Study on the biomass catalytic pyrolysis over hierarchically porous ZSM-5 catalyst derived from solid wastes by means of photoionization mass spectrometry

Abstract

Catalytic fast pyrolysis (CFP) is one of the most efficient methods for directly converting biomass into green aromatics. Although ZSM-5 catalyst is efficient at producing aromatics, the catalyst deactivation brings challenge to industrial applications. Constructing additional mesoporous structure in ZSM-5 catalyst can overcome this drawback. In this study, two solid wastes are used as raw materials to synthesize hierarchically porous ZSM-5 catalyst based on solvent-free method, aligning with the target of “green chemistry”. Comparing with the commercial ZSM-5 catalyst, the synthesized catalyst achieves a higher BTX yield (benzene, toluene, and xylene), with increases of approximately 44 %, 7 %, and 12 %, respectively. The mesopore-to-micropore volume ratio is a key factor in determining catalytic efficiency. Moreover, PI-MS is used to monitor the deactivation behavior of catalyst online during the CFP process, showing that the synthesized catalyst has a slower deactivation rate. The hierarchically porous structure plays a crucial role in slowing the transformation of oxygenated coke into graphite-like coke, which is a major contributor to catalyst deactivation. This work can provide a green and convenient method for producing hierarchically porous ZSM-5 catalyst and be useful for improving the selectivity of aromatic compounds, offering a promising alternative to conventional ZSM-5 catalyst in industrial applications.