WO2017091531A1

WO2017091531A1 - Process to produce and purify monoethylene glycol

Info

Publication number: WO2017091531A1
Application number: PCT/US2016/063228
Authority: WO
Inventors: William Gong
Original assignee: BP Corp North America Inc
Current assignee: BP Corp North America Inc
Priority date: 2015-11-24
Filing date: 2016-11-22
Publication date: 2017-06-01
Anticipated expiration: 2018-05-24

Abstract

A process for producing purified monoethylene glycol (MEG) is provided. The process comprises contacting a mixture comprising MEG and primary co-products with an acid to provide a distillable MEG product, wherein the primary co-products have boiling points substantially similar to a boiling point of MEG, and wherein the distillable MEG product comprises MEG and secondary co-products that do not boil closely with MEG; and distilling the distillable MEG product to provide purified MEG and secondary co-products. A process for increasing production of MEG is also provided, comprising contacting a bio- derived MEG mixture comprising MEG and 1,2-butanediol (1,2-BDO) with an acid to provide a second MEG product, wherein the 1,2-BDO is converted to MEG.

Description

PROCESS TO PRODUCE AND PURIFY MONOETHYLENE GLYCOL

FIELD

[0001] This disclosure relates to processes for producing monoethylene glycol (MEG), specifically, processes for converting co-products with boiling points close to MEG to co- products that do not boil closely with MEG and processes for increased production of MEG.

BACKGROUND

[0002] Monoethylene glycol (MEG or EG) may be produced by aqueous phase catalyzed hydrogenolysis (i.e., using hydrogen (H₂) to cleave C-0 and C-C bonds of a feedstock). One disadvantage of this process, however, is that MEG is not the only glycol (vicinal diol) produced. Depending on the catalyst system, the feedstock, and the process conditions, varying amounts of byproducts such as 1,2-propanediol (PDO) and isomeric (1,2-, 1,3-, and 1,4-) butanediols (BDOs) may also be produced, which must then be separated from MEG. Erythritol and sorbitol may also be produced. While PDO and BDOs are useful byproducts, they are not as commercially valuable as MEG. The primary difficulty posed by co- production of these glycols is that they are difficult to separate efficiently from MEG by conventional distillation because their boiling points are too close to that of MEG.

[0003] Current separation processes include conventional distillation and azeotropic distillation. However, both of these processes can result in design and operational complexity and can add large capital expenditures and energy costs.

[0004] Thus, there exists a need for processes to convert these byproducts into more easily separable components. There also exists a need for processes to increase the amount of MEG produced.

BRIEF SUMMARY

[0005] In one aspect, a process for producing purified monoethylene glycol (MEG) is provided. The process comprises contacting a mixture comprising MEG and primary co- products with an acid to provide a distillable MEG product, wherein the primary co-products have boiling points substantially similar to a boiling point of MEG, and wherein the distillable MEG product comprises MEG and secondary co-products that do not boil closely with MEG; and distilling the distillable MEG product to provide purified MEG and secondary co-products.

[0006] In another aspect, a process for producing monoethylene glycol (MEG) is provided. The process comprises contacting a bio-derived MEG mixture comprising MEG and 1,2- butanediol (1,2-BDO) with an acid to provide a second MEG product, wherein the 1,2-BDO is converted to MEG.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a graph showing the effect of ethylene glycol feed concentration on the rate of ethylene glycol conversion at 135 °C and 3 hours.

[0008] Figure 2 is a graph showing the effect of temperature on the rate of ethylene glycol conversion for zeolite catalysts.

DETAILED DESCRIPTION

[0009] The present disclosure provides processes for producing purified monoethylene glycol (MEG or EG). This process may be applicable to any processes where one desires to convert a vicinal diol into an aldehyde, ketone, another diol, or ether. The process may also be applicable to any process where MEG purification is desired, regardless of how the MEG product is made. This process offers distinct advantages from conventional processes: (1) the ability to produce purified MEG with lower capital expenditures (i.e., fewer distillation trays); and (2) the ability to convert less desirable 1,2-BDO to MEG. Conventional processes require distillation towers of about 120 trays and a large condenser/reboiler due to the need to use a high reflux ratio. Another conventional process, azeotropic distillation with octene as a solvent reduces the number of trays required, but adds complexity and costs with the handling of another component (octene). This process allows for conversion of primary byproducts (or co-products) having boiling points that are substantially similar to that of MEG into secondary byproducts (or co-products) which have boiling points that are much different from MEG. Thus, separation of the co-products and MEG is easier and thus requires fewer towers and does not require the use of azeotropic distillation.

