Process for producing ethylene glycol and / or propylene glycol from aldose and / or ketose-producing carbohydrates, with recovery of an integrated tungsten catalyst.

Abstract

The present invention provides compositions produced in an integrated process for the catalytic conversion of carbohydrates to ethylene glycol and / or propylene glycol, using a homogeneous tungsten-containing reverse aldol catalyst. [Solution] A composition comprising a dissolved tungsten compound and one or more high-boiling point polyols including sorbitol, erythritol, treitol, and glycerin, wherein the mass ratio of the tungsten compound calculated as the total high-boiling point polyol to the metal is 0.01:1 to 1:1.

Description

Technical Field

[0001] (Cross-Reference to Related Applications) This application claims the benefit of U.S. Provisional Application No. 63 / 300,696, filed on January 19, 2022, entitled "PROCESSES FOR MAKING ETHYLENE GLYCOL AND / OR PROPYLENE GLYCOL FROM ALDOSE- AND / OR KETOSE-YIELDING CARBOHYDRATES WITH INTEGRATED TUNGSTEN CATALYST RECOVERY", the entire content of which is incorporated herein by reference.

[0002] (Field of the Invention) The present invention relates to a process for the catalytic production of ethylene glycol and / or propylene glycol from aldose- and / or ketose-yielding carbohydrates, particularly to a process with integrated tungsten catalyst recovery.

Background Art

[0003] Ethylene glycol and propylene glycol are valuable general-purpose chemicals, each having a wide range of applications. These chemicals are currently produced from starting materials based on fossil hydrocarbons (petrochemical routes).

[0004] Proposals have been made to produce ethylene glycol and propylene glycol from renewable resources, such as carbohydrates, for example sugars. One such route is commercially practiced and involves fermentation of sugars to ethanol, catalytic dehydrogenation of ethanol to ethylene, and then ethylene is catalytically converted to ethylene oxide which can react with water to produce ethylene glycol. This route requires three conversion steps and suffers from loss of conversion efficiency, so it is not economically attractive. For example, the theoretical yield of ethanol is 0.51 grams per gram of sugar, and theoretically one mole of carbon dioxide is produced per mole of ethanol.

[0005] Therefore, alternative processes are needed for producing ethylene glycol and propylene glycol from renewable resources. These alternative processes include catalytic pathways such as the hydrogenation of sugars, as well as two-catalyst processes ("reverse aldol pathways") that use reverse aldol catalysts to produce intermediates from sugars that can be hydrogenated on a hydrogenation catalyst to produce ethylene glycol and propylene glycol.

[0006] In the reverse aldol pathway, the carbohydrate is converted to an intermediate over a reverse aldol catalyst, which is then catalytically converted to ethylene glycol and / or propylene glycol over a hydrogenation catalyst ("Hcat"). The desired initial reverse aldol reaction is endothermic and requires high temperatures, often above 230°C, to provide a reaction rate that is favorably skewed towards the conversion of the carbohydrate to the intermediate over the hydrogenation of the carbohydrate to a polyol such as sorbitol.

[0007] The catalyst used for the reverse aldol conversion is typically homogeneous, contains tungsten, and therefore exits the reaction system with the product. Various proposals have been made to separate monoethylene glycol and propylene glycol from the reactor effluent and recirculate at least a portion of the tungsten-containing residue back into the reactor. See, for example, U.S. Patent Nos. 10,294,181 and 10,647,646 and U.S. Patent Application Publication 2021 / 0087128. While recirculation can preserve tungsten, tungsten species that are catalytically inactive or have reduced or undesirable catalytic activity may form during use.

[0008] Tungsten can also be recovered, for example, by ion exchange or precipitation, and the recovered tungsten can be converted into a catalytically active species for reverse aldol conversion. See U.S. Patent Application Publication No. 2021 / 0087128.

[0009] A process for producing lower glycols from carbohydrates via a reverse aldol process is sought to recover tungsten compounds from a process involving a purge flow, which is easily operated, requires little energy, and provides recovered tungsten compounds with desirable catalytic activity for reverse aldol conversion. [Overview of the Initiative]

[0010] The present invention includes an energy-efficient and effective method for recovering tungsten from a process for producing lower glycols from carbohydrates via an inverse aldol process. This process includes the integration of ion exclusion chromatography for the selective recovery of the tungsten compound and, if desired, the recycling of the tungsten compound, while also providing a higher boiling point organic phase that can be subjected to hydrocracking to enhance the conversion of the carbohydrate to the lower glycol, if desired.

[0011] The present invention provides an integrated process for the catalytic conversion of carbohydrates to ethylene glycol and / or propylene glycol using a homogeneous tungsten-containing reverse aldol catalyst. In these processes, the carbohydrate is subjected to reverse aldol conversion and hydrogenation to provide a reaction product containing ethylene glycol and / or propylene glycol, and other reaction processes include organic acids, thiols, and tungsten species. Ethylene glycol and propylene glycol are separated from the reaction product for purification, and at least a portion of the remaining fraction ("retained fraction") is subjected to ion exclusion chromatography to provide an eluent containing tungsten species, and a subsequent eluent containing organic acids and substantially reduced concentrations of tungsten species. At least a portion of the tungsten species-containing eluent can be recycled for reuse, either directly or with intervening unit operations to enhance the catalytic activity of the tungsten species.

[0012] Despite the very small fraction in which tungsten species are retained, a considerable portion of the tungsten, often at least about 60 percent, and sometimes about 70 or 80 percent (based on atomic tungsten), can be recovered by ion exclusion chromatography, and at least 90 mass percent of organic matter is found to be separated into the subsequent eluent phase. Therefore, the tungsten-containing eluent is suitable for recycling without excessive accumulation of unreactive organic matter in the reaction zone, and any intervening treatment of the tungsten species in the recycled eluent includes treatment of reduced volume liquid. Furthermore, if the content of organic acids is reduced by intervening treatments such as pH adjustment, less pH adjuster is required for the desired pH change to convert the tungsten compound into what is desired for recycling.

