One vessel process for making 1,2-propanediol from a high fructose feedstock

Abstract

A process is described for directly converting a high fructose feedstock to a product mixture including one or more lower polyols in which 1,2-propanediol is produced in preference to any other lower polyols, wherein a high fructose feed and a source of hydrogen are supplied to a reaction vessel and reacted in the presence of a copper-containing, supported ruthenium catalyst to provide the product mixture.

Claims

1. A process for converting a high fructose feedstock to a product mixture including one or more lower polyols in which 1,2-propanediol is produced in preference to any other lower polyols in a single stage, wherein a high fructose feed and a source of hydrogen are supplied to a reaction vessel and reacted in the presence of a copper-containing, supported ruthenium catalyst to provide the product mixture.

2. The process of claim 1, wherein the high fructose feed comprises at least 42 percent by weight of fructose.

3. The process of claim 2, wherein the high fructose feed comprises 53 percent by weight of glucose.

4. The process of claim 1, wherein the high fructose feed comprises 55 percent by weight of fructose and 42 percent by weight of glucose.

5. The process of claim 1, wherein the high fructose feed comprises 90 percent by weight of fructose and 10 percent by weight of glucose.

6. The process of claim 1, wherein the high fructose feed is comprised of the hydrogenolysis product of a fructose-containing biomass.

7. The process of claim 1, wherein the copper-containing, supported ruthenium catalyst is a copper-containing, sulfided ruthenium catalyst on a support.

8. The process of claim 7, wherein the support is carbon.

9. The process of any of claims 1-8, conducted as a semi-batch process wherein the high fructose feed is supplied to the reaction vessel at a first concentration and subsequently at one or more later times in the course of a batch at the first or a greater concentration.

10. The process of any of claims 1-8, conducted as a continuous process wherein the high fructose feed is supplied to the reaction vessel at a first concentration and at one or more points along the length of the reaction vessel downstream of the reaction vessel inlet at the first or a greater concentration.

Description

DESCRIPTION OF EMBODIMENTS

(1) As earlier mentioned, a context of use for the present invention that is especially of interest is in the conversion of currently-manufactured high fructose syrups to 1,2-propanediol, an important commodity chemical that has historically been made from non-renewable resources and that has only recently been manufactured commercially from biobased, renewable resources. Such high fructose syrups are commercially made and used as sweeteners throughout the world under various customary namesbeing commonly referenced as high fructose corn syrup (HFCS) in the United States, glucose-fructose in Canada, isoglucose, glucose-fructose syrup or fructose-glucose syrup in Europe and as high fructose maize syrup in some countriesbut in recent years have been viewed by some as contributing to obesity and a number of other adverse health effects.

(2) In the United States, these high fructose syrups are conventionally made from corn as a starch source and thus identified as high fructose corn syrups (HFCS), and it will be in the context of these commercial HFCS sweetener products that the present detailed description will be presented, though it will be clearly understood that high fructose feed or high fructose feedstocks as used herein extend to mixtures of fructose with one or more additional sugars wherein the fructose is at least 42 percent by weight of the sugars as a whole however these mixtures are derivedwhether from another starch source or from the processing of a biomass, for example but without limitation, a non-food biomass such as the fructose-containing Jerusalem artichoke tuber investigated by Zhou et al.

(3) With this understanding, a preferred application of the present invention will be for the conversion of a high fructose feedstock in the form of a commercial HFCS 90 sweetener product to a product mixture including lower polyols and wherein 1,2-propanediol is produced in preference to any other lower polyols. Even more preferably, 1,2-propanediol is favored over sorbitol as a product.

(4) In one embodiment, HFCS 90 and hydrogen are combined and reacted in the presence of a copper-containing, supported ruthenium catalyst to provide the product mixture. In a preferred embodiment, the catalyst comprises sulfided ruthenium and copper on a support. Carbon is a presently preferred support material.

(5) The process can be carried out in a batch, semi-batch or continuous mode, but preferably will be carried out in a semi-batch or continuous manner according to a method of the type described in our WO 2015/119767 published application, wherein HFCS 90 is combined with an inert solvent and the resultant high fructose feed contains preferably not more than 50 percent by weight of fructose, more preferably contains not more than 30 percent by weight of fructose and still more preferably contains not more than 10 percent by weight of fructose. Thereafter, in a semi-batch method, one or more additions are made of the high fructose feed over time to closely approach and preferably achieve, but not substantially exceed, the initial fructose concentration within the batch. Preferably, by means of one or more subsequent additions of the high fructose feed, the fructose feed concentration within the batch will be maintained on average within 20 percent of the initial fructose concentration over the duration of a batch, more preferably within 10 percent of the initial fructose concentration and still more preferably within 5 percent of the initial fructose concentration over the duration of a batch.

