Production of Light Aromatic Hydrocarbons from Biomass by Catalytic Pyrolysis

Abstract

Abstract Catalytic pyrolysis of three kinds of woody biomass was carried out using a dual-particle powder fluidized bed reactor to produce light aromatic hydrocarbons such as benzene, toluene, xylene, and naphthalene (BTXN). The results showed that pyrolysis temperature of biomass was very low, and about 92% of the volatile matter in the biomass can be released at 673 K, indicating that the biomass was suitable for catalytic pyrolysis at low temperature. The tar in the volatile matter was the product of the primary decomposition, and it was then transformed to lower molecular hydrocarbon compounds at higher temperature during the secondary reaction. The biomass pyrolysis product distribution could be controlled by adjusting the secondary reaction parameters. The test results of the catalytic hydropyrolysis of the biomass over different catalysts showed that the pyrolysis product distribution depended much on the catalyst types and the pyrolysis temperature. BTXN were the intermediates of the secondary reaction during the pyrolysis or hydropyrolysis process. When biomass was hydropyrolyzed in the fluidized bed with the CoMo-S/Al2O3 catalyst, BTXN yield reached 6.3% (BTX: 5.5%; N: 0.8%) at 863 K. However, the highest CH4 yield of 99.5% was obtained when a NiMo/Al2O3 catalyst was used. Therefore, it is important to select a catalyst with proper hydrogenation activity to obtain the highest yield of BTXN. Different types of woody biomass with similar compositions results in similar product distributions.