Method for preparing sugar alcohols

Abstract

A method for reducing sugars. The first step is to provide a solution of sugars containing 5 to 20 carbon atoms. The second step is to contact the solution with hydrogen gas and a catalyst. The catalyst is an ion exchange resin containing Ru.

Description

[Technical Field]

[0001] The present invention relates generally to methods for the reduction of sugars and the preparation of sugar alcohols from sugars. [Background technology]

[0002] The reduction of glucose to sorbitol by hydrogenation using several transition metals as heterogeneous catalysts is known. For example, VN Sapunov et al., J. Phys. Chem. A, 2013, 117, 4073-4083, discloses the reduction of glucose to sorbitol using ruthenium embedded in a hypercrosslinked polystyrene matrix. However, this reference reports low glucose conversion rates and also uses a special procedure for embedding ruthenium in a hypercrosslinked polymer matrix. Other heterogeneous reduction systems for sugars may also be useful. Summary of the Invention [Means for solving the problem]

[0003] The present invention relates to a method for reducing sugars, the method comprising: a) providing a solution of sugars containing 5 to 20 carbon atoms; and b) contacting the solution with hydrogen gas and a catalyst; wherein the catalyst comprises an ion exchange resin containing Ru. DETAILED DESCRIPTION OF THE INVENTION

[0004] Unless otherwise specified, all percentages are weight percentages (wt%) and all temperatures are in °C. Averages are arithmetic means unless otherwise specified. All operations are performed at room temperature (18-25°C) unless otherwise specified. Monomer percentages are based on the weight of the dry polymer, i.e., dry ion exchange resin beads, and the same percentages apply to the monomer mixture used to prepare the beads. The terms "(meth)acrylate" and "(meth)acrylic" refer to acrylate or methacrylate, and acrylic or methacrylic, respectively. References to transition metals, such as ruthenium, refer to the zero-valent metal. Particle size is determined using a dynamic imaging particle analyzer, such as a FlowCam™ Macro analyzer, and is an average value, described herein as the harmonic mean size (HMS).

[0005] Preferably, the harmonic mean size of the ion exchange resin is at least 200 microns, preferably at least 300 microns, preferably at least 400 microns; preferably no more than 1100 microns, preferably no more than 1000 microns, preferably no more than 900 microns, preferably no more than 800 microns, preferably no more than 700 microns.

[0006] Preferably, the particle size distribution has a uniformity coefficient of at least 1.01, 1.2 or less for uniform particle size (UPS) resins, and 1.6 or less for normal particle size distribution resins. UPS resins are resins made by injecting monomer droplets into an aqueous phase synthesis, while normal particle size distribution resins are made in a stirred reactor.

[0007] Useful ion exchange resins include strong acid cation exchange resins, weak acid cation exchange resins, strong base anion exchange resins, and weak base anion exchange resins. Preferably, the ion exchange resin is a cation exchange resin, preferably a strong acid cation exchange resin, i.e., one having sulfonic acid groups. Preferred ion exchange resins can be acrylic (>70% by weight, preferably >85% by weight of polymerized units acrylic monomer) or styrene (>70% by weight, preferably >85% by weight of polymerized units styrene or substituted styrene).

[0008] In a preferred embodiment of the present invention, the ion exchange resin is a gel resin (having a surface area <5 m as measured by the BET technique). 2 / g dry resin), preferably 10% by weight or less, preferably 8% by weight or less, preferably 7% by weight or less, preferably 6% by weight or less; preferably at least 1% by weight, preferably at least 2% by weight, preferably at least 2.5% by weight, preferably at least 3% by weight of polymerized units of crosslinker. In another preferred embodiment, the ion exchange resin is a macroreticular resin. The macroreticular resin is preferably 10 to 100 m 2 / g, preferably 20 to 50m 2 Preferably, the macroreticular resin has a surface area of ​​0.1 to 0.9, preferably 0.2 to 0.7, preferably 0.25 to 0.5 cm 3 / g and has an average pore size of 50 to 2500 angstroms, preferably 150 to 1000 angstroms. Porosity is defined according to IUPAC (International Union of Pure and Applied Chemistry) nomenclature as follows: Microporosity = pores smaller than 20 Angstrom units Mesoporosity = pores between 2 and 500 angstroms Macroporosity = pores greater than 500 Angstrom units. Preferably, the macroreticular resin comprises at least 8% by weight of polymerized units of the crosslinker, preferably at least 10% by weight, preferably at least 12% by weight; preferably no more than 20% by weight, preferably no more than 19% by weight, preferably no more than 17% by weight.

