IMPROVED PROCESS OF MAKING BIODERIVED PROPYLENE GLYCOL

Abstract

An improved process for making bioderived propylene glycol by reacting a feed composition including glycerol with hydrogen in the presence of a catalyst, wherein the improvement involves causing the reaction to take place in the presence of one or more additives selected 10 from the group consisting of the soluble acetate, citrate, lactate, gluconate, propionate and glycerate salts.

Claims

1. In a process for making bioderived propylene glycol by reacting a feed composition including glycerol with hydrogen in the presence of a catalyst, the improvement comprising causing the reaction to take place in the presence of one or more additives selected from the group consisting of the soluble acetate, citrate, lactate, gluconate, propionate and glycerate salts.

2. The improved process of claim 1, wherein one or more soluble acetate salts are used as the one or more additives.

3. The improved process of claim 1, wherein the catalyst is a Re-containing multimetallic catalyst.

4. The improved process of claim 1, wherein a glycerol-containing feed composition contains less than 5 weight percent of water.

5. The improved process of claim 4, wherein the glycerol-containing feed composition contains less than 3 weight percent of water.

6. The improved process of claim 5, wherein the glycerol-containing feed composition contains less than 2 weight percent of water.

7. The improved process of claim 6, wherein the glycerol-containing feed composition contains less than 1 weight percent of water.

8. The improved process of claim 7, wherein the glycerol-containing feed composition contains less than 0.5 weight percent of water.

9. The improved process of any one of claims 4-8, wherein the glycerol-containing feed composition consists of a product recycle portion from the process and a makeup portion of a virgin glycerol feed.

10. The improved process of claim 9, wherein the glycerol-containing feed composition consists essentially of 1,2-propanediol produced by the hydrogenolysis reaction combined with glycerol.

11. The improved process of claim 10, wherein the glycerol-containing feed composition contains less than 1 percent by weight of anything other than 1,2-propanediol, glycerol and water.

12. The improved process of claim 11, wherein the glycerol-containing feed composition contains from 5 to 50 weight percent of glycerol.

13. The improved process of claim 12, wherein the glycerol-containing feed composition contains from 10 to 40 weight percent of glycerol.

14. The improved process of claim 13, wherein the glycerol-containing feed composition contains from 20 to 30 weight percent of glycerol.

15. The improved process of claim 9, wherein the virgin glycerol feed is a refined, USP grade glycerol product that is at least 99.5 percent glycerol and which contains less than 0.5 weight percent of water.

16. The improved process of claim 9, further comprising a dewatering step to provide a glycerol-containing feed composition of the requisite dryness, performed on one or more of the crude product mixture from the hydrogenolysis reaction, a glycerol-containing fraction of the crude product mixture, the virgin glycerol feed or a combination of two or more of these.

17. The improved process of claim 16, wherein the glycerol-containing feed composition is produced by steps comprising limiting the per-pass conversion of glycerol in the hydrogenolysis to less than full conversion, distilling off overhead substantially all of the water and lighter byproducts in the resultant product mixture in a first, water removal column, passing the bottoms from the first, water removal column to a product recovery column wherein a saleable propylene glycol product of at least 95 percent purity is recovered overhead and the bottoms is used as the product recycle portion from the hydrogenolysis process.

18. The improved process of claim 17, wherein the saleable propylene glycol product from the product recovery column is at least 99.5 percent pure glycerol.

19. A process for producing biobased 1,2-propanediol, comprising: reacting a glycerol-containing feed composition containing less than 5 weight percent of water with hydrogen in the presence of a heterogeneous copper-containing catalyst and in the presence of one or more additives selected from the group consisting of the soluble acetate, citrate, lactate, gluconate, propionate and glycerate salts, to partially convert glycerol in the glycerol-containing feed composition to a crude reaction product mixture including 1,2-propanediol; removing water from the crude reaction product mixture; recovering a portion but not all of the 1,2-propanediol from the crude reaction product mixture; and recycling the remainder of the 1,2-propanediol with unconverted glycerol and combining these with makeup glycerol to provide additional of the glycerol-containing feed composition.

20. The process of claim 19, wherein the heterogeneous copper-containing catalyst is a copper alloy-based sponge metal catalyst prepared from an alloy comprising copper and aluminum.

21. The process of claim 20, wherein the catalyst further comprises zinc as a promoter.

22. The process of any of claims 19-21, carried out at a temperature of less than 250 degrees Celsius.

23. The process of claim 22, carried out at a temperature of less than 230 degrees Celsius.

24. The process of claim 23, carried out at a temperature of less than 215 degrees Celsius.

25. The process of any of claims 22-24, wherein by means of removing water from the crude reaction product mixture and by controlling the relative amounts used to provide the additional glycerol-containing feed composition of the recycled 1,2-propanediol and unconverted glycerol on the one hand and of makeup glycerol on the other hand, the additional glycerol-containing feed composition contains less than 3 weight percent of water.

26. The process of claim 25, wherein the additional glycerol-containing feed composition contains less than 2 weight percent of water.

27. The process of claim 26, wherein the additional glycerol-containing feed composition contains less than 1 weight percent of water.

28. The process of claim 27, wherein the additional glycerol-containing feed composition contains less than 0.5 weight percent of water.

