Process for the production of sugars from biomass

Abstract

Process for the production of sugars from biomass including at least one polysaccharide which comprises putting a biomass in contact with an aqueous solution of at least one organic acid having from 1 to 6 carbon atoms, preferably from 1 to 3 carbon atoms, the pH of said aqueous solution being ranging from 0.6 to 1.6, preferably ranging from 0.9 to 1.3. The sugars thus obtained can be advantageously used as carbon sources in fermentation processes for the production of alcohols (e.g., ethanol, butanol), diols (e.g., 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol), lipids, or other intermediates or products. Said alcohols, diols, lipids, or other intermediates or products, can be advantageously used in the chemical industry or in the formulation of fuels for motor vehicles. Said alcohols and said diols can also be advantageously used in the bio-butadiene production.

Claims

1. A process for the production of one or more sugars having from 5 to 6 carbon atoms from a biomass that comprises hemicellulose, the process comprising: contacting said biomass with an aqueous solution comprising an organic acid having from 1 to 3 carbon atoms, wherein said aqueous solution has a pH ranging from 0.6 to 1.6, and wherein the organic acid is an alkyl-sulfonic acid having the formula RSO.sub.3H where R represents a linear or branched C.sub.1-C.sub.3 alkyl group, and obtaining the one or more sugars having from 5 to 6 carbon atoms, wherein said process provides a yield of said one or more sugars having from 5 to 6 carbon atoms that is higher than or equal to 95%, said yield being calculated with respect to a total quantity of hemicellulose present in the starting biomass.

2. The process according to claim 1, wherein said biomass is a lignocellulosic biomass.

3. The process according to claim 2, wherein said lignocellulosic biomass is selected from the group consisting of material from guayule (Parthenium argentatum), thistle (Cynara cardunculus L.), conifers and mixtures thereof.

4. The process according to claim 1, wherein said biomass is subjected to a preliminary grinding process before contacting it with said aqueous solution.

5. The process according to claim 1, comprising contacting said biomass with an aqueous solution comprising an organic acid having from 1 to 2 carbon atoms, wherein R represents a linear or branched C.sub.1-C.sub.2 alkyl group.

6. The process according to claim 5, wherein said organic acid is methane-sulfonic acid (CH.sub.3SO.sub.3H).

7. The process according to claim 1, wherein said process comprises: a. contacting the biomass with the aqueous solution in a reactor thus obtaining a first reaction mixture; b. heating the first reaction mixture in the reactor to a desired temperature for a time ranging from 20 minutes to 2 hours, thus obtaining a second reaction mixture comprising a first solid phase and a first aqueous phase; c. optionally, maintaining said second reaction mixture at said desired temperature for a time ranging from 30 seconds to 1 hour; and d. removing said second reaction mixture from said reactor.

8. The process according to claim 7, wherein said biomass is present in said first reaction mixture in a quantity ranging from 5% by weight to 40% by weight with respect to the total weight of said first reaction mixture.

9. The process according to claim 7, wherein said reactor is a reactor with continuous feeding of the biomass.

10. The process according to claim 7, wherein said first solid phase comprises lignin and cellulose and said first aqueous phase comprises at least one sugar having from 5 to 6 carbon atoms and said organic acid.

11. The process of claim 1, wherein said aqueous solution has a pH ranging from 0.9 to 1.3.

12. The process of claim 2, wherein said lignocellulosic biomass is selected from the group consisting of: a product of a miscanthus, foxtail millet, or common cane crop or another crop expressly cultivated for energy use, or a waste product, residue or scraps of said crop or of its processing; a product of agricultural cultivations, forestation and silviculture, comprising wood, plants, residues or waste products of agricultural processing, of forestation or of silviculture; waste of agro-food products destined for human nutrition or zootechnics; residues, not chemically treated, of the paper industry; waste products coming from a differentiated collection of urban waste paper, urban waste of vegetable origin or other solid urban waste, and mixtures thereof.

13. The process of claim 7, wherein said desired temperature ranges from 100? C. to 180? C.

14. The process of claim 7, wherein said desired temperature ranges from 130? C. to 150? C.

15. The process of claim 1, wherein said aqueous solution has a pH ranging from 0.6 to 1.6 and consists essentially of water and the organic acid.

16. The process of claim 1, wherein said aqueous solution has a pH ranging from 0.6 to 1.6 and consists of water and the organic acid.

