# US 10,246,477 B2 · Isomerisation of C4-C6 aldoses with zeolites > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,246,477 B2 - Document ID: US10246477B2 - Status: Granted - Kind: B2 - Application number: 14/425,182 - Filed: 2013-09-03 - Published: 2015-08-20 - Granted: 2019-04-02 - Earliest claimed: 2012-09-03 - Assignees: Danmarks Tekniske Universitet - Applicants: Danmarks Tekniske Universitet - Inventors: Anders Riisager; Shunmugavel Saravanamurugan - Web page: https://patentgrep.com/patent/US10246477B2 ## CPC - C07H 3/02: Monosaccharides - C07H 1/00: Processes for the preparation of sugar derivatives - C07H: SUGARS; DERIVATIVES THEREOF; NUCLEOSIDES; NUCLEOTIDES; NUCLEIC ACIDS (derivatives of aldonic or saccharic acids C07C, C07D; aldonic acids, saccharic acids C07C59/105, C07C59/285; cyanohydrins C07C255/16; glycals C07D; compounds of unknown constitution C07G; polysaccharides, derivatives thereof C08B; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification C12N15/00; sugar industry C13) ## Abstract The present invention relates to isomerization of C4-C6 aldoses to their corresponding C4-C6 ketoses. In particular, the invention concerns isomerization of C4-C6 aldoses over solid zeolite catalysts free of any metals other than aluminum, in the presence of suitable solvent(s) at suitable elevated temperatures. C6 and C5 aldose sugars such as glucose and xylose, which are available in large amounts from biomass precursors, are isomerized to fructose and xylulose respectively, in a one or two-step process over inexpensive commercially available zeolite catalysts, containing aluminum as the only metal in the catalyst. The ketoses obtained are used as sweeteners in the food and/or brewery industry, or treated to obtain downstream platform chemicals such as lactic acid, HMF, levulinic acid, furfural, MMHB, and the like. ## Claims ### Claim 1 A method of isomerizing C4-C6 aldoses to their corresponding 2-ketoses, comprising the step of a) providing a first solution of one or more C5 aldoses, one or more C6 aldoses, or a mixture thereof in a first solvent, the first solvent being a C1-C3 alcohol or a combination of C1-C3 alcohol and water; or a second solution of one or more C4 aldoses in a second solvent, the second solvent being water or a combination of C1-C3 alcohol and water and b) heating the first solution or the second solution in the presence of a solid acidic zeolite catalyst containing aluminum as the only metal (“Zeolite-Al”). ### Claim 2 (depends on 1) The method according to claim 1, comprising a) providing a first solution of one or more C5 aldoses, one or more C6 aldoses, or a mixture thereof in a first solvent, the first solvent being a C1-C3 alcohol; b) heating the first solution in the presence of a solid acidic zeolite catalyst containing aluminum as the only metal (“Zeolite-Al”), the method optionally further comprising c) adding water to the reaction mixture from step b) to obtain an aqueous mixture, and d) heating the aqueous mixture in the presence of said zeolite catalyst. ### Claim 3 (depends on 2) The method according to claim 2, wherein the alcohol solution is heated to between 60 and 140° C. for between 5 minutes and 24 hours in step b). ### Claim 4 (depends on 2) The method according to claim 2, which includes step c) and step d). ### Claim 5 (depends on 4) The method according to claim 4, wherein the aqueous mixture is heated to between 60 and 140° C. in step d). ### Claim 6 (depends on 2) The method according to claim 2 wherein heating in step b) and step d) independently are to a temperature from about 60° C. to about 120° C. ### Claim 7 (depends on 1) The method according to claim 1 which is a one-pot method. ### Claim 8 (depends on 1) The method according to claim 1 where heating is provided by thermal heating, electrical heating, steam or microwave heating. ### Claim 9 (depends on 1) The method according to claim 1, comprising a) providing a first solution of one or more C5 aldoses, one or more C6 aldoses, or a mixture thereof in a first solvent, the first solvent being a C1-C3 alcohol, b) heating the first solution in the presence of a suitable solid acidic zeolite catalyst containing aluminum as the only metal (“Zeolite-Al”) to a temperature between 60 and 140° C. for between 5 minutes and 24 hours to obtain a reaction mixture, c) adding water to the reaction mixture to obtain an aqueous mixture, d) heating said aqueous mixture in the presence of a said zeolite catalyst to a temperature between 60 and 140° C. for between 5 minutes and 24 hours. ### Claim 10 (depends on 1) The method according to claim 1, wherein the CO aldose is glucose or mannose and the corresponding ketose is fructose. ### Claim 11 (depends on 1) The method according to claim 1, wherein the C5 aldose is xylose or lyxose and the corresponding ketose is xylulose. ### Claim 12 (depends on 1) The method according to claim 1, when the first solvent is methanol, ethanol, n-propanol, or isopropanol. ### Claim 13 (depends on 1) The method according to claim 1, comprising a) providing a second solution of one or more C4 aldoses in a second solvent, the second solvent being water, b) heating the second solution in the presence of a suitable solid acidic zeolite catalyst containing aluminum as the only metal (“Zeolite-Al”) to a temperature between 60 and 140° C. for between 5 minutes and 24 hours. ### Claim 14 (depends on 13) The method according to claim 13, wherein the C4 aldose is erythrose or threose and the corresponding ketose is erythrulose. ### Claim 15 (depends on 1) The method according to claim 1, wherein a suitable solid acidic zeolite catalyst is a solid zeolite with pore size above 5Λ. ### Claim 16 (depends on 1) The method according to claim 1 wherein the solid zeolite catalyst is selected from the group consisting of HY catalysts and Hbeta catalysts. ### Claim 17 (depends on 2) The method according to claim 2, wherein the reaction times in step b) and in step d) independently are between 20 minutes and 24 hours. ### Claim 18 (depends on 15) The method according to claim 15, wherein the solid acidic zeolite catalyst is a solid zeolite with pore size between 6 and 12 Å. ### Claim 19 (depends on 1) The method according to claim 1, wherein the solid acidic zeolite catalyst has a Si/ratio of at least 6.