Abstract:In view of the low mechanical strength and easy breakage of calcined dolomite when it is used as a biomass pyrolysis catalyst, one preparation method of porous ceramic balls with dolomite and quartz sand as main aggregate was proposed. The porous ceramic balls with high mechanical strength were impregnated with Al2(SO4)3 solutions (0.3mol/L, 0.5mol/L and 1.0mol/L) at 25℃ for 6 h after firing. The load of Al2O3 on dolomite base porous ceramic balls was increased with the increase of Al2(SO4)3 solution concentration. In horizontal tube furnace, the dolomite base porous ceramic balls supported Al2O3 were used as catalyst to carry out fast pyrolysis experiment of corn straw powder. The results showed that the yield of the biooil was increased firstly and then decreased with the increase of relative mass content of dolomite, while the yield of biochar was decreased firstly and then increased when the proportion of dolomite to quartz sand was 30∶70, 40∶60, 45∶55 and 50∶50, respectively. The yield of biooil reached the highest production rate of 3685% and the yield of biochar reached the lowest production rate of 25.11% when the proportion of dolomite to quartz sand was 40∶60. With the increase of Al2(SO4)3 solution concentration, the yield of biooil was decreased and that of biochar was decreased firstly and then increased. Compared with the untreated Al2(SO4)3 solution, the yield of biooil was decreased by 10.69%, 15.33% and 21.55%, respectively. The relative content of alcohols in the biooil was increased slightly and that of ketones, acids, aldehydes was decreased gradually. However, compared with those without catalyst and Al2(SO4)3 solution, the yield of phenols was increased significantly, indicating that the presence of Al2O3 was beneficial to the production of phenols. The main components of noncondensable pyrolysis biogas were CO, CO2, CH4 and H2, among which CO2 had the high volume fraction, accounting for about 63%. The volume fraction of CO was about 32%. The volume fraction of CO2, CH4 and H2 was increased and that of CO was decreased when the porous ceramic balls loading dolomite were used as catalysts. The experimental results would provide a reference for obtaining high valueadded chemicals from agricultural biomass.
