U.S. patent application number 13/039590 was filed with the patent office on 2011-06-23 for method for stabilizing a cation exchange resin prior to use as an acid catalst and use of said stabilized cation exchange resin in a chemical process.
This patent application is currently assigned to DOW GLOBAL TECHNOLOGIES LLC. Invention is credited to Edward Alan Fraini, Harlan Robert Goltz, James Richard Stahlbush, Katherine H. Stahlbush, Thomas Caldwell Young.
Application Number | 20110152578 13/039590 |
Document ID | / |
Family ID | 36754161 |
Filed Date | 2011-06-23 |
United States Patent
Application |
20110152578 |
Kind Code |
A1 |
Stahlbush; James Richard ;
et al. |
June 23, 2011 |
METHOD FOR STABILIZING A CATION EXCHANGE RESIN PRIOR TO USE AS AN
ACID CATALST AND USE OF SAID STABILIZED CATION EXCHANGE RESIN IN A
CHEMICAL PROCESS
Abstract
A method for preventing the degradation of a catalyst during
storage of the catalyst and prior to using the catalyst in a
chemical process comprising treating the catalyst with an
antioxidant and storing the treated catalyst until further use. The
stabilized treated catalyst may be used in a process for producing
organic chemicals such as in a process for producing bisphenol
A.
Inventors: |
Stahlbush; James Richard;
(Midland, MI) ; Stahlbush; Katherine H.; (Midland,
MI) ; Goltz; Harlan Robert; (Midland, MI) ;
Young; Thomas Caldwell; (Lake Jackson, TX) ; Fraini;
Edward Alan; (Spring, TX) |
Assignee: |
DOW GLOBAL TECHNOLOGIES LLC
Midland
MI
|
Family ID: |
36754161 |
Appl. No.: |
13/039590 |
Filed: |
March 3, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11792935 |
Apr 10, 2008 |
7923586 |
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PCT/US06/02279 |
Jan 24, 2006 |
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13039590 |
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60647866 |
Jan 28, 2005 |
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Current U.S.
Class: |
568/728 ;
502/100; 502/159; 502/167; 502/168; 502/172; 502/208 |
Current CPC
Class: |
B01J 2231/32 20130101;
Y02P 20/52 20151101; C07C 37/20 20130101; C07C 39/16 20130101; B01J
2231/347 20130101; C07C 37/20 20130101; B01J 31/10 20130101; C07C
39/16 20130101 |
Class at
Publication: |
568/728 ;
502/100; 502/159; 502/172; 502/167; 502/168; 502/208 |
International
Class: |
C07C 37/20 20060101
C07C037/20; B01J 33/00 20060101 B01J033/00; B01J 31/10 20060101
B01J031/10; B01J 31/02 20060101 B01J031/02; B01J 31/18 20060101
B01J031/18 |
Claims
1. A process for preventing the degradation of a cation exchange
resin catalyst during storage, handling, processing, and drying of
the catalyst and prior to using the catalyst in a chemical process
comprising treating the catalyst with an antioxidant prior to the
use of such catalyst.
2. The process of claim 1 wherein the antioxidant treatment
comprises dissolving the antioxidant in the water retained in the
catalyst prior to use.
3. The process of claim 1 wherein the antioxidant treatment
comprises partially neutralizing the acid functionality of the
catalyst with the antioxidant.
4. The process of claim 1 wherein the antioxidant treatment
comprises copolymerizing a monomer with antioxidant properties with
other monomers to form the cation resin copolymer.
5. A process for producing a chemical product in a chemical process
using a catalyst comprising: (a) providing a cation exchange resin
catalyst with an antioxidant; and (b) contacting the catalyst with
reactants to produce the chemical product in such chemical
process.
6. The process of claim 5 wherein the catalyst is treated with an
antioxidant by polymerizing the antioxidant into the polymer
resin.
7. The process of claim 5 wherein the cation exchange resin
catalyzes the reaction between hydroxy-containing aromatic
compounds and carbonyl-containing compounds to produce a
bisphenol.
8. The process of claim 5 wherein the cation exchange resin
catalyzes the alkylation of a hydroxyl-containing aromatic
compound.
9. (canceled)
10. The process of claim 1 or claim 5 including washing the treated
catalyst with deionized water after the treatment step.
11. The process of claim 1 or claim 5 wherein the ion-exchange
resin catalyst is a sulfonic acid-type cation-exchange resin
catalyst.
12. The process of claim 11 wherein the resin catalyst is a
sulfonated styrene-divinyl benzene copolymer.
13. The process of claim 1 or claim 5 wherein the antioxidant is a
monocyclic or polycyclic phenol, an amine, a diamine, a thioester,
a phosphate, a quinoline, or a mixture thereof.
14. The process of claim 1 or claim 5 wherein the antioxidant is
2,6-di-t-butyl-.alpha.-dimethylamino-p-cresol.
15. The process of claim 1 or claim 5 wherein the amount of
antioxidant incorporated into the catalyst resin is from 0.001 to
10 percent by weight.
16. The process of claim 1 or claim 5 wherein the resin is stable
when stored for 3 months or more.
17. The process of claim 1 or claim 5 wherein the color increase of
water when contacted with the catalyst is less than 500 APHA during
a seven day accelerated aging test.
18. The process of claim 1 or claim 5 wherein the increase in the
TOC levels of water when contacted with the catalyst is less than
500 ppm during a seven day accelerated aging test.
19. The process of claim 1 or claim 5, including preventing oxygen
from contacting the catalyst during storage.
