Background :

Ethylene glycol can be prepared by a variety of routes in ^¬ cluding from sugars, e.g. monosaccharides, via fermentation and hydrogenolysis processes, or by hydroformylation . The fermentation route is a five-step process wherein glu ^¬ cose is fermented to ethanol and carbon dioxide, followed by conversion of ethanol to ethylene, ethylene to ethylene oxide and ethylene oxide to ethylene glycol. One disad ^¬ vantage of this method is that per mole of glucose ferment- ed, two moles of carbon dioxide are produced together with two moles of ethanol; this has the effect that a theoreti ^¬ cal maximum 67% of the carbon present in the glucose can be transformed to ethanol. The hydrogenolysis route is a two-step process wherein glu ^¬ cose is reduced to sorbitol followed by hydrogenolysis of sorbitol to ethylene glycol, as illustrated by US 6,297,409 Bl and US 2008/0228014 Al . Significant quantities of pro ^¬ pylene glycol, compared to ethylene glycol, are formed via the hydrogenolysis process. Additionally, the amount of catalyst used is significant and appears difficult to re ^¬ generate in order to reuse. Furthermore, the byproducts formed, in particular butanediols, are difficult to sepa ^¬ rate from the desired product. In particular, the industri- ally favorable method of distillation for separation (purification) purposes is extremely difficult to apply as the byproducts have very similar boiling points to the final product, and the desired product may react further, as il ^¬ lustrated in US2014/0039224 Al and US 5,393,542 Bl .

The hydroformylation route is a two-step process wherein glycolaldehyde is prepared from formaldehyde, carbon monox ^¬ ide and hydrogen, followed by hydrogenation of the gly ^¬ colaldehyde to ethylene glycol, as illustrated in US

4,496,781 Bl . There appears to be several extraction steps present in order to separate formaldehyde from glycolalde- hyde and proceed with the hydrogenation reaction.

Therefore it is desirable to provide an alternative, im ^¬ proved, high yielding and industrially feasible process for the preparation of ethylene glycol from sugars. An addi- tional advantage would be the use of greater than 67% of the sugar carbon atoms present in the final product or a commercial byproduct.

It could be conceived that ethylene glycol may be prepared via a process comprising two steps; such as the preparation of glycolaldehyde from sugars and its subsequent hydrogena ^¬ tion to ethylene glycol. The two steps of the proposed pro ^¬ cesses appear to be independently successful as illustrated in the following paragraphs.

It is known that sugars may be pyrolysed to obtain a pyrol- ysis product composition comprising oxygenate compounds such as glycolaldehyde US 7,094,932 B2; the crude pyrolysis product composition comprises C1-C3 oxygenate compounds, including formaldehyde, glycolaldehyde, glyoxal, pyruvalde- hyde and acetol. The main product of this reaction is gly- colaldehyde [US 7,094,932 B2]. Water is the solvent of the reaction .

It is also known that pure glycolaldehyde may be hydrogen- ated to ethylene glycol in the liquid phase. US 4,200,765 Bl discloses hydrogenation of glycolaldehyde under severe conditions: at high pressure [3000 psi (ca. 345 bar)], high temperature [150 °C] , with an organic solvent [N-methyl pyrrolidine] and a palladium on carbon [Pd/C] catalyst for a prolonged period [5 h] . US 4,321,414 Bl and US 4,317,946 Bl disclose the hydrogenation of glycolaldehyde with a ho ^¬ mogenous ruthenium catalyst and US 4,496,781 Bl discloses a continuous flow hydrogenation at low pressure [500 psi (ca. 35 bar)], high temperature [160 °C] with a ruthenium on carbon catalyst [Ru/C] in ethylene glycol and trace ace- tonitrile as solvent.

As illustrated, the two steps, pyrolysis of glucose to ob ^¬ tain, inter alia glycolaldehyde, and hydrogenation of pure glycolaldehyde in the liquid phase, appear to be inde ^¬ pendently feasible. However, in order for the pyrolysis product composition to be hydrogenated, laborious separa ^¬ tion processes must be employed to remove formaldehyde from the pyrolysis product composition as formaldehyde is a known poison of hydrogenation catalysts [US 5,210,337 Bl].

US 5,393,542 Bl discloses an exemplary purification process comprising multiple distillation steps followed by a sol ^¬ vent-induced precipitation to obtain a glycolaldehyde.

