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.