[0013] According to the present invention, a catalytic process for producing a lower glycol containing at least one of ethylene glycol and propylene glycol from a carbohydrate-containing feed containing at least one of aldose and ketose-producing carbohydrates, wherein the process involves continuously or intermittently supplying a feed to a reaction zone having at least one homogeneous tungsten-containing reverse aldol catalyst and at least one heterogeneous hydrogenation catalyst, in order to produce a reaction product containing a lower glycol and one or more high-boiling point byproducts including sorbitol, erythritol, treitol, and glycerin, wherein the liquid medium is continuously or intermittently supplied under catalytic conversion conditions including the presence of dissolved hydrogen. (b) Continuously or intermittently removing the liquid medium containing the reaction product and the dissolved tungsten compound from the reaction zone, (c) To provide a retained liquid phase containing a dissolved tungsten compound and a high-boiling point by-product, wherein the mass ratio of the tungsten compound to the high-boiling point by-product, calculated as metal, is greater than approximately 4:1, by subjecting at least a portion of the extracted liquid medium to one or more unit operations to remove at least a portion of the lower glycol in the separated fraction. (d) A process is provided which includes contacting at least a portion of the retained liquid phase with an ionic resin for ion exclusion chromatography to provide a first elution fraction containing a dissolved tungsten compound and a mass ratio of less than about 5:1, preferably less than about 1:1, of the tungsten compound calculated as a metal to high-boiling byproducts, and contacting the ionic resin with a sufficient solvent to provide at least one subsequent elution fraction containing one or more high-boiling byproducts and a tungsten compound (calculated as a metal) at a lower concentration than the concentration in the retained liquid phase (often less than about 10 parts by mass of the tungsten compound calculated as a metal per 100 parts by mass of high-boiling byproducts).

[0014] In a preferred process of the present invention, at least about 90 mass percent of the tungsten compound contained in the retained liquid phase in contact with the ion exchange resin is present in the first elution fraction. Preferably, at least a portion of the first elution fraction is recycled to step (a), and optionally, the first elution fraction is provided at a pH of about 6.5 to 8 before being passed through step (a). Optionally, at least a portion of the tungsten compound in the recycled first elution fraction is semi-neutralized tungstic acid. If desired, the subsequent elution fraction is subjected to hydrocracking conditions to convert yitol to lower glycols.

[0015] The present invention also relates to a product composition comprising a dissolved tungsten compound and one or more high-boiling point polyols including sorbitol, erythritol, treitol, and glycerin, wherein the mass ratio of the tungsten compound calculated as total high-boiling point polyol to metal is less than about 5:1, preferably less than about 1:1, and sometimes about 0.01:1 to 1:1. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram of an apparatus for implementing the process of the present invention. [Modes for carrying out the invention]

[0017] All patents, published patent applications and articles referenced in this specification are hereby incorporated by reference in their entireties.

[0018] Definition As used in this specification, unless otherwise stated, or unless otherwise clear from the context of their use, the following terms have the meanings set forth below.

[0019] When ranges are used in this specification, only the endpoints of the range are recited, to avoid the necessity of reciting and setting forth each and every value encompassed by the range in full length. Any suitable intermediate value and any suitable range between the recited endpoints can be selected. By way of example, if a range of 0.1~1.0 is recited, all intermediate values (for example, 0.2, 0.3, 0.63, 0.815, etc.) are included, and all intermediate ranges (for example, 0.2~0.5, 0.54~0.913, etc.) are also included.

[0020] The use of the terms "a" and "an" is intended to include one or more of the described elements.

[0021] Mixing or mixed means forming a physical combination of two or more elements that may have a homogeneous or heterogeneous composition throughout, including but not limited to solid mixtures, solutions, and suspensions.

[0022] An aldose is a carbohydrate that contains only a single aldehyde group (-CH=O) per molecule, and has the general chemical formula C n (H2O) nmeans a monosaccharide having an aldehyde group. Non-limiting examples of aldoses include aldohexoses (all 6-carbon aldehyde-containing sugars, including glucose, mannose, galactose, allose, altrose, idose, talose, and gulose); aldopentoses (all 5-carbon aldehyde-containing sugars, including xylose, lyxose, ribose, and arabinose); aldotetroses (all 4-carbon aldehyde-containing sugars, including erythrose and threose); and aldotrioses (all 3-carbon aldehyde-containing sugars, including glyceraldehyde).

[0023] An aldose-producing carbohydrate means an aldose or a disaccharide or polysaccharide that can produce an aldose upon hydrolysis. For example, although sucrose also produces a ketose upon hydrolysis, it is an aldose-producing carbohydrate.

[0024] Aqueous and aqueous media or solutions mean that water is present, but do not require that water is the main component. For purposes of illustration and not limitation, a solution of 90 volume percent ethylene glycol and 10 volume percent water is an aqueous solution. Aqueous solutions include liquid media containing dissolved or dispersed components, such as, but not limited to, colloidal suspensions and slurries.

[0025] Biologically-derived carbohydrate feedstock means products comprising carbohydrates that are wholly or substantially derived from, or synthesized from, biological products or renewable agricultural materials (including but not limited to plant, animal, and marine materials) or forestry materials.

[0026] Calculated as metal means that calculation is performed as elemental metal, regardless of the molecular structure of the metal-containing compound.

[0027] A catalyst for converting carbohydrates means one or more catalysts for performing catalytic conversion, which are both reverse aldol catalysts and hydrogenation catalysts ("Hcats"), each of which may include one or a mixture of catalysts. A catalyst may contain one or more catalytic metals, and for Hcats, this includes a carrier, a binder, and other auxiliary agents. A catalytic metal is a metal that is in an elemental state or is ionic or covalently bonded. The term catalytic metal refers to a metal that is not necessarily catalytically active but has the potential to become catalytically active if it is not in a catalytically active state. A catalytic metal can provide catalytic activity or modulate catalytic activity, such as by co-catalysts or selectivity modifiers.

[0028] The initiation of contact means that the fluid begins contact with a component, such as a homogeneous or heterogeneous catalyst, such as Hcat, in a medium, but it is not necessary for all molecules of the fluid to come into contact with the catalyst.

[0029] The composition of aqueous solutions is determined using gas chromatography for low-boiling-point components, typically containing three or fewer carbon atoms, and components with a standard boiling point below approximately 300°C, while high-performance liquid chromatography is used for high-boiling-point components, typically containing three or more carbon atoms, and thermally unstable components.

[0030] The conversion rate of aldohexose to ethylene glycol is reported in mass percent and calculated by dividing the mass of ethylene glycol contained in the product solution by the mass of aldohexose theoretically provided by the carbohydrate feedstock, and thus includes any aldohexose itself contained in the carbohydrate feedstock and any aldohexose theoretically produced upon hydrolysis of any disaccharide or polysaccharide contained in the carbohydrate feedstock.

[0031] Hexitol is a C6H molecule with one hydroxyl group per carbon atom. 14 This refers to a six-carbon compound with the empirical formula O6.

[0032] High-shear mixing involves providing a fluid moving at different velocities relative to adjacent regions, which can be achieved by stationary or moving mechanical means to induce shear to facilitate mixing. As used herein, the components subjected to high-shear mixing may be immiscible, partially immiscible, or miscible.

[0033] Water pressure distribution refers to the distribution of aqueous solution within a container, including contact with any catalyst contained within the container.

[0034] "Immediately before" means that there are no intervening unit operations that require a dwell time of more than one minute.

