Wood solubilization and depolymerization by supercritical methanol. Part 2: Analysis of methanol soluble compounds

Methanol treatment of ponderosa pine wood was performed in a batch reactor at temperatures close to and above the critical points of methanol (238 degrees C and 8.3 MPa) to induce wood degradation into its monomeric and oligomeric components. The resultant methanol soluble and insoluble residues and gases were collected. The volatile components of the liquid and gaseous fractions were analyzed by GC-MS. The gases consisted mostly of carbon dioxide and simple aliphatic hydrocarbons. The non-volatile methanol soluble components were analyzed by HPLC and size exclusion chromatography. The mixture was found to be promising as a source of raw materials for fuel and chemical manufacturing. It consists of a blend of carbohydrate and lignin derived compounds and extractives in varying concentrations depending on the reaction conditions. More extractive compounds were found in the subcritical runs. In mild supercritical conditions the yield of lignin monomers and oligomers was increased, while under severe supercritical treatment, lignin and carbohydrate derived compounds were prevalent.