KR19980042063A - Regeneration of Waste Acid Catalyst Resin - Google Patents

Abstract

The spent etherified catalyst resin can be regenerated to almost catalytic activity by treating the spent resin with a sulfonating agent under sulfonation conditions.

Description

Regeneration Method of Waste Acid Catalyst Resin

The present invention relates to the use of cation exchange resins as acid catalysts, and more particularly to the regeneration and recycling of spent acid catalyst resins.

Cation exchange resins are subject to catalytic reactions, including the formation of methyl t-butyl ether (MTBE) from methanol and isobutylene, or the formation of t-amyl methyl ether (TAME) from isoamylene and methanol. Often used. Because of the importance of MTBE as a gasoline additive, and the mass production of this material, large amounts of cation exchange resins are used to catalyze this reaction. In use, the catalytic resin is contaminated by polymeric materials present in the feed material and catalyst inhibitors such as metal ions and nitrogen-containing materials. Such contamination is thought to reduce the porosity and surface area of the catalyst, which in turn reduces the availability of acid catalyst sites. The presence of nitrogen-containing materials tends to reduce the activity of the acid catalyzed resin, which condition is called nitrogen poisoning. Although not a major cause of catalyst activity loss, the catalyst resin also undergoes some limited desulfon leaving. Thus, the gradual deterioration of the catalytic effect proceeds until the catalyst resins are considered waste, until they are no longer suitable for use in the process in which they are used.

It is economically and environmentally beneficial to reduce the amount of cation exchange resins used after use, for example in the MTBE industry, and one way to do this is to regenerate the resin to provide sufficient activity to be useful in the original catalytic process. It is made to regenerate with the catalyst resin which has.

The present inventors have thus found an acid catalyst waste resin regeneration method comprising treating a waste acid catalyst resin with an effective amount of a sulfonating agent under sulfonation conditions, and then separating the catalyst resin from the sulfonating agent.

The inventors further found an example wherein the catalyst resin is a sulfonic acid-functionalized cation exchange resin and more preferably the sulfonating agent is sulfuric acid having a concentration of at least 85% by weight.

The inventors have found another more preferred embodiment in which the sulfonating agent is fumed sulfuric acid (oleum) with a sulfur trioxide content of 10 to 40% by weight, wherein after use the catalyst resin is regenerated into a polysulfonated catalyst resin.

In a particularly preferred embodiment of the present invention, the inventors have described sulfonic acid-functionalized catalyst resins which have been used as etherification catalyst resins until their activity is no longer useful for catalyzing etherification reactions with 60 to 140 An etherification catalyst waste resin regeneration method comprising treatment at 1.5 ° C. for 1.5-6 hours was discovered. A particularly advantageous aspect of the present invention is that existing equipment and procedures for sulfonating copolymers with cation exchange resins can be used for catalyst resin regeneration. This is surprising in view of the limited loss of sulfonic acid groups during broad catalysis such as, for example, etherification catalysis; Observational losses of sulfonic acid groups of minority up to 10% by weight were not expected to explain the observed, large losses of etherification catalyst activity. Conversely, treatment of the catalyst resin under sulfonation conditions did not envision the ideal of regenerating its few percent lost sulfonic acid groups, and adding more sulfonated groups to the already sulfonated aromatic nuclei of the copolymer, It would not have been expected to have another beneficial effect on the catalytic activity of the cation exchange resin in such catalysation reactions such as oxidation.

Catalyst resins useful in the present invention are acid catalyst waste resins, preferably strong acid catalyst resins, prepared by monosulfonating or polysulfonating a macroporous, crosslinked, styrene copolymer to form a sulfonic acid-functionalized catalyst resin. Include things. Such catalyst resins are further subjected to continued use of an organic chemical reaction as a catalyst, preferably for example etherification of methanol and isobutylene to MTBE, or etherification of methanol and isoamylene to TAME. It is used to catalyze until it loses a sufficient portion of its catalytic activity that is no longer practical. Such catalyst resins typically have reduced catalyst capacity, which is believed to result from contamination from a small to small loss of sulfonic acid groups to a lesser extent by polymers, contaminants in the feed mother liquor and other materials. In the specification, it is referred to as catalyst waste resin.