[0035] "Intermittent" means from time to time, and may be at regular or irregular time intervals.

[0036] Ion exclusion chromatography involves an adsorbent material saturated with the same mobile ions (cations or anions) present in the feed, and because it is saturated, similar ions are repelled by the adsorbent material. Ion exclusion chromatography can use an ion exchange resin bed that acts as a charged solid separation medium. Ion exclusion chromatography techniques using porous resin beds can help achieve size exclusion separation, where molecules can be separated by size and molecular weight, with larger and heavier molecules eluting first.

[0037] An itol is a carbon compound that contains at least two hydroxyl groups, each having one hydroxyl group on a carbon atom.

[0038] A ketose is a monosaccharide containing one ketone group per molecule. Non-exclusive examples of ketoses include ketohexoses (all 6-carbon ketone-containing sugars, including fructose, psicose, sorbose, and tagatose), ketopentoses (all 5-carbon ketone-containing sugars, including xylulose and ribulose), ketotetrose (all 4-carbon ketose-containing sugars, including erythrulose), and ketotrioses (all 3-carbon ketose-containing sugars, including dihydroxyacetone).

[0039] Ketose-producing carbohydrates refer to ketoses, disaccharides, polysaccharides, or hemicelluloses that can produce ketoses or ketose precursors upon hydrolysis. Most sugars have a cyclic structure under ambient conditions, and therefore the ketose form arises under the conditions of the process of the present invention. For example, sucrose is a ketose-producing carbohydrate, although it also produces aldoses upon hydrolysis. For the purposes of this specification, carbohydrates that produce both aldoses and ketoses are considered ketose-producing carbohydrates unless the context requires a different interpretation.

[0040] The liquid medium refers to the liquid in the reactor. The liquid is a solvent for the carbohydrates, intermediates, and products, as well as for the homogeneous tungsten-containing reverse aldol catalyst. Typically and preferably, the liquid contains at least some water and is therefore called an aqueous medium.

[0041] Lower glycols are ethylene glycol, propylene glycol, or mixtures thereof.

[0042] The pH of an aqueous solution is determined by the ambient pressure and temperature. For example, when determining the pH of an aqueous hydrogenation medium or product solution, the liquid is cooled, left for 2 hours at ambient pressure and temperature, and then the pH is determined. If the aqueous solution contains less than about 50 mass percent water, for example, in a glycol-rich medium, water is added to the sample to provide a solution containing about 50 mass percent water. For the purpose of consistency, the dilution of the solution is with respect to the same mass percent of water.

[0043] A pH adjuster refers to one or more of the following: a buffering agent and / or an acid or a base.

[0044] Pressure sufficient to maintain at least partial hydration of carbohydrates means that the pressure is sufficient to retain enough hydration water on the carbohydrates to delay caramelization. At temperatures above the boiling point of water, the pressure is sufficient to allow the hydration water to be retained on the carbohydrates.

[0045] Rapid diffusion mixing is a mixing process in which at least one of two or more fluids being mixed is finely divided to facilitate mass transfer and form a substantially homogeneous composition.

[0046] A reactor can be one or more vessels in series or in parallel, and a vessel can contain one or more zones. A reactor can be any suitable design for continuous operation, including but not limited to tanks and pipes or tubular reactors, and can have fluid mixing capabilities if desired. Types of reactors include, but are not limited to, laminar flow reactors, fixed-bed reactors, slurry reactors, fluidized-bed reactors, moving-bed reactors, pseudo-moving-bed reactors, trickle-bed reactors, bubble towers, and loop reactors.

[0047] A separation unit operation is one or more operations for the selective separation of a chemical substance, and includes, but is not limited to, chromatographic separation, sorption, membrane separation, flash separation, distillation, rectification, and evaporation.

[0048] Soluble means that it can form a single liquid phase or a colloidal suspension.

[0049] Solubilized tungsten compounds are tungsten compounds that are dissolved in the reaction medium or suspended colloidally.

[0050] Vapor / liquid separation is a separation that provides one or more vapor streams and one or more liquid streams and can be based on chromatographic separation, cyclic sorption, membrane separation, flash separation, distillation, rectification, and evaporation (e.g., thin film evaporators, flowing thin film evaporators, and wiped film evaporators).

[0051] Carbohydrate supply The process of the present invention uses a carbohydrate feed containing aldohexose-producing carbohydrates or ketose-producing carbohydrates, the former providing an ethylene glycol-rich product under reverse aldol reaction conditions, and the latter providing a propylene glycol-rich product. When a product solution containing a high mass ratio of ethylene glycol to propylene glycol is desired, the carbohydrates in the feed contain at least about 90 mass percent, preferably at least about 95 or 99 mass percent, of aldohexose-producing carbohydrates. Often, the carbohydrate feed contains carbohydrate polymers such as starch and cellulose, or fractions of such polymers that are partially to essentially completely hydrolyzed, or mixtures of polymers, or mixtures of polymers and partially hydrolyzed fractions.

[0052] Carbohydrate sources are, in most cases, pentoses and hexoses, or at least one of compounds that produce pentoses or hexoses. Examples of pentoses and hexoses include xylose, lyxose, ribose, arabinose, xylulose, ribulose, glucose, mannose, galactose, allose, altrose, idose, talose, and growthfructose, psicose, sorbose, and tagatose. Most bio-derived carbohydrate sources produce glucose when hydrolyzed. Glucose precursors include, but are not limited to, maltose, trehalose, cellobiose, kordibiose, nigerose, isomaltose, β,β-trehalose, α,β-trehalose, sophorose, laminaribiose, gentiobiose, and mannobiose. Carbohydrate polymers and oligomers (such as hemicellulose and partially hydrolyzed forms of hemicellulose), disaccharides (such as sucrose, lactulose, lactose, turanose, maltulose, palatinose, genthiobiurose, melibiose, melibiurose, etc.), or combinations thereof may be used.

[0053] If desired, the carbohydrate feedstock can be processed to remove one or more impurities, particularly those that may affect one or more of the catalysts. For example, a portion that may oxidize or sulfurize one or more of the catalysts used in the process.

[0054] The carbohydrate feed can be solid, or preferably in a liquid suspension, or soluble in a solvent such as water. If the carbohydrate feed is in a non-aqueous environment, the carbohydrate is preferably at least partially hydrated. Suitable non-aqueous solvents include alkanols, diols and polyols, ethers, or other suitable carbon compounds with 1 to 6 carbon atoms. Suitable solvents include mixed solvents, particularly those containing water and one of the non-aqueous solvents. Certain mixed solvents can have a higher concentration of dissolved hydrogen under the conditions of the hydrogenation reaction, thus reducing the possibility of hydrogen deficiency. Preferred non-aqueous solvents can be hydrogen donors such as isopropanol. Often, these hydrogen donor solvents have hydroxyl groups converted to carbonyl groups when donating hydrogen atoms, and this carbonyl can be reduced under the conditions in the reaction zone. Most preferably, the carbohydrate feed is provided in aqueous solution. In any case, in order to provide a continuous process, the volume of the feed must be balanced with the volume of the raw material product to be extracted.

