METHOD OF PRODUCING PROPYLENE GLYCOL

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62/792,133, filed on January 14, 2019, which is incorporated herein in its entirety.

FIELD OF THE INVENTIONS

[0002] The compositions, articles, and methods disclosed herein relates to the production of propylene glycol and other useful chemicals.

BACKGROUND

[0003] In 2016 the propylene glycol market was valued at $3.47 billion and was projected to grow 7-8% annually. Food, pharmaceuticals and cosmetics is projected to be the fastest growing application segment of the global propylene glycol market, which requires high purity USP grade (99.8% purity).

[0004] There is a need for new and improved methods for producing propylene glycol, such as USP grade propylene glycol. Such methods are described herein.

SUMMARY OF THE INVENTION

[0005] Disclosed herein is a method comprising the steps of: a) contacting a mixture of glycerol, ethylene glycol and propylene glycol with a dehydration/dehydrogenation catalyst, thereby producing a first product comprising acetol, and i) ethylene glycol and/or ii) acrolein, acetone, propanal, dioxin, and dioxolane; b) separating the acetol from the i) ethylene glycol and/or ii) acrolein, acetone, propanal, dioxin, and dioxolane in the first product to produce a second product comprising at least 95 wt % acetol on dry basis; and c) hydrogenating the second product to produce a third product comprising at least 95 wt % propylene glycol on dry basis.

[0006] Additional advantages will be set forth in part in the description which follows, and in part will be obvious from the description, or can be learned by practice of the aspects described below. The advantages described below will be realized and attained by means of the chemical compositions, methods, and combinations thereof particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive. DESCRIPTION OF THE FIGURES

[0007] The accompanying figures, which are incorporated in and constitute a part of this specification, illustrate several aspects and together with the description serve to explain the principles of the invention.

[0008] FIG. 1A and FIG. IB show two non-limiting examples of the method disclosed herein.

[0009] .FIG. 2 shows the conversion and selectivity of glycerol to acetol, and propylene glycol to acetol as feeds and using Cu/C^Cb as catalyst at 280 °C.

[0010] FIG. 3 shows conversion of ethylene glycol to 4-methyl 1,3-Dioxolane, 2-methyl-l,3- dioxolane and 2, 3-dihydro-l, 3-Dioxin at various temperatures.

[0011] FIG. 4 shows the conversion and selectivity for the production of acetol obtained from co-feeding glycerol and propylene glycol at 240 °C using (Ai/(¾q ₃ as catalyst.

[0012] Additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or can be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

DETAILED DESCRIPTION

[0013] The disclosed methods and articles can be understood more readily by reference to the following detailed description.

[0014] Before the present compounds, compositions, articles, systems, devices, and/or methods are disclosed and described, it is to be understood that they are not limited to specific articles or methods unless otherwise specified. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.

Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, example methods and materials are now described.

[0015] All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided herein can be different from the actual publication dates, which can require independent confirmation.

1. Definitions

[0016] As used herein, nomenclature for compounds, including organic compounds, can be given using common names, IUPAC, IUBMB, or CAS recommendations for nomenclature. When one or more stereochemical features are present, Cahn-Ingold-Prelog rules for stereochemistry can be employed to designate stereochemical priority, E/Z specification, and the like. One of skill in the art can readily ascertain the structure of a compound if given a name, either by systemic reduction of the compound structure using naming conventions, or by commercially available software, such as CHEMDRAWTM (Cambridgesoft Corporation, U.S.A.).

[0017] In this specification and in the claims which follow, reference will be made to a number of terms which shall be defined to have the following meanings:

[0018] It must be noted that, as used in the specification and the appended claims, the singular forms“a,”“an” and“the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to“a therapeutic agent” includes mixtures of therapeutic agents, reference to“a pharmaceutical carrier” includes mixtures of two or more such carriers, and the like]

[0019]“Optional” or“optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event or circumstance occurs and instances where it does not. For example, the phrase“optionally comprising an adhesive material” means that the adhesive material can or cannot be present and that the description includes both situations.