In practice, the user of the catalyst resin determines that the catalyst resin should be replaced when the reaction conversion is lowered to the point where the catalyst resin is used and the continuous operation of the process with the current catalyst is no longer stalled. The user will typically monitor the concentration of the reactants, such as, for example, reactive olefins in the etherification reaction, both before and after the reactants pass through the bed of catalyst resin, and the conversion is a percent reduction in reactant concentration. Of course, instead of monitoring the reactants entering and leaving the bed, one may choose to monitor the concentration of the reaction product exiting the catalyst resin bed.

For the purpose of illustrating how to determine when the catalyst resin is consumed, the catalyst resin can be operated in a process in which isobutylene and methanol are etherified with MTBE and the feed concentration of isobutylene is 16%. The new catalyst resin gives a conversion of 95% at the beginning of the operation, which means that the concentration of isobutylene at the reactor outlet is only 0.8%. As the reaction proceeds, the catalytic activity of the catalyst resin will decrease and the isobutylene concentration at the reactor outlet will increase. For example, when the concentration of isobutylene increases to 1.92% at the reactor outlet and correspondingly reduces the conversion to 88%, it may be determined that the catalyst resin should be replaced.

The specific decision depends on the user of the catalyst resin and is influenced by such things as the downstream processing unit's ability to treat unconverted reactants, the cost of separating the reactants from the product and the reduced purity of the final product. However, at some point, each user of the acid catalyst resin determines that the catalytic activity of the resin has decreased until it is economical to replace the resin rather than continue to operate. The resin removed in the process equipment is a spent catalyst resin.

As used herein, the term sulfonation conditions means average reaction conditions, ie temperatures, pressures and times suitable for incorporation of sulfonic acid functional groups into the aromatic nucleus of crosslinked, aromatic copolymers that are not previously sulfonated, e.g. For example, polysulfonation of the copolymer may be carried out under conditions suitable for monosulfonation of the copolymer, such as treatment of the copolymer with concentrated sulfuric acid at elevated temperatures, and treatment of the copolymer with high concentration exothermic sulfuric acid, for example, at elevated temperatures. Suitable conditions are included. The treatment time of the used resin is approximately equal to the time suitable for sulfonating similar aromatic copolymers which have not been sulfonated beforehand. Such conditions are well known to those skilled in the art. The treatment time of a selected set of sulfonation conditions can be determined more accurately by gradually processing a sample of the spent catalyst resin for a longer time and determining the time required to return to the catalytic activity of the near-catalyst resin before use as a catalyst. have.

When sulfuric acid is used to regenerate the resin after use of the present invention, the sulfuric acid has a concentration of at least 85% by weight. The temperature at which the catalyst resin is treated with sulfuric acid after use is 60 ° C to 150 ° C, preferably 80 ° C to 140 ° C, and more preferably 110 ° C to 135 ° C. The pressure for treating the catalyst resin with sulfuric acid after use is 100 to 200 kPa, more preferably at ambient pressure. The treatment time should be sufficient to regenerate the catalytic activity of the catalyst resin, preferably 0.5 hours to 6 hours, more preferably about 1 to 3 hours.

When fuming sulfuric acid is used to treat the catalyst waste resin of the present invention, the fuming sulfuric acid has a concentration of 10 to 40% by weight of sulfur trioxide dissolved in 100% of sulfuric acid in order to generate or regenerate the polysulfonated catalyst resin. The temperature at which the catalyst resin is treated with fuming sulfuric acid after use is 40 ° C to 150 ° C, preferably 60 ° C to 140 ° C, and more preferably 80 ° C to 130 ° C. The pressure for treating the catalyst resin with fuming sulfuric acid after use is 100 to 200 kPa, more preferably at ambient pressure. The treatment time should be sufficient to produce or regenerate the catalytic activity of the polysulfonated catalyst resin, preferably 0.5 to 6 hours, more preferably 1 to 3 hours. Polysulfonated catalyst resins are those having an average of at least one sulfonic acid group per available aromatic ring, ie per aromatic ring available for sulfonation. Since not all aromatic rings are used in sulfonation in highly crosslinked copolymers and resins, the actual sulfonic acid functionality of polysulfonated resins will be less than the theoretical maximum for monosulfonated resins. More details on this are described in US Pat. No. 4,839,331 to Maroldo et al.

