Influence of physicochemical properties of metal modified ZSM-5 catalyst on benzene, toluene and xylene production from biomass catalytic pyrolysis.

Biomass catalytic pyrolysis with various metals (Zn, Fe, Ca, Ce and La) modified ZSM-5 catalysts were analyzed, in order to investigate the relationship between the physicochemical properties of catalysts and the benzene, toluene and xylene (BTX) products. Results revealed that the BTX products were positively correlated with the strong acid site contents of the catalysts. Appropriate amount (0.5-4 wt%) of loaded Zn species increased the strong acid site contents of the catalysts as well as BTX yields, and the highest yield of BTX was observed under Zn loading amount of 2 wt%. While excessive metal loading amount (10 wt%) decreased both the acidity and the physical properties of the catalyst, resulting in poor diffusion of reactants and products in the channel and decreased the BTX yield. It is recommended that ZSM-5 catalyst with higher strong acid site content and pore volume should be used for BTX production.