(6) Likewise, in a continuous mode of operation, fructose is introduced (typically in the form of HFCS 90 or in the form of additional of another such high fructose feed) at a plurality of locations in the direction of fluid flow through the reactor toward the product outlet, so as to maintain (or substantially maintain) the inlet fructose concentration along some portion of the length of the reactor. Preferably, over the length of the reactor, the fructose concentration is maintained on average within 15 percent of the inlet fructose concentration, more preferably is maintained within 10 percent of the inlet fructose concentration and still more preferably is maintained within 5 percent of the inlet fructose concentration. The reactor will preferably be a fixed bed reactor of the trickle bed or packed bubble column variety or in a series of such reactors including quench boxes wherein downstream additions of fructose are accomplished, though continuous multiphase, low mixing slurry reactors (transported bed reactors) are contemplated as well.

(7) If conducted in semi-batch mode, batch times are preferably from 1 to 6 hours in duration, more preferably from 1 to 4 hours in length, and still more preferably from 2 to 3 hours in duration, at a reaction temperature of from 50 to 250 degrees Celsius, preferably of from 100 to 250 degrees Celsius and more preferably from 150 to 200 degrees Celsius. Hydrogen will be supplied at a pressure of from 3.5 MPa to 17.5 MPa, gauge (500 to 2500 pounds per square inch, gauge), preferably at a pressure of from 7.0 MPa to 14.0 MPa, gauge (1000 to 2000 psig), and more preferably at a pressure of from 10.5 MPa to 14.0 MPa, gauge (1500 to 2000 psig).

(8) The catalyst is a copper-containing, supported ruthenium catalyst and will preferably comprise from 0.5 to 10.0 weight percent of ruthenium based on the total weight of the catalyst, more preferably from 1.0 to 5.0 weight percent of ruthenium and still more preferably will comprise from 2.0 to 3.0 weight percent of ruthenium with from 1.0 to 20.0 weight percent of the catalyst being copper, more preferably from 1.0 to 10.0 weight percent and still more preferably from 2.0 to 5.0 percent by weight of the catalyst being copper. A catalyst further containing sulfur is further preferred, with sulfur contents ranging from 0.1 to 5.0 percent by weight, more preferably from 0.5 to 2.0 weight percent and still more preferably from 0.5 to 1.0 percent by weight of the catalyst. It should be noted, parenthetically, that the specification of a more preferred Ru content, a more preferred Cu content and a more preferred S content should by no means be taken to imply that values of Ru, Cu and S within broader ranges of preferred weight percentages for one or both of the other components are excluded in combination with a value of a particular component selected within a more preferred range; thus, for example, a Ru content selected within the narrowest range indicated above (from 2.0 to 3.0 weight percent) does not require that the Cu and S contents are correspondingly from within the narrowest ranges indicated for these materials or within the next narrowest range of values.

(9) In a continuous mode of operation, particularly with reference to a fixed bed reactor system, the temperature, hydrogen pressure and catalyst aspects are as specified for the semi-batch mode, but a liquid hourly space velocity ranging from 0.5 to 3.0 hr.sup.1, preferably from 0.5 to 2.0 hr.sup.1 and more preferably from 0.5 to 1.0 hr.sup.1 will be employed.

(10) As reflected in the examples following, the product mixture from the inventive process will generally comprise the hydrogenation product sorbitol as well as materials consistent with the occurrence of both hydrogenolysis and hydrogenation, for example, glycerol, erythritol, 1,2-butanediol, ethylene glycol, propylene glycol (1,2-propanediol) and the like. Again as shown in the examples, with the inventive process propylene glycol can be produced in preference to any other lower polyol, and in certain embodiments can be produced in preference both to sorbitol and the various other lower polyols.

(11) Separation of the propylene glycol from the remainder of the product mixture can be accomplished by a number of known methods, see, for example, U.S. Pat. No. 8,143,458 to Kalagias (azeotropic distillation) and U.S. Pat. No. 8,177,980 to Hilaly et al. (simulated moving bed chromatography), but preferably simple distillation may be employed to recover the propylene glycol.

(12) This invention is further illustrated by the following non-limiting examples:

Examples 1-9

(13) A sulfided ruthenium on carbon catalyst including 2 percent of ruthenium and 1 percent of sulfur based on the total weight of the catalyst was loaded with 5 percent by weight of copper by spraying a copper nitrate solution on the dry sulfided ruthenium catalyst, then drying and reducing the catalyst under hydrogen at 250 degrees Celsius.

