANALYSIS
Calcium 5 mg. per liter
Magnesium 1 ~ n
Sodium 230 " 1!
Carbonate 11 " "
Bicarbonate 432 " "
Sulfate 3 " "
Chloride 83 " "
Flouride 2.3 n n
Nitrate as in
CaC03 0.01 n 1l
Dissolved Solids 547 " "
Alkalinity as in
CaC03 003 n 1l
pH 8.7 ~'
- 23 -
~Z19~352
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- 24 -
