Catalytic Hydrothermal Conversion of Glucose to Light Petroleum Alkanes

The production of carbon-neutral liquid fuels from renewable biomass has attracted worldwide interest in an age of depletion of fossil fuel reserves and pollutions caused by utilization of fossil petroleum. Currently, commercial bio-oil production technologies include bio-ethanol, bio-diesel and pyrolysis bio-oil. But, these bio-oils mainly consist of alcohols and aromatic chemicals rather than alkanes of the main components of gasoline and diesel. Direct utilization of these bio-oils can corrode car engines as well as emitting large unburned hydrocarbons particles through automotive combustion system. Therefore, in this study, catalytic hydrothermal conversion (CHTC) of glucose to alkanes in a single batch reactor was investigated with respect to effects of conversion parameters such as initial pressure of process gas H₂, pH level of aqueous solution and catalysts on alkane yields and compositions. Results showed that the highest alkane yield of 21.6% (based on the mol of the input glucose) was obtained at 265 °C, with 300 psi of H₂ process gas, 0.5 g catalyst of 1w%. Pt/Al₂O₃ and a residence time of 15 h. The alkane yield was significantly influenced by the initial pressure of H₂, which increased with increasing H₂ pressure. On the other hand, the alkane yields first increased and then decreased with pH levels. Also, more alkanes were produced by Pt/Al₂O₃ than Pd/Al₂O₃. Regarding alkane compositions, high initial pressure of H₂ favored the production of relatively heavy C_3–4 alkanes. With 300 psi of initial H₂, C₃H₈ and C₄H₁₀ accounted for 75% of the total produced alkanes. All of the experimental data in this study lead to one conclusion that petroleum alkanes can be directly produced from glucose.