20. The process of claim 19 wherein oxygen is prevented from
contacting the catalyst by storing the catalyst in the absence of
oxygen by using oxygen barrier packaging, inert gas blanketing or
vacuum packaging.
Description
[0001] The present invention relates to stabilizing a strong acid
ion exchange resin for use as an acid catalyst to protect the resin
from oxidative degradation and the use of said stabilized ion
exchange resin in chemical production processes. More particularly,
the present invention relates to the treatment of a strong acid ion
exchange resin for use as an acid catalyst with an antioxidant to
protect the resin from oxidative degradation and the use of said
treated ion exchange resin in chemical production processes.
[0002] Polymeric ion exchange resins, such as
styrene-divinylbenzene types of strong acid ion exchange resins are
used as catalysts in the production of various organic chemicals
including for example bisphenol-A and phenol alkylation. These
catalysts are susceptible to oxidation during manufacture, storage,
handling, processing, washing, and drying prior to use. Oxidative
degradation leads to the release of low and medium molecular weight
acidic material from the polymeric resins, such as low molecular
weight organic sulfonates, sulfonated oligomers and sulfonated
polystyrene polymers. Release of these acidic components into, for
example, a bisphenol production process can lead to the generation
of undesired impurities and color bodies, resulting in the
production of off-spec product.
[0003] There is a need to protect ion exchange resins from
oxidative degradation prior to and during storage; prior to and
during washing; prior to and during drying; and prior to use of the
ion exchange resin in a chemical production process.
[0004] U.S. Pat. No. 4,973,607 discloses a method of stabilizing a
cation exchange resin against oxidation by treating the resin with
an antioxidant and then using the stabilized antioxidant-treated
cation exchange resin exclusively for water applications, wherein
the purpose of the stabilization is to prevent decomposition of
resin during such use of the stabilized resin.
[0005] U.S. Pat. No. 4,973,607 does not disclose the use of an
antioxidant-stabilized ion exchange resin in catalytic chemical
processes such as bisphenol-A or phenol alkylation production; and
does not disclose that the purpose of stabilization is to prevent
degradation of the cation exchange resin prior to use as a
catalyst. Oxidative decomposition of cation exchange resins during
use as catalysts in chemical processes is generally not an issue in
the industry, because oxygen is typically excluded from chemical
production processes due to flammability concerns. Also, in many
chemical production processes, such as the manufacture of
bisphenol-A, the catalyst is immersed in a process stream which is
typically also a very good antioxidant. Therefore, there is still a
need in the industry for stabilizing a catalyst prior to use in a
chemical process.
[0006] U.S. Pat. No. 4,973,607 also does not recognize that
antioxidant stabilization makes ion-exchange resins easier to wash
prior to use as a catalyst. In addition, U.S. Pat. No. 4,973,607
does not recognize that leachable material may be acidic in nature,
and that the release of this acidic material, for example in a
bisphenol-A production process or in other processes in which an
ion-exchange resin is used as a catalyst, could cause significant
production problems. For example, Stahlbush et al., "Prediction and
Identification of Leachables from Cation Exchange Resins",
Proceedings of 48.sup.th International Water Conference, Nov. 2-4,
1987; and Stahlbush et al., "Identification, Prediction and
Consequence of the Decomposition Products from Cation Exchange
Resins", in "IEX '88--Ion Exchange for Industry", M. Streat,
editor, Ellis Horwood, Chichester, 1988; describes leachables
produced by the oxidation of cation exchange resins, describes a
test for accelerated aging of the resins, describes the levels of
leachables produced by different types of resins, and shows that
anion exchange resins are not effective in adsorbing sulfonated
polystyrene leachables of higher molecular weight.
[0007] Japanese Patent Publication 20021132(A), Japanese Patent
Publication 20021133(A) and Japanese Patent Publication 20021134(A)
specifically address degradation of the thiol portion of an
aminothiol promoter of a bisphenol-A ion exchange resin catalyst
which has been modified with an aminothiol promoter, but do not
teach preventing degradation of the ion-exchange catalyst
itself.
[0008] Ion exchange resin catalysts are normally washed prior to
use to remove contaminants that can affect the operation of the
process. Methods of optimizing the washing of the catalyst prior to
use have been previously disclosed, for example, in European Patent
765685; U.S. Pat. No. 6,723,881; U.S. Pat. No. 5,723,691; Japanese
Patent Publication 2000143565(A); and Japanese Patent Publication
Kokai 09010598(A). U.S. Pat. No. 6,723,881 discloses, as part of a
catalyst preparation procedure, the use of "water free of dissolved
oxygen" in the water washing step. The catalyst preparation
procedure is taught as being effective in removing oligomer content
which occurs as a part of the catalyst production process; catalyst
degradation is not discussed in U.S. Pat. No. 6,723,881.
[0009] The prior known technologies described above relate to
methods of removing leachable material from a catalyst prior to its
use. What is needed in the industry is a method that will prevent
the leachable material from being formed in the first place, that
is, from being formed prior to use of the ion-exchange resin as a
catalyst. The prior known technologies described above relate to
methods which are used to remove leachable material after the
leachable material has been formed.
[0010] It is, therefore, desired to provide an economical method
for stabilizing an ion-exchange resin to prevent degradation of the
resin prior to its use as a catalyst.
[0011] One aspect of the present invention is directed to
stabilizing a strong acid ion exchange resin for use as an acid
catalyst to protect the resin from oxidative degradation and the
use of said stabilized ion exchange resin in chemical production
processes.
[0012] The degradation of ion exchange resin catalysts during
storage and prior to use may be prevented by storing the resin in
the absence of oxygen, for example, by using oxygen barrier
packaging, inert gas blanketing or vacuum packaging or some other
method that excludes oxygen from contacting the catalyst.