[0009] Preferred crosslinkers include divinylbenzene, trivinylcyclohexane, TMPTMA (trimethylolpropane trimethacrylate), and DEGDVE (diethylene glycol divinyl ether); divinylbenzene is preferred. Preferably, the ion exchange resin contains 80 to 99% by weight of polymerized units of a monofunctional monomer. Preferred monofunctional monomers include vinyl aromatic monomers (e.g., styrene, methylstyrene, ethylstyrene, α-methylstyrene; preferably styrene) and acrylic monomers (alkyl (meth)acrylates, (meth)acrylic acid). Preferably, the styrene-based ion exchange resin has 0.9 to 2.5 equivalents of acid sites per liter of resin, preferably at least 1.3 equivalents / liter, and preferably no more than 1.8 equivalents / liter. Preferably, the acrylic ion exchange resin has 3.0 to 5.5 equivalents of acid sites per liter of resin, preferably at least 3.5 equivalents / liter, and preferably no more than 5.0 equivalents / liter. Preferably, the styrenic ion exchange resin has 2.5 to 5.3 equivalents of acid sites per kg of dry resin, preferably at least 4.2 equivalents per kg of dry resin, preferably no more than 5.0 equivalents per kg of dry resin.

[0010] Preferably, the total loading of Ru on the ion exchange resin is 0.5 to 200 g per liter of resin, preferably at least 1 g / liter, preferably at least 2 g / liter, preferably at least 5 g / liter, preferably at least 10 g / liter, preferably at least 20 g / liter; preferably not more than 100 g per liter of resin, preferably not more than 80 g / liter, preferably not more than 70 g / liter, preferably not more than 60 g / liter. In a preferred embodiment of the present invention, the catalyst contains Ru and at least one of Mo, W, V, Mn, Ni, Cu, Zn, Cr, Ge, Sn, Ti, Au, and Zr, preferably at least one of Mo, W, Ni, Cu, and Sn. Preferably, the total loading of metal on the ion exchange resin is 0.5 to 200 g per liter of resin, preferably at least 1 g / liter, preferably at least 2 g / liter, preferably at least 5 g / liter, preferably at least 10 g / liter, preferably at least 20 g / liter; preferably not more than 100 g per liter of resin, preferably not more than 80 g / liter, preferably not more than 70 g / liter, preferably not more than 60 g / liter.

[0011] The sugar is provided as a solution, preferably an aqueous solution, i.e., a solution in which the main solvent is water, preferably at least 50% by volume of water, preferably at least 75%, preferably at least 85%. Preferably, the sugar concentration is 10-65% by weight, preferably 30-40% by weight. Preferably, the sugar contains 5-20 carbon atoms; preferably at least 6 carbon atoms; preferably 18 or less, preferably 17 or less, preferably 16 or less, preferably 15 or less, preferably 12 or less carbon atoms. Preferred sugars include ribose, arabinose, xylose, lyxose, glucose, fructose, mannose, galactose, sedoheptulose, mannoheptulose, and sucrose; preferably glucose, fructose, and mannose; preferably glucose. Preferably, the sugar is a monosaccharide or polysaccharide; preferably a monosaccharide or disaccharide; preferably a monosaccharide.

