Method for the simultaneous delignification of wood and other ligno-cellulosic materials and hydrolysis of the hemicellulose component thereof

A method for simultaneous delignification of wood and other lingo-cellulosic materials and hydrolysis of the hemicellulose component thereof into monomeric sugars in which said wood and other lingo-cellulosic materials are heated with acidic aqueous phenol or other phenolic compounds and with ultimately separating a delignified cellulose from said aqueous acidic phenol, which comprises:

• (a) contacting one part by weight solids of said wood or other lignocellulosic materials with a liquid of at least 1.0 to 10.0 parts by weight of a dilute aqueous acid of a pH below 1.5 and having an acid concentration of 0.5 to 6.0% by weight, and 0.4 to 6.0 parts by weight of phenol or other phenolic compounds;
• (b) heating the aqueous mixture under ambient pressure or slightly above or below ambient pressure and only at reflux temperatures of from 90.degree. to 110.degree. C. for 1 to 8 hours to form a delignified and hydrolysed pulp;
• (c) filtering and draining the pulp of step (b) without further heating to provide a residual solid and a liquid filtrate;
• (d) washing the residual solid with warm water made alkaline by NaOH or KOH and recovering a wash liquid;
• and
• (e) combining the liquid filtrate and wash liquid and separating by decantation an organic phase containing said phenol and lignin from an aqueous phase containing said sugars.