[0055] Further considerations when supplying carbohydrates to the reaction zone include minimizing energy and capital costs. For example, in steady-state operation, the solvent contained in the feed needs to be separated from the reaction zone along with the raw material products to recover the desired glycol product.

[0056] Preferably, the feed is introduced into the reaction zone in a manner that avoids excessive concentrations of the feed that could lead to hydrogen deficiency. Using multiple locations for the supply of carbohydrates per unit volume of the reaction zone allows for a greater concentration of carbohydrates in the feed. Generally, the water-to-carbohydrate mass ratio in the carbohydrate feed is preferably in the range of 4:1 to 1:4. Aqueous solutions of 600 g / liter or more of certain carbohydrates, such as dextrose and sucrose, may also be commercially available.

[0057] In some cases, a recirculated hydrogenated solution substantially free of the hydrogenation catalyst, or an aliquot or separated portion thereof, is added as a component to the carbohydrate feed. The recirculated hydrogenated solution may be a portion of the feedstock product stream or one or more of the internal recirculation from which the hydrogenation catalyst is removed. Suitable solid separation techniques include, but are not limited to, filtration and density separation (e.g., cyclones, vane separators, and centrifugation). This recirculation reduces the amount of fresh solvent for the feed, but the carbohydrates are supplied at a rate sufficient to maintain a high conversion rate per unit volume of the reaction zone. The use of recirculation allows for the supply of low concentrations of carbohydrates to the reaction zone while maintaining a high conversion rate of carbohydrates to ethylene glycol, especially when the recirculation is an aliquot portion of the feedstock product stream. Additionally, it is possible to maintain the recirculated stream at or near the temperature of the reaction zone, and since the recirculated stream contains a tungsten-containing catalyst, the reverse aldol conversion may occur before the feed enters the reaction zone. When using a recirculating hydrogenation solution, the mass ratio of carbohydrates to the total recirculated product flow and added solvent is often in the range of approximately 0.05:1 to 0.4:1, and sometimes between approximately 0.1:1 and 0.3:1. The recycled raw material product flow is often about 20 to 80 volume percent of the product flow.

[0058] The carbohydrates contained in the carbohydrate feed are supplied at a rate of at least 50 or 100 grams per hour per liter of reactor volume, preferably about 150 to 500 grams. If necessary, a separate reaction zone containing an inverse aldol catalyst and essentially free of a hydrogenation catalyst may be used.

[0059] Conversion process In this process, the carbohydrate feedstock is introduced into a solvent containing a catalyst for catalytic conversion and hydrogen. The solvent is often water, but may also be a lower alcohol or polyalcohol with 1 to 6 carbon atoms, particularly methanol, ethanol, n-propanol, and isopropanol.

[0060] The carbohydrate feedstock may or may not be subjected to reverse aldol conditions before being introduced into the reaction zone, and may or may not be heated through a temperature zone of 170°C to 230°C when it comes into contact with the liquid medium in the reaction zone. Therefore, in some cases, the reverse aldol reaction may not occur until the carbohydrate feedstock is introduced into the liquid medium, and in other cases, the reverse aldol reaction may occur at least partially before the introduction of the carbohydrate feedstock into the liquid medium in the reaction zone. Rapid dispersion of the carbohydrate feedstock in the liquid medium is generally preferred, especially when a hydrogenation medium is used to provide direct heat exchange to the carbohydrate feedstock. This dispersion can be achieved by any preferred procedure, including, but not limited to, the use of mechanical and static mixers and rapid diffusion mixing. The use of multiple ports for introducing the feedstock into the reactor also facilitates rapid dispersion.

[0061] The preferred temperature for the reverse aldol reaction is typically about 230°C to 300°C, more preferably about 240°C to 280°C, although the reverse aldol reaction can occur at lower temperatures, for example, as low as 90°C or 150°C. The absolute pressure is typically in the range of about 15 to 200 bar (1500 to 20,000 kPa), for example, about 25 to 150 bar (2500 to 15000 kPa). The conditions for the reverse aldol reaction include the presence of a reverse aldol catalyst. The reverse aldol catalyst is a catalyst that catalyzes the reverse aldol reaction. Examples of tungsten compounds that can provide a reverse aldol catalyst include, but are not limited to, heterogeneous and homogeneous catalysts, including catalysts supported on a carrier, and include tungsten and its oxides, sulfates, phosphides, nitrides, carbides, halides, acids, and the like. This also includes tungsten carbide, soluble phosphotungsten, and tungsten oxide supported on zirconia, alumina, and alumina-silica. Preferred catalysts are provided by soluble tungsten compounds and mixtures of tungsten compounds. Soluble tungstates include, but are not limited to, ammonium and alkali metals (e.g., sodium and potassium), paratungstates, partially neutralized tungstic acid, ammonium and alkali metal metatungstates, and ammonium and alkali metal tungstates. Often, the presence of ammonium cations leads to the formation of undesirable amine byproducts in the lower glycol product. Although not intended to be limited to theory, the catalytically active species may or may not be the same as the soluble tungsten compound introduced as a catalyst. Rather, the catalytically active species may be formed as a result of exposure to reverse aldol reaction conditions. Tungsten-containing complexes are typically pH-dependent. For example, a solution containing sodium tungstate at a pH greater than 7 will produce sodium metatungstate as the pH decreases. The morphology of complexed tungstate anions is generally pH-dependent. The rate at which complexed anions are formed from the condensation of tungstate anions is influenced by the concentration of tungsten-containing anions.Preferred reverse aldol catalysts include ammonium or alkali metal tungstates that are partially neutralized with an acid, preferably an organic acid with 1 to 6 carbon atoms, such as, but not limited to, formic acid, acetic acid, glycolic acid, and lactic acid. Partial neutralization is often about 25 to 75%, i.e., an average of 25 to 75% of the tungstate cations become acidic sites. Partial neutralization may be performed before introducing the tungsten-containing compound into the reactor, or it may be performed with an acid already present in the reactor.