Description

DETAILED DESCRIPTION OF EMBODIMENTS

[0025] As used in this application, the singular forms a, an and the include plural references unless the context clearly indicates otherwise. The term comprising and its derivatives, as used herein, are similarly intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. This understanding also applies to words having similar meanings, such as the terms including, having and their derivatives. The term consisting and its derivatives, as used herein, are intended to be closed terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but exclude the presence of other unstated features, elements, components, groups, integers, and/or steps. The term consisting essentially of, as used herein, is intended to specify the presence of the stated features, elements, components, groups, integers, and/or steps, as well as those that do not materially affect the basic and novel characteristic(s) of stated features, elements, components, groups, integers, and/or steps.

[0026] Unless otherwise indicated, any definitions or embodiments described in this or in other sections are intended to be applicable to all embodiments and aspects of the subjects herein described for which they would be suitable according to the understanding of a person of ordinary skill in the art.

[0027] As indicated above, the present invention in one aspect relates to a process for making bioderived propylene glycol by reacting a feed composition including glycerol with hydrogen in the presence of a suitable catalyst under conditions effective to carry out the conversion, wherein one or more additives selected from the group consisting of the soluble (in the glycerol-containing feed composition) acetate, citrate, lactate, gluconate, propionate and glycerate salts are combined with or included in the feed composition.

[0028] In preferred embodiments, one or more acetate, glycerate or lactate salts are combined with or included in the feed composition in amounts sufficient to improve the yield of propylene glycol by at least fifteen (15) percent, preferably by at least twenty (20) percent, more preferably by at least thirty (30) percent and still more preferably by at least forty (40) percent over that achieved in the absence of the additives under the same conditions. The degree of improvement that can be realized can be expected to vary dependent on the particular hydrogenolysis method and catalyst used and upon the conditions under which a particular process is carried out, but in general it is expected that the additives of the present invention will be effective for improving at least to some degree the yield realized from any of the known hydrogenolysis catalysts and methods. For example, in the context of a process using a Re-containing multimetallic catalyst for the hydrogenolysis of glycerol as taught in Werpy '085, more specifically, a nickel/rhenium on carbon catalyst, 0.03 mols of the soluble lactate, glycerate and acetate salts were sufficient under the conditions specified in the examples below to provide yields 17.6 percent, 22.2 percent and 47.5 percent greater, respectively, than those realized with the same catalyst, under the same conditions but in the absence of the soluble lactate, glycerate and acetate salts.

[0029] In certain embodiments, the additives are used in a process of a type described in Patent Cooperation Treaty Application No. PCT/US17/60187, filed Nov. 6, 2017 for Process for Producing 1,2-Propanediol from Glycerol, wherein a biobased propylene glycol is produced from an essentially anhydrous glycerol-containing feed, especially an essentially anhydrous glycerol-containing feed obtained by removing water from a product mixture resulting from the hydrogenolysis of the glycerol-containing feed and by partially separating the desired propylene glycol product from unreacted glycerol, with recycling at least a part of the remaining combined propylene glycol and glycerol and combining this recycle with a refined glycerol product, especially a USP (United States Pharmacopeia) grade glycerol product, which typically is at least 99.5 to 99.7% pure glycerol with a corresponding maximum moisture content of 0.5% to 0.3% by weight.

[0030] The resulting essentially anhydrous feed, where essentially anhydrous refers to a feed which contains less than 5 weight percent of water, preferably less than 3 weight percent, more preferably less than 2 weight percent, still more preferably less than 1 weight percent and even more preferably less than 0.5 weight percent of water, is thus comprised of a recycle component and a makeup, refined glycerol component. As a consequence, it will be particularly desirable in the context of such processes to reduce the number and/or the extent of side reactions that occur in the hydrogenolysis of the glycerol-containing feed by means of the present additives, and in particular to reduce the production of those byproducts which are separated from 1,2-propanediol only with great difficulty and/or expense (such as the four carbon and higher diols) and that might therefore pose a risk of being built up over time, except (in the absence of the use of the additives of the present invention) through the use of exceptional and expensive measures to separate these byproducts out and avoid their recycle.

[0031] The present invention is further demonstrated by the non-limiting examples that follow:

Examples 1-6

[0032] 120 milliliters of a feed comprised of a) a solution of 30 weight percent of glycerol in water, b) 0.03 mols of salts of a selected organic acid, c) 1. 4 grams of sodium hydroxide and d) 5 grams of a purchased nickel-rhenium (5% Ni-1% Re on Norit ROX carbon) (wet) on carbon catalyst were placed in a 300 mL stainless steel high pressure autoclave reactor, and reacted with hydrogen at 9.7 MPa, gauge (1400 pounds per square inch, gauge). The reactor contents were stirred at 600 rpm for three hours at 215 degrees Celsius, and the reactor contents were then filtered for analysis. The percentages of ethylene glycol, combined butanediols (BDO), combined pentanediols (PDO) and overall PG yield were then determined, and are reported in Table 1 below:

TABLE-US-00001 TABLE 1 EG/PG BDO/PG PDO/PG PG Yield Control 7.63 2.73 0.93 37.38 Acetate 7.65 1.97 0.74 55.74 Citrate 7.61 2.76 0.91 41.28 Lactate 8.07 3.14 1.26 44.44 Gluconate 7.85 3.31 1.14 41.33 Propionate 8.72 4.66 2.16 42.95 Glycerate 8.23 3.09 1.10 46.16