[0012] Preferably, the catalyst is prepared by contacting an ion exchange resin with an aqueous metal salt solution followed by reduction of the metal ions with a reducing agent. Preferred reducing agents include sodium borohydride, hydrogen, hydrazine, formaldehyde, and lithium aluminum hydride; sodium borohydride is preferred. The initial metal salt can be reduced in solution to a lower positive valence state than the original metal ion, or completely reduced to zero-valent metal. Preferably, the catalyst contains a zero-valent metal. Preferably, the reducing agent contains sodium or potassium cations. Preferably, the acid groups in the resin remain as metal salts with Na, K, Ca, Mg, Ba, Fe, or Al cations, preferably Na, K, Ca, or Mg cations. When a resin loaded with a metal salt is reduced with hydrogen, the acid groups on the resin could also be in an acid form such as -SO3H. Preferably, when the metal is reduced with hydrogen, the acid groups in the resin remain as acid (H+).

[0013] Preferably, the hydrogenation of the sugar solution is carried out at a temperature of 25 to 180°C, preferably at least 40°C, preferably at least 60°C, preferably at least 80°C, preferably at least 100°C, preferably at least 115°C, preferably at least 125°C; preferably at most 170°C, preferably at most 160°C, preferably at most 150°C. Preferably, the hydrogenation of the sugar solution is carried out at a hydrogen pressure of 40 to 600 psi (275 kPa to 4.2 MPa); preferably at least 60 psi (410 kPa), preferably at least 100 psi (690 kPa), preferably at least 150 psi (1.0 MPa), preferably at least 200 psi (1.4 MPa); preferably at most 500 psi (3.5 MPa), preferably at most 400 psi (2.8 MPa). The preferred reaction time may vary from 0.25 to 15 hours, preferably from 0.5 to 5 hours. The preferred pressures, times, and temperatures described above are not considered to be critical parameters (especially the upper limits of time and pressure), and the combination of these parameters can be adjusted by one skilled in the art to efficiently achieve the desired conversion and reaction time. Hydrogenation can be carried out batchwise using a stirred tank reactor, in a series of continuous stirred tank reactors, in a continuous slurry bubble column reactor, and in a continuous multi-tubular reactor. Preferably, the continuous process for producing sorbitol utilizes a mixing tank and a fixed-bed catalytic reactor containing a solid acid catalyst. An aqueous solution of glucose is introduced into the mixing tank. Hydrogen is sparged into the mixing tank. The glucose solution is pumped into the catalytic reactor together with the hydrogen. The desired product, sorbitol, produced in the fixed-bed reactor in aqueous solution exits the process, and a portion of the discharged stream is recycled to the process.

[0014] Sorbitol analysis and quantification method used: Method I: Chromatography The quantitative ion exclusion chromatography method was performed under the following conditions: Column: Aminex HPX-87H ion exclusion column. Column temperature: 80°C. Detector: Agilent 1260 RID (G7162A). RID temperature: 50°C. Flow rate: 0.4mL / min. Injection volume: 2μL

[0015] Area and concentration calibration was performed using Sigma Aldrich standards for sorbitol, mannitol, glucose, and fructose; other peaks found as by-products were reported as unknowns. Calculations using HPLC data were performed as follows: Conversion rate (%) = 100 - [glucose (time zero) / glucose (time x)] * 100 Selectivity (%) = sorbitol (peak) / (total of all peaks - glucose peak) * 100 Yield (%) = Conversion rate * Selectivity

[0016] Method II: NMR Quantitative 1D 1 H NMR data were collected on an Agilent DD2 or Bruker NEO spectrometer operating at 500 MHz, maintained by a trained operator. Spectra were acquired with eight transients, a 30-second recycle delay, a 90° pulse width, a 3.17-second acquisition time, a 25.8-kHz spectral window, and 82 k points. Data processing was performed with Bruker Topspin software. Raw data were zero-filled to 131 k data points and processed with 0.3-Hz exponential multiplication. The resulting NMR spectra were phased and baseline-corrected. Chemical shifts were referenced to DO = 4.65 ppm. Analyte integrals were corrected for slope and bias. The conversion rate was calculated from the molar ratio of glucose to sorbitol obtained from the processed NMR spectrum as follows: % Yield = ((mol sorbitol) / (mol sorbitol + mol glucose))*100 The number of moles of sorbitol was determined from the resonance isolated from glucose. The number of moles of protons in this region was found to be 3 based on comparison with a standard reference spectrum whose total integrated area was normalized to 8. Moles of sorbitol = ∫(δ3.54 ppm ~ 3.44 ppm) / 3; Complex The moles of glucose were measured as the sum of the anomeric protons corresponding to αβ-glucose. Number of moles of glucose = ∫(δ5.12 ppm~5.04 ppm) + ∫(δ4.52 ppm~4.47 ppm); α / β anomeric protons