[0013] Another aspect of the present invention is directed to a
method for preventing the degradation of a catalyst during storage
of the catalyst which may be subjected to contact with an oxygen
environment and prior to using the catalyst in a chemical process
comprising treating the catalyst with an antioxidant. In this
instance, the antioxidant-treated catalyst can then be stored
without taking special precautions to prevent contact with oxygen
until further use.
[0014] Still another aspect of the present invention is directed to
a process for producing a chemical product in a chemical process
using a catalyst comprising (a) treating the catalyst with an
antioxidant; and (b) contacting the catalyst with the necessary
reactants to produce the chemical product in such chemical
process.
[0015] One embodiment of the chemical process for producing a
chemical product using a treated catalyst of the present invention
is, for example, a process for producing bisphenol A.
[0016] One objective of the present invention is to stabilize a
strong acid ion exchange resin for use as an acid catalyst to
protect the resin from oxidative degradation and the use of said
stabilized ion exchange resin in chemical production processes, for
example in the production of bisphenol A.
[0017] For the purposes of describing the present invention, the
"stability" of the resin refers to the resin's ability to withstand
decomposition during storage, handling, processing, and drying.
Decomposition is primarily caused by oxidation and can result in
unwanted color throw, leachables and elevated total organic carbon
(TOC) levels which can in turn affect the resins performance and
perceived quality. A stabilized resin resists oxidation upon
storage, handling, processing, and drying. Improving the stability
of the resin enhances the resins ability to resist oxidative
decomposition after long periods of storage, handling, processing,
and drying eliminating the color throw, leachables and elevated TOC
levels when such resin is brought into service.
[0018] Oxidative degradation can be observed as a progressive
discoloration of a cation exchange resin sample when stored without
special precautions to prevent oxygen contact. Immersion of such a
sample in water would result in a discoloration of the water, and a
noticeable increase in the acidity and the TOC content of the
water. An ion exchange resin that resists oxidative degradation is
said to have good shelf life, and would not discolor significantly
on storage, nor cause a large increase in water color, acidity or
TOC content when placed in water. Typical unstabilized cation
exchange resins do not have good shelf life, and begin to discolor
after storage of one month or less. A stabilized catalyst of the
present invention, on the other hand, will have a shelf life of
generally three months or more, preferably six months or more, and
most preferably greater than one year.
[0019] One embodiment of the present invention for preventing the
degradation of the ion exchange resin is to store the resin in such
a way as to prevent exposure of the resin to oxygen, that is, in a
way that prevents the resin from coming into contact with oxygen
before further use. Various means of preventing contact with oxygen
may be used, including the use of oxygen barrier packaging, inert
gas blanketing or vacuum packaging or some other method that
excludes oxygen from contacting the catalyst. Cation exchange
resins are often packaged in a water wet condition, and the
packaging used is typically a good barrier for water transmission
but not for oxygen transmission. For the purposes of the present
invention, the preferred oxygen barrier packaging would have an
oxygen permeability of 250 cc/m.sup.2.atm.day or less. Packaging
with an oxygen permeability of 100 cc/m.sup.2.atm.day or less is
preferred, and an oxygen permeance of 50 cc/m.sup.2.atm.day or less
is most preferred.
[0020] Preferred inert gases for blanketing include gases which
have low oxygen content and are generally considered to be
unreactive. More preferred gases include, for example, nitrogen,
argon, carbon dioxide and mixtures thereof. Nitrogen is the most
preferred gas. The oxygen content of the gas used for blanketing is
preferable less than 5 percent and more preferably less than 1
percent. The inert gas blanketing would preferably be used in
combination with the oxygen barrier packaging described above.
[0021] If vacuum packaging is used, the package is evacuated to
remove air. Preferably, the package is evacuated so that the gas
pressure in the package is less than 0.25 atmosphere (atm). More
preferably, the gas pressure in the package is less than 0.1 atm.
If the cation exchange resin is packaged in a water wet condition,
the gas pressure in the vacuum package is preferably no more than
0.1 atm over the vapor pressure of water at the temperature of the
package.
[0022] One preferred embodiment of the present invention for
preventing the degradation of the ion exchange resin includes
treating the ion exchange resin with an antioxidant. The
antioxidant and the steps necessary to apply the antioxidant to the
ion exchange resin are described below. The antioxidant is added to
the ion exchange resin, preferably at the time of manufacture of
the ion-exchange resin, to prevent degradation of the resin by
suppressing the free-radical mechanism.
[0023] The ion exchange resin used in the present invention
includes, for example, a cation exchange resin. Cation exchange
resins and processes for preparing cation exchange resins are well
known in the art, as exemplified in Helfferich, Ion Exchange,
McGraw-Hill Book Co., Inc., pp. 26-47 (1962). Advantageously, the
resins are prepared by first copolymerizing one or more monovinyl
monomers and one or more polyvinyl monomers to prepare a
crosslinked copolymer matrix, and then functionalizing the
copolymer matrix with groups which can exchange cations. Preferred
monovinyl monomers include styrene and its derivatives, acrylic or
methacrylic acid, esters of acrylic or methacrylic acid and
mixtures thereof. More preferred monovinyl monomers are the
monovinyl aromatic monomers, styrene being the most preferred.