[00010] In one aspect, a process for producing purified MEG is provided. The process comprises contacting a mixture comprising MEG and primary co-products with an acid to provide a distillable MEG product. The mixture may be a bio-derived mixture, i.e., may be the product of a biomass conversion. In other embodiments, the mixture may be the product of any processes known in the art. The primary co-products have boiling points substantially similar to a boiling point of MEG. The primary co-products may be, for example, one or more of 1,2-propanediol (1,2-PDO), 1,2-butanediol (1,2-BDO), 1,3-butanediol (1,3-BDO), 1,4-butanediol (1,4-BDO), erythritol, and sorbitol. Other co-products may include 2- oxopropanal and l-hydroxy-2-butanone. 1,2 BDO and 1,2 PDO have boiling points (196.4 °C and 187.6 °C, respectively) that are very close to that of MEG (197.3 °C). Thus, these compounds are particularly difficult to separate from MEG. Physical properties of key components for separation are shown in Table A below.

Table A. Physical Properties of Key Components for Separations

Hydrogen ¾ 2.0 -252.8

Carbon Dioxide C0₂ 44.0 -194.7

Methane CH₄ 16.0 -161.5

1-Octene C₈Hi6 112.2 121.3

2-oxopropanal C₃H₄0₂ 72.1 72.0

l-hydroxy-2- C₂H₅COCH₂OH 88.1 152.0-154.0 butanone

[00011] The acid may be a solid acid catalyst and may resist solubility in water, which is the medium in which this reaction occurs (i.e., hydrophobicity). The acid catalyst may be, for example, a zeolite, a metal oxide, an ion-exchange resin, or a heteropolyacid. Specific examples of such catalysts include: H-ZSM-5 (5), H-ZSM-5(30), H-ZSM-5(50), H-ZSM-5 (80), amberlyst-15, Zr0₂ W0₃, Cs_{2 5}HPA, and Nb₂0₅.

[00012] The reaction provides a distillable MEG product and secondary co-products that do not boil closely with MEG, such as propanal, butanal, or tetrohydrofuran (THF). The PDO and BDOs are converted to their corresponding aldehydes (propanal and butanal) and ether or other lower/higher secondary products by chemical reaction removal of an equivalent of water from the primary co-product. At least about 50 percent of the primary co-products are converted to secondary co-products. The probable mechanism of these reactions is acid- catalyzed dehydration of the glycol, which produces a carbocationic intermediate. This intermediate then isomerizes to produce an oxonium ion intermediate, which is deprotonated to yield the aldehyde. 1,4-BDO can participate in this dehydration-isomerization pathway. It is also likely that 1,4-BDO will proceed via an acid-catalyzed, intramolecular etherification to produce THF. The reactions are shown in Schemes 1-3 below.

1 ,2-Propanediol Propanal Scheme 1. Conversion of 1,2 PDO to propanal.

1 ,2- and 1 ,3-Butanediol

Scheme 2. Conversion of 1,2 BDO and 1,3 BDO to butanal.

Scheme 3. Conversion of 1,4 BDO to butanal and THF.

Boiling points of the secondary co-products and MEG are shown in Table B below.

Table B. Boiling Points of New Volatile Reaction Products

[00013] The distillable MEG product is then distilled or separated to provide purified MEG and the secondary co-products. The hydrogenolysis of carbohydrates to produce glycols is typically performed in an aqueous solution, approximately 1-30 wt% in water. The described preferred intermolecular reactions could predominate in dilute solutions. Thus, the preferred mode of operation is to convert the undesired glycols to the light boiling components in the presence of water. The solvent water is then subsequently removed by a multi-effect evaporator followed by conventional distillation. The large boiling point difference between the aldehydes and the MEG ensure that essentially all the aldehydes and THF are removed during the dehydration process. They dehydration tower may have about 10 trays. A heavies tower of about 35 trays may be used to remove heavies such as sorbitol, unreacted feed, and the catalyst. Finally, an MEG tower of about 15 trays may be used to achieve target purity.