[0062] The concentration of the reverse aldol catalyst used may vary widely and depend on the catalyst activity as well as other conditions of the reverse aldol reaction, such as acidity, temperature, and carbohydrate concentration. Typically, the reverse aldol catalyst is supplied in an amount that provides about 0.01 or 0.05 to 100 grams of tungsten per liter of aqueous hydrogenation medium, calculated as elemental metal, for example, about 0.02 or 0.1 to 50 grams. The reverse aldol catalyst can be added as a mixture with all or part of the carbohydrate feed, as a separate feed to the liquid medium, or with the recirculated liquid medium, or in any combination thereof. If the reverse aldol catalyst contains two or more tungsten species, they can be supplied to the reaction zone separately or together. In some preferred embodiments, the carbohydrate feed is mixed with the reverse aldol catalyst before contact with the hydrogenation catalyst. The pH of the mixture is preferably greater than 4, often greater than 5.5, and possibly about 6 to 7.5, for example, 6.5 to 6.8.

[0063] In most cases, the carbohydrate feedstock is subjected to reverse aldol conditions before being introduced into the hydrogenation medium within a reaction zone containing a hydrogenation catalyst. Preferably, the introduction into the aqueous hydrogenation medium occurs less than one minute, most often less than 10 seconds, from the start of the introduction of the carbohydrate feedstock into the reverse aldol conditions. Part or all of the reverse aldol reaction may occur within the reaction zone containing the hydrogenation catalyst. In any case, the most preferred process is one with a short time between the reverse aldol transformation and hydrogenation.

[0064] Under many process conditions useful in the process of the present invention, tungsten-containing precipitates may form and may be suspended or deposited on surfaces, including the surface of the hydrogenation catalyst, which may affect the activity of the hydrogenation catalyst.

[0065] Hydrogenation, i.e., the addition of hydrogen atoms to organic compounds without cleaving carbon-carbon bonds, can be carried out at temperatures in the range of approximately 100°C or 120°C to 300°C or higher. Typically, the hydrogenation medium is maintained at a temperature of at least approximately 230°C until substantially all carbohydrates have reacted and the carbohydrate carbon-carbon bonds have been broken by a reverse aldol reaction, thereby enhancing selectivity to ethylene and propylene glycol. The temperature of the hydrogenation medium can then be reduced if desired. However, hydrogenation proceeds rapidly at these higher temperatures. Therefore, the temperature for hydrogenation reactions is often approximately 230°C to 300°C, for example, approximately 240°C to 280°C. Typically, in the reverse aldol process, the pressure (absolute) is typically in the range of approximately 15 to 200 bar (1500 to 20,000 kPa), for example, approximately 25 to 150 bar (2500 to 15000 kPa). The hydrogenation reaction requires the presence of hydrogen and a hydrogenation catalyst. Hydrogen has low solubility in aqueous solutions. The hydrogen concentration in the aqueous hydrogenation medium increases with increasing hydrogen partial pressure in the reaction zone. The pH of the aqueous hydrogenation medium is often at least about 2.5 or 3, for example, about 3 or 3.5 to 8, and in some cases about 3.5 or 4 to 7.5.

[0066] Hydrogenation is carried out in the presence of a hydrogenation catalyst. Often, the hydrogenation catalyst is a supported heterogeneous catalyst. It can be arranged in any preferred configuration, including but not limited to fixed beds, fluidized beds, trickle beds, moving beds, slurry beds, loop beds such as the Buss Loop® reactor available from BUSS ChemTech AG, and structured beds. One type of reactor that can provide high hydrogen concentration and rapid heating is a cavitation reactor, such as the one disclosed in U.S. Patent No. 8,981,135(B2), which is incorporated herein by reference. Cavitation reactors generate heat in localized regions, and therefore, the temperature in these localized regions, rather than the bulk temperature of the liquid medium in the reaction zone, is the temperature process parameter for the purposes of this invention. Cavitation reactors are of interest to this process because the reverse aldol conversion can be very rapid at the temperatures at which it can be achieved within a cavitation reactor.

[0067] Nickel, ruthenium, palladium, and platinum are more widely used reducing metal catalysts. However, many reducing catalysts function in this application. The catalyst may be supported or unsupported, such as Raney nickel. The reducing catalyst can be selected from a wide variety of supported transition metal catalysts. One particularly preferred catalyst for the reducing catalyst in this process is the supported Ni-Re catalyst. Similar versions of Ni / Re or Ni / Ir can be used with good selectivity for the conversion of the formed glycolaldehyde to ethylene glycol. Nickel-rhenium is a preferred reducing metal catalyst and may be supported on alumina, alumina-silica, silica, or other supports. Supported Ni-Re catalysts with B as a co-catalyst are useful. Generally, for slurry reactors, the supported hydrogenation catalyst is supplied in amounts of less than 10 grams of nickel (calculated as elemental nickel) per liter of liquid medium in the reactor, sometimes less than about 5 grams, for example, about 0.1 or 0.5 to 3 grams. As mentioned above, not all nickel in the catalyst is in a zero-valent state, nor is all nickel in a zero-valent state readily accessible by glycolaldehyde or hydrogen. Therefore, the optimal mass of nickel per liter of liquid medium varies for a given hydrogenation catalyst. For example, Raney nickel catalysts provide a much higher concentration of nickel per liter of liquid medium. Often, in slurry reactors, the hydrogenation catalyst is supplied in an amount of at least about 5 or 10 grams, more often about 10 to 70 or 100 grams, per liter of aqueous hydrogenation medium, and in packed-bed reactors, the hydrogenation catalyst constitutes about 20 to 80 volume percent of the reactor. In some cases, the gravimetric space-time rate is about 0.01 or 0.05 to 1 hr, based on the total carbohydrates in the feed. -1 Preferably, the residence time is sufficient so that glycolaldehyde and glucose are less than 0.1 mass percent of the reaction product, and most preferably less than 0.001 mass percent of the reaction product.

[0068] The carbohydrate supply is at least 50 grams of carbohydrates per liter per hour, and is often in the range of approximately 100 to 700 or 1000 grams of carbohydrates per liter per hour.

[0069] In the process of the present invention, combinations of reaction conditions (e.g., temperature, hydrogen partial pressure, catalyst concentration, hydraulic distribution, and residence time) are sufficient to convert at least about 95 mass percent, often at least about 98 or 99 mass percent, and sometimes essentially all, of the carbohydrate that produces the aldose or ketose. Determining the set(s) of conditions that provide the desired conversion of the carbohydrate is well within the scope of the art of those skilled in the art who benefit from the disclosure herein.

[0070] Ion exclusion chromatography separation In the process of the present invention, ion exclusion chromatography separation is used to obtain a product composition rich in dissolved tungsten compounds as the desired product, while excluding lower glycols and high-boiling by-products recovered in the subsequent eluent. The product composition has a substantially reduced ratio of lower glycols and high-boiling by-products to tungsten compounds compared to the ratio in the retained liquid phase. Therefore, the recovery of the tungsten compound can be carried out without significant loss of lower glycols and high-boiling by-products, and the subsequent eluent can be purged and / or treated without excessive loss of tungsten compounds.

