(19) DANMARK (1°) DK/EP 3204155 T3 (12) Oversættelse af europæisk patentskrift Patent- og Varernærkestyreken (51) Int.CI.: B 01 J 23/52 (2006.01) B 01 J 23/66 (2006.01) C 07 C 51/235 (2006.01) C 07 H 1/00(2006.01) C 07 H 7/02(2006.01) C 07 H 7/033(2006.01) (45) Oversættelsen bekendtgjort den: 2019-10-14 (80) Dato for Den Europæiske Patentmyndigheds bekendtgørelse om meddelelse af patentet: 2019-08-28 (86) Europæisk ansøgning nr.: 15817590.1 (86) Europæisk indleveringsdag: 2015-10-06 (87) Den europæiske ansøgnings publiceringsdag: 2017-08-16 (86) International ansøgning nr.: NL2015050703 (87) Internationalt publikationsnr.: WO2016056907 (30) Prioritet: 2014-10-06 EP 14187763 (84) Designerede stater: AL AT BE BG CH CY CZ DE DK EE ES Fl FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR (73) Patenthaver: Coöperatie Koninklijke Cosun U.A., Van de Reijtstraat 15, 4814 NE Breda, Holland (72) Opfinder: FRISSEN, Augustinus Emmanuel, Nude 18, NL-6702 DL Wageningen, Holland VAN HAVEREN, Jacobus, Bovenbuurtweg 60, NL-6717 XB Ede, Holland VAN DER KLIS, Frits, Prins Hendrikstraat 5, NL-3361 ΧΝ Sliedrecht, Holland PAZHAVELIKKAKATH PURUSHOTHAMAN, Rajeesh Kumar, Thorbeckestraat 246, NL-6708 CA Wageningen, Holland VAN ES, Daniel Stephan, Ooievaarsbek 10, NL-6721 RP Bennekom, Holland (74) Fuldmægtig i Danmark: NORDIC PATENT SERVICE A/S, Bredgade 30,1260 København K, Danmark (54) Benævnelse: OXIDERING AF URONSYRER TIL ALDARSYRER (56) Fremdragne publikationer: WO-A1 -2005/003072 WO-A1 -2013/151428 US-A1-2011 306 790 BIELLA S ET AL: "Selective Oxidation of D-Glucose on Gold Catalyst", JOURNAL OF CATALYSIS, ACADEMIC PRESS, DULUTH, MN, US, vol. 206, no. 2, 10 March 2002 (2002-03-10), pages 242-247, ΧΡ027233441, ISSN: 0021-9517 [retrieved on 2002-03-10] SEN GUPTA K K ET AL: "Reactivity of some sugars and sugar phosphates towards gold(lll) in sodium acetate­ acetic acid buffer medium", CARBOHYDRATE RESEARCH, PERGAMON, GB, vol. 330, no. 1,10 January 2001 (2001-01-10), pages 115-123, ΧΡ027210787, ISSN: 0008-6215 [retrieved on 2001-01-10] Ulf Prüsse ET AL: "Catalytic conversion of renewables : Kinetic and mechanistic aspects of the gold-catalyzed liquid-phase glucose oxidation", Landbauforschung-vTI Agriculture and Forestry Research 3 (61), 1 January 2011 (2011-01-01), pages 261-271, ΧΡ55449453, Retrieved from the Internet: URL:http7/www.thuenen.de/media/publikatio nen/landbauforschung/Landbauforschung_Vo!6 1_3.pdf [retrieved Fortsættes ... DK/EP 3204155 T3 on 2018-02-08] DK/EP 3204155 T3 DESCRIPTION Field of the Invention [0001] The invention pertains to the synthesis of aldaric acids and derivatives thereof, from uronic acids under base-free circumstances. Also, the invention pertains to a method of producing galactaric acid from sugar beet pulp. Background of the invention [0002] Aldaric acids are a group of sugar acids, where the terminal hydroxyl or aldehyde groups of the sugars have been replaced by terminal carboxylic acids. These acids are characterized by the formula HOOC-(CHOH)n-COOH, with n being an integer of from 1 to 5. These dicarboxylic acids, on account of their combined functionalities, are interesting chemicals. E.g., as sequestering agents, corrosion inhibitors or monomers for making polymers made on the basis of dicarboxylic acids, such as polyesters or polyamides. Preferred aldaric acids are those wherein n is an integer of from 3 to 5. Aldaric acids of particular interest are those derived from C5 and C6 sugars, like xylaric acid, glucaric acid, mannaric acid, gularic acid and idaric acid. An aldaric acid of particular interest is galactaric acid, the aldaric acid corresponding to the sugar galactose. Applications for galactaric acid range from sequestering agents (Kohn et al. Collect. Czech. Chem. Commun. 1986, 1150) to building blocks for polymers (e.g. Moore & Bunting Polym. Sei. Technol., Adv. Polym. Synth., 51). Other aldaric acids of particular interest are glucaric acid, mannaric acid and gularic acid, aldaric acids that can be obtained from the carbohydrate fraction of biomass sources including pectins and a variety of different seaweeds. [0003] In WO 2013/151428 a method is disclosed to produce aldaric acids by the oxidation of the corresponding uronic acid, wherein a starting material comprising the uronic acid is subjected to oxygen under the influence of a supported gold catalyst and in the presence of a base. An interesting aspect of this method, is that it makes it possible to unlock the chemical potential present in the form of uronic acids in hemicellulosic streams, which are typically obtainable from biorefineries. [0004] Biorefineries serve to conduct the sustainable processing of biomass into a spectrum of marketable biobased products and bioenergy. A biorefinery is an installation that can process biomass into multiple products using an array of processing technologies. In general, biomass coming from plants, will result in streams based on lignin, cellulose, and hemicellulose, respectively. Hemicelluloses can