Process for pretreating cellulosic substrates and for producing sugar therefrom
AssigneeTrustees of Dartmouth College
InventorHans E. Grethlein
Life of this patent
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Abstract
Processes for treating cellulosic substances prior to hydrolysis which lead to shortening hydrolysis time and to increasing sugar yield. As exemplary, an aqueous slurry of the cellulosic substance is acidified and heated to and maintained at a temperature to produce a change in the cellulosic structure; the heating period is controlled so that there is little glucose formation. The pretreated cellulose may be subsequently hydrolyzed by acid or enzyme.
Claims34
A process for pretreating a cellulosic substance, that comprises:
- preparing a slurry of the cellulosic substance;
- adding an acid to the slurry to serve as a catalyst;
- heating the slurry to a reaction temperature at which the cellulose structure of the cellulosic substance is modified by interaction with the acid to a form which is significantly more susceptible to hydrolysis than the untreated substance;
- maintaining the reaction temperature of the slurry with the acid therein at said temperature for a time period that is long enough for most of the cellulosic substance therein to be modified to said form, said time period being short enough to prevent formation of significant amounts of glucose from cellulose and/or significant recrystallization of the cellulose structure;
- and quenching the slurry to reduce to insignificance the reaction between the acid and the thusly modified cellulosic substance.
A process for pretreating a cellulosic substance, that comprises forming an aqueous slurry containing the cellulosic substance;
- heating the slurry to a reaction temperature in the range from about 180.degree. C. to 300.degree. C. for a period of time respectively in the range from about five minutes to a fraction of a minute;
- and quenching the slurry.
A process for pretreating a cellulosic substance which is to be used as a raw material for making glucose that comprises:
- forming a slurry containing the cellulosic substance;
- heating the slurry to a reaction temperature at which a change occurs in the cellulose structure of the cellulosic material that renders the same more susceptible to subsequent hydrolysis to glucose but without forming significant amounts of glucose therefrom;
- and quenching the slurry to a holding temperature at which there is insignificant further reaction.
A continuous-flow pretreatment process for cellulosic substrates to render the substrates more susceptible to hydrolysis to glucose and/or other sugars that comprises the steps of producing a slurry comprising cellulosic materials and water;
- pumping the slurry to provide a flow thereof and to increase the pressure thereof to one which is at least equal to the vapor pressure of water at the operating temperature;
- rapidly heating the slurry to a reaction temperature sufficient that changes occur in the cellulosic structure of the substrate, due to a chemical reaction between the slurry and an acid therein, for a time sufficiently short that no substantial amount of glucose and/or other sugars are formed from the cellulose;
- and quenching the slurry.
A process for pretreating cellulose that comprises:
- preparing an aqueous slurry of the cellulose;
- adding an acid to the aqueous slurry in an amount to provide a dilute acid slurry solution;
- establishing the slurry with the acid therein at a temperature at which the cellulose structure is modified to a form which is significantly more susceptible to hydrolysis than the untreated cellulose and maintaining said temperature for a time period that is long enough for most of the cellulose therein to be modified to said form, said time period being short enough to prevent formation of significant amounts of glucose from cellulose and/or significant recrystallization of the cellulose;
- and quenching the aqueous slurry to reduce to insignificance the reaction between the acid and the thusly modified cellulose.
Dependencies are inferred from the claim text.