Converting lignocellulosic biomass to glucose using a low temperature sulfur dioxide pretreatment

A method for converting lignocellulosic biomass to glucose comprising:

• pretreating the lignocellulosic biomass to provide a pretreated material, said pretreating comprising subjecting the lignocellulosic biomass to a SO2 pretreatment, said SO2 pretreatment comprising heating said lignocellulosic biomass with at least one of sulfur dioxide and sulfurous acid, said heating conducted between 110° C. and 150° C. for more than 90 minutes;
• and
• hydrolyzing at least 60% of the cellulose in the pretreated material to glucose, said hydrolyzing including adding enzyme to at least a solid fraction of the pretreated material, said enzyme including a cellulase,
• wherein said SO2 pretreatment is conducted with a total amount of sulfur dioxide greater than 70 wt % based on dry weight of lignocellulosic biomass.

A method for converting lignocellulosic biomass to glucose comprising:

• pretreating the lignocellulosic biomass to provide a pretreated material, said pretreating comprising subjecting the lignocellulosic biomass to a SO2 pretreatment, said SO2 pretreatment comprising heating said lignocellulosic biomass with at least one of sulfur dioxide and sulfurous acid, said heating conducted between 110° C. and 150° C. for more than 90 minutes, said SO2 pretreatment conducted with a total amount of sulfur dioxide greater than 20 wt % based on dry weight of lignocellulosic biomass;
• and
• hydrolyzing at least 60% of the cellulose in the pretreated material to glucose, said hydrolyzing including adding enzyme to at least a solid fraction of the pretreated material, said enzyme including a cellulase,
• wherein said hydrolyzing provides a cellulose conversion of at least 80% within 72 hours, and
• wherein said pretreating is conducted in the absence of added alkali.

A method for converting lignocellulosic biomass to glucose comprising:

• pretreating the lignocellulosic biomass to provide a pretreated material, said pretreating comprising subjecting the lignocellulosic biomass to a SO2 ;
• pretreatment, said SO2 pretreatment comprising heating said lignocellulosic biomass with at least one of sulfur dioxide and sulfurous acid, said heating conducted between 110° C. and 150° C. for more than 90 minutes, said SO2 pretreatment conducted with a total amount of sulfur dioxide greater than 20 wt % based on dry weight of lignocellulosic biomass;
• and
• hydrolyzing at least 60% of the cellulose in the pretreated material to glucose, said hydrolyzing including adding enzyme to at least a solid fraction of the pretreated material, said enzyme including a cellulase,
• wherein said hydrolyzing provides a cellulose conversion of at least 80% within 72 hours, and
• wherein said pretreating is conducted in the absence of added organic solvent.

A process for the production of an alcohol from lignocellulosic biomass, said process comprising:

• feeding the lignocellulosic biomass into a pretreatment reactor;
• pretreating the lignocellulosic biomass in the pretreatment reactor to provide a pretreated material, said pretreating comprising heating the lignocellulosic biomass with at least one of sulfur dioxide and sulfurous acid between 110° C. and 150° C. for more than 100 minutes, where a total amount of sulfur dioxide is greater than 20 wt % based on dry weight of lignocellulosic biomass, where alkali is added in an amount in the range from 0 to 0.5 wt % based on dry weight of incoming lignocellulosic biomass and organic solvent is added in an amount in the range from 0 to 5 wt % based on dry weight of incoming lignocellulosic biomass;
• hydrolyzing at least 60% of the cellulose in the lignocellulosic biomass to glucose, said hydrolyzing including adding cellulase;
• fermenting the glucose to produce the alcohol;
• and
• recovering the alcohol.