Preferred polyvinyl monomers include divinylbenzene (DVB)
(commercially available DVB containing less than 45 weight percent
ethylvinylbenzene), trivinylbenzene, and diacrylates or
dimethacrylates. More preferred polyvinyl monomers are divinyl
monomers, especially divinyl aromatic monomers. The most preferred
polyvinyl monomer is DVB. A small amount of a third monomer may be
added. Such monomers include for example polyacrylonitrile and
ethylene glycol dimethacrylate. Amounts of such monomer may be, for
example, less than 10 wt percent, preferably less than 5 wt
percent, and more preferably less than 3 wt percent. The copolymer
matrix is advantageously functionalized with sulfonic, phosphinic,
phosphonic, arsenic, or carboxylic acid groups, or phenolic groups.
The copolymer matrix is preferably functionalized with sulfonic
acid groups.
[0024] Cation exchange resins useful in the present invention
include for example styrene-divinylbenzene types of strong acid ion
exchange resins such as DOWEX 50WX4, DOWEX 50WX2, DOWEX M-31, DOWEX
MONOSPHERE M-31, DOWEX DR-2030 and DOWEX MONOSPHERE DR-2030
catalysts commercially available from The Dow Chemical Company.
[0025] Other examples of commercially available ion exchange resins
useful in the present invention include Diaion SK104, Diaion SK1B,
Diaion PK208, Diaion PK212 and Diaion PK216 manufactured by
Mitsubishi Chemical Industries, Limited; A-15, A-35, A-121, A-232
and A-131 manufactured by Rohm & Haas; T-38, T-66 and T-3825
manufactured by Thermax; Lewatit K1131, Lewatit K1221, Lewatit
K1261 and Lewatit SC104 manufactured by Bayer; Indion 180 and
Indion 225 manufactured by Ion Exchange India Limited; and Purolite
CT-175, Purolite CT-222 and Purolite CT-122 manufactured by
Purolite.
[0026] The sulfonic acid-type cation-exchange resin catalyst useful
in the present invention can be, for example, a sulfonated
styrene-divinyl benzene copolymer, a sulfonated crosslinked styrene
polymer, a phenol formaldehyde-sulfonic acid resin, or a benzene
formaldehyde-sulfonic acid resin. The sulfonated styrene-divinyl
benzene copolymer copolymer being preferred. These resins can be
used in gel, porous, or seeded (U.S. Pat. No. 4,564,644; U.S. Pat.
No. 5,834,524; U.S. Pat. No. 5,616,622; U.S. Pat. No. 4,419,245)
forms. These resins can have narrow (U.S. Pat. No. 4,427,794; U.S.
Pat. No. 4,444,961; U.S. Pat. No. 3,922,255) or broad particle size
distributions. These resins can also be sulfone cross-linked
(EP1222960A2), shell functionalized (EP0552541A1, U.S. Pat. No.
5,081,160) and or contain greater than 1 sulfonic acid group per
benzene ring. And these resins can be used singly or in
combinations of two or more.
[0027] Antioxidants that may be used in the present invention
include soluble antioxidants, bound antioxidants and antioxidants
incorporated into the backbone of the cation exchange resin
polymer. Soluble antioxidants can be applied to the ion exchange
resin by dissolving them in water, then mixing the water dissolved
antioxidant with the cation resin. When the excess liquid is
drained from the resin, a portion of the antioxidant would be
retained in the water absorbed by the cation resin, if the cation
resin is left in a "water wet" condition. In some cases, if
desired, the soluble antioxidants can be removed from the cation
resin prior to use; and in such cases the antioxidant may be
removed from the cation resin prior to use by washing.
[0028] Bound antioxidants contain functionalities that cause the
antioxidants to become bound to the sulfonic acid groups of the
cation resin. For example,
2,6-di-t-butyl-.alpha.-dimethylamino-p-cresol contains an amine
group, a weak base, which binds strongly to the sulfonic acid
groups of the cation resin, and can only be rinsed off by using
strong acids or by neutralizing the strong acid groups
(neutralization would render the cation resin unusable as a strong
acid catalyst).
[0029] Antioxidants incorporated into the backbone of the cation
exchange resin polymer by copolymerization include monomers with
antioxidant properties that can be reacted with the other monovinyl
and/or polyvinyl monomers to be made part of the resin polymer
structure. Monomers with antioxidant activity may be incorporated
into the polymer backbone of the ion-exchange resin during
copolymer preparation prior to sulfonation. For example, EP 1078941
describes an ion-exchange resin containing a vinylpyridine as a
comonomer, wherein the vinylpyridine, which is incorporated into
the polymer, acts as an antioxidant. EP 1078940 describes
ion-exchange resins containing phenol derivatives as a comonomer,
in which the phenol derivative incorporated into the polymer acts
as an antioxidant.
[0030] The antioxidant useful in the present invention are
substances which retard deterioration of the cation exchange resin
by oxidation over time and may include for example those described
in U.S. Pat. No. 4,973,607. In addition the antioxidants used in
the present invention may include those described in Dexter et al.,
Encyclopedia of Polymer Science and Technology, Copyright .COPYRGT.
2002 by John Wiley & Sons, Inc.; Thomas et al., Kirk-Othmer
Encyclopedia of Chemical Technology, Copyright .COPYRGT. 2002 by
John Wiley & Sons; Ash, Michael and Irene, The Index of
Antioxidants and Antiozonants, Copyright 1997 by Gower; Denisov, E.
T., Handbook of Antioxidants, Copyright 1995 by CRC Press; and
Index of Commercial Antioxidants and Antiozonants, Copyright 1983
by Goodyear Chemicals; all of which are incorporated here by
reference.
[0031] Antioxidants which may be used in the present invention,
include for example, monocyclic of polycyclic phenols, amines,
diamines, hydroxylamines, thioesters, phosphites, quinolines,
benzofuranones, or mixtures thereof. The antioxidant should
preferably be unreactive in the chemical process for which the
cation resin is intended, especially if a bound or copolymerized
type of antioxidant is used. Other possible types of antioxidants
that may be used in the present invention are described in U.S.