[00014] These aldehydes and THF have sufficiently high volatility that they may also be substantially separated from the solvent and used as fuel or recovered as salable products. Any aldehydes remaining in the MEG should be removed to satisfy quality issues for the polyethylene terephthalate (PET) market. Therefore, a mild hydrogenation of the crude glycols (preferably after removal of the solvent water) may be performed to convert residual aldehydes to their corresponding alcohols. Conducting the mild hydrogenation after the solvent water has been removed significantly reduces the size of the hydrogenation reactor, thus saving money.

[00015] The reaction may take place at a temperature of between about 80 °C and about 200 °C, and preferably 100 °C to 180 °C. At temperatures at or greater than 200 °C, significant, unwanted conversion of MEG may occur. However, unexpectedly, during the reaction at between 100 °C and 180 °C, substantially all of the distillable MEG remains intact (i.e., about 80 percent is not converted).

[00016] Also unexpectedly, in addition to the conversion of PDO and BDOs, erythritol and sorbitol can also be converted by more than 90% in water at 200 °C, in the absence of catalyst, to propanal. Propanal yield from erythritol and sorbitol are 41.1 mol% and 96.8 mol%, respectively, for schemes 4 and 5.

Scheme 4. Conversion of Erythritol to Propanal.

Scheme 5. Conversion of Sorbitol to Propanal.

[00017] This disclosure also provides a process for conversion of the primary co- products to MEG. The process comprises contacting a bio-derived MEG mixture comprising MEG and 1,2-BDO with an acid to provide a second MEG product. Unexpectedly, when a mixture containing various amounts of MEG, 1,2-diols, and other polyhydroxylated hydrocarbons such as erythritol and sorbitol is heated in the presence of solid acidic materials, as in the reactions above, there is a net production of MEG. At progressively lower concentrations of MEG, as the temperature is increased, there is conversion of other co-products to MEG. For example, the 1,2-BDO is converted to MEG. The reaction may occur at a reaction temperature of between about 100 °C and about 150 °C. The amount of MEG present in the bio-derived MEG mixture may be between about 0 wt% to about 0.3 wt%. EXAMPLES

Solid acidic materials considered are listed in Table C.

Table C. Solid Acidic Materials Examined as Catalysts for Invented Processes

Material Si ΛΙ (zeolites onlv) BE 1 Surf sice Area (in «)

H-ZSM-5 (5) 5 : 1 391

H-ZSM-5 (30) 30: 1 387

H-ZSM-5 (50) 50: 1 425

H-ZSM-5 (80) 80: 1 425

Amberlyst-15 — NA

Nb₂O_s — 150

Zr0₂ ^«W0₃ — 65.8

Cs_{2 5}HPA — NA

[00018] Two types of experiments are performed: (1) examination of single components of anticipated impurities over different temperatures (135 °C and 200 °C) at reaction times varying from 0.5 to 3.0 hours over six catalysts and a blank (Example 1); and (2) examination of synthetic feedstock over three different catalysts at temperatures that range from 80°C to 200°C (Examples 2-5). The synthetic feed has the same relative compositions (82.0 wt% ethylene glycol (EG or MEG), 4.8 wt % 1,2-propanediol (1,2-PDO), 8.1 wt% 1,2-butanediol (1,2-BDO), 3.0 wt% erythritol (ERY), and 2.0 wt% sorbitol (SOR), but the sum total of these components varies in the weight percent concentration in water, as shown in Table D.

T n

of 1,4-BDO

1,2-BDO replaced by equal amounts

_F 20* 20.0

of 1,4-BDO

1,2-BDO replaced by equal amounts

F 35* 35.0

of 1,4-BDO

Example 1: Catalyst Screening on Single Components

[00019] The results of experiments conducted at 1 mL liquid scale are displayed in Tables 1-20. Six solid acids and a blank are examined. Each experiment is run for 3.0 hours.

• Tables 1 and 2 display the results of catalyst screening on 1,2-PDO at 135 - 200 °C. Table 1. Acid-Catalyzed Conversions of 1,2-Propanediol at 135 to 200 °C, 3.0 Hrs

Table 2. Acid-Catalyzed Conversions of 1,2-Propanediol at 135 - 200 °C, 3 Hrs (cont.)

Table 4. Acid-Catalyzed Conversions of Ethylene Glycol at 135 - 200 °C, 3 Hrs (cont.)