[0020] Ranges can be expressed herein as from“about” one particular value, and/or to“about” another particular value. When such a range is expressed, a further aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent“about,” it will be understood that the particular value forms a further aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as“about” that particular value in addition to the value itself. For example, if the value“10” is disclosed, then“about 10” is also disclosed. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

[0021] A weight percent (wt. %) of a component, unless specifically stated to the contrary, is based on the total weight of the therapeutic composition or composition or material, in which the component is included.

[0022] References in the specification and concluding claims to parts by weight, of a particular element or component in a composition or article, denote the weight relationship between the element or component and any other elements or components in the composition or article for which a part by weight is expressed. Thus, in a composition containing 2 parts by weight of component X and 5 parts by weight component Y, X and Y are present at a weight ratio of 2:5, and are present in such ratio regardless of whether additional components are contained in the composition.

[0023] Disclosed are the components to be used to prepare the compositions of the invention as well as the compositions themselves to be used within the methods disclosed herein. These and other materials are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed that while specific reference of each various individual and collective combinations and permutation of these compounds cannot be explicitly disclosed, each is specifically contemplated and described herein. For example, if a particular compound is disclosed and discussed and a number of modifications that can be made to a number of molecules including the compounds are discussed, specifically contemplated is each and every combination and permutation of the compound and the modifications that are possible unless specifically indicated to the contrary. Thus, if a class of molecules A, B, and C are disclosed as well as a class of molecules D, E, and F and an example of a combination molecule, A-D is disclosed, then even if each is not individually recited each is individually and collectively contemplated meaning combinations, A-E, A-F, B-D, B-E, B-F, C-D, C-E, and C-F are considered disclosed. Likewise, any subset or combination of these is also disclosed. Thus, for example, the sub-group of A-E, B-F, and C-E would be considered disclosed. This concept applies to all aspects of this application including, but not limited to, steps in methods of making and using the compositions of the invention. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific embodiment or combination of embodiments of the methods of the invention. [0024] It is understood that the compositions disclosed herein have certain functions.

Disclosed herein are certain structural requirements for performing the disclosed functions, and it is understood that there are a variety of structures that can perform the same function that are related to the disclosed structures, and that these structures will typically achieve the same result.

2. Method of Producing Propylene Glycol

[0025] Disclosed herein is a method of producing propylene glycol. The disclosed method can be a cost-effective method for the production of high purity USP/EP food grade (99.8%) propylene glycol. The disclosed method produces a first product comprising acetol, and i) ethylene glycol and/or ii) acrolein, acetone, propanal, dioxin, and dioxolane (low boiling point intermediates) from a mixture of glycerol, ethylene glycol and propylene glycol by contacting the mixture of glycerol, ethylene glycol and propylene glycol with a

dehydration/dehydrogenation catalyst. Thus, in the disclosed method at least some of the ethylene glycol is not converted to products.

[0026] In the disclosed method, the glycerol can be converted to acetol, acrolein, and methanol; propylene glycol (PG) can be converted to acetol, acetone, propanal, and hydrogen; and ethylene glycol (EG) can be converted to dioxolane and dioxin. As described above, some of the ethylene glycol might not converted to dioxolane and dioxin in the disclosed method. The boiling points of the feed (glycerol, ethylene glycol and propylene glycol) and products are listed in Table 1.