Pat. No. 4,973,607.
[0032] Other examples of antioxidants useful in the practice of the
present invention may include various chemical preservatives that
are substances generally recognized as safe (GRAS) based upon the
Code of Federal Regulations, for Food and Drugs, 21CFR182.1 Subpart
D-Chemical Preservatives, reference 21CFR Parts 170-199, Apr. 1,
2001 revision. The preferred chemical preservatives for cation
exchange resin are used to improve storage and to control color
throw and TOC for long term storage. The additive to a typical
strong acid cation exchange resin stabilizes said resin to reduce
both visual and extractive color throw and to retard the
development of TOC leachables. The antioxidants or preservatives
are either GRAS or have been tested and approved for using in
indirect food contacting applications. Examples of GRAS chemical
preservatives can be found in Table I as listed in the Code of
Federal Regulations 21, Part 182.1 Subpart D or as commercially
tested and approved for indirect food contacting.
TABLE-US-00001 TABLE I Antioxidants/Chemical Preservatives Known to
GRAS as Listed in 21CFR182.1 Subpart D 182.3013 Ascorbic acid
182.3041 Erythorbic acid 182.3089 Sorbic acid 182.3109
Thiodipropionic acid 182.3149 Ascorbyl palmitate 182.3225 Calcium
sorbate 182.3280 Dilauryl thiodipropionate 182.3637 Potassium
metabisulfite 182.3640 Potassium sorbate 182.3731 Sodium ascorbate
182.3739 Sodium bisulfite 182.3766 Sodium metabisulfite 182.3795
Sodium sorbate 182.3798 Sodium sulfite 182.3862 Sulfur dioxide
182.3890 Tocopherols
[0033] Preferred examples of preservatives used in the present
invention include erythorbic acid, thiodipropionic acid, potassium
metabisulfite, ascorbic acid and Ethanox 703, ascorbyl palmitate,
sorbic acid, vitamin E, 1,3,5-trimethyl-2,4,6-tris
(3,5-di-tert-butyl-4-hydroxybenzyl)benzene (Ethanox 330), and
octadecyl-3-(3,5-di-T-butyl-4-hydroxphenyl) propionate (Ethanox
376).
[0034] A preferred antioxidant used in the present invention is
2,6-di-t-butyl-.alpha.-dimethylamino-p-cresol, an antioxidant sold
under the tradename Ethanox 703 by Albemarle Corporation.
[0035] The cation resin should preferably contain enough
antioxidant to effectively prevent oxidation of the resin prior to
use. If a bound antioxidant is used, the cation resin should not
contain so much antioxidant that the functionality of the acid
resin is impaired. A permissible range might include an antioxidant
content of from 0.001 to 10 percent of the cation resin by weight.
A preferable range of antioxidant content may be from 0.01 to 0.5
percent by weight.
[0036] Various methods may be used to apply the antioxidant to the
cation resin. For example, in one embodiment, the antioxidant may
be applied to the cation resin by first preparing a solution of the
antioxidant in water, and then mixing the aqueous antioxidant
solution with the cation resin until at least a portion of the
antioxidant present in the solution is adsorbed by the cation
resin. The excess solution is then drained from the cation
resin.
[0037] The aqueous antioxidant solution may contain other
components that are either optional or necessary to form the
solution. For example, the antioxidant
2,6-di-t-butyl-.alpha.-dimethylamino-p-cresol is sparingly soluble
in water, and therefore an acid such as hydrochloric acid is
preferably used to form an amine salt so that the antioxidant will
become soluble.
[0038] Optionally, the cation resin may be rinsed after the
antioxidant solution is applied to remove the unabsorbed elements
of the antioxidant from the resin. This rinsing step is
particularly desirable if a bound antioxidant, such as
2,6-di-t-butyl-.alpha.-dimethylamino-p-cresol, is used; or if the
antioxidant solution also contains other components that might
cause problems in the subsequent use of the cation resin. For
example, when treating a cation resin with a solution containing
the hydrochloric acid salt of
2,6-di-t-butyl-.alpha.-dimethylamino-p-cresol, hydrochloric acid
may be released. Thus, it may be preferable to rinse the
hydrochloric acid from the stabilized cation resin after applying
the hydrochloric acid salt of
2,6-di-t-butyl-.alpha.-dimethylamino-p-cresol to the cation
resin.
[0039] Optionally, the antioxidant application step can be combined
with an existing step in the manufacturing process of the cation
resin. For example, one step in a cation resin manufacturing
process is the sulfonation of the cation resin using sulfuric acid;
and after the sulfonation step of the cation resin, sulfuric acid
is present and must be rinsed from the resin. Application of the
sulfuric acid salt of 2,6-di-t-butyl-.alpha.-dimethylamino-p-cresol
could be done before the rinsing step is complete; since the
application would release sulfuric acid, the rinsing of this
sulfuric acid and the final traces of the residual sulfuric acid
from the resin during manufacturing of the resin could be done at
the same time.
[0040] The stabilized cation resin of the present invention may be
used in various chemical production processes where a catalyst is
used and wherein there is a need to prevent catalyst oxidation
regardless of the final end use. Such processes can include, for
example, condensation reactions of phenols and ketones;
phenol/acetone production; phenol or cresol alkylation; production
of methyl-t-butyl ether (MTBE) or other ethers by addition of an
alcohol to an alkene; acrylic or aliphatic ester production by
esterification or transesterification; isopropanol manufacture;
butene oligomerization; phenylphenol production; interconverting
MTBE with t-amyl-methyl ether (TAME), methyl isobutyl ketone (MIRK)
production; dianone production that is reduced to o-Phenyl phenol;
acrylic- and methacrylic ester production for fibers; and dihydric
phenol 2,2 bis(4'-hydroxyphenyl) propane production. The
antioxidants of the present invention are useful in processes
wherein color and acid throw may be a problem and offer the
potential to make cleaner, lower color solvents and the reduction
of acid release.
