Method for preparation of amorphous silica from biomass

Patent metadata

Field	Value
Publication number	US-9403687-B2
Application number	US-201414324058-A
Country	US
Kind code	B2
Filing date	Jul 3, 2014
Priority date	Jan 5, 2012
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

A method for preparation of amorphous silica from biomass. The method includes pyrolyzing the biomass under anaerobic conditions to yield a pyrolysis gas and solid residues, collecting the pyrolysis gas, and calcining the solid residues under aerobic conditions to yield amorphous silica.

First claim

The invention claimed is:

1. A method for preparation of amorphous silica from biomass, the method comprising:
washing the biomass with 3 to 5 wt. % hydrochloric acid, sulfuric acid, or nitric acid, and drying the biomass;
after drying, pyrolyzing the biomass under anaerobic conditions to yield a pyrolysis gas and solid residues, collecting the pyrolysis gas; and
calcining the solid residues in the presence of air to remove carbon residues and to yield amorphous silica.

2. The method of claim 1 , wherein the biomass comprises rice hull.

3. The method of claim 1 , wherein before washing the biomass with 3 to 5 wt. % hydrochloric acid, sulfuric acid, or nitric acid, and drying of the biomass, the method further comprises washing with water the biomass for removal of impurities.

4. The method of claim 3 , wherein washing the biomass with 3 to 5 wt. % hydrochloric acid, sulfuric acid, or nitric acid, and drying of the biomass comprise: soaking the biomass in 3 to 5 wt. % hydrochloric acid, sulfuric acid, or nitric acid at room temperature for between 8 and 24 hours, or at between 80 and 100° C. for between 2 and 6 hours, washing the biomass to be neutral, and drying the biomass.

5. The method of claim 1 , wherein the biomass is pyrolyzed at a temperature of between 500 and 1000° C.

6. The method of claim 1 , wherein the pyrolysis gas comprises CO, CO 2 , H 2 , CH 4 , C 2 H 2 , C 2 H 4 , C 2 H 6 , C 3 H 8 , C 3 H 10 , or a mixture thereof.

7. The method of claim 1 , wherein a calcination temperature of the solid residues is between 500 and 800° C.

8. The method of claim 1 , wherein a thermal flue gas resulting from the calcination of the solid residues is conveyed back to a pyrolysis furnace for the heat cycle of the pyrolysis.

Assignees

• Wuhan Kaidi General Res Inst Of Eng & Tech Co Ltd
• Wuhan Kaidi Eng Tech Res Inst

Inventors

• Zhang Yanfeng
• Cao Minxia
• Li Hong
• Rao qi

Classifications

• C01B33/126 Primary

  Preparation of silica of undetermined type · CPC title

• C01P2004/64

  Nanometer sized, i.e. from 1-100 nanometer · CPC title

• C01B33/12 Primary

  Silica; Hydrates thereof, e.g. lepidoic silicic acid · CPC title

• C01B33/18

  Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof (preparation of aerogels by dehydrating gels C01B33/158; treatment to enhance the pigmenting or filling properties C09C) · CPC title

• C01B33/023

  by reduction of silica or {free} silica-containing material · CPC title