Microwave-assisted co-pyrolysis of lignin and waste oil catalyzed by hierarchical ZSM-5/MCM-41 catalyst to produce aromatic hydrocarbons

• Composite catalysts (ZSM-5/MCM-41) were synthesized and its optimum catalytic conditions were studied. • Microwave-assisted catalytic fast co-pyrolysis (co-MACFP) was adopted in this experiment. • The synergistic effect of lignin and catalyst promotes the formation of aromatic compounds. Microwave-assisted catalytic fast co-pyrolysis (MACFP) of lignin and waste oil with SiC as microwave absorbent and hierarchical ZSM-5/MCM-41 as catalyst were implemented in a microwave-induced reactor. ZSM-5/MCM-41 is a kind of composite catalyst with MCM-41 as shell and ZSM as core. The effects of catalyst temperature, the ratio of feedstock-to-catalyst and the ratio of two reactants (lignin and waste oil) on product distribution and yield were studied. The study shows that catalytic co-pyrolysis is a complex reaction process, and many reaction conditions could affect the final reaction results. The optimum reaction conditions are as follows: catalytic temperature 400 °C, the feedstock-to-catalyst ratio of 10:1 and the ratio of lignin to waste oil of 2:1. Under this reaction condition, the conversion of feedstocks reached 76.00%, the proportion of aromatics was 50.31% and the selectivity of monocyclic aromatic hydrocarbons (MAHs) was 42.83%.