Methods and systems for supplying hydrogen to a hydrocatalytic reaction
View Patent ↗A bottom fraction of a product of a hydrocatalytic reaction is gasified to generate hydrogen for use in further hydrocatalytic reactions. In one embodiment, an overhead fraction of the hydrocatalytic reaction is further processed to generate higher molecular weight compounds. In another embodiment, a product of the further processing is separated into a bottom fraction and an overhead fraction, where the bottom fraction is also gasified to generate hydrogen for use in further hydrocatalytic reactions.
1. A method comprising:
(a) providing a biomass feedstock comprising cellulose and water;
(b) contacting the biomass feedstock with hydrogen in the presence of a catalyst capable of activating molecular hydrogen in a hydrocatalytic treatment at a temperature in a range of about 180 to 290 degrees C. to form a hydrocatalytically treated mixture comprising a plurality of hydrocarbon and oxygenated hydrocarbon molecules;
(c) separating the hydrocatalytically treated mixture into at least a first overhead fraction comprising at least one of the hydrocarbon and oxygenated hydrocarbon molecules and a first bottom stream comprising at least one compound having a separation point having a temperature in a range of about 100 to 600 degrees C. at a pressure of about atmospheric pressure, wherein the first bottom fraction comprises at least one of phenol, o-cresol, p-cresol, anisole, 4-methylanisole, catechol, guaiacol, 4-methylguaiacol, 1,3-dimethoxybenzene, syringol, vanillin, methoxyphenol, methyl phenol, dimethyl phenol, ethyl phenol, methyl ethyl phenol, methoxypropylphenol, benzene diol, and propyl phenol;
(d) partially oxidizing the first bottom fraction to produce a gas mixture comprising carbon monoxide and hydrogen;
(e) providing the gas mixture to a water gas shift reaction zone external to where the biomass feedstock is contacted with hydrogen to generate hydrogen and carbon dioxide; and
(f) providing the hydrogen from step (e) for use in step (b).
2. The method of claim 1 wherein the first bottom fraction comprises at least one compound having a separation point having a temperature in a range of about 100 to 500 degrees C. at a pressure in a range of about 1 to 100 Torr.
3. The method of claim 1 wherein the first overhead fraction is subject to a further processing reaction to produce a product stream comprising a higher molecular weight compound comprising ≧C 4 hydrocarbons.
4. The method of claim 3 further comprising:
separating the product stream comprising a higher molecular weight compound comprising ≧C 4 hydrocarbons into a second overhead fraction and a second bottom fraction, wherein the second bottom fraction comprises at least one compound having a separation point having a temperature in a range of about 100 to 500 degrees C. at a pressure in a range of about 75 to 5250 Torr and wherein the second bottom fraction comprises C 14 or greater hydrocarbons;
partially oxidizing the second bottom fraction to produce a gas mixture comprising carbon monoxide and hydrogen;
subjecting the gas mixture generated from partial oxidation of the second bottom fraction to a water gas shift reaction to generate hydrogen and carbon dioxide; and
providing the hydrogen from the second bottom fraction to step (b).
5. The method of claim 4 wherein the second bottom fraction comprises at least one compound having a separation point having a temperature in a range of about 150 to 400 degrees C. at a pressure in a range of about 75 to 5250 Torr.
6. The method of claim 1 wherein the partially oxidizing step of the first bottom fraction comprises using a gasifier.
7. The method of claim 6 wherein the gasifier is selected from the group consisting of a moving-bed gasifier, a fluid-bed gasifier, an entrained-flow gasifier, and any combination thereof.
8. The method of claim 6 further comprising routing the first bottom fraction to the gasifier, wherein said first bottom fraction is a solid, liquid, or combination thereof.
9. The method of claim 8 wherein the gasifier comprises an entrained-flow gasifier and said first bottom fraction is routed as a liquid.
10. The method of claim 4 wherein the partially oxidizing step of the second bottom fraction comprises using a gasifier.
11. The method of claim 10 wherein the same gasifier is used for the partially oxidizing step of the first bottom fraction and the partially oxidizing step of the second bottom fraction.
12. The method of claim 1 wherein the first bottom fraction subject to partial oxidation has a viscosity of about 1 to 10,000 centipoise (cP) at a temperature of about 75 degrees C.
13. The method of claim 1 wherein the first bottom fraction subject to partial oxidation has a viscosity of about 320 centistokes or less at a temperature at which the first bottom fraction is produced.
14. The method of claim 1 wherein the first bottom fraction subject to partial oxidation comprises at least one component selected from lignin, a lignin-derived compound, unextracted cellulose, unextracted hemicellulose, and a caramelan.
15. The method of claim 1 wherein the hydrocatalytic treatment occurs in liquid phase.
16. The method of claim 1 wherein the hydrocatalytic treatment occurs in an aqueous phase solvent.
17. The method of claim 1 wherein the hydrocatalytic treatment occurs in an organic phase solvent.
18. The method of claim 1 wherein the first bottom fraction comprises at least one compound having a separation point having a temperature in a range of about 200 to 450 degrees C. at a pressure of about 3 to 20 Torr.