Catalytic pyrolysis of rice straw: Screening of various metal salts, metal basic oxide, acidic metal oxide and zeolite catalyst on products yield and characterization

Abstract

Lignocellulosic biomass is a promising renewable feedstock for the production of chemicals and fuels in light of the extensive use of fossil fuels associated with increasingly serious environmental problems. In this study, pyrolysis of rice straw with different types of catalyst such as metal salts (FeCl3, CuCl2, MgCl2 and MnCl2), metal basic oxides (MgO, CaO, MgCO3 and CaCO3), acidic metals (ZnO, ZrO2, CeO2 and TiO2), zeolites catalysts (ZSM-5, Y-Zeolite, Mordenite and SBA-15), catalyst amount (5, 10, 15 and 20 wt%) and reaction temperatures (350, 400, 450 and 500 °C) were examined on product yield and products characterization. The maximum bio-oil (38.5 wt%) was obtained for non-catalytic reaction at 450 °C. However for catalytic reaction highest bio-oil yield were observed 55.2, 52.1, 48.7 and 48.4 wt% with Y-zeolite, MgO, ZrO2 and MgCl2 catalyst at 450 °C respectively. GC-MS, FT-IR, NMR, GPC, TGA, and CHNS were used for bio-oil characterization. Y-zeolite effectively produced phenolics monomers as compare to basic (MgO), acidic (CeO2) and metal salt (MgCl2) catalyst. The use of catalysts was increased the boiling point range and the higher boiling point range was observed in case of Y-zeolite and MgO catalytic bio-oil. The highest higher heating value (HHV) 36.7 MJ/kg and highest carbon 75.2% was observed for zeolite catalytic bio-oil. Moreover lower molecular weight in the catalytic bio-oil was observed as compare to non-catalytic bio-oil.