Description

EXAMPLE 1 (INVENTION)

(1) 25 g of previously ground coniferous wood (particle diameter <2 mm) were charged into an open-top B?chi autoclave type 3E/1.01t.

(2) 500 g of an aqueous solution of methane-sulfonic acid (CH.sub.3SO.sub.3H), at pH 1.1, were then charged. The first reaction mixture thus obtained was kept under vigorous stirring (600 revs/min), until a temperature of 140? C. had been reached, over a period of 45 minutes, obtaining a second reaction mixture comprising a first solid phase containing lignin and cellulose and a first aqueous phase containing sugars deriving from hemicellulose.

(3) After leaving the autoclave to cool to room temperature (23? C.), said phases were separated by filtration.

(4) The composition of the starting biomass, determined as described above, was the following: 45.1% by weight of cellulose, 25.2% by weight of hemicellulose, 24.4% by weight of lignin, with respect to the total weight of the starting biomass. The remaining part proved to consist of organic acids, protein and non-protein nitrogenous substances, lipids, mineral salts.

(5) The first aqueous phase was analyzed as described above, obtaining the following results: yield: 97.6% (with respect to the total quantity of hemicellulose contained in the starting biomass); degradation ratio C.sub.6:1.9%; degradation ratio C.sub.5:0.9%; C.sub.5 content: 83.7%.

EXAMPLE 2 (INVENTION)

(6) 25 g of previously ground thistle bagasse (Cynara cardunculus L.) (particle diameter<2 mm) were charged into an open-top B?chi autoclave type 3E/1.01t.

(7) 500 g of an aqueous solution of methane-sulfonic acid (CH.sub.3SO.sub.3H), at pH 1.1, were then charged. The first reaction mixture thus obtained was kept under vigorous stirring (600 revs/min), until a temperature of 140? C. had been reached, over a period of 45 minutes, obtaining a second reaction mixture comprising a first solid phase containing lignin and cellulose and a first aqueous phase containing sugars deriving from hemicellulose.

(8) After leaving the autoclave to cool to room temperature (23? C.), said phases were separated by filtration.

(9) The composition of the starting biomass, determined as described above, was the following: 41.2% by weight of cellulose, 17.5% by weight of hemicellulose, 25.7% by weight of lignin, with respect to the total weight of the starting biomass. The remaining part proved to consist of organic acids, protein and non-protein nitrogenous substances, lipids, mineral salts.

(10) The first aqueous phase was analyzed as described above, obtaining the following results: yield: 96.1% (with respect to the total quantity of hemicellulose contained in the starting biomass); degradation ratio C.sub.6: 1.4%; degradation ratio C.sub.5: 0.9%; C.sub.5 content: 74.3%.

EXAMPLE 3 (INVENTION)

(11) 25 g of previously ground guayule bagasse (Parthenium argentatum) (particle diameter <2 mm) were charged into an open-top B?chi autoclave type 3E/1.01t.

(12) 500 g of an aqueous solution of methane-sulfonic acid (CH.sub.3SO.sub.3H), at pH 1.1, were then charged. The first reaction mixture thus obtained was kept under vigorous stirring (600 revs/min), until a temperature of 140? C. had been reached, over a period of 45 minutes, obtaining a second reaction mixture comprising a first solid phase containing lignin and cellulose and a first aqueous phase containing sugars deriving from hemicellulose.

(13) After leaving the autoclave to cool to room temperature (23? C.), said phases were separated by filtration.

(14) The composition of the starting biomass, determined as described above, was the following: 42.9% by weight of cellulose, 21.2% by weight of hemicellulose, 26.3% by weight of lignin, with respect to the total weight of the starting biomass. The remaining part proved to consist of organic acids, protein and non-protein nitrogenous substances, lipids, mineral salts.

(15) The first aqueous phase was analyzed as described above, obtaining the following results: yield: 98.8% (with respect to the total quantity of hemicellulose contained in the starting biomass); degradation ratio C.sub.6: 0.0%; degradation ratio C.sub.5: 1.6%; C.sub.5 content: 80.6%.

EXAMPLE 4 (COMPARATIVE)

(16) 25 g of previously ground coniferous wood (particle diameter <2 mm) were charged into an open-top B?chi autoclave type 3E/1.01t.