Table 1. Boiling points of feed, intermediates, and products

[0027] The proximity of the boiling points of propylene glycol (188 °C) and ethylene glycol (197.3 °C) makes traditional separation of ethylene glycol and propylene glycol capital and energy intensive, which is one major obstacle to achieve desired propylene glycol purity levels. Glycerol has a boiling point of 290 °C. Purifying propylene glycol from glycerol and ethylene glycol conventionally requires high vacuum distillation. The relative volatility between propylene glycol and ethylene glycol is 1.1 which makes it nearly impractical to separate them using conventional distillation columns requiring at least 118 plates theoretically to achieve 99.5% purity (Table 2). On the other hand, relative volatility of acetol with respect to glycerol and glycols are significantly higher (> 4.0) (Table 2). This means purification of acetol from glycerol and glycols by distillation is rather simpler requiring less than 10 theoretical stages to achieve 99.5% purity (Table 2). . Alternatively, solvent extraction/azeotropic distillation rely on expensive solvents and their recovery. Dhale et al. developed a less capital and energy intensive reactive distillation route that separates propylene glycol and ethylene glycol (not glycerol) at ~ 1: 1 ratios using acetaldehyde ($0.45/lb, costs same as ¾ and requires additional recovery unit) to their respective low boiling point acetals (Dhale, Atul D., et al. Chemical engineering science 59.14 (2004): 2881-2890). However, this method has not been tested in presence of glycerol and for high propylene glycol: ethylene glycol ratios e.g. 9-14: 1, which are the preferred ratios used herein.

Table 2. Relative volatilities of different binary mixtures and number of theoretical plates required for separation by distillation at total reflux, 99.5% purity

[0028] The method disclosed herein utilizes favorable conditions for high propylene glycol purity and yield. For example, it is well established in literature that glycerol to propylene glycol conversion takes place in two steps: first dehydration to acetol and then hydrogenation to propylene glycol. The dehydration, which is performed at 200-320 °C, is favored at much higher temperatures than the hydrogenation, which can be performed at 110-150 °C. Producing propylene glycol in these two steps at their respective favorable temperatures improves the overall propylene glycol selectivity at milder operating conditions (Akiyama, Masaki, et al. Applied Catalysis A: General 371.1 (2009): 60-66). Also in this the overall mechanism ethylene glycol formation is produced directly from glycerol or propylene glycol, and not from acetol, at higher temperatures and in presence of Fh (Dieuzeide, M. L, et al. Catalysis Today (2017)), which is preferably circumvented by the method disclosed herein by conducting the dehydration step in absence of ¾ and the hydrogenation step uses acetol at low temperature, which eliminates further significant ethylene glycol formation. Rivera-Ramos et al. conducted a series of carefully conducted experiments at various temperatures and pressures to study the equilibrium of glycerol to propylene glycol reaction (Lizanette Rivera-Ramos, MSC thesis, University of Missouri-Columbia, 2006). They showed that higher temperatures and lower Fh pressures increase the formation of acetol but decrease propylene glycol if glycerol is used as reactant. Similarly using propylene glycol as reactant they showed that higher temperatures and lower pressures boosts acetol formation from propylene glycol. Thus the

dehydration/dehydrogenation step disclosed herein could maximize the formation of acetol from both glycerol and propylene glycol as higher temperatures (200-320 °C) and lower pressures (atmospheric) are applied. The same study also used acetol as reactant and showed that its conversion to propylene glycol is maximized at lower temperatures and moderate pressures which also justifies the use of similar condition (110-150 °C and 1-4 atmosphere) for the hydrogenation step.

[0029] The method disclosed herein is less capital and energy intensive, as compared to traditional methods. In the disclosed method the acetol is separated from the i) ethylene glycol and/or ii) acrolein, acetone, propanal, dioxin, and dioxolane in the first product to produce a second product comprising at least 95 wt % acetol on dry basis. The second product can be hydrogenated to produce a third product comprising at least 95 wt % propylene glycol on dry basis. [0030] Catalytic conversion of a variety of biomass derived raw materials (such as, hemicellulose and/or cellulosic sugars) notably produce a mixture of glycerol, ethylene glycol and propylene glycol. Separation and purification of the raw product slate imposes a daunting challenge to these biomass derived processes. The method described herein addresses this challenge and produces a high value and high purity chemical from a glycerol, propylene glycol and ethylene glycol product mixture which could enhance the economic viability of any such processes that produce product with these aforementioned components.

[0031] Accordingly, disclosed herein is a method comprising the steps of: a) contacting a mixture of glycerol, ethylene glycol and propylene glycol with a dehydration/dehydrogenation catalyst, thereby producing a first product comprising acetol, and i) ethylene glycol and/or ii) acrolein, acetone, propanal, dioxin, and dioxolane; b) separating the acetol from the i) ethylene glycol and/or ii) acrolein, acetone, propanal, dioxin, and dioxolane in the first product to produce a second product comprising at least 95 wt % acetol on dry basis; and c) hydrogenating the second product to produce a third product comprising at least 95 wt % propylene glycol on dry basis.