Of course, it is possible to complex sulfonate a monosulfonated catalytic waste resin, i.e., a polysulfonated cation exchange resin used as a catalyst resin in an etherification reaction, at the same time regenerating contaminants that reduced its catalytic activity and It is also within the scope of the present invention to convert to fonned catalyst resin.

Once regenerated by treatment with a sulfonating agent under sulfonating conditions, the catalyst resin is separated from the sulfonating agent. This is done, for example, by washing the catalyst resin with water or another solvent to remove the sulfonating agent. Those skilled in the art, such as initial cleaning with dilute sulfonating agents, whether one or two or more times with progressively less sulfonating agents in water or other solvents, respectively, before washing with pure water or solvents Methods known to the art can be used. The catalyst resin is then separated from the water or solvent by filtration, drainage or other known methods.

When the used catalyst resin is treated according to the present method, polymer contamination, contamination by nitrogen-containing materials and desulfon leaving effect are much eliminated, and the used catalyst has the same catalytic activity as the unused catalyst resin in the use of the catalyst and It is regenerated into a useful catalyst resin with a long lifetime.

In the following examples, all reagents used are of good industrial quality unless otherwise stated, and all percentages and percentages are by weight unless otherwise indicated.

Example 1

This example illustrates the regeneration of monosulfonated acid catalyzed waste resin with sulfuric acid used in the preparation of MTBE.

To the reactor containing 8616 kg 98% sulfuric acid was added 1524 kg of sulfonic acid-functionalized used catalyst resin used as etherification catalyst resin in the preparation of MTBE. After the mixture was heated to 122 ° C. and maintained at that temperature for three hours, water was added at a rate that kept the temperature of the mixture between 80 ° C. and 110 ° C. until the concentration of sulfuric acid became less than 10%. The regenerated sulfonic acid-functionalized catalyst resin was then washed with deionized water in a backwash tower and taken out. The regenerated catalyst resin had a cation exchange capacity of 4.8 meq / g, and a cation exchange capacity of 4.40 meq / g before regeneration, of 4.9 meq / g. The regenerated catalyst resin is yellowish brown to black in contrast to yellowish brown.

Example 2

This example illustrates the regeneration of another sample of spent catalyst resin used for etherification of another feed mother liquor to prepare MTBE.

The procedure of Example 1 was followed. The regenerated catalyst resin had a cation exchange capacity of 4.8 meq / g compared to the cation exchange capacity of the new catalyst resin was 4.8 meq / g, and the precation cation exchange capacity was 4.76 meq / g.

Example 3

This example illustrates the regeneration of polysulfonated catalyst resin of the monosulfonated spent acid catalyst resin used in the preparation of MTBE with fuming sulfuric acid.

The procedure of Example 1 was followed except that for every kg of catalyst resin after use, sulfuric acid was replaced with 15 kg of 20% fuming sulfuric acid and the mixture was heated to 130 ° C. and its temperature maintained for 4 hours. The resulting polysulfonated catalyst resin was 5.5 meq / g, while the cation exchange capacity of the new polysulfonated catalyst resin was 5.4 meq / g.

Example 4

This example illustrates the use of the regenerated catalyst resin of Example 1 to etherify isobutylene and methanol with methyl t-butyl ether.

A sample of approximately 900 ml volume of water-hydrated catalyst resin regenerated in Example 1 was gradually concentrated in an aqueous methol solution, initially 10 wt% methanol, then 20 and 30 wt% methanol respectively, and finally Was slurried in pure methanol, about 2 L each, and saturated with methanol, discarding excess liquid from the catalyst before adding the next methanol solution.