[0071] The feed to the ionic resin for ion exclusion chromatography separation is at least a portion (may be an aliquot or aliquant portion) of the retained liquid phase from the separation of the lower glycol from the reaction product. Any suitable unit operation (one or more) can be used to separate the lower glycol, including but not limited to chromatographic separation, sorption, membrane separation, flash separation, distillation, rectification, and evaporation. Gas-liquid separation is typically used. In some examples, the removed reaction product is depressurized with gases to be captured for hydrogen recovery and removal of unwanted gaseous by-products such as methane and carbon dioxide. The gas-liquid separation then provides a vapor overhead containing at least a portion of the lower glycol and other volatile compounds such as acetic acid. The retained liquid phase often contains the lower glycol, in addition to higher boiling point by-products and tungsten compounds. When distillation, flashing, or evaporation is used, the bottom temperature is often in the range of about 120°C to 200°C, and the vapor phase pressure is about 500 to 10,000, for example, 1,000 to 5,000 kPa (absolute pressure). In these embodiments of the present invention, since most of the water, as well as all ethylene glycol and propylene glycol, is passed through the vapor phase, the liquid phase is sometimes rich in heavy components, which can increase the difficulty of processing. Therefore, water is preferably added to the liquid phase from a gas-liquid separator to provide a liquid containing at least about 25 mass percent, and sometimes at least about 35 mass percent, of water.

[0072] The composition of the retained liquid phase depends, in particular, on the unit operations used to separate the lower glycols and the extent to which these unit operations are used to remove the lower glycols; the conversion process operations and the composition of the reaction products; the concentration of tungsten compounds in the reaction products; whether water or other solvents are added to the retained liquid phase; and, if so, in what amount. In most cases, lower glycols are the most dominant organic species in the retained liquid phase, and the retained liquid phase also contains higher boiling point byproducts, namely sorbitol, erythritol, threitol, and glycerol, as well as potentially carboxylic acids or esters. The retained liquid phase also contains tungsten compounds. The tungsten compounds include soluble tungsten compounds and may also include solid tungsten compounds such as tungsten bronze and tungstic acid. The tungsten compounds are typically oxygenated tungsten anions such as tungstic acid, partially neutralized tungstic acid, tungstates, metatungstates, and paratungstates, and may or may not have catalytic activity. One or more unit operations can be performed on the retained liquid phase to change its composition, such as adding water or another solvent, or performing further gas-liquid separation, sorption, or chemical reactions.

[0073] The process of the present invention can be used with a retained liquid phase in which the concentration of lower glycols varies widely, since both ethylene glycol and propylene glycol elute from ion exclusion chromatography after most of the tungsten compound has been eluted. Therefore, the lower glycols may constitute about 50 or 60 mass percent of the organic matter in the retained liquid phase, for example, about 10 to 50 mass percent. Since high-boiling byproducts are hardly separated from the reaction products along with the lower glycols, the mass ratio of high-boiling byproducts to tungsten compound (calculated as a metal) is useful to explain the chromatographic separation. In most cases, this ratio is greater than about 4:1, may be up to about 300:1 or 500:1, and in some cases may be about 25:1 to 100:1.

[0074] All of the retained liquid phase, or aliquots or aliquant portions, can be brought into contact with an ionic resin for ion exclusion chromatography separation. Contact may be continuous, semi-continuous, intermittent, or batch. The retained liquid phase can be diluted, for example, with water, to reduce its viscosity. Sometimes, the viscosity at the contact temperature with the ionic resin is less than about 100 Pascal-seconds, and in some cases, about 0.1 to 50 Pascal-seconds. The temperature of the retained liquid phase in contact with the ionic resin is below a temperature that would adversely affect the resin, and is often in the range of about 0°C to 150°C, for example, about 10°C to 100°C. The pressure of the feed can be in a wide range, for example, about 100 to 100,000 kPa (absolute pressure). The liquid-time space velocity of the feed into the ionic resin depends, among other things, on the properties and composition of the feed, the desired degree of chromatographic separation, the properties of the ionic resin, and the design of the equipment used for ion exclusion chromatography. In most cases, the space-time velocity of a liquid is approximately 0.1 to 50 hours. -1 It is within the range.

[0075] Contact with the ionic resin can be performed on a moving bed or a fixed bed, and can be carried out in batch, semi-continuous, or continuous operation mode. The ionic resin is typically packed into a column, and the feed is passed through the column to provide an eluate. Then, a solvent is passed through the column to elute other components in the feed. The determination of the column diameter and height is well within the scope of the art of those skilled in the art who are interested in the disclosure herein. In some cases, the process of the present invention uses a simulated moving bed (SMB). The SMB apparatus can be operated continuously if desired. The SMB apparatus includes a plurality of columns containing ionic resin connected in series. The arrangement of valves and columns is such that, in the series of columns, the feed and solvent addition points and the extraction points for the desired product (product composition) rich in tungsten compounds and organic products move periodically from column to column. The movement is opposite to the flow of liquid in the series of columns, to give the impression of a moving bed. For a general discussion of SMBs, see, for example, U.S. Patent Nos. 2,985,589, 4,340,724, and 6,479,716.

[0076] Any suitable ionic resin, including strong and weak anionic resins and strong and weak cationic resins, can be used. The resin may be a gel, or preferably a macroreticular resin. In some cases, the resin has a degree of crosslinking of at least about 3 percent, for example, up to about 15 percent or more. Often, resins with a degree of crosslinking of at least about 6 percent, preferably at least about 8 percent, are used to enhance stability and provide greater porosity. In some cases, the porosity is such that organic matter is eluted without the use of excessive amounts of solvent. In these cases, the focus of chromatographic separation is to achieve the desired tungsten compound-containing eluent, and it is not desirable to use chromatographic separation for the separation of various organic matter. The effectiveness of an ionic resin for separating the tungsten-containing fraction from organic matter can be recognized by comparing the total excluded volume with the total contained volume. Generally, the larger the difference, the more effective the separation. The total excluded volume is the amount of solvent required to exclude aliquots of ionic compounds on the resin, such as tungstates. The total volume is the amount of solvent required to dissolve aliquots of nonionic compounds such as glycerin.

[0077] Many commercially available ionic resins contain one of the following: polystyrene, polymethacrylate, and polyacrylate, and are often crosslinked using agents such as divinylbenzene. The ionic functional group may be an amine in the case of anionic resins, and a carboxylic acid group, phosphonic acid group, or sulfonic acid group in the case of cationic resins. In some cases, the size of the ionic resin particles is in the range of 100 to 10,000 microns or more in major dimensions. Preferred ionic resins are macroreticular cationic resins having carboxylic acid or sulfonic acid functional groups for resin stability. Preferably, cations associated with the new cationic resin do not form precipitates with tungsten compounds, but after multiple cycles, any cations that do form precipitates are eluted. Sodium cationic resins are preferred. In some cases, the cationic resin is a polystyrene sulfonic acid strong cation exchange resin having a degree of crosslinking of at least about 4, for example, at least about 6, for example, about 6 to 15 percent.

