Patent Number: 6,251,221

Title: Process for preparing cellulose from lignin-poor cellulose-containing feed stocks

Abstract: The method of the invention involves treating cellulosic vegetable matter (the "Feed Stocks") for the selective recovery of lignin (when present in the feed-stock), cellulose and hemi-celluloses by: (1) reducing the material to be processed to an appropriate size; (2) adjusting the moisture content of the ligno-cellulosic feed stock to 15 percent to 30 percent water; (3) impregnating the ligno-cellulosic feed stock with an extraction liquor containing a glycol and an organic or Lewis acid; (4) rapid heating of said impregnated feed stock to a temperature of about 118.degree. C. to about 145.degree. C.; (5) maintaining the desired temperature for about 1 minute to about 6 minutes to solubilize the lignin therefrom (a period of about 2 minutes to about 5 minutes is preferred); (6) stopping the reaction immediately by lowering the temperature to <100.degree. C. in a quenching bath of fresh or recycled liquor or other suitable liquid; (7) removing the lignin-enriched extraction liquor from the quenched impregnated matter and (8) recovering the extracted lignin. If the feed stock is non-ligneous (for example, cotton linters), the quenching step (step 6) may be combined with a wash (alcohol is exemplified) to remove the cooking liquor from the cooked material. The cellulosic material may then be recovered from the liquid using separatory means known in the art such as filtration, centrifugation or vacuum screening. Alcohol may be recovered by evaporation under reduced pressure.

Inventors: Burkart; Leonard (Loveland, CO)

Assignee:

International Classification: C08B 15/00 (20060101); C08B 15/02 (20060101); C08H 5/00 (20060101); C08H 5/02 (20060101); D21C 5/00 (20060101); D21C 3/20 (20060101); D21C 5/02 (20060101); D21C 3/00 (20060101); D21C 005/02 (); D21H 011/12 ()

Expiration Date: 06/26/2018