(14) This catalyst was loaded into a 30 cubic centimeter fixed bed reactor, and hydrogen was thereafter supplied to the reactor at 12.4 MPa, gauge (1800 pounds per square inch, gauge), at a rate of 0.4 liters per minute, together with a liquid feed comprised of 0.794 percent by weight of dextrose, 5.93 weight percent of fructose, 8 percent by weight of ethanol and the remainder of water. The reactor temperature was 190 degrees Celsius, and the liquid hourly space velocity was 0.7 hr.sup.1.

(15) The process was continuously run over a period of two weeks, with product samples being drawn on a number of consecutive days within that timeframe. The results are shown below in Table 1, where Example 1 corresponds to the first of six consecutive daily samples drawn and analyzed by GC/MS. All amounts are reported as percents by total weight.

(16) TABLE-US-00001 TABLE 1 Dex- Fruc- 1,2- Ex. Sorb..sup.a trose tose Eryth.sup.b Gly.sup.c EG PG BDO (Feed) 0.794 5.93 1 0.829 0.052 1.146 0.436 1.557 0.192 2 0.793 0.046 1.155 0.411 1.503 0.013 3 0.785 0.044 1.133 0.405 1.492 0.195 4 0.758 0.041 1.112 0.393 1.458 0.035 5 0.914 0.05 1.281 0.386 1.494 0.022 6 0.941 0.048 1.305 0.377 1.529 0.196 .sup.aSorbitol; .sup.bErythritol; .sup.cGlycerol; EG = ethylene glycol, PG = propylene glycol; 1,2-BDO = 1,2-butanediol

Example 7

(17) A sulfided ruthenium on carbon catalyst, an experimental apparatus and the same experimental conditions as used in Examples 1-6 were employed on a high fructose feed comprised of a sugars mixture of 0.1 percent by weight of dextrose and 3.4 percent by weight of fructose, with again 8 percent by weight of ethanol and the remainder of water. A sample of the product taken the next day was analyzed by GC/MS, with the results reported in Table 2.

(18) TABLE-US-00002 TABLE 2 Dex- Fruc- 1,2- Ex. Sorb..sup.a trose tose Eryth.sup.b Gly.sup.c EG PG BDO (Feed) 0.1 3.4 7 0.65 0 0.74 0.20 0.97 0 .sup.aSorbitol; .sup.bErythritol; .sup.cGlycerol; EG = ethylene glycol, PG = propylene glycol; 1,2-BDO = 1,2-butanediol

Example 8

(19) A high fructose feed comprised of 3.53 percent by weight of dextrose, 3.56 weight percent of fructose (thus consistent with an HFCS 42 sweetener product) with 8 percent by weight of ethanol and the remainder of water was processed using a sulfided Ru/C catalyst, an experimental apparatus and experimental conditions as in previous examples. Analysis of a product sample drawn the following day yielded the results shown in Table 3.

(20) TABLE-US-00003 TABLE 3 Dex- Fruc- 1,2- Ex. Sorb..sup.a trose tose Eryth.sup.b Gly.sup.c EG PG BDO (Feed) 3.53 3.56 8 1.58 0 1.07 0.46 1.30 0 .sup.aSorbitol; .sup.bErythritol; .sup.cGlycerol; EG = ethylene glycol, PG = propylene glycol; 1,2-BDO = 1,2-butanediol

Example 9

(21) A sulfided ruthenium on carbon catalyst including 2 percent of ruthenium and 1 percent of sulfur based on the total weight of the catalyst was loaded into a 30 cubic centimeter fixed bed reactor, and hydrogen was thereafter supplied to the reactor at 12.4 MPa, gauge (1800 pounds per square inch, gauge), at a rate of 0.4 liters per minute, together with a liquid feed including a sugars mixture of 3.2 percent by weight of dextrose and 3.8 weight percent of fructose (thus, consistent with an HFCS 55 sweetener product) with 10 percent by weight of ethanol and the remainder of water. The reactor temperature was 190 degrees Celsius, and the liquid hourly space velocity was 0.7 hr.sup.1. Analysis of a product sample taken the following day yielded the results shown in Table 4 as follows.

(22) TABLE-US-00004 TABLE 4 Dex- Fruc- 1,2- Ex. Sorb..sup.a trose tose Eryth.sup.b Gly.sup.c EG PG BDO (Feed) 3.2 3.8 9 1.43 0 1.16 0.36 1.45 0 .sup.aSorbitol; .sup.bErythritol; .sup.cGlycerol; EG = ethylene glycol, PG = propylene glycol; 1,2-BDO = 1,2-butanediol