[0078] drawing Drawings provided to facilitate understanding of the present invention are referenced but are not intended to limit the invention. The drawings omit small devices such as pumps, compressors, valves, equipment, heat exchangers, and other devices whose arrangement and operation are well known to those skilled in the art of chemical engineering. The drawings also omit auxiliary unit operations.

[0079] Referring to Figure 1, the apparatus 100 includes a catalytic conversion reactor 102 for converting carbohydrates to ethylene glycol and / or propylene glycol. The reactor may be a single vessel or two or more vessels of the same or different design arranged in parallel or in series. At least one vessel contains a heterogeneous hydrogenation catalyst. At least one vessel contains an inverse aldol catalyst, in particular a soluble inverse aldol catalyst.

[0080] As shown, the carbohydrate feed is passed through reactor 102 via line 104, and hydrogen for catalytic conversion is passed through reactor 102 via line 106. The tungsten compound for the reverse aldol catalyst is supplied by at least lines 110 and 112, as will be discussed later. The reaction product is removed from reactor 102 via line 108.

[0081] The reaction product contains either or both of ethylene glycol and propylene glycol, and includes higher boiling point by-products (sorbitol, erythritol, threitol, glycerol, and 1,2-butanediol). Since the catalytic conversion is carried out under high pressure in the presence of hydrogen, the reaction product contains dissolved hydrogen and dissolved tungsten compounds.

[0082] As described, the reaction products are passed through a gas-liquid separator 114. The gas-liquid separator may include, for example, one or more unit operations involving the recovery of hydrogen and light gases, followed by one or more unit operations for the recovery of water, as well as ethylene glycol and propylene glycol, from the reaction products. Hydrogen and other light gases such as carbon dioxide and methane are withdrawn via line 116 for the recovery of hydrogen for recirculation. The liquid components can then be subjected to one or more unit operations for the recovery of lower glycols (including additional gas-liquid separation or liquid-liquid separation (e.g., selective membrane permeation and selective sorbation)). In another embodiment, the gas-liquid separation provides a vapor overhead containing a substantial portion of the ethylene glycol and propylene glycol in the reaction products. Often, at least about 30 mass percent, more frequently at least about 50 mass percent, for example, about 50–75 or 95 mass percent of total ethylene glycol and propylene glycol is provided in the overhead. The overhead in line 118 is subjected to unit operations for the purification of ethylene glycol and propylene glycol, as well as the separation of ordinary gaseous components that are not removed along with hydrogen and light gases.

[0083] All or part (aliquots or aliquants) of the retained liquid phase is withdrawn from the gas-liquid separator 114 via line 120. Embodiments are shown in which high-boiling-point components in the retained liquid are subjected to catalytic conditions to convert at least a portion of the high-boiling-point byproducts into lower glycols, for example, by hydrocracking. A portion of the retained liquid phase, even if it contains tungsten compounds, can be withdrawn from line 120 via line 122 for such catalytic treatment. In this way, the volume of the retained liquid phase subjected to ion exclusion chromatography can be controlled, especially when plant growth fluctuates. As will be discussed later, organic phases from ion exclusion chromatography can also be subjected to such catalytic treatment.

[0084] All or the remainder of the retained liquid phase in line 120 is passed through a pseudo-mobile bed unit 124 for ion exclusion chromatography to provide a separated tungsten compound-containing elution phase and a separated organic matter-containing elution phase. If desired, a portion of the retained liquid phase may be subjected to chemical and / or physical unit operations to reduce the presence of solids (e.g., filtration, oxidation).

[0085] For the purpose of consideration and not to limit the present invention, a simulated moving bed contains 10 strongly cationic resin columns connected in series with valves for adding liquid to each column and removing liquid from each column. A certain amount of retained liquid phase is introduced into one of the series of columns over a predetermined time, and the liquid passing through that column is passed to the next column in the series, and so on for all 10 columns. After the predetermined time, the feed of the retained liquid phase is passed to the column before it in series. This arrangement determination is repeated in a continuous sequence. The tungsten-containing elution phase is removed from a later column in the direction of the liquid flow, for example, from the fourth column from the column into which the retained liquid phase is introduced. The selection of columns is well within the scope of ion exclusion chromatography techniques in simulated moving beds and depends in part on the portion of the tungsten compound to be recovered and the acceptable concentration of organic matter in the tungsten compound-containing elution phase. Ion exclusion chromatography can be manipulated to ensure a high proportion of tungsten compounds eluting the tungsten compound-containing phase, for example, to contain at least about 90 atomic percent, preferably at least about 95 or 99 atomic percent tungsten. Alternatively, ion exclusion chromatography can be manipulated such that contamination of the tungsten compound-containing phase with organic compounds is usually not significant, but minimizing organic acids is preferred to reduce the amount of base required for pH adjustment, especially when the tungsten compound-containing phase is subjected to pH adjustment, for example, to convert the tungsten complex into a partially neutralized tungstate. Often, the mass ratio of total organic matter to tungsten compounds (calculated as elements) is less than about 10:1, and in some cases less than about 1:1, for example, about 0.1:1. The tungsten compound-containing phase is withdrawn from the dummy moving bed 124 via line 126. If desired, a portion of the eluted phase can be withdrawn from line 126 via line 128 for purging or recovery of tungsten.

[0086] The relative volume of the purge stream depends, in particular, on the portion of the tungsten species that is catalytically inert or relatively inert during the reaction process, such as tungstic acid or tungsten bronze. The purging may be continuous or intermittent. When purging is used, in many cases about 5 to 40 mass percent of the eluting phase, for example, about 10 to 25 mass percent, is purged. Tungsten can be recovered from the purge stream. Tungsten can be recovered using any suitable process or combination of processes, including but not limited to ion exchange and acidification for precipitation of tungstic acid for separation.

[0087] All or part of the tungsten compound-containing elution phase can be passed through the treatment vessel 130 continuously or intermittently via line 126. Since the tungsten compound containing the elution phase may include, but not limited to, several tungsten compounds including meta and paratungstates, tungstic acid, and partially neutralized tungstates, species conversion to partially neutralized tungstates facilitates providing more predictable reverse aldol catalytic activity for the recycled tungsten compound. As shown, a base such as sodium hydroxide is added to the treatment vessel 130 via line 132 in an amount sufficient to adjust the pH to about 6–8, often about 6.5–6.8. The treated effluent is removed from the vessel 130 via line 134 for recycling to reactor 102.

