Process for the conversion of a carbohydrate-containing feedstock
A carbohydrate-containing feedstock is converted in a process by contacting the feedstock in a first step with an alcohol in the presence of a first acid catalyst at a temperature below 100° C. to yield an intermediate product, and contacting at least part of the intermediate product in a second step with an alcohol in the presence of a second acid catalyst at a temperature of at least 100° C. Products of such conversion may include hydroxymethylfurfural, hydroxymethylfurfural ethers, levulinic acid, esters thereof and furfural.
1. A process for dehydrating a carbohydrate-containing feedstock, wherein the process comprises:
contacting the feedstock in a first step with an alcohol, selected from the group consisting of methanol, ethanol and a mixture thereof, in a presence of a first acid catalyst at a temperature below 100° C. to yield an intermediate product; and contacting at least part of the intermediate product in a second step with a second alcohol, selected from the group consisting of methanol, ethanol and a mixture thereof, in a presence of a second acid catalyst at a temperature ranging from 105 to 300° C.
2. The process according to claim 1 , wherein the first step is carried out at a temperature of at least 10° C.
3. The process according to claim 1 , wherein the carbohydrate-containing feedstock and the alcohol are contacted with the first acid catalyst in the first step during a contact time which ranges from 0.1 to 12 hr.
4. The process according to claim 1 , wherein the carbohydrate is selected from the group consisting of monosaccharides, disaccharides, oligosaccharides and polysaccharides.
5. The process according to claim 4 , wherein the disaccharide is sucrose.
6. The process according to claim 4 , wherein the monosaccharide is fructose, glucose or a mixture thereof.
7. The process according to claim 1 , wherein the carbohydrate-containing feedstock comprises from 50 to 100% wt of carbohydrate, based on the carbohydrate-containing feedstock.
8. The process according to claim 1 , wherein in addition to water that is formed in the first and second steps, a diluent is added to the first and/or second steps.
9. The process according to claim 8 , wherein the diluent is water.
10. The process according to claim 8 , wherein the alcohol and added diluent are present in a weight ratio that varies from 50:1 to 0.1:1 w/w.
11. The process according to claim 1 , wherein the first acid catalyst is a homogeneous catalyst.
12. The process according to claim 1 , wherein the first acid catalyst is a heterogeneous catalyst.
13. The process according to claim 1 , wherein the second acid catalyst is a homogeneous catalyst.
14. The process according to claim 1 , wherein the second acid catalyst is a heterogeneous catalyst.
15. The process according to claim 1 , wherein the first and the second acid catalysts are the same.
16. The process according to claim 1 , wherein the second step is carried out at a temperature ranging from 150 to 280° C.
17. The process according to claim 1 , wherein at least the second step is carried out in a continuous mode.
18. The process according to claim 17 , wherein the continuous mode is carried out in a continuous stirred tank reactor, a plug flow reactor or a fixed bed reactor.
19. The process according to claim 17 , wherein the continuous mode is carried out at a liquid hourly space velocity from 0.1 to 1,000 hr −1 .
20. The process according to claim 2 , wherein the first step is carried out at a temperature ranging from 30 to 80° C.
21. The process according to claim 10 , wherein the alcohol and added diluent are present in a weight ratio that varies from 20:1 to 1:1 w/w.
22. The process according to claim 11 , wherein the first acid catalyst is a mineral acid.
23. The process according to claim 12 , wherein the first acid catalyst is selected from the group consisting of zeolites and acidic ion exchange resins.
24. The process according to claim 13 , wherein the second acid catalyst is a mineral acid.
25. The process according to claim 14 , wherein the second acid catalyst is selected from the group consisting of zeolites and acidic ion exchange resins.
26. The process according to claim 19 , wherein the continuous mode is carried out at a liquid hourly space velocity from 1 to 100 hr −1 .