Process for transformation of lignocellulosic biomass or cellulose by tungsten-based solid lewis acids

1. A process for transformation of lignocellulosic biomass into lactic acid, comprising contacting the lignocellulosic biomass or cellulose in the presence of water with a heterogeneous catalyst having a tungsten content of 2 to 20% by weight, expressed in % by weight of metal relative to the total mass of the catalyst, said catalyst being dispersed on an oxide-based substrate, and said catalyst having greater than 50% Lewis-type acid sites.

2. The process according to claim 1 , wherein said oxide-based substrate is an oxide(s) of aluminum and/or zirconium and/or titanium and/or niobium.

3. The process according to claim 1 , wherein the tungsten content of the catalyst is between 10 to 20% by weight expressed in % by weight of metal relative to the total mass of catalyst.

4. The process according to claim 1 , wherein the transformation is implemented in a water-containing medium.

5. The process according to claim 4 , wherein the content by mass of water in the medium is greater than 1%.

6. The process according to claim 4 , wherein said medium is water.

7. The process according to claim 1 , wherein the transformation is carried out at a temperature of between 160 and 250° C., and at a pressure of between 0.5 and 20 MPa.

8. The process according to claim 1 , wherein the transformation is carried out in the presence of a gas that is air, a neutral gas or a reducing gas.

9. The process according to claim 1 , wherein the catalyst is introduced at a rate of a quantity that corresponds to a biomass/catalyst mass ratio of between 1 and 1,000.

10. The process according to claim 1 , wherein the biomass or cellulose is introduced at a rate of a quantity that corresponds to a (water-containing medium)/biomass mass ratio of between 1 and 1,000.

11. The process according to claim 1 , wherein the tungsten-based heterogeneous catalyst is prepared by ion exchange, impregnation or by co-precipitation, followed by a heat treatment.

12. The process according to claim 11 , wherein the tungsten precursor of the catalyst is tungstic acid, peroxotungstic acid, ammonium metatungstate, or tungsten-based isopolyanions or heteropolyanions.

13. The process according to claim 1 , wherein the tungsten-based heterogeneous catalyst is prepared by an anion exchange between a tungstic acid solution in hydrogen peroxide and hydroxide of Zr and/or Ti and/or Al and/or Nb, followed by calcination.

14. The process according to claim 1 , wherein before its transformation, the lignocellulosic biomass undergoes a stage of mechanical, thermochemical, thermal-mechanical-chemical or biochemical pretreatment.

15. The process according to claim 14 , wherein the size of the biomass particles after pretreatment is less than 5 mm.

16. The process according to claim 1 , wherein the transformation is implemented in a water-containing medium, with said medium being a liquid medium that is ethanol, water, an ionic liquid or a supercritical medium of liquid-type density.

17. The process according to claim 1 , wherein the transformation is carried out at a temperature of between 175 and 250° C., and at a pressure of between 2 and 10 MPa.

18. The process according to claim 1 , wherein the transformation is carried out in the presence of a gas that is air, a neutral gas or a reducing gas hydrogen.

19. The process according to claim 1 , wherein the catalyst is introduced at a rate of a quantity that corresponds to a biomass/catalyst mass ratio of between 1 and 50.

20. The process according to claim 1 , wherein the biomass or cellulose is introduced at a rate of a quantity that corresponds to a (water-containing medium)/biomass mass ratio of between 5 and 100.