Therefore, it is not possible to hydrogenate the product of the pyrolysis step (the pyrolysis product composition) di ^¬ rectly as formaldehyde is present in the composition in a significant amount. In addition to the requirement of removing formaldehyde, which would increase the number of process steps required, it would also be a great advantage industrially to use a solvent that is non-toxic, for example water. Therefore it would be a significant advantage to be able to carry out the hydrogenation step in the presence of formaldehyde, us ^¬ ing a non-toxic solvent and in the solvent of the previous (pyrolysis) reaction.

With regard to hydrogenation of glycolaldehyde, although there is the provision of suitable reaction conditions to obtain a high yield in organic solvents, the reaction with water as a solvent appears to be less successful. US

5,393,542 Bl discloses thermal degradation of glycolalde ^¬ hyde (2-hydroxyacetaldehyde) when subjected to temperatures of 90 °C or higher and where water is the solvent.

EP 0 002 908 Bl discloses the variation in yield (conver- sion and selectivity) of the hydrogenation of glycolalde ^¬ hyde reaction with the use of various catalysts in an aque ^¬ ous solution at 110 °C : Raney Nickel [100% conversion 49.4% selectivity], 10% Pd/C [62% conversion, 61% selectivity] and 10% Pt/C [100% conversion, 73% selectivity] . An addi- tional disadvantage of catalysts used in liquid water is the strain on the catalyst. In particular at high tempera ^¬ tures (>160 °C) many supports are not stable and will dis ^¬ solve, degrade or the surface area is reduced; Energy & Fuels 2006, 20, 2337-2343. Hence, special catalysts are needed and the long-term catalyst performance is often problematic, consequently, the catalyst must be replaced frequently (ca. 3-6 months). Consequently, mild reaction conditions are favorable in order to ensure longevity of the catalyst on an industrial scale.

In addition, the choice of catalyst may affect the decompo- sition of glycolaldehyde when in the presence of the cata ^¬ lyst; US 5,210,337 Bl discloses the problem of glycolalde ^¬ hyde ^x unzipping' to form formaldehyde and consequently poi ^¬ soning the hydrogenation catalyst. It is also possible that glycolaldehyde may self-condense or condense with another C1-C3 oxygenate compounds, also illustrated in US 5,210,337 Bl . Additionally, the choice of catalyst and stability of the glycol product may affect the degree of reduction of the glycolaldehyde. It is possible that a catalyst may re ^¬ duce the glycolaldehyde to ethanol or ethane, i.e. over re- duce the glycolaldehyde.

Additionally, it is known that an increase in temperature, concentration of the substrate and amount and identity of catalyst present affects the yield (conversion and selec- tivity) of hydrogenation reactions of glycolaldehyde. Hand ^¬ book of Heterogeneous Catalytic Hydrogenation for Organic Synthesis, Shigeo Nishimura, ISBN: 978-0-471-39698-7, April 2001. As demonstrated, an industrial scale process for preparing ethylene glycol from monosaccharides via pyrolysis of mono ^¬ saccharides and subsequent hydrogenation in the liquid phase is hindered from two perspectives. The first is the requirement to remove formaldehyde from the pyrolysis prod- uct composition in order to enable successful hydrogena ^¬ tion. The second is the provision of mild reaction condi- tions that are high yielding. These two disadvantages are with respect to liquid phase hydrogenation reactions.

Consequently, it is desirable to provide a high yielding two-step process that is more efficient than known process ^¬ es; utilizes non-toxic solvents and cheaper catalysts; re ^¬ duces byproduct production; enables purification on an industrial scale; and is unaffected by the presence of addi- tional compounds such as formaldehyde. The ability to sepa ^¬ rate byproducts from the ethylene glycol product enables the ethylene glycol to be used in processes such as polymer production. Polymer production requires substrates to be in a highly pure form. All of these desirable aspects enable improved processes that are more attractive industrially and enable processes to become commercially feasible.

It has now been discovered that glycolaldehyde may be hy- drogenated when the hydrogenation process is in the gas phase. A significant advantage is that the gas phase hydro ^¬ genation process will proceed in the presence of formalde ^¬ hyde. The gas phase hydrogenation process has several fur ^¬ ther advantages, namely that it is high yielding, more ef ^¬ ficient in comparison to solely liquid phase processes, proceeds in the presence of water and with reduced 1,2- butanediol production compared to hydrogenolysis processes.

A further significant advantage is that the yield of the commercially valuable propylene glycol byproduct is in- creased. This has two consequences: firstly, a larger amount of a commercially valuable byproduct is formed; sec ^¬ ondly, it is thought that the higher yield of propylene glycol byproduct could affect the yield of alternative by ^¬ products, such as 1, 2-butanediol, consequently providing a product composition that is more easily purified. A further advantage is the type of catalyst used. Catalysts comprising metals such as copper and nickel are significantly cheaper than catalysts comprising noble metals; con ^¬ sequently, the use catalysts comprising metals such as cop ^¬ per and nickel reduce production costs.