• Tables 5 and 6 display the results of catalyst screening on 1,2-BDO at 135 - 200 °C.

Table 5. Acid-Catal zed Conversions of 1,2-Butanediol at 135 - 200 °C, 3 Hrs

Butanal Rate 1.0

Tables 7 and 8 display the results of catalyst screening on erythritol (ERY) at 135 200 °C.

Table 7. Acid-Catalyzed Conversions of Erythritol at 135 - 200 °C, 3.0 Hrs

• Tables 9 and 10 display the results of catalyst screening on sorbitol (SOR) at 135 -

200 °C.

Table 9. Acid-Catalyzed Conversions of Sorbitol at 135 - 200 °C, 3 Hrs

Table 10. Acid-Catalyzed Conversion of SOR at 135 - 200 °C, 3 Hrs

[00020] The catalysts variously convert PDO with the main product as propanal. In some of these cases, the propanal selectivity is 100%. The level of 1,2-PDO conversion increases with temperature as does the propanal yield. Even in the absence of catalyst, 1,2- PDO is readily converted to propanal (135 °C). Unexpectedly, 2,3-butanediol (2,3-BDO) is made in significant levels in these reactions (only at 200 °C). The conversions of MEG are much lower than PDO.

[00021] Conversion of 1,2-BDO is substantial even at 135 °C. At higher temperature of 200 °C, propanal is made. Formation of 2-butanone via the Pinacol rearrangement also occurs when certain catalysts were employed.

[00022] Erythritol can be converted at rates greater than 90% even at low temperature of 135 °C, and propanal is made in approximately 50% selectivity. Unexpectedly, propanal can be made at 200 °C in good yield in the absence of any catalyst. The nearly equivalent yields of propanal in all cases would suggest that the catalyst might not be responsible for propanal formation.

[00023] Sorbitol can be converted in greater than 90% even at low temperature of 135 °C. Propanal is the major product in very high yields in water at 200 °C in the absence of any catalyst. At 135 °C, certain catalysts can produce up to approximately 60 mol% of propanal.

[00024] The results indicate that it is possible to convert some of these impurities, particularly 1,2-BDO and 1,2-PDO which are materials that boil at a temperature that is nearest to MEG. Furthermore, these diols are converted to very volatile propanal. Additionally, erythritol and sorbitol are converted in high yields to propanal, reactions that are unexpected. These compounds are also converted to propanal in the absence of any catalyst. The relative ease in which these conversions can occur in water under mild conditions also translates to a longer catalyst life; because very high temperature is not required and that it can occur in aqueous phase, solutes are readily desorbed from active catalyst sites reducing the probability for catalyst fouling.

Example 2: Catalyst Screening of Synthetic Feeds

[00025] These experiments are conducted in the same equipment and pursuant to the same procedure as in Example 1. Initially, the experiments are conducted on the following feedstocks: F 1.75, F_05, F 20, and F 35. The data are summarized in Tables 11 through 21. Table 11. Acid-Catalyzed Conversion of Synthetic Feed F 1.75 at 135 - 200 °C, 0.5 to

3.0 Hrs.

Table 12. Acid-Catalyzed Conversion of Synthetic Feed F 1.75 (Cont.)

Table 13. Acid-Catalyzed Conversion of Synthetic Feed F 05 at 135 - 150 °C, 0.5 to 3.0

Hrs.

1,3-BG Rate — 1.2 0.4 0.7 — 1.2 0.4 0.2

Table 14. Acid-Catal zed Conversion of S nthetic Feed F 05 Cont.

Table 15. Acid-Catal zed Conversion of S nthetic Feed F 05 cont.

Table 16. Acid-Catalyzed Conversion of Synthetic Feed F 20 from 135 - 150 °C, 0.5 -

3.0 Hrs.

Butanal Rate 0.3 0.2 0.1

Table 17. Acid-Catalyzed Conversion of Synthetic Feed F 20 (cont.)

PDO Rate -1.0 -0.5 -0.1 -1.0 -0.1 -0.1

1,2-BDO Rate -18.1 -6.1 -2.9 -18.5 -6.0 -3.0

ERY Rate -5.6 -2.0 -1.0 -5.7 -2.0 -1.0

SOR Rate -4.2 -1.5 -0.7 -4.3 -1.5 -0.8

Propanal Rate 6.6 1.9 0.9 6.6 1.9 0.9

1,3-BDO Rate 1.7 0.4 0.2 1.9 0.5 0.3

Butanal Rate 0.4 0.3

Table 18. Acid-Catal zed Conversion of S nthetic Feed F 20 cont.