[0041] The stabilized cation resin is preferably used in a process
for producing the dihydric phenol 2,2 bis(4'-hydroxyphenyl) propane
(commonly referred to as "bisphenol A") which is commercially
prepared by condensing 2 moles of phenol with a mole of acetone in
the presence of an acid catalyst. A mole of water co-product is
coproduced. The bisphenol A process is a well-known process and is
described, for example in U.S. Pat. Nos. 4,400,555; 6,703,530;
6,307,111; 6,465,697; and 6,737,551.
[0042] The strong acid cation resins of the present invention
generally show both a low color throw and a low TOC leachables
after treatment with the antioxidant described above. Such benefits
are shown after the resin is stored, for example, for up to 6
months with no significant increase in color throw and TOC
leachables.
[0043] Colorimetric testing methods can be applied to evaluate for
color throw. Such testing as well as visual observation is often
applied at the point of packaging a resin to assure the quality as
manufactured is acceptable and that the resin has been properly
processed and washed. Resins may develop color upon storage, which
are both measurable by a colorimetric test and/or visual
observation. Color throw may impart undesirable colored materials
into a process stream.
[0044] One method for testing the oxidative stability of cation
exchange resins is to use an accelerated aging test. An example of
such a test is described as follows: 100 mL of water wet cation
exchange resin and 500 mL of deionized water are placed in a
jacketed flask and stirred to equilibrate the mixture. Initial
samples of the water are removed for analysis. The flask contents
are heated to 80.degree. C. Pure oxygen is bubbled through the
flask at approximately 50 cubic centimeters/minute, while the
contents are agitated by stirring. A condenser is used to prevent
the evaporative loss of water from the flask. The flask contents
are maintained in contact with oxygen at 80.degree. C. for 7 days.
At the end of 7 days, the samples of water are removed for
analysis. The above procedure shall be hereafter referred to as the
Accelerated Aging Test.
[0045] In the present invention, the increase in the color of the
water after 7 days in the above test should be no more than 500
APHA as measured by a Hunterlab Color Quest analyzer or other known
color analyzers. The amount of color throw may also depend upon the
application use and the acceptable levels in such application.
[0046] Organic extractives for cation ion exchange resins can be
measured using a number of known TOC testing methods such as for
example a Shimadzu TOC analyzer. In the present invention, the
increase in the TOC levels of the water after seven days in the
above test should be no more than 500 ppm as measured by a Shimadzu
TOC analyzer or equivalent instrument. The amount of TOC will also
depend upon the application use and the acceptable levels in such
application.
[0047] The following examples are included herein to illustrate the
present invention; and are not to limit the scope of the present
invention.
EXAMPLE 1
Part A
Application of the Antioxidant
[0048] In this Part A of Example 1, varying amounts of an
antioxidant, 2,6-di-t-butyl-.alpha.-dimethylamino-p-cresol, were
incorporated into a styrene/divinylbenzene gel cation exchange
resin sold commercially by The Dow Chemical Company under the
trademark DOWEX 50WX4.
[0049] In a first step, solutions of the antioxidant and an acid in
water were prepared by adding the desired amount of the antioxidant
and the acid to deionized water and then stirring the mixture until
the materials dissolved in the water.
[0050] In a second step, 100 mL of the antioxidant solution and 100
mL (80 g) of a well-washed water-wet cation resin were combined in
a flask and stirred for 30 minutes. After 30 minutes, the
antioxidant solution and the cation resin were separated by
filtration and the cation resin was washed thoroughly with
deionized water to remove any traces of acid from the resin.
[0051] Uptake of the antioxidant on the resin was estimated by
analyzing the solution's level of total organic carbon (TOC) before
and after the cation resin was treated. The use of TOC for uptake
estimation is approximate; since the TOC measurement may respond to
components that leach from the resin, the actual uptake may be
greater than the calculated estimate. The treatment solution
composition (antioxidant solution) and the uptake data are listed
in Table 1. Uptake of this bound antioxidant is accomplished by
partial neutralization of the acid groups on the cation resin with
the amine group of the antioxidant. The fraction of the acid groups
neutralized was calculated and is also listed in Table 1. Nine
catalyst samples were prepared in this Part A of Example 1: Samples
1-8 were treated with antioxidant and Sample 9(C) is a comparative
sample containing no antioxidant.