A further advantage is the possibility of directly hydro- genating the pyrolysis product composition obtainable from the pyrolysis of sugars without condensation of the product composition. The advantage enables a significant increase in process efficiency for the preparation of ethylene gly ^¬ col from sugars.

Disclosure of the Invention: The present invention provides a process for the prepara ^¬ tion of ethylene glycol wherein a gas phase composition comprising Ci-3-oxygenate compounds is hydrogenated in the presence of a catalyst to obtain a gas phase hydrogenation product composition.

Gas phase composition means that the composition comprising Ci-3-oxygenate compounds to be hydrogenated (reduced) is in the gas phase during the hydrogenation process. It may be possible that the composition comprising Ci-3-oxygenate com- pounds is introduced into the reaction vessel in a phase other than the gas phase; however, the contact of the com- pounds with the catalyst occurs when the compounds are in the gas phase.

C ₁ -C3 oxygenate compounds means oxygenated compounds com- prising a carbon chain length of one, two or three carbon atoms. For example, Ci oxygenate compounds comprise a car ^¬ bon chain length of one carbon atom, such as formaldehyde and formic acid; C2 oxygenate compounds comprise a carbon chain length of two carbon atoms, such as glycolaldehyde, glyoxal and acetic acid; C3 oxygenate compounds comprise a carbon chain length of three carbon atom, such as pyru- valdehyde and acetol. C ₁ -C3 oxygenate compound composition means a composition comprising one or more compounds se ^¬ lected from the group consisting of formaldehyde, formic acid, glycolaldehyde, glyoxal, acetic acid, pyruvaldehyde and acetol. For example, C ₁ -C3 oxygenate compounds includes a composition comprising C2~oxygenate compounds and may comprise C2~oxygenate compounds only. A composition com ^¬ prising C2~oxygenate compounds means a composition compris- ing one or more compounds selected from the group consist ^¬ ing of glycolaldehyde and glyoxal. C2~oxygenate compounds means oxygenated compounds comprising a carbon chain length of two carbon atoms, for example, glycolaldehyde (2- hydroxyacetaldehyde) and glyoxal. A composition comprising C2~oxygenate compounds may be obtainable by pyrolysis of sugars or may be a solution comprising glycolaldehyde, gly ^¬ oxal or glycolaldehyde and glyoxal. Where the composition comprising Ci-3-oxygenate compounds is obtainable by pyroly ^¬ sis of sugars, typically, the C2~oxygenate compound compo- nent of the composition comprising C ₁ -C3 oxygenate com ^¬ pounds is for example 10 wt% or greater, 30 wt % or great ^¬ er. It is an embodiment of the present invention that the gas phase composition comprising Ci-3-oxygenate compounds comprises formaldehyde.

In a first embodiment of the invention the composition com ^¬ prising Ci-3-oxygenate compounds is present in the gas phase by virtue of the method of its preparation. For example, the composition comprising Ci-3-oxygenate compounds is ob ^¬ tainable from the pyrolysis of sugars (prepared according to US 7,094,932 B2), and is used directly in the following hydrogenation reaction. I.e. the product of the pyrolysis of monosaccharides is not condensed prior to the following gas phase hydrogenation reaction; however, the product may be conditioned (e.g. filtered to remove solids) .

In a second embodiment of the invention the composition comprising Ci-3-oxygenate compounds obtainable by pyrolysis of monosaccharides is present in the liquid phase and brought into the gas phase in order to hydrogenate . For ex- ample, the composition comprising Ci-3-oxygenate compounds is obtainable from the pyrolysis of monosaccharides (pre ^¬ pared according to US 7,094,932 B2) and is condensed to a liquid composition according to the US 7,094,932 B2 disclosure. The liquid composition is brought into the gas phase and hydrogenated; i.e. the product of the pyrolysis of sug ^¬ ars is condensed prior to being brought into the gas phase and following hydrogenation. The liquid phase composition comprising Ci-3-oxygenate compounds may be in the crude or a purified form prior to being brought into the gas phase.

In order to bring the composition comprising Ci-3-oxygenate compounds into the gas phase the composition comprising Ci- 3-oxygenate compounds is introduced into the reaction ves ^¬ sel, for example, via a nozzle that allows the dispersion of the composition comprising Ci-3-oxygenate compounds. Any compounds that are introduced into the reaction vessel in a phase other than the gas phase is converted to the gas phase by heat.

