Production and conditioning of synthesis gas obtained from biomass
View Patent ↗A method of producing and treating synthesis gas in which a biomass-rich material is gasified in a gasifier containing a fluidized bed at a temperature that does not exceed 750° C. to produce a crude synthesis gas product. The crude synthesis gas then is quenched, scrubbed, and then subjected to at least one adsorption step to provide a clean synthesis gas. The clean synthesis gas then may be reformed catalytically to provide a synthesis gas with a desired H 2 :CO ratio, and/or may be employed in the synthesis of desired chemicals.
1. A method of producing and treating synthesis gas, comprising:
(a) gasifying a biomass rich material in the presence of (i) air, oxygen-enriched air, and/or oxygen and (ii) steam in a gasifier containing a fluidized bed at a temperature that does not exceed 750° C. to produce a crude synthesis gas;
(b) subjecting said crude synthesis gas to steam reforming in the presence of steam and air, oxygen-enriched air, and/or oxygen at a temperature of from about 750° C. to about 1,000° C.;
(c) quenching said crude synthesis gas from step (b);
(d) scrubbing said quenched synthesis gas from step (c); and
(e) subjecting said scrubbed synthesis gas to at least one adsorption step to provide a clean synthesis gas.
2. The method of claim 1 wherein said biomass-rich material is gasified at a temperature that does not exceed 725° C.
3. The method of claim 2 wherein said biomass-rich material is gasified at a temperature which does not exceed 700° C.
4. The method of claim 1 wherein said biomass-rich material is gasified at a pressure which does not exceed 3 atm.
5. The method of claim 4 wherein said biomass-rich material is gasified at a pressure which does not exceed 1.5 atm.
6. The method of claim 1 wherein said quenching of said crude synthesis gas comprises contacting said crude synthesis gas with alkaline water.
7. The method of claim 1 wherein said steam reforming is effected at a temperature of from about 750° C. to about 850° C.
8. The method of claim 1 wherein said steam reforming is effected in the presence of a catalyst.
9. The method of claim 8 wherein said catalyst comprises NiCr/MgO.La 2 O 3 .Al 2 O 3 .
10. The method of claim 1 wherein said scrubbing of said synthesis gas is effected at a gas entry temperature of from about 150° C. to about 350° C., and an exit temperature of from about 30° C. to about 90° C.
11. The method of claim 1 wherein said at least one adsorption step comprises passing said synthesis gas through an adsorption column packed with at least one material having a porosity of greater than 40%.
12. The method of claim 1 wherein said scrubbing of said synthesis gas comprises:
(i) scrubbing said synthesis gas under alkaline conditions; and
(ii) scrubbing said synthesis gas at a pH of from 4 to 7.
13. The method of claim 1 wherein said at least one adsorption step comprises:
(i) passing said scrubbed synthesis gas through a reactive adsorption bed comprising calcium oxide or calcium oxide and magnesium oxide; and
(ii) passing said scrubbed synthesis gas through a zinc oxide filtration bed.
14. The method of claim 1 , and further comprising:
(f) subjecting said synthesis gas, subsequent to step (e), to catalytic reforming in the presence of a catalyst.
15. The method of claim 14 wherein said catalyst is NiCr/MgO.La 2 O 3 .Al 2 O 3 .
16. The method of claim 14 wherein said catalytic reforming is effected at a temperature of from about 750° C. to about 900° C.
17. The method of claim 16 wherein said catalytic reforming is effected at a temperature of from about 750° C. to about 800° C.
18. The method of claim 1 wherein said fluidized bed includes one or more materials selected from the group consisting of alumina, olivine, anthracite, and desulfurized petroleum coke.