TABLE-US-00002 TABLE 1 Application of the Antioxidant SAMPLE NUMBER
1 2 3 4 5 6 7 8 9(C) SOLUTION PREPARATION Acid Type HCl HCl HCl HCl
H.sub.2SO.sub.4 H.sub.2SO.sub.4 H.sub.3PO.sub.4 H.sub.3PO.sub.4
None Acid 1 1 1 1 1 1 1 1 Concentration (N) Acid Amount (mL) 7 2.1
0.7 50 27 100 38 150 Antioxidant 1 0.3 0.1 1 1 1 1 1 None Amount
(g) Total Solution 1000 1000 1000 1000 1000 1000 1000 1000 Amount
(g) Acid Concentration 0.007 0.0021 0.0007 0.05 0.027 0.1 0.038
0.15 in solution (N) Antioxidant 0.1 0.03 0.01 0.1 0.1 0.1 0.1 0.1
Concentration in solution (percent) ANTIOXIDANT APPLICATION Cation
Resin 100 100 100 100 100 100 100 100 100 Amount (mL) Solution
Amount (mL) 100 100 100 100 100 100 100 100 0 Initial TOC (ppm) 764
236 77 798 836 824 804 819 N/A Final TOC (ppm) 31 93 3 5 3.4 6 3.4
51 N/A Antioxidant .gtoreq.96 .gtoreq.60 .gtoreq.96 .gtoreq.99.4
.gtoreq.99.6 .gtoreq.99.3 .gtoreq.99.6 .gtoreq.94 N/A Uptake
(percent) Antioxidant 0.12 0.023 0.012 0.12 0.12 0.12 0.12 0.12 0
Concentration on Resin (percent by weight) Resin Acid Content 0.28
0.053 0.028 0.28 0.28 0.28 0.28 0.28 0 Neutralized (percent)
[0052] As shown in Table 1 above, greater than 90 percent of the
antioxidant was taken up by the cation resin in all of the samples
but one (Sample 2). The results in Table 1 show that the uptake of
the antioxidant is not strongly affected by the type and amount of
acid used. This is demonstrated even though in some cases a
significant excess of acid was used over the amount necessary to
form a salt of the antioxidant.
Part B
Catalyst Aging
[0053] In this Part B of Example 1, an Accelerated Aging Test was
carried out on the catalyst to show that an antioxidant suppresses
degradation of a cation resin. The testing is designed to simulate
the aging of the catalyst.
[0054] 100 mL of a catalyst sample and 500 mL of deionized water
were placed in a jacketed flask. Then the flask contents were
heated to 80.degree. C. Pure oxygen was bubbled through the flask
contents at approximately 50 cubic centimeters/minute, while the
contents were agitated by stirring. A condenser was used to prevent
the evaporative loss of water from the flask. The flask contents
were maintained in contact with oxygen at 80.degree. C. for up to 7
days, and samples of the water were removed periodically for pH,
TOC and color analysis.
[0055] Color analysis was done using a HunterLab Color Quest
colorimeter. TOC analysis was done using a Shimadzu analyzer.
Samples 1, 2, 3 and 9(C) from Part A of Example 1 were tested in
this way, and the results are shown in Table 2.
TABLE-US-00003 TABLE 2 Results of Accelerated Aging Test Effect of
Antioxidant Concentration on Oxidation SAMPLE NUMBER 9 (C) 1 2 3
Antioxidant Concentration 0 percent 0.12 percent 0.023 percent
0.012 percent Color TOC Color TOC Color TOC Color TOC pH (APHA)
(ppm) pH (APHA) (ppm) pH (APHA) (ppm) pH (APHA) (ppm) Initial 3.37
13 15 3.38 15 17 4.51 9 7 5.01 3 4 24 hours 3.17 200 117 3.48 90 42
3.17 143 60 3.1 180 83 48 hours 3.01 383 221 3.40 110 48 3.30 198
77 2.91 286 129 72 hours 2.84 592 349 3.35 122 56 3.00 227 89 2.82
385 190 96 hours 2.78 861 511 3.35 138 61 2.90 255 101 2.60 523 265
120 hours 2.69 1087 628 3.11 141 65 -- -- -- 2.47 718 393 144 hours
2.55 1439 849 3.09 155 70 -- -- -- 2.38 925 541 168 hours 2.28 1794
1113 3.07 162 74 2.59 292 121 2.32 1215 766
[0056] The results for Sample 9(C) from Table 2 show that the
cation resin suffers substantial degradation due to the oxidation
conditions of this test, and that the material that leaches into
the water is acidic. Leaching of this material into bisphenol
process streams would cause significant operational problems. The
results for Samples 1, 2 and 3 from Table 2 show that the
antioxidant suppresses the degradation of the cation resin, since
only a minimal increase of the solution color and TOC is observed
for these Samples. The solution pH is also shown to be stable after
the initial equilibration of the water and the cation resin. The
results of Table 2 also show that larger amounts of antioxidant are
more effective in suppressing the oxidation of the cation
resin.
[0057] Samples 5 and 7 from Part A of Example 1 were also tested as
described above, and the results are shown in Table 3.
TABLE-US-00004 TABLE 3 Results of Accelerated Aging Test Effect of
Acid Used in Antioxidant Treatment on Oxidation SAMPLE NUMBER 9 (C)
1 5 7 Acid used to apply antioxidant None HCl H.sub.2SO.sub.4
H.sub.3PO.sub.4 Antioxidant Concentration 0 percent 0.12 percent
0.12 percent 0.12 percent Color TOC Color TOC Color TOC Color TOC
pH (APHA) (ppm) pH (APHA) (ppm) pH (APHA) (ppm) pH (APHA) (ppm)
Initial 3.37 13 15 3.38 15 17 4.27 9 7 4.68 8 54 24 hours 3.17 200
117 3.48 90 42 3.74 58 24 3.60 44 20 48 hours 3.01 383 221 3.40 110
48 -- -- -- -- -- -- 72 hours 2.84 592 349 3.35 122 56 -- -- -- --
-- -- 96 hours 2.78 861 511 3.35 138 61 3.54 101 41 3.33 92 37 120
hours 2.69 1087 628 3.11 141 65 3.50 109 54 3.25 105 46 144 hours
2.55 1439 849 3.09 155 70 3.55 119 50 3.10 114 44 168 hours 2.28
1794 1113 3.07 162 74 -- -- -- -- -- --
[0058] The results described in Table 3 above show that the
antioxidant applied using solutions prepared with H.sub.2SO.sub.4
and H.sub.3PO.sub.4 in Part A of this Example 1 are just as
effective in suppressing oxidation as the antioxidant applied using
solutions prepared using HCl.