[0088] Returning to line 126, if desired, all or part of the tungsten compound-containing elution phase can be continuously or intermittently sent to line 136 for recirculation to reactor 102, bypassing the processing vessel 130. When bypassing is performed, typically about 20–100 mass percent, sometimes about 25–80 mass percent, of the tungsten compound-containing elution phase is passed from line 126 to line 136. In some cases, the bypassed tungsten compound-containing elution phase is such that the pH of the mixture of feed in line 104, organic recirculation, and reverse aldol catalyst is at least about 4.5, preferably at least about 5, for example, 5.5–8, sometimes about 5.5–6.8.

[0089] The treated effluent in line 134 from the processing vessel 130 is described as being combined with any bypass in line 136 for recirculation to reactor 102. All or part of the recirculated tungsten compound in line 136 can be sent to line 104 via line 112 for mixing with the feed, and all or part of the recirculated tungsten compound in line 136 can be passed directly to reactor 102 via line 138. If the recirculated tungsten compound is added directly to reactor 102, it is particularly beneficial if it has passed through the processing vessel 130 and has a higher pH range, for example, about 6.5 to 8, and for this reason it can be used in part to control the pH in the reactor.

[0090] Returning to the dummy moving bed 124, a solvent such as water is added to the fifth column via line 125 to elute the organic matter from the sorbent medium in the dummy moving bed 124, providing an eluent containing the organic matter to the last column in the series of columns. Due to the dummy moving bed arrangement, the organic eluent is withdrawn via line 140. A portion of this eluent is typically purged via line 142 to ensure steady-state operation of the composition in reactor 102. The purging is often in the range of 1 to 30 mass percent of the eluent, and a larger percentage is often used if a significant portion of the retained liquid phase is bypassed via line 122. All or part of the organic eluent and the bypassed retained liquid phase can be passed directly to reactor 102, or, as shown, can be subjected to unit operations to enhance the conversion efficiency of the feed to monoethylene glycol. In the figure, the organic eluent in line 140 is combined with the retained liquid phase in line 122 and passed through the hydrocracking reactor. In the hydrocracking reactor 144, hydrogen supplied via line 150 and a hydrocracking catalyst are brought into contact with organic matter supplied via line 122 under hydrocracking conditions to provide hydrocracking products that, in particular, contain monoethylene glycol and propylene glycol, as well as reduced concentrations of carboxylic acids and higher boiling point by-products. It should be understood that the hydrogen for hydrocracking may be an off-gas taken from reactor 102 via line 150. Hydrocracking conditions often involve temperatures of about 150°C or 200°C-240°C, preferably about 200°C-230°C. The hydrogen partial pressure is about 2500-12,000, for example, about 5000-10,000 kPa, and the liquid-time space velocity is about 0.01-20hr -1 Any suitable hydrocracking catalyst can be used, such as one or more containing nickel, cobalt, ruthenium, rhodium-platinum, and palladium. For convenience, the hydrocracking catalyst may be Hcat used for hydrogenation.

[0091] The hydrocracking products are removed from the hydrocracking reactor 144 via line 146, and the gas is removed via line 148 for recovery and purification. All or part of the hydrocracking products in line 146 can be sent to line 108 for the recovery of ethylene glycol and propylene glycol in the gas-liquid separator 114.

Claims

1. A catalytic process for producing a lower glycol containing at least one of ethylene glycol and propylene glycol from a carbohydrate-containing feed containing at least one of aldose and ketose-producing carbohydrates, wherein the process comprises: (a) To produce a reaction product comprising the lower glycol and one or more high-boiling point byproducts comprising sorbitol, erythritol, threitol, and glycerin, the feed is continuously or intermittently supplied to a reaction zone having inside a dissolved tungsten compound, at least one of which is a homogeneous tungsten-containing reverse aldol catalyst, and at least one heterogeneous hydrogenation catalyst, wherein the liquid medium is under catalytic conversion conditions including the presence of dissolved hydrogen, and the feed is continuously or intermittently supplied. (b) Continuously or intermittently removing the liquid medium containing the reaction product and the dissolved tungsten compound from the reaction zone, (c) To provide a retained liquid phase containing a dissolved tungsten compound and a high-boiling point by-product, wherein the mass ratio of the tungsten compound to the high-boiling point by-product, calculated as metal, is greater than approximately 4:1, by subjecting at least a portion of the extracted liquid medium to one or more unit operations to remove at least a portion of the lower glycol in the separated fraction. (d) A catalytic process comprising: contacting at least a portion of the retained liquid phase with an ionic resin for ion exclusion chromatography to provide a first elution fraction containing a dissolved tungsten compound and the tungsten compound in a mass ratio of less than about 1:1 calculated as a high-boiling byproduct to the metal; and contacting the ionic resin with a sufficient solvent to provide at least one subsequent elution fraction containing one or more high-boiling byproducts and the tungsten compound at a concentration lower than that in the retained liquid phase.

2. The process according to claim 1, wherein at least about 90 mass percent of the tungsten compound contained in the retained liquid phase in contact with the ionic resin is present in the first elution fraction.

3. The process according to claim 1, wherein the portion of the retained liquid phase in contact with the cationic resin is a purge flow.

4. The process according to claim 1, wherein at least a portion of the first elution fraction is recycled back to step (a).

5. The process according to claim 4, wherein the pH of the recycled first elution fraction is provided at about 6.5 to 8 before being passed through step (a).

6. The process according to claim 5, wherein at least a portion of the tungsten compound in the recycled first elution fraction is half-neutralized tungstic acid.

7. The process according to claim 1, wherein at least a portion of the at least one subsequent elution fraction containing one or more high-boiling point byproducts is subjected to hydrocracking conditions to provide at least one of ethylene glycol and propylene glycol.

8. The process according to claim 1, wherein the ionic resin includes a cationic resin.

9. The process according to claim 8, wherein the cationic resin comprises a polystyrene sulfonate strong cation exchange resin.

10. The process according to claim 1, wherein the ionic resin has a degree of crosslinking of at least 6 percent.

11. The process according to claim 10, wherein the ionic resin has a degree of crosslinking of at least 8 percent.

12. The process according to claim 1, wherein step (d) is performed as a pseudo-moving floor.

13. The process according to claim 1, wherein one or more unit operations in step (c) include gas-liquid separation.

14. A composition comprising a dissolved tungsten compound and one or more high-boiling point polyols including sorbitol, erythritol, threitol, and glycerin, wherein the mass ratio of the tungsten compound calculated as total high-boiling point polyols to metal is less than about 5:

1.

15. The product composition according to claim 14, wherein the mass ratio of the tungsten compound calculated as the total high-boiling point polyol to the metal is about 0.01:1 to 1:1.

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