be removed from biomass, e.g. by treatment with hot pressurized water. This results in formation of water soluble oligomeric and monomeric sugars and their dehydration products such as furfural and hydroxymethyl furfural. Another source of hemicelluloses is in the agro-food industry. Whilst hemicelluloses, in theory, are a source of a DK/EP 3204155 T3 wide variety of useful chemicals, it is desired to find methods to make better use of this potential, by providing economically attractive processes to harvest such chemicals therefrom. A particular interesting hemicellulosic feedstock from the agro-food industry comprises sugar beet pulp, a by-product of the sugar beet industry. Sugar beet pulp contains a high content of pectic substances, being composed of arabinose and galacturonic acid as the main monomers. Other sources of pectins are all kinds of different fruits, including e.g. apples, carrots, cherries and citrus fruits, especially citrus peels. Another potential source of uronic acids is being formed by alginates. A large variety of seaweeds including red and brown seaweeds like Laminaria digitata, Saccharina latissima and Ulva lactuca contain huge amounts of alginates being composed of mannuronic acid and guluronic acid as the composing monomers; after hydrolysis of the alginates such monomers can be used as feedstock for the production of aldaric acids. [0005] Whilst the process disclosed in the aforementioned reference is highly suitable, it would be desired to be able to convert the uronic acids under acidic, rather than basic circumstances. This would bring about a substantial advantage in that the stream of raw materials by nature is neutral to acidic, so that the addition of large amounts of base can be dispensed with. Also, the desired end-products, viz. aldaric acids, can only be isolated as a free acid by ultimately adjusting the pH to acidic. Thus, a process in which the whole oxidative conversion would take place under acidic conditions, would avoid both the use of additional base and the generation of a relatively large amount of salts as a by-product of ultimately acidifying the reaction product, so as to isolate the free aldaric acid. Summary of the invention [0006] In order to address one or more of the foregoing desires, the invention, in one aspect, provides a process for the preparation of an aldaric acid by the oxidation of the corresponding uronic acid, wherein a starting material comprising the uronic acid is subjected to oxygen under the influence of a supported gold catalyst at a pH below 7, at a temperature in the range of from 30°C to 100°C. [0007] In another aspect, the invention presents the use of a uronic acid as a starting material for the production of the corresponding aldaric acid, wherein the uronic acid is subjected to oxygen under the influence of a supported monometallic or bimetallic gold catalyst, at a pH below 7, at a temperature in the range of from 30°C to 100°C. Detailed description ofthe invention [0008] In a broad sense, the invention is based on the unexpected finding that, in putting to use the versatile chemical potential available of bio-based uronic acids by catalytic oxidation, no basic conditions need to be created. These bio-based uronic acids are available in, e.g., DK/EP 3204155 T3 hemicellulosic and pectin rich waste streams or seaweeds. [0009] To this end, the inventors have judiciously identified supported gold catalysts to catalyse the oxidation, whilst conducting the oxidation at a neutral to acidic pH. The gold catalyst can be a monometallic or bimetallic gold catalyst. In the former case, gold is the only catalytically active metal present. In the latter case, the gold is present together with a metal from the platinum group of metals, viz. selected from the group consisting of palladium, platinum, rhodium, ruthenium, iridium and osmium. Therein the molar ratio of gold to the other metal will generally range from 9.5:0.5 to 2:8. Throughout this description, the term "gold catalyst" is used to refer to the aforementioned monometallic or bimetallic gold catalyst, with monometallic gold catalysts being preferred. [0010] The starting material for the catalytic oxidation of the invention can be the uronic acid itself. Preferred uronic acids include: galacturonic acid, glucuronic acid, mannuronic acid, iduronic acid, guluronic acid and most preferably galacturonic acid. The invention provides an efficient, and highly selective catalytic oxidation of the uronic acid to the corresponding aldaric acid, e.g. from galacturonic acid to galactaric acid. To this end, supported gold catalysts are used. Such catalyst comprise support of a metal oxide, e.g. TiO2 or AI2C>3, or other materials customary in the art of providing supported catalysts for heterogeneous catalysis. [0011] The metal oxide support generally is a catalyst support made of at least one oxide of a main group or transition metal or metalloid, including compounds which comprise more than one metal and/or metalloid.