Studies on the effect of heterogeneous catalysts on the hydrothermal liquefaction of sugarcane bagasse to low-oxygen-containing bio-oil

Development of suitable catalysts having deep deoxygenation activity is the key for the hydrothermal liquefaction (HTL) of biomass to auto fuels directly. In this study 12 catalysts, namely Fe-MCM-41, Co-MCM-41, Mo-MCM-41, Ti-MCM-41, and oxides of Fe, Co, Mo, Ti, Fe-Mo, Fe-Co, Co-Mo and Ti-Zr, were synthesised, and characterised by X-Ray Diffraction (XRD), textural analysis, Fourier Transform Infra Red (FTIR) and Scanning Electron Microscope (SEM). They were evaluated for HTL of sugarcane bagasse to bio-oil in the presence of hydrogen and carbon monoxide. For non-catalytic HTL, oil obtained in the presence of hydrogen contained less oxygen, whereas for catalytic HTL oil obtained in the presence of carbon monoxide contained less oxygen. Among the catalysts studied, iron-cobalt oxide was found to be the most selective as it gave the highest oil yield of 57.6 weight% containing the least oxygen of 10.8 weight% in the presence of CO. Co-MCM-41 and cobalt oxide yielded bio-oil with the least oxygen among the metal-substituted MCM-41 and metal oxides studied, indicating that cobalt may be the most active catalytic species for strong deoxygenation activity. Metal-substituted MCM-41 yielded oil with less oxygen compared to its simple metal oxides except Ti, which may be due to very high surface area owing to its mesoporous structure.