A kinetic study on biomass fast catalytic pyrolysis

An apparatus for the fast pyrolysis of biomass is designed and set up to simulate the fast heating rate in the fluidized bed. The features of biomass fast catalytic pyrolysis in the apparatus are studied, whereas the kinetics model of biomass catalytic pyrolysis is presented. The results show that both calcined dolomite and a nickel-based catalyst can elevate the hydrogen content greatly. The nickel-based catalyst has a stronger effect, and the hydrogen content is almost doubled. The content of methane (CH4) can be greatly reduced through the use of nickel-based catalysts. Calcined dolomite can also decrease the content of CH4, to a smaller extent. A simplified model is presented, in which the entire process is treated as a single reaction. It assumes that biomass first decomposes to gaseous products, tars, and chars via three competitive reactions and then tars go through a second cracking reaction to produce gases and chars. Through the proposed model, the calculated data fit well with the experimental data obtained from pyrolysis tests of pine sawdust, lignin, and cellulose. The calculated reaction order is in the range of n = 0.66-1.57. It is concluded that calcined dolomite must be used at a temperature of >800 degreesC