Table 19. Acid-Catalyzed Conversion of Synthetic Feed F 35 at 135 at 150 °C, 0.5 - 3.0

Hrs.

Table 20. Acid-Catal zed Conversion of S nthetic Feed F 35 cont.

Butanal Rate 0.3 0.2

Table 21. Acid-Catalyzed Conversion of Synthetic Feed F 35 (cont.)

EG Rate -30.5 -2.7 -2.0 -32.1 -11.3 1.5

PDO Rate -3.3 -0.1 -0.2 -2.7 -1.0 0.04

1,2-BDO Rate -7.5 -1.3 -1.0 -29.5 -9.3 -4.5

ERY Rate -10.4 -3.6 -1.8 -10.9 -3.5 -1.8

SOR Rate -7.8 -2.7 -1.4 -8.3 -2.6 -1.3

Propanal Rate 7.1 2.1 1.0 6.9 2.2 1.5

1,3-BDO Rate 1.2 0.4 1.2 0.4 0.2

Butanal Rate 0.6 0.1 0.3 0.1

[00026] In general, all of the feed components are converted to various extents. As the temperature and/or reaction times are increased, there is an increase in conversion. For experiments on F 1.75 (the most diluted feed) (Tables 11 and 12), Blank experiment (Entry 65) shows that it can convert nearly all of the ERY and SOR non-catalytically. But intervention of catalysts such as H-ZSM-5 (30) (Entry 70), Cs₂₅ (Entry 73), Amberlystl5 (Entry 76), and H-ZSM-5 (80) (Entry 77) all can significantly boost EG, PDO and 1,2- BDO conversions versus the Blank. PDO and 1,2-BDO can be nearly quantitatively converted (see Entries 70, and 76). Metal oxide catalysts such as Nb₂0₅ (Entry 78) and Zr0₂ ^'W0₃ (Entry 79) are less effective, consistent with the findings from the single component experiments in Example 1.

[00027] For experiments on F 05 at 135 °C, and shorter reaction times (Tables 13 to

15) (Entries 81, 82, 94 and 95), there is a very high conversion of EG, and there is a very high net production of 1,2-PDO (net production indicated by negative conversion). In all cases except for one (Entry 91), there is a quantitative conversion of 1,2-BDO for this feedstock. Even in the Blank (Entry 80), up to 12% 1,3-BDO is made, an unexpected product. Extending the reaction time to 3.0 hours brought about a net production of EG, which is not expected. [00028] For experiments on F_20 at 135 to 150 °C, 1,2-BDO is converted in nearly all cases (Tables 16 to 18). Unlike F_05, the conversion of 1,2-PDO is much lower. There is a net production of EG, at levels exceeding 19% (Entries 115 and 1 16). There is production of 1,3-BDO as well in almost all cases except for the Blank (Entry 100 and Entry 1 16). Both propanal and butanal are produced with the former made in higher yield.

[00029] In experiments on F 35, much lower conversions are obtained at 135 and 150

°C for all organic components (Tables 19 to 21). As in all previous cases, ERY and SOR were converted in nearly 100%.

[00030] These experiments demonstrate the conversion of glycols and formation of propanal. Unexpectedly, but desirably, 1,2-BDO can be isomerized to products of greater boiling point difference with EG. Lastly, the conditions examined could also produce EG, which is not anticipated.

Example 3: Catalyst Screening of Synthetic Feeds:

[00031] F 05, F 20, and F 35 are modified to have 1,2-BDO replaced with 1,4-BDO in order to examine the impact this change has on production of secondary products. These became F_05*, F_20*, and F_35*.

[00032] Findings for F 05* are summarized in Table 22 where three catalysts were screened at 135 and 150 °C for 3.0 hours, including a Blank. EG is made in the span of these experiments. 1,2-PDO is also made in all cases except for two (Entries 138 and 142). Comparisons of F 05 and F_05* are made in Tables 23 (135 °C) and 24 (150 °C) for the same catalysts. Without any exceptions, the use of F 05* produced approximately twice the level of 1,3-BDO than F 05 (see "1,3-BDO Prod (%)"Tables 23 and 24). Additionally, F_05* also generated THF (from intramolecular dehydration of 1,4- BDO in the feed). Table 22. Acid-Catalyzed Conversion of Synthetic Feed F 05* from 135 - 150 °C, 0.5 -

3.0 Hrs.

Table 23. Comparison of Conversions of Synthetic Feed F 05* and F 05 at 135 °C, 3.0

Hrs.