Part C
Washing the Aged Catalyst
[0059] In this Part C of Example 1, the aged cation resin of
Samples 1 and 9(C) were washed to demonstrate that an antioxidant
stabilized resin is more easily washed than an unstabilized resin
in preparation for use in a bisphenol process.
[0060] The washing procedure was carried out as follows: 20 mL of a
catalyst sample were placed in a graduated burette, with glass wool
at the bottom of the burette to retain the resin sample. Then, 40
mL of deionized water was added to the graduated burette and
allowed to flow slowly through the resin. The wash water was
collected, then tested for pH, TOC and color using the test methods
described in Part A of this Example 1. Several washes of each
sample were done using successive 40 mL aliquots of deionized
water. The results are shown in Table 4.
TABLE-US-00005 TABLE 4 Results of Washing Aged Resin Samples SAMPLE
NUMBER 9 (C) 1 Resin Antioxidant Concentration Successive 0 percent
0.12 percent Water Wash Color TOC Color TOC Aliquots pH (APHA)
(ppm) pH (APHA) (ppm) Before Washing 2.06 1737 1355 3.00 164 97
1.sup.st 3.43 71 59 3.92 15.6 21 2.sup.nd 4.55 3.7 5.9 5.06 1.3 4.0
3.sup.rd 4.96 2.2 2.8 5.47 2.0 2.4 4.sup.th 4.78 2.6 2.7 5.07 1.3
1.8 5.sup.th 4.86 2.1 3.0 5.30 1.5 1.9 6.sup.th 5.04 2.6 2.5 5.38
1.1 1.7 7.sup.th 5.10 1.8 2.3 5.46 1.8 1.6
[0061] The results described in Table 4 above demonstrate that low
levels of wash water color and TOC are achieved more rapidly with
the antioxidant-stabilized resin. The results of Table 4 also show
that a high pH in the wash water is achieved more rapidly with the
antioxidant-stabilized resin.
[0062] After washing the Samples with seven 40 mL aliquots of
water, the water was drained from the aged catalyst samples, and
the Samples were then washed with 40 mL aliquots of phenol using
the above procedure. During the phenol washes the volume of each
resin sample shrank from 20 mL to 13 mL. The color of the collected
phenol aliquots was measured and the measurements are shown in
Table 5. The first and fourth phenol aliquots were collected and
allowed to age for 48 hours at 80.degree. C. The phenol color was
then remeasured, and is also shown in Table 5.
TABLE-US-00006 TABLE 5 Results of Phenol Wash of Aged and Washed
Resin Samples SAMPLE NUMBER 9 (C) 1 Resin 0 percent 0.12 percent
Antioxidant Concentration Successive Color Color 40 mL Phenol
(APHA) (APHA) Wash Aliquots 1st 22 18 2nd 20 10 3rd 18 11 4th 15 8
Phenol Wash Color After 48 Hours at 80.degree. C. 1st 33 20 2nd --
-- 3rd -- -- 4th 17 12
[0063] Even after the extensive water washing of the above Samples,
some acidic leachables still remained in the resin and discolored
the phenol. The acidic leachables caused a color increase in the
phenol during storage at elevated temperature, and the color
increase in the phenol used to wash the untreated resin was worse
than for the treated resin. The tests conducted under this Part C
of Example 1 demonstrate that the stabilized resin is easier to
wash than the untreated resin. The results under this Part C of
Example 1 also demonstrate that even extensive water washing is
inadequate to remove all of the leachables from the untreated
resin, and that the leachables can enter the phenol when it
contacts the resin and cause degradation of the phenol.
EXAMPLE 2
Use of Stabilized Catalyst to Produce Bisphenol-A
[0064] 1.2 grams (g) of 2,6-di-t-butyl-alpha-dimethylamino-p-cresol
were dissolved in an acidified water solution. Then, the solution
was slowly added to a stirred vessel containing 600 mL of DOWEX
50WX4 cation exchange resin and excess water. The above amount of
2,6-di-t-butyl-alpha-dimethylamino-p-cresol is enough to neutralize
approximately 0.56 percent of the acid content of the cation
exchange resin.
[0065] The treated cation exchange resin was rinsed thoroughly with
deionized water, and then stored in a closed plastic container for
three months.
[0066] After three months, the treated resin was removed from
storage and found not to have discolored, as untreated cation resin
usually does during this length of storage.
[0067] 213 mL of the water-wet treated resin was placed in a flask
with excess water. 8.47 g of dimethylthiazolidine (DMT) was slowly
added to the flask while stirring. The excess water was removed
from the treated resin, and then the treated resin was rinsed
thoroughly with deionized water. A sample of this resin was tested
by titration, and 22 percent of the acid sites of the resin were
found to be neutralized.
[0068] 15 mL of the DMT-promoted cation exchange resin was placed
in a jacketed, continuous-flow reactor and dried by passing phenol
over the resin. Phenol containing 4.05 percent acetone by weight
was fed to the reactor, using a space-time velocity of 1 hr.sup.-1
based on the water wet resin volume. The reactor temperature was
maintained at 65.degree. C. The product from the reactor was
analyzed and found to contain 12.4 percent p,p'-bisphenol-A by
weight. The selectivity was characterized by a 0.0298 ratio of
o,p'-bisphenol-A to p,p'-bisphenol-A. The acetone conversion was
found to be 75 percent.
* * * * *