In a third embodiment of the invention, a solution of a composition comprising Ci-3-oxygenate compounds is brought into the gas phase and hydrogenated.

Hydrogenated or hydrogenation means that the composition comprising Ci-3-oxygenate compounds is subjected to hydro ^¬ genation reaction conditions. For example, the composition comprising Ci-3-oxygenate compounds is subjected to a cata ^¬ lyst and hydrogen wherein the substrate is reduced, e.g. glycolaldehyde is reduced to obtain ethylene glycol. Exam ^¬ ples of conventional reaction schemes and conditions of hy ^¬ drogenation reactions are disclosed in Ullmann' s Encyclo- paedia of Industrial Chemistry: Hydrogenation and Dehydro- genation .

Catalyst means a catalyst comprising a metal. Exemplary catalysts are disclosed in Handbook for Heterogeneous Cata- lytic Hydrogenation for Organic Synthesis by Shigeo Nishi- mura. Exemplary gas phase hydrogenation catalysts include a heterogeneous catalyst comprising a one or more metals se ^¬ lected from the group consisting of Cu, Ni, Co, Mo, Fe, Pt, Pd, Ru, Rh, Ir, preferably copper or nickel. The catalyst may further comprise a support; the support may comprise of for example, carbon, silica, alumina, silicon carbide, ti- tania and zirconia. Examples of a catalyst include copper on a carbon support, copper on a silica support, copper on an alumina support, copper on a silicon carbide support, copper on a titania support, copper on a zirconia support, nickel on a carbon support, nickel on a silica support, nickel on an alumina support, nickel on a silicon carbide support, nickel on a titania support, nickel on a zirconia support, platinum on a carbon support, platinum on a silica support, platinum on an alumina support or platinum on a silicon carbide support.

Gas phase hydrogenation product composition means a compo ^¬ sition comprising ethylene glycol obtainable by the hydro ^¬ genation of a gas phase composition comprising C ₁ -3- oxygenate compounds. The gas phase hydrogenation product composition may also comprise propylene glycol and metha ^¬ nol; i.e. the reduced products of Ci-3-oxygenate compounds including formaldehyde, pyruvaldehyde and acetol. The gas phase hydrogenation product composition may also comprise unreacted C2~oxygenate compounds, i.e. glycolaldehyde . The first product composition may also comprise unreacted or semi-reduced Ci-3-oxygenate compounds, i.e. formaldehyde, glycolaldehyde, glyoxal, pyruvaldehyde, acetol.

The product of the present invention may be the product composition obtainable or obtained from the gas phase hy ^¬ drogenation comprising ethylene glycol obtainable by the gas phase hydrogenation reaction. Alternatively, the prod ^¬ uct of the present invention may be the gas phase hydro ^¬ genation product composition that has been purified. Alter- natively, the product of the present invention may be the product of the gas phase hydrogenation product composition that has been further hydrogenated, e.g. in the liquid phase, to obtain a subsequent, liquid phase hydrogenation product composition. Alternatively, the product of the present invention may be the subsequent, liquid phase hy ^¬ drogenation product composition that has been purified.

Sugar means one or more sugars selected from monosaccha ^¬ rides and disaccharides . Preferably, sugar means one or more sugars selected from the group consisting of glucose, sucrose, fructose, xylose, mannose, arabinose and galac- tose. Preferably the sugar is glucose. The sugar may be in the form of a solution, wherein the sugar solution comprises a monosaccharide and a solvent. The solvent of the mono ^¬ saccharide solution is a solvent selected from the group consisting of: water or water and alcohol. Alcohol means one or more alcohol selected from the group consisting of methanol and ethanol. For example, the sugar solution may be present as an aqueous sugar solution, preferably an aqueous glucose solution. An aspect of the present invention is the temperature of the hydrogenation reaction. The composition comprising C ₁ -3- oxygenate compounds is hydrogenated at a temperature from 150 °C to 350 °C, from 150 °C to 300 °C, from 200 °C to 300 °C, from 200 °C to 280 °C .

An aspect of the present invention is the pressure of the hydrogenation reaction. The composition comprising C ₁ -3- oxygenate compounds is hydrogenated at a pressure from 0.1 bar to 30 bar, from 0.1 to 5 bar.