Table 24. Comparison of Conversions of Synthetic Feed F 05* and F 05 at 150 °C

[00033] Findings for F_20* are summarized in Table 25 in the screening of three catalysts at 135 and 150 °C. Notable is that in the absence of catalyst, 1,3-BDO was made in 22.87% yield (Entry 145), presumably from 1,4-BDO. Additionally, in the absence of catalyst there was a net production of 16% of EG and 9.71% propanal at 135 °C. In the presence of catalyst, 1,3-BDO is present at much lower levels, and there is a substantial level of THF produced. Tables 26 and 27 display a comparison of F_20 and F_20* conversions. In all cases, 1,2-BDO and 1,4-BDO are completely converted. EG is made in all cases for both feedstocks except in one instance there was a slight conversion (Entry 151). Only when F_20* is examined is there a higher 1,3-BDO yield than from F 20.

Table 26. Comparison of Conversions of Synthetic Feed F 20* and F 20 at 135 °C, 3.0

Hrs.

Table 27. Comparison of Conversions of Synthetic Feed F 20* and F 20 at 150 °C, 3.0

[00034] Findings for F_35* are summarized in Table 28 in the screening of three catalysts and a Blank at 135 and 150 °C for 3.0 hours. Comparisons of F 35* and F 35 are found in Tables 29 (135 °C) and 30 (150 °C). In all cases, 1,4-BDO is readily converted, THF is the major product and 1,3-BDO is made only in very minor amounts. able 28. Acid-Catalyzed Conversion of Synthetic Feed F 35* at 135 - 150 °C, 3.0 Hrs

Table 29. Comparison of Conversions of Synthetic Feed F 35 and F 35* at 135 °C, 3.0

Hrs.

Table 30. Comparison of Conversions of Synthetic Feed F 35 and F 35* at 150 °C, 3.0

Hrs.

[00035] When the feed is modified to replace 1,2-BDO with 1,4-BDO, the latter is readily converted and very high yields of THF are made. Furthermore, 1,4-BDO is isomerized to higher extent to 1,3-BDO than from 1,2-BDO.

Example 4: Catalyst Screening of Synthetic Feeds:

[00036] Further examination of other feed concentrations is also conducted, but at lower temperatures ranging from 80 to 135 °C. Feedstocks F 10, and F 25 are examined. The data is arranged in Tables 31 through 34.

Table 32. Acid-Catalyzed Conversion of Synthetic Feed F 10 from 80 to 135 °C, 3.0

Hours

Table 33. Acid-Catalyzed Conversion of Synthetic Feed F 10 from 80 to 135 °C, 3.0

Hours (cont.)

Table 34. Acid-Catalyzed Conversion of Synthetic Feed F 25 from 80 - 135 °C, 3.0 Hrs.

[00037] Under these conditions, conversion of EG is quite high with nearly matching levels of PDO conversions for the F_10. For the first time, the formation of 1,4-BDO in the Blank as well as reactions catalyzed by an acid is seen (Entries 159, 161, 162, 164, 168, 170, and 174).

[00038] In examination of F 25 (data summarized in Table 34), again at lower temperature (not greater than 135 °C), there is high EG conversion for both catalytic and non- catalytic examples (Entry 178). The Blank in Entry 175 also produces nearly 34% yield of 1,4-BDO. In the catalyzed reactions, Entries 178 and 181 also produce significant quantities of 1,4-BDO.

[00039] It is significant to reveal in this part of the experiments that there is a conversion of these materials to a much higher boiling, 1,4-BDO. Should 1,4-BDO dehydrate to THF, this ether is a much more volatile byproduct than EG and would also be easily separated, achieving the aims of this invention.

Example 5: Catalyst Screening of F 20 containing Variable EG:

[00040] Three separate feeds are prepared and tested in the last part of this investigation. The total weight percent loading of organics is fixed at 20 wt%, but the reduction in EG in the feed is compensated by increase of the other organic components. The level of EG present in the feed is indicated by a fraction, which is a fraction of F_20 previously examined. The objective is to evaluate this inventive process on the conversion of a feedstock where one component has varied in its relative concentration. Table E summarizes the mole fractions of these components.

