Thermochemical Decomposition of Microcrystalline Cellulose Using Sub- and Supercritical Tetralin and Decalin with Fe₃O₄

Direct thermochemical liquefaction of microcrystalline cellulose was investigated in sub- and supercritical solvents in a batch reactor. The liquefaction efficiency of hydrogen donor solvents (tetralin and decalin) was compared to that of m-xylene. Tetralin was the most effective solvent with respect to the conversion at every tested condition starting from 350 °C. At 400 °C, the total conversion of cellulose in tetralin approached 96.8-98.3% with a negligible amount of char formation. The pressure of hydrogen had little effect on conversion for any solvent, while the addition of iron oxide catalyst (Fe₃O₄) led to improved conversion and liquid yield from the reaction compared to reactions without the catalyst at temperatures higher than 350 °C. Hydrogen pressure in the presence of iron oxide catalyst significantly suppressed the char formation and improved liquid production. The thermal-treated chars collected after liquefaction reactions showed a fair adsorption capacity of CO₂ compared to activated carbon.