(17) 500 g of an aqueous solution of p-toluenesulfonic acid (CH.sub.3C.sub.6H.sub.4SO.sub.3H), at pH 1.1, were then charged. The first reaction mixture thus obtained was kept under vigorous stirring (600 revs/min), until a temperature of 140? C. had been reached, over a period of 45 minutes, obtaining a second reaction mixture comprising a first solid phase containing lignin and cellulose and a first aqueous phase containing sugars deriving from hemicellulose.

(18) After leaving the autoclave to cool to room temperature (23? C.), said phases were separated by filtration.

(19) The composition of the starting biomass, determined as described above, was the following: 45.1% by weight of cellulose, 25.2% by weight of hemicellulose, 24.4% by weight of lignin, with respect to the total weight of the starting biomass. The remaining part proved to consist of organic acids, protein and non-protein nitrogenous substances, lipids, mineral salts.

(20) The first aqueous phase was analyzed as described above, obtaining the following results: yield: 83.6% (with respect to the total quantity of hemicellulose contained in the starting biomass); degradation ratio C.sub.6: 5.0%; degradation ratio C.sub.5: 3.7%; C.sub.5 content: 77.3%.

EXAMPLE 5 (COMPARATIVE)

(21) 25 g of previously ground thistle bagasse (Cynara cardunculus L.) (particle diameter <2 mm) were charged into an open-top B?chi autoclave type 3E/1.01t.

(22) 500 g of an aqueous solution of p-toluenesulfonic acid (CH.sub.3C.sub.6H.sub.4SO.sub.3H), at pH 1.1, were then charged. The first reaction mixture thus obtained was kept under vigorous stirring (600 revs/min), until a temperature of 140? C. had been reached, over a period of 45 minutes, obtaining a second reaction mixture comprising a first solid phase containing lignin and cellulose and a first aqueous phase containing sugars deriving from hemicellulose.

(23) After leaving the autoclave to cool to room temperature (23? C.), said phases were separated by filtration.

(24) The composition of the starting biomass, determined as described above, was the following: 41.2% by weight of cellulose, 17.5% by weight of hemicellulose, 25.7% by weight of lignin, with respect to the total weight of the starting biomass. The remaining part proved to consist of organic acids, protein and non-protein nitrogenous substances, lipids, mineral salts.

(25) The first aqueous phase was analyzed as described above, obtaining the following results: yield: 88.1% (with respect to the total quantity of hemicellulose contained in the starting biomass); degradation ratio C.sub.6: 3.8%; degradation ratio C.sub.5: 8.8%; C.sub.5 content: 72.9%.

EXAMPLE 6 (COMPARATIVE)

(26) 25 g of previously ground guayule bagasse (Parthenium argentatum) (particle diameter <2 mm) were charged into an open-top B?chi autoclave type 3E/1.01t.

(27) 500 g of an aqueous solution of p-toluenesulfonic acid (CH.sub.3C.sub.6H.sub.4SO.sub.3H), at pH 1.1, were then charged. The first reaction mixture thus obtained was kept under vigorous stirring (600 revs/min), until a temperature of 140? C. had been reached, over a period of 45 minutes, obtaining a second reaction mixture comprising a first solid phase containing lignin and cellulose and a first aqueous phase containing sugars deriving from hemicellulose.

(28) After leaving the autoclave to cool to room temperature (23? C.), said phases were separated by filtration.

(29) The composition of the starting biomass, determined as described above, was the following: 42.9% by weight of cellulose, 21.2% by weight of hemicellulose, 26.3% by weight of lignin, with respect to the total weight of the starting biomass. The remaining part proved to consist of organic acids, protein and non-protein nitrogenous substances, lipids, mineral salts.

(30) The first aqueous phase was analyzed as described above, obtaining the following results: yield: 91.2% (with respect to the total quantity of hemicellulose contained in the starting biomass); degradation ratio C.sub.6: 0.0%; degradation ratio C.sub.5: 4.8%; C.sub.5 content: 74.6%.

(31) From the examples described above, it is evident that, operating under the same conditions, the yields of sugars having from 5 to 6 carbon atoms proved to be lower and the quantity of by-products [i.e. furfural (F) and hydroxy-methyl-furfural (HMF)] proved to be higher, using p-toluenesulfonic acid [Examples 4-6 (comparative)], with respect to [Examples 1-3 (invention)] in which methane-sulfonic acid was used in accordance with the present invention.