An aspect of the present invention is the reduction in the amount of formaldehyde present in the composition compris- ing Ci-3-oxygenate compounds during the gas phase hydrogena ^¬ tion process. The formaldehyde is reduced in order for a subsequent liquid phase hydrogenation to be successful. The formaldehyde is reduced in order for a subsequent liquid phase hydrogenation to produce a yield of at least 50% eth ^¬ ylene glycol from the hydrogenation of the first product composition .

A further aspect of the present invention is the yield of ethylene glycol from C2~oxygenate compounds prepared by the gas phase hydrogenation of a composition comprising C ₁ -3- oxygenate compounds is equal to or greater than 50%, equal to or greater than 60% equal to or greater than 70% equal to or greater than 75%.

A further aspect of the present invention is the yield of propylene glycol and acetol from C3~oxygenate compounds prepared by the gas phase hydrogenation of a composition comprising Ci-3-oxygenate compounds is equal to or greater than 30%, equal to or greater than 35% equal to or greater than 40%.

An embodiment of the present invention is the hydrogenation of the gas phase hydrogenation product composition prepared by the gas phase hydrogenation of a composition comprising Ci-3-oxygenate compounds. The gas phase hydrogenation prod ^¬ uct composition may be subsequently hydrogenated in the presence of a catalyst and a solvent; a subsequent, liquid phase hydrogenation product composition is obtained, i.e. the subsequent hydrogenation process may be a liquid phase process . The solvent is a solvent selected from the group consisting of: water; alcohol or water and alcohol. Alcohol means one or more alcohol selected from the group consisting of meth ^¬ anol, ethanol, ethylene glycol and propylene glycol.

The solvent may be a mixture of water and alcohol. Where the solvent is water and alcohol, the water and alcohol are in a ratio of equal to or greater than 95:5, 90:10, 80:20, 70:30, 60:40, 50:50, 40:60 and 30:70. The optional, subsequent liquid phase hydrogenation process is carried out in the presence of a heterogenous catalyst comprising a catalyst metal component such as ruthenium, ruthenium alloy, palladium or nickel. The catalyst metal component is supported by a support such as carbon. Known hydrogenation catalysts include ruthenium on a carbon support. For example, the subsequent liquid phase hydrogena ^¬ tion process may be carried out in the presence of a cata ^¬ lyst such as ruthenium on a carbon support catalyst. For example, the subsequent liquid phase hydrogenation process may be carried out in the presence of catalyst such as a 5% or 10% ruthenium on a carbon support catalyst. Examples of ruthenium alloy catalysts comprising 0.5 - 2% ruthenium are disclosed in WO 2014/066052 Al . The liquid phase hydrogenation process catalyst may be pre ^¬ sent in the reaction solution in a wt/wt ratio of formalde ^¬ hyde : catalyst metal component of from 1:1 to 15:1, from 1:1 to 11:1; from 1:1 to 10:1; from 1:1 to 7:1; from 1:1 to 5:1; from 3.0:1 to 15:1; from 3.1:1 to 15:1; from 3.2:1 to 15:1. Preferably, the liquid phase hydrogenation process catalyst is present in the reaction solution in a wt/wt ra ^¬ tio of formaldehyde : catalyst metal component of from 1:1 to 15:1, from 1:1 to 11:1; from 1:1 to 10:1; from 1:1 to 7:1; from 1:1 to 5:1; from 3.0:1 to 15:1; from 3.1:1 to 15:1; from 3.2:1 to 15:1. The subsequent liquid phase hydrogenation process may be carried out at a pressure of from about 10 bar to 90 bar, from 10 bar to 120 bar, from 10 bar to 150 bar. Preferably, the subsequent liquid phase hydrogenation process is car ^¬ ried out at a pressure of from about 10 bar to 90 bar, from 10 bar to 120 bar, from 10 bar to 150 bar.

The subsequent liquid phase hydrogenation process may be carried out at a temperature of from 40 to 160 °C, from 50 to 140 °C, from 60 to 130 °C, preferably from 80 to 120 °C . Preferably, the subsequent liquid phase hydrogenation pro ^¬ cess is carried out at a temperature of from 40 to 160 °C, from 50 to 140 °C, from 60 to 130 °C, preferably from 80 to 120 °C. The yield of ethylene glycol for the subsequent liquid phase hydrogenation process is equal to or greater than 80%, greater than 85%, greater than 90%, greater than 95%.

The yield of propylene glycol for the subsequent liquid phase hydrogenation process is equal to or greater than

80%, greater than 85%, greater than 90%, greater than 95%.