[0032] In one aspect, the first product can further comprise acetaldehyde and glyoxal. In another aspect, the first product can further comprise acetaldehyde, glyoxal, and methanol.

[0033] In one aspect, the second product can comprise at least 96 wt % acetol on dry basis. For example, the second product can comprise at least 97 wt % acetol on dry basis. In yet another example, the second product can comprise at least 99 wt % acetol on dry basis. In yet another example, the second product can comprise at least 99.8 wt % acetol on dry basis. In yet another example, the second product can comprise at least 99.9 wt % acetol on dry basis.

[0034] In one aspect, the third product can comprise at least 96 wt % propylene glycol on dry basis. For example, the third product can comprise at least 97 wt % propylene glycol on dry basis. In another example, the third product can comprise at least 98 wt % propylene glycol on dry basis. In yet another example, the third product can comprise at least 99 wt % propylene glycol on dry basis. In yet another example, the third product can comprise at least 99.5 wt % propylene glycol on dry basis. In yet another example, the third product can comprise at least 99.8 wt % propylene glycol on dry basis. In yet another example, the third product can comprise at least 99.9 wt % propylene glycol on dry basis. In yet another example, the third product can high purity USP/EP food grade propylene glycol, which has a purity of at least 99.8 wt% on dry basis. [0035] In one aspect, the step a) of contacting a mixture of glycerol, ethylene glycol and propylene glycol with a dehydration/dehydrogenation catalyst, thereby producing a first product comprising acetol is performed with no or limited addition of hydrogen. The term “limited addition of hydrogen” refers to atmospheric hydrogen. For example, the step can take place at or near atmospheric pressure, for example from about 1 bar to about 4 bar.

[0036] Two non-limiting schemes of the method disclosed herein is shown in FIGs. 1A and IB. As shown in FIGs. 1 A and IB the glycols and glycerol are co-processed in a fixed bed reactor where glycerol and propylene glycol are dehydrated and dehydrogenated, respectively to acetol (also known as hydroxyacetone) in absence of Fh over a Cu/Cr203 catalyst or Cu/AhCb catalyst at full conversion and >95% selectivity, see Example section. Next, acetol hydrogenation is performed at full conversion and high selectivity on over a Cu/C^Cb catalyst or C11/AI2O3 catalyst at mild conditions resulting in high purity food grade propylene glycol (purity of about 99.8%) as the final product (Akiyama, Masaki, et al. Applied Catalysis A: General 371.1 (2009): 60-66).

[0037] In one aspect, the multifunctional catalyst comprises one or more metals selected from the group consisting of Cu, Zn, Sn, Ni, Pt, Pd, Ru, and Re, and a support. In one aspect, the support is selected from the group consisting of C^Cb, AI2O3, SiCb, TiCh, ZrCb, MgO, and alumino-silicate, or a mixture thereof. For example, the support can be selected from the group consisting of Cr ₂ Cb, AI ₂ O ₃ , and SiCb, TiCb, ZrCb, and MgO or a mixture thereof. In another example, the support is Cr ₂ 0 _3. In yet another example, the support is AI ₂ O ₃ . In yet another example, the support is S1O2. In yet another example, the support is T1O2. In yet another example, the support is Zr02. In yet another example, the support is MgO. In yet another example, the support is alumino-silicate.