[0017] Catalyst synthesis and metal impregnation-reduction Preparation of metal-supported ion-exchange resin catalysts Metal-loaded ion-exchange resin catalysts were prepared using commercially available ion-exchange resins (e.g., AmberLyst™ 15, 131, 35, and 46 resins) and aqueous solutions of Ru and Ni salts (RuCl3.xH2O, NiCl2.x6H2O, and NiSO4.xH2O). The catalysts used for metal impregnation were resins in their initial ionic salt form (H, Na, or Ca). Examples of this ionic form for commercially available resins are AmberLite CR99310Ca, AmberLite FPC16UPS Na, and AmberLite FPC88UPS H. Metal impregnation used two different methods: a) the incipient wetness method or b) ion exchange in water. These are described in the following paragraphs. After the metal is impregnated into the resin, the next basic process is reduction to the zero-valent state by one of the following procedures: a) hydrogenation or b) NaBH4 solution.

[0018] Incipient Wetness Method: The amount of metal to be loaded onto the resin (based on the desired metal loading) and the amount of water needed to swell the resin were calculated. Based on the above calculations, a metal salt solution was prepared. The resin was dried overnight in a vacuum oven at 100°C. The dried resin was placed in a large beaker and an aqueous solution containing the metal salt (20% water was used to ensure complete wetting of the resin) was added dropwise. The wet beads containing the metal salt were allowed to sit for approximately 30 minutes to allow for complete adsorption. The beaker was then placed in an ice bath, and 12% NaBH4 in 14 M NaOH solution was slowly added to the resin using a pipette. (Note: This reaction can be very vigorous depending on the metal loading selected. High metal loadings will cause a lot of bubbling / foaming / heating.) After the vigorous bubbling stopped, the beaker was removed from the ice bath and allowed to reduce overnight. The reduced metal-loaded ion-exchange resin catalyst was then transferred to a Buchner funnel and rinsed with water until the wash water reached a neutral pH (approximately 6 or 7). The catalysts thus prepared were ready for activity testing or catalytic characterization. Optionally, the catalysts could be dried in a vacuum oven (the dried resin mass was more homogeneous than the wet state). All catalysts contained 2.5 g of Ru per liter of resin.

