Catalytic fast pyrolysis of biomass: Selective deoxygenation to balance the quality and yield of bio-oil.

Firstly, the operating conditions were screened for biomass pyrolysis in a fixed bed with respect to higher oil yield. A temperature of 600 °C with an N2 flow of 80 ml/min exhibited the highest bio-oil yield. Then, the catalytic pyrolysis of biomass with various catalysts (Al2O3, CaO, MgO, CuO, Fe2O3, NiO, ZnO, ZrO2, TiO2, HZSM-5 and MCM-41) was studied to identify the selective deoxygenation method with respect to improve bio-oil quality with smaller drop in bio-oil yield. With the addition of CaO, the oxygen was mainly removed in the form of CO2, while, in other cases, more oxygen was removed in the form of H2O. Furthermore, more decarboxylation or less dehydration is better for the balance between yield and deoxygenation amount, and the preferred decarboxylation would lead to a higher pH and lower moisture content of bio-oil.