[0038] In one aspect, the multifunctional catalyst comprises Cu and a support. In one aspect, the multifunctional catalyst comprises Cu and a support selected from the group consisting of Cr203, AI2O3, S1O2, T1O2, Zr02, MgO, and alumino-silicate, or a mixture thereof. For example, the multifunctional catalyst comprises Cu and a support selected from the group consisting of Cr203, AI2O3, and S1O2, T1O2, Zr02, and MgO or a mixture thereof. In another example, the multifunctional catalyst comprises Cu and ¾0 _3. In yet another example, the multifunctional catalyst comprises Cu and AI2O3. In yet another example, the multifunctional catalyst comprises Cu and S1O2. In yet another example, the multifunctional catalyst comprises Cu and T1O2. In yet another example, the multifunctional catalyst comprises Cu and Zr0 ₂ . In yet another example, the multifunctional catalyst comprises Cu and MgO. In yet another example, the multifunctional catalyst comprises Cu and alumino-silicate.

[0039] In one aspect, the multifunctional catalyst is Cu/C^Cb. In another aspect, the multifunctional catalyst is Cu/AhCb

[0040] In one aspect, the mixture comprises from about less than 10 wt % of ethylene glycol, and from about 70 wt % to about 98 wt % of propylene glycol and glycerol. In one aspect, the first product comprises from about less than 5 wt % of ethylene glycol, and from about 80 wt % to about 97 wt % of propylene glycol and glycerol.

[0041] In one aspect, the mixture comprised a ratio of propylene glycol to ethylene glycol from about 7: 1 to 18: 1, such as from about 9: 1 to 14: 1.

[0042] In one aspect, the method can further comprise the step of contacting the mixture of ethylene glycol, propylene glycol, and glycerol with a dehydration/dehydrogenation catalyst disclosed herein, thereby producing a first product comprising acetol, and i) ethylene glycol and/or ii) acrolein, acetone, propanal, dioxin, and dioxolane.

[0043] In one aspect, in the step of contacting a mixture of glycerol, ethylene glycol and propylene glycol with a dehydration/dehydrogenation catalyst, thereby producing a first product comprising acetol, and i) ethylene glycol and/or ii) acrolein, acetone, propanal, dioxin, and dioxolane, the dehydration/dehydrogenation catalyst comprises Cu and a support. In one aspect, the support is selected from the group consisting of C^Cb, AhCb, SiCb, TiCb, ZrCh, MgO, and alumino-silicate, or a mixture thereof. For example, the support can be selected from the group consisting of Cr203, AI2O3, and S1O2, T1O2, Zr02, and MgO or a mixture thereof. In another example, the support is Cr ₂ 0 _3. In yet another example, the support is AI ₂ O ₃ . In yet another example, the support is S1O ₂ . In yet another example, the support is T1O ₂ . In yet another example, the support is Zr0 ₂ . In yet another example, the support is MgO. In yet another example, the support is alumino-silicate.

[0044] In one aspect, the dehydration/dehydrogenation catalyst comprises Cu and a support. In one aspect, the dehydration/dehydrogenation catalyst comprises Cu and a support selected from the group consisting of ¾03, AI2O3, S1O2, T1O2, Zr02, MgO, and alumino-silicate, or a mixture thereof. For example, the dehydration/dehydrogenation catalyst comprises Cu and a support selected from the group consisting of Cr203, AI2O3, and S1O2, T1O2, Zr02, and MgO or a mixture thereof. In another example, the dehydration/dehydrogenation catalyst can comprise Cu and ¾0 _3. In yet another example, the dehydration/dehydrogenation catalyst can comprise Cu and AI2O3. In yet another example, the dehydration/dehydrogenation catalyst can comprise Cu and S1O2. In yet another example, the dehydration/dehydrogenation catalyst can comprise Cu and TiC . In yet another example, the dehydration/dehydrogenation catalyst can comprise Cu and ZrC . In yet another example, the dehydration/dehydrogenation catalyst can comprise Cu and MgO. In yet another example, the dehydration/dehydrogenation catalyst can comprise Cu and alumino-silicate.

[0045] In one aspect, the dehydration/dehydrogenation catalyst is Cu/C^Cb. In another aspect, the dehydration/dehydrogenation catalyst is C11/AI2O3.