Table E. Mole Fractions of Compositions of F 20 (1/2, 1/4, and 1/8)

[00041] In Table 35, it is shown that F 20 (1/4) without any catalyst (Entry 182) also generates significant amounts of propanal and 1,4-BDO. It is notable to report that F_20 (1/4) can generate over 62 mol% propanal at 80 °C when this feed is exposed to CS₂.5 (Entry 184).

[00042] As the temperature is increased from 80 to 135 °C, there is a trend towards reducing the level of EG converted in the feedstock containing the lowest concentration of EG to eventually producing EG. At 135 °C, F_20 (1/8) displayed that there was a negative conversion or a net production of EG at 259% and 237%) (Entries 212 and 218 of Tables 39 and 40, respectively). It appears that as level of EG is reduced in the feedstock, this reaction shifts its equilibrium towards production of EG, which is clearly an unexpected result.

Table 35. Acid-Catalyzed Conversion of Synthetic Feed F 20 with Variable EG at 80

Table 36. Acid-Catalyzed Conversion of Synthetic Feed F 20 with Variable EG at 80

Table 37. Acid-Catalyzed Conversion of Synthetic Feed F 20 with Variable EG at 100

Table 38. Acid-Catalyzed Conversion of Synthetic Feed F 20 with Variable EG at 100

Table 39. Acid-Catalyzed Conversion of Synthetic Feed F 20 with Variable EG at 135

Table 40. Acid-Catalyzed Conversion of Synthetic Feed F 20 with Variable EG at 135

Example 6: Increased Production of EG

[00043] A series of synthetic feedstocks is prepared and tested. The feedstocks have a total concentration of 20 wt% comprising of the following components in water: ethylene glycol (EG), 1,2-propanediol (PDO), 1,2-butanediol (BDO), erythritol (ERY), and sorbitol (SOR). Table E above summarizes the mole fractions of various components. As the EG loading is reduced, the concentrations of the remaining components are increased so that the weight percent loading is maintained constant. Solid acidic catalysts H-ZSM-5 (5), H-ZSM-5 (30), H-ZSM-5 (50), and Cs_{2 5}HPA are evaluated. The mixtures are heated from 80 to 135 °C for three hours.

[00044] The experimental results are summarized in Tables 35-40, shown above. The reactions are assessed by the conversions of the various feed components, the yield of new products, and the rate of component charge (mol/g-catalyst/h) for each catalyst and for each temperature. Tables 35 and 36 summarize the data for all four catalysts and feedstocks at 80 °C. Tables 37 and 38 summarize the data for all four catalysts and feedstocks at 100 °C. Tables 39 and 40 summarize the data for all four catalysts and feedstocks at 135 °C.

[00045] At all temperatures, the conversions of erythritol and sorbitol are at least 85% and can range to above 95%. As the feed EG loading is reduced, the EG conversion is reduced. The EG rate also becomes less negative as the EG loading is decreased. At the same time, the conversions of PDO and BDO increase and correspondingly, their rate becomes more negative (i.e. indication that rate of disappearance has increased). As one would anticipate, as the EG concentration of the feed is reduced, one expects the rate of its conversion to be decreased. This is seen in entries 4, 7, 10, 13, 16, 19, 22, and 25 for F_20 (1/8), which has the lowest concentration of feed EG. Therefore, this rate should approach zero and would be zero when the EG concentration is zero weight percent. However, unexpectedly, at 135 °C for the catalysts H-ZSM-5 (5) and (Table 39, Entry 212) and H- ZSM-5 (50) (Table 40, Entry 218), the EG rate became positive in the conversion of F_20 (1/8). A positive rate is an indication that EG is being made at a net rate of 10.1 mol/g catalyst/hr and 8.9 mol/g catalyst/hr for H-ZSM-5 (5) and H-ZSM-5 (50), respectively. For H-ZSM-5 (5), the % conversion of EG is -259.3% (Entry 218), an indication that the final EG concentration is increased by 2.6-fold. Likewise for H-ZSM-5 (50), the % conversion of EG is -236.7% or 2.4-fold higher than the initial EG charge (Entry 212). Figure 1 plots the data for F_20 of various EG content for all three of the H-ZSM-5 catalysts. Both H-ZSM-5 (5) and H-ZSM-5 (50) are catalysts to promote net production of EG. H-ZSM-5 (30) (Table 40, Entry 215) is also reversing the rate, but it is not as effective as H-ZSM-5 (5) and H-ZSM-5 (50). It appears that once the EG mol fraction is reduced to approximately 0.22, the H-ZSM- 5 (5) and H-ZSM-5 (50) catalyst promotes formation of more EG.

