Method of cleaning resins

Abstract

Provided is a method of cleaning a collection of resin beads, wherein the method comprises bringing the collection of resin beads into contact with an aqueous solution, wherein the aqueous solution comprises one or more dissolved amine compounds, wherein the collection of resin beads comprises polymer that comprises attached carboxylic acid groups or sulfonic acid groups or a mixture thereof.

Claims

1. A method of cleaning a collection of resin beads, wherein the method comprises bringing the collection of resin beads into contact with an aqueous solution, wherein the aqueous solution comprises one or more dissolved amine compounds, wherein the collection of resin beads comprises polymer that comprises attached carboxylic acid groups or sulfonic acid groups or a mixture thereof.

2. The method of claim 1, wherein the amine compound has the structure (I) ##STR00004## wherein R.sup.1 is an organic group comprising 1 to 30 carbon atoms; wherein each of R.sup.2 and R.sup.3 is independently either hydrogen or an organic group comprising 1 to 30 carbon atoms.

3. The method of claim 2, wherein R.sup.1 additionally comprises one or more atom of oxygen, one or more atom of nitrogen, or a combination thereof.

4. The method of claim 1, wherein the amine compound is present in the aqueous solution at a concentration of 0.1% to 6% by weight based on the weight of the aqueous solution.

5. The method of claim 1, wherein the amine compound has a pKa of the conjugate acid of 6 to 10.

6. The method of claim 1, wherein the polymer comprises attached sulfonic acid groups.

7. The method of claim 1, wherein the collection of resin beads comprises gel resin beads.

Description

EXAMPLE 1: CONCENTRATIONS OF AMINE COMPOUND

(1) Washing of the resin was accomplished as follows. A glass chromatography column equipped with circulated-water heating jacket was installed vertically. The water in the jacket was circulated and brought up to 75° C. Then 100 mL of resin was loaded into the column (i.e., bed volume “BV”=100 mL). Then 5 BV of Test Wash solution was passed through the column at 1.2 BV/hr. Then the heating jacket was returned to RT, and 1.4 BV of DIW was passed through the column at 4 BV/hr. The resin was siphoned dry and stored in glass bottles for 7 days, and then tested by the shake test.

(2) Five Test Wash solutions were prepared of TEA in deionized water. Concentrations were, by weight, 0.2%, 1%, 2%, 3%, and 5%. Results were as follows:

(3) TABLE-US-00001 TABLE 1 Concentrations of Amine Compound TEA % Conductivity (μs/cm) pH TOC (ppm) 0 19 4.26 7.11 0.2 14 4.3 4.8 1 11 4.45 2.89 2 5.95 5.32 3.1 3 4.88 5.47 3.76 5 4.23 6.03 5.53
The conductivity and pH results show that the higher the concentration of TEA, the better the result. The TOC results show that 1% to 2% TEA is optimum.

EXAMPLE 2: LONGER STORAGE

(4) Washing of the resin was accomplished as follows. A glass chromatography column equipped with circulated-water heating jacket was installed vertically. The water in the jacket was circulated and brought up to test temperature (“temp”) (either RT or 90° C.). Then 100 mL of resin was loaded into the column (i.e., bed volume “BV”=100 mL). Then 1.2 BV of “Test Wash” solution (either DIW or 1.5% TEA by weight dissolved in DIW) was loaded onto the column and held for 30 minutes. Then the Test Wash solution was drained from the column. Then the heating jacket was set at RT, and 1.4 BV of DIW was passed through the column at 4 BV/hr. The resin was siphoned dry and stored in glass bottles for either 13 days or 60 days, and then tested by the shake test. Results were as follows:

(5) TABLE-US-00002 TABLE 2 Results after 13 days storage Test Wash Test temp Conductivity (μm/cm) pH TOC (ppm) DIW RT 66 3.82 24.9 DIW 90° C. 58.1 3.89 19.2 1.5% TEA RT 49.5 3.95 19.2 1.5% TEA 90° C. 27.2 4.16 12.8

(6) TABLE-US-00003 TABLE 3 Results after 60 days storage Test Wash Test temp Conductivity (μm/cm) pH TOC (ppm) DIW RT 992 2.66 231 DIW 90° C. 950 2.7 234 1.5% TEA RT 429 3.01 124 1.5% TEA 90° C. 301 3.15 97.8
For a given storage duration and a test temperature, in every case the TEA-washed sample had better conductivity, better pH, and better TOC than the corresponding DIW-washed sample.

(7) Additionally, the samples in Table 3 were observed by eye. The two TEA-washed samples are noticeably lighter in color than the DIW-washed samples.

EXAMPLE 3: CATALYST FOR BPA PRODUCTION

(8) Washing of the resin was accomplished as follows. A glass chromatography column equipped with circulated-water heating jacket was installed vertically. The water in the jacket was circulated and brought up to test temperature (either RT or 90° C.). Then 100 mL of resin was loaded into the column (i.e., bed volume “BV”=100 mL). Then 1.2 BV of “Test Wash” solution (either DIW or 1.5% TEA by weight dissolved in DIW) was loaded onto the column and held for 40 minutes, and the Test Wash solution was drained from the column. Then a fresh 1.2 BV of the same type of Test Wash solution was loaded onto the column and held for 40 minutes, and the Test Wash solution was drained from the column. Then the heated water was drained from the heating jacket, returning the column to RT, and 1.4 BV of DIW was passed through the column at 4 BV/hr.

(9) To improve performance as a catalyst, the resin was loaded with a “promoter,” 2,2-dimethylthiazolidine (“DMT”), as follows. The washed resin was placed in a round-bottom flask with sufficient DIW to make a slurry. 1.71 g. of DMT was dissolved in 10 mL of DIW to make a solution, and the solution was added dropwise to the slurry under stirring. Stirring continued for 1 hour. The liquid was removed by filtration, and the resin returned to the column. The resin was then washed with 5 BV of DIW at 2 BV/hour. Resin was transferred out of the column, surface water was removed by vacuum, and the resin was packed into a plastic bottle.

(10) Reaction to make BPA was performed as follows. Resin was dried overnight at 90° C. In a round-bottom flask in a water bath at 70° C., 3 g of dried resin were placed into the flask, along with 28.8 g of phenol. After stirring for 1 hour, 1.2 g of acetone was quickly added to the flask. The liquid reaction mixture was sampled and analyzed by gas chromatography for acetone content and BPA content after 0.5 hr, 1 hr, 2 hr, 3 hr, and 4 hr.

(11) Conversion and selectivity were assessed as follows:
Conversion=100×(PI−PF)/PI
Selectivity=100×B/(PI−PF)
where PI=initial moles of acetone, PF=final moles of acetone, and B=moles of para-, para-BPA produced.

(12) Results were as follows:

(13) TABLE-US-00004 DIW wash at 90° C. TEA wash at RT TEA wash at 90° C. Time Conversion Selectivity Conversion Selectivity Conversion Selectivity (min) (%) (%) (%) (%) (%) (%) 30 39.69 95.90 19.56 96.58 8.60 96.33 60 61.44 95.85 39.44 96.62 16.59 96.58 120 65.96 95.76 52.74 96.42 32.36 96.40 180 84.54 95.64 68.17 96.28 53.57 96.35 240 83.33 95.58 73.06 96.13 57.60 96.22
The resins that were washed with TEA solution showed acceptable conversion and improved selectivity over the DIW-washed resin.

(14) Also, the solution in the flask was inspected by eye at the end of the reaction. The DIW sample was darkest; the sample washed in TEA solution at 90° C. was noticeably lighter, and the sample washed in TEA solution at RT was lighter still.