[0046] In one aspect, hydrogenating the second product to produce a third product comprising at least 95 wt % propylene glycol on dry basis comprises contacting the second product with a hydrogenation catalyst. In one aspect, the hydrogenation catalyst comprises Cu and a support. In one aspect, the support is selected from the group consisting of C^Cb, AI2O3, SiCh, TiCh, ZrCh, MgO, and alumino-silicate, or a mixture thereof. For example, the support can be selected from the group consisting of ¾0 ₃ , AI ₂ O ₃ , and S1O ₂ , T1O ₂ , Zr0 ₂ , and MgO or a mixture thereof. In another example, the support is Cr ₂ 0 _3. In yet another example, the support is AI ₂ O ₃ . In yet another example, the support is S1O ₂ . In yet another example, the support is T1O ₂ . In yet another example, the support is Zr0 ₂ . In yet another example, the support is MgO. In yet another example, the support is alumino-silicate.

[0047] In one aspect, the hydrogenation catalyst comprises Cu and a support. In one aspect, the hydrogenation catalyst comprises Cu and a support selected from the group consisting of ¾0 ₃ , AI2O3, S1O2, T1O2, Zr0 ₂ , MgO, and alumino-silicate, or a mixture thereof. For example, the hydrogenation catalyst can comprise Cu and a support selected from the group consisting of Cr203, AI2O3, and S1O2, T1O2, Zr02, and MgO or a mixture thereof. In another example, the hydrogenation catalyst can comprise Cu and Cr203 _. In yet another example, the hydrogenation catalyst can comprise Cu and AI2O3. In yet another example, the hydrogenation catalyst can comprise Cu and S1O2. In yet another example, the hydrogenation catalyst can comprise Cu and T1O2. In yet another example, the hydrogenation catalyst can comprise Cu and Zr02. In yet another example, the hydrogenation catalyst can comprise Cu and MgO. In yet another example, the hydrogenation catalyst can comprise Cu and alumino-silicate.

[0048] In one aspect, the hydrogenation catalyst is Cu/Cr203. In another aspect, the hydrogenation catalyst is C11/AI2O3.

[0049] In one aspect, the step of contacting a mixture of glycerol, ethylene glycol and propylene glycol with a dehydration/dehydrogenation catalyst, thereby producing a first product comprising acetol, and i) ethylene glycol and/or ii) acrolein, acetone, propanal, dioxin, and dioxolane, is performed at a temperature from about 190 °C to about 320 °C, for example from about 200 °C to about 260 °C, for example from about 230 °C to about 250 °C, such as for example about 240 °C. At such reaction temperature, the glycerol and propylene glycol are converted to acetol, while the ethylene glycol has much lower reaction rates toward the conversion to glyoxal and acetaldehyde.

[0050] In one aspect, the step of hydrogenating the second product to produce a third product comprising at least 95 wt % propylene glycol on dry basis, is performed at a temperature from about 100 °C to about 170 °C, for example from about 110 °C to about 150 °C.

[0051] In one aspect, step a) is performed in the absence of ¾. In one aspect, step a) is performed without the addition of Fb. The prior art disclosed that refined glycerol to propylene glycol can be obtained near full conversion and selectivity, but that such a process requires the use of high ¾ pressure, and dilution via recycle (U.S. Patent 7.790,937).

[0052] In one aspect, the first product comprises acetol, and ii) acrolein, acetone, propanal, dioxin, and dioxolane.

[0053] In one aspect, the first product comprises acetol, and i) ethylene glycol and ii) acrolein, acetone, propanal, dioxin, and dioxolane.

[0054] In one aspect, the separation in step b) of the acetol from the i) ethylene glycol and ii) acrolein, acetone, propanal, dioxin, and dioxolane in the first product comprises the steps of: 1) separating ethylene glycol from the acetol, acrolein, acetone, propanal, dioxin, and dioxolane; and 2) separating acetol from the acrolein, acetone, propanal, dioxin, and dioxolane, thereby producing the second product comprising at least 95 wt % acetol on dry basis. For example, separating ethylene glycol from the acetol, acrolein, acetone, propanal, dioxin, and dioxolane can be done via distillation (FIG. 1 A). In another example, separating acetol from the acetone, propanal, dioxin, and dioxolane, thereby producing the second product comprising at least 95 wt % acetol on dry basis can also be done using distillation (FIG. IB). In one aspect, multiple distillation stages can be used to increase the purity of the acetol in the second product. For example, 3-15 distillation stages can be used to increase the purity of the acetol in the second product, such as for example 5-10 distillation stages can be used to increase the purity of the acetol in the second product.