[0019] Ion exchange in metal-doped water. The amount of metal to be loaded onto the resin is calculated based on the weight percent loading target for the desired metal loading of each resin. A solution of the metal salt is prepared in water, some hydrochloric acid is added, and the whole is mixed with the resin. This mixture is stirred for 24 hours to allow equilibration and exchange of the metal to sulfone sites. At the end of the stirring period, the resin is Buchner dried, after which the metal reduction process can proceed. For reduction with sodium borohydride (aqueous NaBH4 / NaOH) or hydrogen in a column or reactor, either dry or wet forms of the resin are considered. The aspects of the present invention are listed below. (Aspect 1) A method for reducing sugars, comprising: a) providing a solution of sugars containing 5 to 20 carbon atoms; and b) contacting the solution with hydrogen gas and a catalyst; wherein the catalyst comprises an ion exchange resin comprising Ru. (Aspect 2) A method according to aspect 1, wherein the total amount of Ru supported on the ion exchange resin is 0.5 to 200 g per liter of resin. (Aspect 3) 3. The method of claim 2, wherein the ion exchange resin is a gel resin containing 1 to 10 wt. % polymerized units of a crosslinker, or a macroreticular resin containing 8 to 20 wt. % polymerized units of a crosslinker. (Aspect 4) 4. The method of embodiment 3, wherein the catalyst further comprises at least one of Mo, W, V, Mn, Re, Fe, Zr, Cu, Zn, Cr, Ge, Sn, Ti, Ni, and Au. (Aspect 5) 4. The method of embodiment 3, wherein the sugar comprises 5 to 12 carbon atoms. (Aspect 6) 4. The method of claim 3, wherein the ion exchange resin is a styrene-based resin having acid sites in an amount of 0.9 to 2.5 equivalents per liter of resin. (Aspect 7) 4. The method of claim 3, wherein the ion exchange resin has a harmonic mean size of 200 to 1100 microns. (Aspect 8) 8. The method of embodiment 7, wherein the sugar comprises 5 to 12 carbon atoms. (Aspect 9) 9. The method of claim 8, wherein the ion exchange resin is a styrene-based resin having acid sites in an amount of 0.9 to 2.5 equivalents per liter of resin. (Aspect 10) 9. The method of claim 8, wherein the sugar is glucose or fructose. (Aspect 11) 11. The method of claim 10, wherein the ion exchange resin is a macroreticular resin containing 10 to 20 wt. % polymerized units of a crosslinker. (Aspect 12) 11. The method of claim 10, wherein the ion exchange resin is a gel resin containing 2 to 8 weight percent polymerized units of a crosslinker. [Example]

[0020] Selected examples for the synthesis process described and results for all catalysts.

[0021] Example: AmberLyst™ 15 WET impregnated with 5% Ru and sodium borohydride reduction process. 10 mL of AmberLyst™ 15 WET was placed in a reactor. 0.225 g of RuCl3, 0.2 g of HCl, and 50 mL of HPLC-grade water were mixed in a stirred tank. The mixture was stirred at 200 rpm at room temperature overnight. The contents of the reactor were filtered to isolate the metal-impregnated resin. The resin was then dried overnight in a vacuum oven at 70°C with a nitrogen sweep. The yield was 9 mL of wet catalyst, 5 wt% Ru. Reduction of the metal to zero valence was carried out using the sodium borohydride procedure exemplified as follows: 50 mL of sodium borohydride solution was added to the wet catalyst in a beaker. After 3 hours, the reaction was complete, and the resin was washed with excess HPLC-grade water, filtered, and dried overnight in a vacuum oven at 90°C with a nitrogen sweep.

[0022] Example: AmberLyst™ 15 WET impregnated with 1% Ru and sodium borohydride reduction process. 10 mL of AmberLyst™ 15 WET was placed in a reactor. 0.045 g of RuCl3, 0.2 g of HCl, and 50 mL of HPLC-grade water were mixed in a stirred tank. The mixture was stirred at 200 rpm at room temperature overnight. The contents of the reactor were filtered to isolate the metal-impregnated resin. The resin was then dried overnight in a vacuum oven at 70°C with a nitrogen sweep. The yield was 9 mL of wet catalyst, 1 wt% Ru. Reduction of the metal to zero valence was carried out using the sodium borohydride procedure exemplified as follows: 50 mL of sodium borohydride solution was added to the wet catalyst in a beaker. After 3 hours, the reaction was complete, and the resin was washed with excess HPLC-grade water, filtered, and dried overnight in a vacuum oven at 90°C with a nitrogen sweep.

[0023] Example: Ru-impregnated AmberLyst™ 45 and the sodium borohydride reduction process. 12.0 g of AmberLyst™ 45 was placed in a reactor. 1.6 g of RuCl3, 0.4 g of HCl, and 256 g of HPLC-grade water were mixed in a stirred tank. The mixture was stirred at 200 rpm at room temperature overnight. The contents of the reactor were filtered to isolate the metal-impregnated resin. The resin was washed with 100 mL of water to remove excess Ru. The resin was then dried overnight in a vacuum oven at 70°C with a nitrogen sweep. The yield was 14.1 g of dried catalyst, 1 wt% Ru. Reduction of the metal to zero valence was achieved using the sodium borohydride procedure exemplified as follows: 50 mL of sodium borohydride solution was added to the dried catalyst in a beaker. After 3 hours, the reaction was complete, and the resin was washed with excess HPLC-grade water, filtered, and dried overnight in a vacuum oven at 90°C with a nitrogen sweep.