[00046] Figure 2 shows the EG rate as a function of temperature for F 20 (1/8) for all three zeolite catalysts. In this case, the temperature of reaction is increased from 80 to 135 °C, both H-ZSM-5 (5) and H-ZSM-5 (50) produces a significant gain in EG rate towards production (i.e. the rates were positive). Again, H-ZSM-5 (30) approaches net production, but does not surface in the net positive. It appears from Figure 2 that as the temperature approaches a minimum of approximately 108 °C, F 20 (1/8) would begin to produce more EG for H-ZSM-5 (5) and H-ZSM-5 (50).

[00047] Based on these findings, one would anticipate that as temperature increases and EG feed decreases to little or no EG, the rate of EG formation would be even higher at the expense of other feed components due to a reforming reaction. As EG is consumed, the equilibria are shifted towards more EG production.

[00048] The foregoing description of the specific embodiments will reveal the general nature of the disclosure so others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and therefore such adaptations and modifications are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation.

Claims

WHAT IS CLAIMED IS:

1. A process for producing purified monoethylene glycol (MEG) comprising:

contacting a mixture comprising MEG and primary co-products with an acid to provide a distillable MEG product, wherein the primary co-products have boiling points substantially similar to a boiling point of MEG, and wherein the distillable MEG product comprises MEG and secondary co-products that do not boil closely with MEG; and

distilling the distillable MEG product to provide purified MEG and secondary co- products.

2. The process of claim 1, wherein the mixture comprising MEG and primary co- products is a product of a biomass conversion.

3. The process of claim 1 or claim 2, wherein substantially all of the distillable MEG product remains intact.

4. The process of any one of claims 1-3, wherein the acid is an acid catalyst selected from the group consisting of: zeolites, metal oxides, ion-exchange resin, and heteropolyacid.

5. The process of any one of claims 1-4, wherein the acid is an acid catalyst selected from the group consisting of: H-ZSM-5 (5), H-ZSM-5(30), H-ZSM-5(50), H-ZSM-5 (80), amberlyst-15, Zr0₂ W0₃, Cs_{2 5}HPA, and Nb₂0₅,

6. The process of any one of claims 1-5, wherein the primary co-products comprise one or more of 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, erythritol, and sorbitol.

7. The process of any one of claims 1-6, wherein the secondary co-products comprise propanal, butanal, and/or tetrahydrofuran.

8. The process of any one of claims 1-7, wherein 1,2-propanediol is converted to propanal.

9. The process of any one of claims 1-8, wherein 1,2-butanediol is converted to butanal.

10. The process of any one of claims 1-9, further comprising converting the secondary co- products to fuel.

11. The process of any one of claims 1-10, wherein at least about 50 percent of the primary co-products are converted to secondary co-products.

12. The process of any one of claims 1-11, wherein the process occurs at a temperature of between about 135 °C and about 200 °C.

13. A process for producing monoethylene glycol (MEG) comprising:

contacting a bio-derived MEG mixture comprising MEG and 1,2-butanediol (1,2-BDO) with an acid to provide a second MEG product, wherein the 1,2-BDO is converted to MEG.

14. The process of claim 13, wherein the acid is an acid catalyst is selected from the group consisting of: H-ZSM-5 (5), H-ZSM-5(30), H-ZSM-5(50), H-ZSM-5 (80), Amberlyst-

15. Zr0₂ W0₃, Cs_{2 5}HPA, and Nb₂0₅,

15. The process of claim 13 or claim 14, wherein the reaction occurs at a temperature of between 100 °C and 150 °C.

16. The process of any one of claims 13-15, wherein the MEG is present in the bio- derived MEG mixture in an amount of about 0 wt% to about 0.3 wt%.

17. The process of any one of claims 13-16, wherein between about 25% and 75% of the 1,2 BDO is converted to MEG.