The catalyst resin was then charged as slurry in two 152 cm reactor sections and then connected in series and heated by circulating hot water through a kit of attention to the reactor section. After a short run the effective catalyst resin bed was placed at a depth of about 274 cm. Initially the reactor section was heated to 55 ° C. and the feed liquid with the composition shown in Table 1 was fed to the reactor inlet at a 3.3 to 3.8 liquid hourly space velocity (ie, volume of feed / volume of catalyst). By raising the temperature in the reactor to 75 ° C. (from the exothermic reaction) the conversion of isobutylene was 94.6 ± 1.50, 94.0 ± 0.50 and 96.1 ± 1.44 mol%, respectively, for three consecutive operations with a total feed of 80 kg each. The fractional selectivity (conversion to methyl t-butyl ether) for each operation was 0.996.

For comparison, under similar conditions the new catalyst resin had the same fractional selectivity of 0.996 and the isobutylene conversion yielded about 92 mol%. In a typical operation, the catalyst resin will be well replaced when the conversion of isobutylene to methyl t-butyl ether drops to about 88 mole percent.

Feed solution composition for regenerated catalyst resin evaluation ingredient Molecular Weight weight% mole% n-pentanepropanemethanolisobutyleneisobutanen-butane 72.1544.1132.0456.1158.1258.12 0.4110.3985.2498.02142.67843.24320 ppm 0.31650.50139.01237.942540.798641.3388

Example 5

This example illustrates the use of the regenerated catalyst resin of the present invention to catalyze the etherification of t-amyl methyl ether of isoamylene with methanol, a novel and post-use and regenerated monosulfonated catalyst resin and a new and regenerated The comparison between the polysulfonated catalyst resins is shown.

The catalyst resins of Examples 1 and 3, in fresh, post-use and regenerated form, were used in the t-amyl methyl ether etherification reaction. The feed mother liquor containing isoamylene and methanol was reacted at elevated temperature over a separate bed of fresh, used, monosulfonated catalyst and the spent catalyst was regenerated according to Example 1; The new polysulfonated catalyst and the spent polysulfonated catalyst were regenerated according to Example 3. Each synthesis condition was approximately equal, allowing for comparison between several processes. The total production of t-amyl methyl ether by the synthesis operation with the catalyst, respectively, was recorded at 30 and 60 minutes and is shown in Table 2 below.

Synthesis of t-amyl Methyl Ether Hour Example 1 Fresh Catalyst Example 1 Post-Use Catalysts Example 1 Regenerated Catalyst Example 3 Fresh Catalyst Example 3 Regenerated Catalyst 3060 0.1550.255 0.0900.180 0.1600.270 0.2200.295 0.2250.300

At any time, the ether production (catalytic activity) of the regenerated catalyst resin was at least as high as the activity of the new catalyst resin and was much better than the activity of the catalyst resin after use.

According to the above, the present invention can regenerate the activity of the resin to almost original value by treating the used etherification catalyst resin with a sulfonating agent under sulfonation conditions.

Claims (8)

Treating the spent acid catalyst resin with an effective amount of sulfonating agent under sulfonation conditions, Then separating the catalyst resin from the sulfonating agent. The method of claim 1 wherein the spent acid catalyst resin is a sulfonic acid-functionalized cation exchange resin. The method of claim 2 wherein the sulfonating agent is sulfuric acid having a concentration of at least 85% by weight. The method of claim 2, wherein the sulfonating agent is fuming sulfuric acid having a content of sulfur trioxide of 10 to 40% by weight. The method of claim 2, wherein the catalyst resin is used as an etherification catalyst, the temperature rise is 60 to 140 ℃, and a time sufficient to restore the catalyst activity to the catalyst is 0.5 hours to 6 hours. Used as etherification catalysts until their activity is no longer useful for catalyzing etherification reactions and regenerated by treating the spent catalysts with sulfonating agents, Recycled etherification catalyst resin. 7. The regenerated catalyst resin of claim 6, wherein the sulfonating agent is sulfuric acid having a concentration of at least 85% by weight and the regenerated catalyst resin is a monosulfonated catalyst resin. The regenerated catalyst resin of claim 6, wherein the sulfonating agent is fuming sulfuric acid having a concentration of sulfur trioxide of 10 to 40 wt%, and the regenerated catalyst resin is a polysulfonated catalyst resin.