Chemical conversion of cellulose as treated in supercritical methanol

The chemical conversion of cellulose as treated in supercritical methanol was studied using a batch-type reaction vessel at temperatures from 220 to 450 degreesC and pressures from 14 to 72 MPa. Supercritical methanol treatment at 350 degreesC and 43 MPa for 7 min was sufficient to convert microcrystalline cellulose (avicel) to the methanol-soluble. To study the kinetics of the decomposition of cellulose, the decomposition rate constants were obtained, and rapid increase was observed at about 270 degreesC which was about 30 degreesC higher than the critical temperature of methanol. The main products from cellulose decomposition were methylated cellotriose, methylated cellobiose, methyl alpha- and beta -D-glucosides, levoglucosan and 5-hydroxymethylfurfural. Monomeric compounds such as methyl alpha- and beta -D-glucosides were stable in supercritical methanol, allowing high yields of monomeric products by supercritical methanol treatment. Based on these results, a pathway of cellulose decomposition treated in supercritical methanol was proposed. These findings suggest that the supercritical methanol treatment of various cellulosic materials may be suitable to obtain useful chemicals and liquid fuels without using fossil resources.