The total yield of ethylene glycol for the gas phase hydro ^¬ genation process and the subsequent liquid phase hydrogena- tion process is equal to or greater than 70%, greater than 75%, greater than 80%, greater than 85%. The total yield of propylene glycol for the gas phase hy ^¬ drogenation process and the subsequent liquid phase hydro ^¬ genation process is equal to or greater than 70%, greater than 75%, greater than 80%, greater than 82%.

An aspect of the present invention is the duration of the process for hydrogenation of the composition comprising Ci- 3-oxygenate compounds. The duration of the hydrogenation of the product composition is 6.0 hours or less, 3.0 hours or less, 2.5 hours or less, 2.0 hours or less, 1.0 hour or less, 0.5 hours (30 mins) or less, 15 mins or less. It is an embodiment of the present invention to reduce the dura ^¬ tion of the hydrogenation of compositions comprising C ₁ -3- oxygenate compounds through gas phase hydrogenation or gas phase hydrogenation with subsequent liquid phase hydrogena ^¬ tion, compared to a solely liquid phase hydrogenation pro ^¬ cess. A reduction in duration of the hydrogenation of compositions comprising Ci-3-oxygenate compounds process is il ^¬ lustrated by the batch conditions provided. Continuous flow processes correspond to batch conditions, however, varia ^¬ bles such as temperature, pressure, and amount of catalyst present affect the duration of the process. It is intended that the reduction in duration of the hydrogenation process according to the present invention is transferable when comparing liquid phase hydrogenation to either gas phase or gas phase followed by liquid phase.

An embodiment of the present invention is purification of the product of the subsequent liquid phase hydrogenation process (purification of the subsequent product composi ^¬ tion) . For example the subsequent liquid phase product com ^¬ position is purified. Both the gas and liquid phase product compositions comprise a 1 , 2-butanediol ( 1 , 2-BDO) : ethylene glycol wt/wt ratio equal to or less than 0.01:1, 0.008:1, 0.0075:1, 0.005:1, 0.004:1, 0.003:1.

An embodiment of the present invention is a two-step pro ^¬ cess. 'Two step' process means the conversion of sugars to ethylene glycol via two chemical transformations: the py- rolysis of sugars and the hydrogenation of glycolaldehyde obtainable from the pyrolysis of glucose. The two-step pro ^¬ cess of the present invention is the pyrolysis of monosac ^¬ charides to obtain a composition comprising Ci-3-oxygenate compounds followed by a gas phase hydrogenation process and optionally a subsequent liquid phase hydrogenation process. For example the crude pyrolysis product composition is hy- drogenated directly, first in the gas phase then in the liquid phase. Alternatively, the number of process steps may be considered to be the number of reactions of the to- tal process. In this understanding the process would be a two or three step process as there is one pyrolysis reac ^¬ tion followed by either one (gas phase) or two (gas and liquid phase) hydrogenation reactions. Purifying means separating the specific chemical compounds of the (hydrogenated) product composition obtainable by the hydrogenation process of the present invention. I.e. purifying means the separation of ethylene glycol, propylene glycol and other compounds of the (hydrogenated) product composition. Exemplary separation processes are disclosed in US 8, 177, 980 B2 and US 2014/0039224 Al . Such separation (purification) processes may be chromatography and distillation.

Ethylene glycol prepared according to the present invention may be used as a chemical. For example, ethylene glycol may be used as a monomer in the preparation of polymers includ ^¬ ing polyethylene terephthalate (PET) , polyester resins, fi ^¬ bers and films. Ethylene glycol may also be used as a de- icing agent, coolant, in particular in refrigeration appa- ratus, antifreeze agent or solvent. As described on:

http : //www . dow . com/ethyleneglycol /prod/meg . htm

Examples :

Example 1 : A pyrolysis product composition comprising C1-C3 oxygenate compounds was obtained by pyrolysis of a 20 wt% aqueous glucose (D-glucose monohydrate ; Sigma Aldrich) solution as described in US 7, 094, 932 B2. The typical composition of the pyrolysis product composition is provided in Table 1.

Table 1: Composition of the pyrolysis product composition of Example 1 :

GLA = Glycolaldehyde

GLO = Glyoxal

PYR = Pyruvaldehyde

FOR = Formaldehyde

ACE = Acetol

EG = Ethylene glycol

PG = Propylene glycol

MeOH = Methanol

Example 2: Liquid phase hydrogenation with 10% Cu/C cata- lyst, 6 hours.