[0055] In one aspect, the method disclosed herein can be performed in a continuous process. In another aspect, the method disclosed herein can be performed in a batch process. [0056] In one aspect, the method disclosed herein can be performed on an industrial scale.

3. Aspects

[0057] In view of the disclosure herein below are described certain more particularly described aspects of the inventions. These particularly recited aspects should not however be interpreted to have any limiting effect on any different claims containing different or more general teachings described herein, or that the“particular” aspects are somehow limited in some way other than the inherent meanings of the language and formulas literally used therein.

[0058] Aspect 1: A method comprising the steps of: a) contacting a mixture of glycerol, ethylene glycol and propylene glycol with a dehydration/dehydrogenation catalyst, thereby producing a first product comprising acetol, and i) ethylene glycol and/or ii) acrolein, acetone, propanal, dioxin, and dioxolane; b) separating the acetol from the i) ethylene glycol and/or ii) acrolein, acetone, propanal, dioxin, and dioxolane in the first product to produce a second product comprising at least 95 wt % acetol on dry basis; and c) hydrogenating the second product to produce a third product comprising at least 95 wt % propylene glycol on dry basis.

[0059] Aspect 2: The method of aspect 1, wherein the dehydration/dehydrogenation catalyst comprises Cu.

[0060] Aspect 3: The method of aspect 1, wherein the dehydration/dehydrogenation catalyst comprises Cu and a support comprising C^Cb, AI2O3, SiCh, TiCh, ZrCh, MgO, or alumino silicate, or a mixture thereof.

[0061] Aspect 4: The method of aspect 1, wherein the dehydration/dehydrogenation catalyst comprises Cu and a support comprising (¾0 ₃ , AfCb, or SiCh, or a mixture thereof.

[0062] Aspect 5: The method of aspect 1, wherein the dehydration/dehydrogenation catalyst comprises Cu/C^Cb or C11/AI2O3.

[0063] Aspect 6: The method of any one of aspects 1-5, wherein step a) is performed in the absence of Tf.

[0064] Aspect 7: The method of any one of aspects 1-6, wherein the first product comprises acetol, and ii) acrolein, acetone, propanal, dioxin, and dioxolane.

[0065] Aspect 8: The method of any one of aspects 1-6, wherein the first product comprises acetol, and i) ethylene glycol and ii) acrolein, acetone, propanal, dioxin, and dioxolane.

[0066] Aspect 9: The method of aspect 8, wherein the separation in step b) of the acetol from the i) ethylene glycol and ii) acrolein, acetone, propanal, dioxin, and dioxolane in the first product comprises the steps of: 1. separating ethylene glycol from the acetol, acrolein, acetone, propanal, dioxin, and dioxolane; and 2. separating acetol from the acrolein, acetone, propanal, dioxin, and dioxolane, thereby producing the second product comprising at least 95 wt % acetol on dry basis.

[0067] Aspect 10: The method of any one of aspects 1-9, wherein the second product comprises at least 99 wt % acetol on dry basis.

[0068] Aspect 11: The method of any one of aspects 1-10, wherein the hydrogenation in step c) comprises contacting the second product with a hydrogenation catalyst.

[0069] Aspect 12: The method of aspect 11, wherein the hydrogenation catalyst comprises Cu.

[0070] Aspect 13: The method of aspect 11, wherein the hydrogenation catalyst comprises Cu and a support comprising (¾03, AI2O3, S1O2, T1O2, ZrCh, MgO, or alumino-silicate, or a mixture thereof.

[0071] Aspect 14: The method of aspect 11, wherein the hydrogenation catalyst comprises Cu and a support comprising (¾03, AI2O3, or S1O2, or a mixture thereof.

