Regulating light olefins or aromatics production in ex-situ catalytic pyrolysis of biomass by engineering the structure of tin modified ZSM-5 catalyst

Valorization of biomass to olefin or aromatics harbours tremendous practical value due to growing concerns about sustainable production of chemicals. Herein, the olefin or aromatics yields of ex-situ catalytic pyrolysis of pine can be regulated by impregnating Sn on hollow-structured ZSM-5 (M-ZSM-5) and microporous ZSM-5 catalysts in fixed-bed reactor, respectively. Results showed that Sn/ZSM-5 catalyst simultaneously increased medium acidic sites and maintained strong acidic sites, which obtained the maximum carbon yield of aromatics (33.77%) due to enhanced cracking and deoxygenation reactions. In addition, Sn boosted alkylation between olefin and aromatics, generating more alkylbenzene. In contrast, Sn/M-ZSM-5 catalyst produced the highest olefins carbon yield (12.39%) because the reduction of strong acidic sites and microporous volume inhibited the olefin aromatization. Moreover, olefins were easier to desorb from Sn/M-ZSM-5 due to the enhanced mass transfer ability, which weakened the alkylation reactions. The synergistic effect harbours great significance to manipulate the distribution of products.

Automated summary

This study investigates the regulation of olefin or aromatics yields from ex-situ catalytic pyrolysis of pine by impregnating Sn on ZSM-5 catalysts, showing that Sn/ZSM-5 increased aromatics yield while Sn/M-ZSM-5 boosted olefins yield. The synergistic effect plays a significant role in manipulating the distribution of products.