The pyrolysis product composition of Example 1 [described in Table 1] (15.5 g) was loaded into an autoclave along with 10% Cu on carbon (10% Cu/C) catalyst (Sulfusorb 12 from Calgon Carbon, 0.40 g) . Prior to catalyst loading, the catalyst was activated at 300 °C for 2 hours in a flow of 5% hydrogen in nitrogen. The autoclave was purged 3 times with hydrogen and subsequently pressurized to 90 bars with hydrogen. The mixture was heated to 80 °C from room temper ^¬ ature over the course of 15 min and stirred at 80 °C for 6 hours. The autoclave was then cooled to room temperature and the decrease in hydrogen pressure was noted. The hydrogenated product mixture was isolated from the cat ^¬ alyst by filtration and analyzed by HPLC and GC .

The maximum theoretical yield of ethylene glycol was based on hydrogenation of both glyoxal and glycolaldehyde to eth- ylene glycol. The maximum theoretical yield of propylene glycol was based on hydrogenation of pyruvaldehyde and ace- tol to propylene glycol.

The yield of ethylene glycol was <2% and the yield of pro- pylene glycol was <2%.

The conversion of glycolaldehyde was 12.1%.

Example 2 demonstrates that the pyrolysis product composi- tion is not significantly hydrogenated in the liquid phase by a Cu/C catalyst at 80 °C for 6 hours. Example 3: Liquid phase hydrogenation with 5% Ru/C cata ^¬ lyst, 2 hours.

The pyrolysis product composition of Example 1 and de- scribed in Table 1 (15.5 g) was loaded into an autoclave along with 5% Ru on carbon (5% Ru/C) catalyst (Sigma Al- drich, 0.20 g) . The autoclave was purged 3 times with hy ^¬ drogen and subsequently pressurized to 90 bars with hydro ^¬ gen. The mixture was heated to 80 °C from room temperature over the course of 15 min and stirred at 80 °C for 2 hours. After reaction the autoclave was cooled to room temperature and the decrease in hydrogen pressure was noted.

The hydrogenated product mixture was isolated from the cat- alyst by filtration and analyzed by HPLC and GC .

The maximum theoretical yield of ethylene glycol was based on hydrogenation of both glyoxal and glycolaldehyde to eth ^¬ ylene glycol. The maximum theoretical yield of propylene glycol was based on hydrogenation of pyruvaldehyde and ace- tol to propylene glycol.

The yield of ethylene glycol was 12% and the yield of pro ^¬ pylene glycol was <1% (acetol is formed) .

The conversion of glycolaldehyde was 14%.

Conversion means the transformation of C ₂ ~oxygenate compounds to another compound or compounds. Selectivity means the transformation of C ₂ ~oxygenate compounds to ethylene glycol rather than other compounds such as ethanol or ethane . Example 3 demonstrates that the pyrolysis product composi ^¬ tion is not significantly hydrogenated in the liquid phase by a 5% Ru/C catalyst at 80 °C for 2 hours.

Example 4: Gas Phase hydrogenation with 10% Cu/C catalyst.

A pyrolysis product composition comprising C1-C3 oxygenate compounds was obtained by pyrolysis of a 20 wt% aqueous glucose (D-glucose monohydrate ; Sigma Aldrich) solution as described in US 7,094,932 B2. Prior to condensation of the pyrolysis product composition, the composition was hydro ^¬ genated in the gas phase. The hydrogenation was performed in a fixed bed reactor loaded with a 10 wt% Cu on Carbon catalyst (Sulfusorb 12 from Calgon Carbon) . The catalyst had been activated in situ at 300°C for 2 hours in a flow of hydrogen. Before entering the hydrogenation reactor, the pyrolysis product composition was mixed with hydrogen to give a partial pressure of hydrogen of 0.46 atm. (corre ^¬ sponding to a ¾ : C ratio of 50) . The pyrolysis product com ^¬ position was hydrogenated at 230°C with a residence time in the reactor of 0.15 seconds to obtain a first product com ^¬ position

The typical composition of the pyrolysis product composi ^¬ tion is given in Table 1; Example 1.

The yield of ethylene glycol was 79%. The yield of propyl- ene glycol was 41%. A 77% reduction of formaldehyde originally present in the pyrolysis product composition was observed.

Table 2. Composition of the gas phase hydrogenation product composition prepared according to Example 4.

GLA = Glycolaldehyde

GLO = Glyoxal

PYR = Pyruvaldehyde

FOR = Formaldehyde

ACE = Acetol

EG = Ethylene glycol

PG = Propylene glycol

MeOH = Methanol

Example 4 demonstrates that hydrogenation of a pyrolysis product composition in the gas phase over a 10% Cu/C cata ^¬ lyst (Sulfusorb 12 from Calgon Carbon) at 230 °C is ex- tremely successful. Example 4 demonstrates that it is pos ^¬ sible to retain glycolaldehyde in the gas phase at a high temperatures (230 °C) , and hydrogenate the pyrolysis prod ^¬ uct composition with a catalyst that is ineffective in the liquid phase (Cu/C) . Example 5: Liquid Phase hydrogenation of the first product composition of Example 4 with 5% Ru/C catalyst, 2 hours.