[0024] Example: Pd-impregnated AmberLyst™ CH28, commercial sample. 50 mL of AmberLyst™ CH28 was dried overnight at 90°C in a vacuum oven under nitrogen sweep conditions. 50 mL of sodium borohydride solution was added to the wet catalyst in a beaker. After 3 hours, the reaction was complete, and the resin was washed with excess HPLC-grade water, filtered, and dried overnight at 90°C in a vacuum oven under nitrogen sweep conditions. At the end of the process, the acid sites on the resin were neutralized to the Na form, and the Pd(II) was reduced to Pd(0). The Pd content was 0.7 mg of Pd per gram of resin.

[0025] Example: Ru-impregnated AmberLyst™ 45 and hydrogenation in column reduction step. 12.0 g of AmberLyst™ 45 was placed in a reactor. 1.6 g of RuCl3, 0.4 g of HCl, and 256 g of HPLC-grade water were combined in a stirred tank. The mixture was stirred at 200 rpm at room temperature overnight. The contents of the reactor were filtered to isolate the metal-impregnated resin. The resin was then dried overnight in a vacuum oven at 70°C with a nitrogen sweep. The yield was 14.1 g of dried catalyst, 1 wt% Ru. The dried catalyst was loaded into a column, and hydrogen was passed through it overnight at 125 psi and 60°C in a continuous process. The reactor was then swept with nitrogen, and the catalyst was removed from the reactor for further use.

[0026] Example: Ni-impregnated AmberLyst™ 131 and the sodium borohydride reduction process. 50 mL of AmberLyst™ 131 WET was placed in a reactor. 17.5 g of NiSO4 heptahydrate, 2 g of HCl, and 256 g of HPLC-grade water were mixed in a stirred tank. The mixture was stirred at 200 rpm overnight at room temperature. The contents of the reactor were filtered, and the metal-impregnated resin was isolated. The resin was then dried overnight in a vacuum oven at 70°C with a nitrogen sweep. The yield was 48 mL of wet catalyst, 4.8 wt% Ru. Reduction of the metal to zero valence was carried out using the sodium borohydride procedure exemplified as follows: 50 mL of sodium borohydride solution was added to the dried catalyst in a beaker. After 3 hours, the reaction was complete, and the resin was washed with excess HPLC-grade water, filtered, and dried overnight at 90°C in a vacuum oven with a nitrogen sweep. The nickel content in the final resin was 4.8 wt% based on the dry basis of the resin.

[0027] [Table 1]

[0028] [Table 2]

[0029] [Table 3]

[0030] [Table 4]

[0031] Sugar hydrogenation reaction Hydrogenation reactions of glucose, fructose, or sucrose were carried out in a 450 mL Parr reactor using 10-50% aqueous glucose solutions and the specified amount of catalyst at temperatures of 120-160 °C and H2 pressures of 240-800 psig (1.66-5.52 MPa) for 24 hours. The reactions were carried out using batch or particle loading of the reactor, with semi-continuous glucose / water addition for the first 3 hours of the process. All Ru- and Ni-loaded ion-exchange resin catalysts tested had metal loadings of 1.0-14 g / L unless otherwise specified. After the desired reaction time, the reactor was cooled to ambient temperature and the pressure was slowly released. Subsequent workup and / or 1 H NMR, 13 The reactor contents were filtered into sample vials for analysis using CNMR or HPLC. Quantification of glucose conversion and sorbitol yield were determined based on the analytical methods described below. The results of the catalytic activity tests are shown in Table 2. Hydrogenations were carried out as described above except where noted in the table. The data are shown in Tables 3, 4, and 5.

