Biomass processing methods and systems

A process for producing cellulose from recalcitrant lignocellulosic biomass, the process comprising:

• combining the biomass with a transition metal catalyst, wherein the transition metal catalyst optionally comprises an iron-based nanoparticulate catalyst, a polyvalent carboxylic acid and hydrogen peroxide;
• incubating the reaction mixture at an alkaline pH;
• and
• recovering cellulose.

A process for producing bioproducts from lignocellulosic biomass, the process comprising:

• extracting lignin and/or hemicellulose from a soluble fraction of the lignocellulosic biomass under alkaline conditions, wherein the alkaline conditions optionally comprise a pH of about 11 to about 13, optional a pH of approximately 12, at a temperature in the range of 10° C. to 160° C., optionally 60° C. to 95° C., optionally for a period of between about 30 minutes and 10 hours;
• washing the lignocellulosic biomass until the pH of the lignocellulosic biomass is approximately neutral;
• adding a polyvalent carboxylic acid, trace amounts of a transition metal catalyst, wherein the transition metal catalyst optionally comprises an iron-based nanoparticulate catalyst, and hydrogen peroxide to the lignocellulosic biomass to produce a reaction mixture, wherein the concentration of biomass in the reaction mixture is optionally in the range of 2.5% to 5% w/v, wherein the pH is optionally reduced to a pH in the range of 2.5 to 5, wherein the polyvalent carboxylic acid optionally comprises an aqueous solution saturated with citrate having a pH in the range of 3.2 to 3.5;
• increasing the pH of the reaction mixture to an alkaline pH;
• incubating the reaction mixture at a predetermined temperature for a treatment period;
• and
• recovering bioproducts from the treated reaction mixture, wherein the bioproducts optionally comprise lignin, hemicellulose, cellulose, and/or crystalline cellulose.