The gas phase hydrogenation product composition (15.5 g) described in Table 2 Example 4, was loaded into an auto ^¬ clave along with 5% Ru on carbon catalyst (Sigma Aldrich, 0.20 g) . The autoclave was purged 3 times with hydrogen and subsequently pressurized to 90 bars with hydrogen. The mix ^¬ ture was heated to 80 °C from room temperature over the course of 15 min and stirred at 80 °C for 2 hours. After reaction the autoclave was cooled to room temperature and the decrease in hydrogen pressure was noted. A liquid phase hydrogenation product composition was obtained. The liquid phase hydrogenation product composition (the product of Example 5) was isolated from the catalyst by filtration and analyzed by HPLC and GC .

The maximum theoretical yield of ethylene glycol was based on hydrogenation of glycolaldehyde into ethylene glycol and the maximum theoretical yield of propylene glycol was based on hydrogenation of acetol into propylene glycol.

The yield of ethylene glycol was ≥98% and the yield of pro- pylene glycol was ≥98%.

Conversion of glycolaldehyde was 100%.

The total yield of ethylene glycol from gas phase hydro- genation (Example 4) followed by liquid phase hydrogenation (Example 5) W3.S —89"6 and the total yield of propylene gly ^¬ col was >84%. Example 5 demonstrates that hydrogenation of the pyrolysis product composition in the gas phase (prior to condensa ^¬ tion) greatly improves a subsequent liquid phase hydrogena- tion step in comparison to hydrogenation with either Cu/C or Ru/C catalysts in the liquid phase only (Examples 2 and 3) .

Example 5 also demonstrates that high ethylene glycol yields are obtainable by the two-step (gas and subsequent liquid phase hydrogenation reactions) . Additionally, an ex ^¬ cellent yield of propylene glycol is obtainable.

Example 6: Liquid Phase hydrogenation of pyrolysis product composition with 5% Ru/C catalyst, 6 hours.

The pyrolysis product composition of Example 1 and de ^¬ scribed in Table 1 (15.5 g) was loaded into an autoclave along with 5% Ru on carbon catalyst (Sigma Aldrich, 0.40 g) . The autoclave was purged 3 times with hydrogen and sub ^¬ sequently pressurized to 90 bars with hydrogen. The mixture was heated to 80 °C from room temperature over the course of 15 min and stirred at 80 °C for 6 hours. After reaction the autoclave was cooled to room temperature and the de ^¬ crease in hydrogen pressure was noted.

The liquid phase hydrogenated product composition was iso ^¬ lated from the catalyst by filtration and analyzed by HPLC and GC . The maximum theoretical yield of ethylene glycol was based on hydrogenation of both glyoxal and glycolaldehyde into ethylene glycol and the maximum theoretical yield of pro ^¬ pylene glycol was based on hydrogenation of pyruvaldehyde and acetol into propylene glycol.

The yield of ethylene glycol was 81% and the yield of pro ^¬ pylene glycol was 57%. Conversion of glycolaldehyde was 100%.

Example 6 demonstrates that the pyrolysis product composi ^¬ tion is hydrogenated in the liquid phase by a 5% Ru/C cata ^¬ lyst; however, longer reaction times [6 hours compared to 2 hours (Example 5) ] and an increased amount of catalyst are required [0.4 g compared to 0.2 g (Example 5)] . Furthermore the selectivity is decreased compared to both Examples 4 and 5.

Table 3: Summary of Experimental Results for Examples 2-6.

Catalyst Phase T P T EG PG Conversion

( ) (bar) (°C) (wt/ (wt/ of C ₂ - wt%) wt%) oxygenate compounds to

EG

10% Cu/C Liquid 6 90 80 <2% <2% 12.1%

5% Ru/C Liquid 2 90 80 12% <1% 14%

10% Cu/C Gas N/A 1 230 77% 24% 91.9%

5% Ru/C Liquid 2 90 80 89* 84* 100%

5% Ru/C Liquid 6 90 80 81 % 57% 100% *The yield provided for Example 5 are the combined yields of Examples 4 and 5. The yield of reaction 5 is >98% for both ethylene glycol and propylene glycol.