[0032] An existing metal-loaded AMBERLYST™ product, AMBERLYST™ CH28 resin, was also tested for glucose hydrogenation. This product is sold in acid and unreduced forms. The catalyst was tested in acidic and neutralized forms with in situ reduction. These catalysts showed very low activity in glucose hydrogenation, as indicated by very low conversion rates at long reaction times. AMBERLYST™ CH28 contains 2.8 g of Pd per liter of resin.

[0033] Example: Synthesis of sorbitol: AmberLite™ FPC88UPS H impregnated with 5% Ru. (Table 5) A 450 mL Parr reactor was charged with 10.0 g of AmberLite FPC88UPS Na-5% Ru impregnated, 100 mL of deionized water, and 63 g of glucose in 150 mL of deionized water. The stirring speed was fixed at 400 rpm, the reaction temperature was 140 °C, and the pressure was 700 psi H2. The reaction was run for 24 h. At the end of this time, the pressure was reduced to atmospheric pressure and the temperature was lowered to room temperature. Liquid samples were taken and analyzed by HPLC. The samples were stored in a freezer until analyzed by HPLC. At the end of the process, the solution was analyzed by ICP to determine the Ru present in the solution. This method and equipment failed to detect Ru at a limit of less than 0.1 ppm, indicating that only negligible amounts of Ru were leached from the catalyst during use.

[0034] [Table 5]

[0035] Example: Synthesis of Mannitol: AmberLite™ FPC88UPS Na impregnated with 5% Ru. (Table 6) A 450 mL Parr reactor was charged with 10.0 g of AmberLite™ FPC88UPS Na-5% Ru impregnated, 100 mL of deionized water, and 63 g of mannitol in 150 mL of deionized water. The stirring speed was fixed at 400 rpm, the reaction temperature was 140°C, and the pressure was 700 psi H2. The reaction was allowed to proceed for 24 hours. At the end of this time, the pressure was reduced to atmospheric pressure and the temperature was reduced to room temperature. Liquid samples were taken and analyzed by HPLC. The samples were stored in a freezer until analysis by HPLC.

[0036] [Table 6]

Claims

1. A method for reducing sugars, comprising: a) providing a solution of sugars containing 5 to 20 carbon atoms; and b) contacting the solution with hydrogen gas and a catalyst; wherein the catalyst comprises an ion exchange resin supported with Ru.

2. 2. The method according to claim 1, wherein the total amount of Ru supported on the ion exchange resin is 0.5 to 200 g per liter of resin.

3. 3. The method of claim 2, wherein the ion exchange resin is a gel resin containing 1 to 10 weight percent polymerized units of a crosslinker, or a macroreticular resin containing 8 to 20 weight percent polymerized units of a crosslinker.

4. 4. The method of claim 3, wherein the catalyst further comprises at least one of Mo, W, V, Mn, Re, Fe, Zr, Cu, Zn, Cr, Ge, Sn, Ti, Ni, and Au.

5. 4. The method of claim 3, wherein the sugar contains 5 to 12 carbon atoms.

6. 4. The method of claim 3, wherein the ion exchange resin is a styrene-based resin having acid sites in an amount of 0.9 to 2.5 equivalents per liter of resin.

7. 4. The method of claim 3, wherein the ion exchange resin has a harmonic mean size of 200 to 1100 microns.

8. 8. The method of claim 7, wherein the sugar contains 5 to 12 carbon atoms.

9. 9. The method of claim 8, wherein the ion exchange resin is a styrene-based resin having acid sites in an amount of 0.9 to 2.5 equivalents per liter of resin.

10. 9. The method of claim 8, wherein the sugar is glucose or fructose.

11. The method of claim 10, wherein the ion exchange resin is a macroreticular resin containing 10 to 20 weight percent polymerized units of a crosslinker.

12. 11. The method of claim 10, wherein the ion exchange resin is a gel resin containing 2 to 8 weight percent polymerized units of a crosslinker.

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