Cellulose production from lignocellulosic biomass

• US 20020148575A1
• Filed: 02/20/2002
• Published: 10/17/2002
• Est. Priority Date: 08/16/2000
• Status: Active Grant

• Current Assignee: PureVision Technology, Inc.
• Original Assignee: PureVision Technology, Inc.
• Inventors: Wingerson, Richard C.
• Granted Patent: US 6,620,292 B2
• Time in Patent Office: Days
• US Class Current: 162/14
• CPC Class Codes: D21C 1/02 with water or steam
• CPC Class Codes: D21C 3/02 with inorganic bases or alkaline reacting compounds, e.g. sulfate processes
• CPC Class Codes: D21C 3/026 in presence of O2, e.g. air
• CPC Class Codes: D21C 3/028 in presence of O3
• CPC Class Codes: D21C 3/18 with halogens or halogen-generating compounds bleaching cellulose pulp D21C9/12
• CPC Class Codes: D21C 3/26 Multistage processes
• CPC Class Codes: Y02P 70/10 Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working

Abstract

A multi-function process is described for the separation of cellulose fibers from the other constituents of lignocellulosic biomass such as found in trees, grasses, agricultural waste, and waste paper with application in the preparation of feedstocks for use in the manufacture of paper, plastics, ethanol, and other chemicals. This process minimizes waste disposal problems since it uses only steam, water, and oxygen at elevated temperature in the range of 180° C. to 240° C. for 1 to 10 minutes plus a small amount of chemical reagents to maintain pH in the range 8 to 13. An energy recuperation function is important to the economic viability of the process.

Claims

1. A method of treating lignocellulosic biomass containing lignin to produce purified cellulose, said method comprising:

providing a lignocellulosic feedstock;

introducing said feedstock into a pressure vessel having at least two reaction zones;

heating said feedstock in a first reaction zone to a temperature of from about 180°

C. to about 240°

C.;

removing hydrolized hemicellulose from the heated feedstock;

transferring said heated feedstock from said first reaction zone to a second reaction zone;

subjecting said feedstock in said second zone to a counterflow of hot wash water containing dissolved oxygen and having a pH of at least 11 to produce residual solids containing cellulose and a wash water containing lignin and other extractives; and

separating the residual solids containing purified cellulose from the filtered wash water, wherein the separated cellulose contains less than 10% lignin.

2. The method of claim 1, wherein the separated cellulose contains less than 5% lignin.

3. The method of claim 1, wherein the separated cellulose contains less than 2% lignin.

4. The method of claim 1, wherein the separated cellulose contains less than 1% lignin.