Supercritical delignification of wood
First Claim
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1. Process for converting wood to pulp which comprises contacting wood with a supercritical fluid that contains a delignification agent comprising sodium hydroxide and/or sodium sulfide and/or sodium bisulfate under supercritical conditions sufficient to remove lignin, extractive and hemicellulose from the wood thereby making a full chemical pulp.
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Abstract
An improved wood pulping process for the delignification of wood in a solvent wherein the solvent is a supercritical fluid under supercritical conditons and contains a delignification agent such as sodium hydroxide, sodium sulfide and/or sodium bisulfate.
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Citations
14 Claims
- 1. Process for converting wood to pulp which comprises contacting wood with a supercritical fluid that contains a delignification agent comprising sodium hydroxide and/or sodium sulfide and/or sodium bisulfate under supercritical conditions sufficient to remove lignin, extractive and hemicellulose from the wood thereby making a full chemical pulp.
- 5. Process for removing lignin from a lignin containing cellulosic material which comprises contacting the cellulose material with a supercritical fluid containing an active delignification agent comprising sodium hydroxide and/or sodium sulfide and/or sodium bisulfate under supercritical conditions whereby lignin is removed from the cellulosic material.
- 9. Process for the delignification of a cellulosic material containing lignin which comprises impregnating the cellulosic material with a delignification agent comprising sodium hydroxide and/or sodium sulfide and/or sodium bisulfate and digesting the impregnated material in an ammonia based fluid comprising ammonia containing less than about 12% by weight water under supercritical conditions.
- 12. Process for making paper which comprises impregnating wood with a first supercritical fluid containing a delignification agent comprising sodium hydroxide and/or sodium sulfide and/or sodium bisulfate under supercritical conditions, digesting the impregnated wood in the presence of a second supercritical fluid maintained under supercritical conditions sufficient to extract lignins, extractives and hemicellulose from the wood and to separate the wood into discrete fibers thereby producing a full chemical pulp, separating a liquor comprising the second fluid containing lignins, extractives and hemicellulose from the pulp and treating the pulp to conditions sufficient to convert the pulp to paper.
Specification