[0072] Aspect 15: The method of aspect 11, wherein the dehydration/dehydrogenation catalyst comprises Cu/toCb or C11/AI2O3.

[0073] Aspect 16: The method of any one of aspects 1-15, wherein the third product comprises at least 99 wt % propylene glycol on dry basis.

[0074] Aspect 17: The method of any one of aspects 1-16, wherein the step of contacting a mixture of glycerol, ethylene glycol and propylene glycol with a dehydration/dehydrogenation catalyst, thereby producing a first product comprising acetol, and i) ethylene glycol and/or ii) acrolein, acetone, propanal, dioxin, and dioxolane, is performed at a temperature from about 190 °C to about 320 °C.

[0075] Aspect 18: The method of any one of aspects 1-17, wherein the step of hydrogenating the second product to produce a third product comprising at least 95 wt % propylene glycol on dry basis, is performed at a temperature from about 100 °C to about 170 °C.

[0076] Aspect 19: The method of any one of aspects 1-18, wherein the step of contacting a mixture of glycerol, ethylene glycol and propylene glycol with a dehydration/dehydrogenation catalyst, thereby producing a first product comprising acetol, and i) ethylene glycol and/or ii) acrolein, acetone, propanal, dioxin, and dioxolane, is performed at a temperature from about 200 °C to about 260 °C. [0077] Aspect 20: The method of any one of aspects 1-19, wherein the method is performed continuously for at least 5 hours.

4. Examples

[0078] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices and/or methods claimed herein are made and evaluated, and are intended to be purely exemplary and are not intended to limit the disclosure. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in °C or is at ambient temperature, and pressure is at or near atmospheric. The Examples are provided herein to illustrate the invention, and should not be construed as limiting the invention in any way.

1. EXPERIMENTAL PARAMETERS AND TESTING OF CATALYSTS

[0079] Various modifications and variations can be made to the compounds, composites, kits, articles, devices, compositions, and methods described herein. Other aspects of the compounds, composites, kits, articles, devices, compositions, and methods described herein will be apparent from consideration of the specification and practice of the compounds, composites, kits, articles, devices, compositions, and methods disclosed herein. It is intended that the specification and examples be considered as exemplary.

[0080] FIGs. 2-4 show the advantages of co-processing the mixed feed of glycerol, propylene glycol, and ethylene glycol at low temperatures.

[0081] FIG. 2 shows the conversion and selectivity of glycerol to acetol, and propylene glycol to acetol as individual feeds and using Cu/C^Ch as catalyst at 280 °C. The reaction was performed at atmospheric pressure in the absence of Eh. FIG. 3 also shows the conversion of ethylene glycol to acrolein, acetone, propanal, dioxin, and dioxolane (low boiling point intermediates) using Cu/C^CE as catalyst at 240 °C, 280 °C, and 320 °C at atmospheric pressure.

[0082] FIG. 3 shows that at 240 °C the conversion of ethylene glycol is small (<5%). The conversion increases as the reaction temperature increases.

[0083] FIG. 4 shows the conversion and selectivity for the production of acetol obtained from co-feeding glycerol and propylene glycol at 240 °C using Cu/C^CE as catalyst. The reaction was performed at atmospheric pressure in the absence of Eh. [0084] FIG. 4 also shows that glycerol and propylene glycol can be co-fed and converted selectively to acetol at high conversion at moderate temperatures (at or below 240 °C) for which EG conversion is very small (see FIG. 3).

[0085] Based on the data presented in FIGs. 2-4 it is clear that a feed mixture of glycerol, propylene glycol, and ethylene glycol can be co-processed to produce acetol along with acrolein, acetone, propanal, dioxin, and dioxolane unreacted ethylene glycol. Thus, glycerol and propylene glycol selectively convert to a lower boiling point product, acetol, and majority of the ethylene glycol remains unconverted. This product substantially alleviate the difficulty of separation of ethylene glycol from glycerol and propylene. It also obviates the use of expensive many stage and/or high vacuum/temperature distillation or solvent extraction processes currently used for the same purpose.