Catalytic upgrading of NaoMaohu and biomass co-pyrolysis over HZSM-5/CuMgAl

Abstract

The catalytic co-pyrolysis of low-rank coal and biomass offers a promising pathway for sustainable energy production by leveraging the hydrogen-donor capability of biomass and the hierarchical conversion potential of coal. Existing studies lack systematic insights into the tandem catalytic mechanisms of acid-base composite systems. This work investigates the catalytic upgrading of co-pyrolysis products from Naomaohu coal and biomass (cotton stalks; corn cobs) over HZSM-5/CuMgAl composite catalysts. The results showed that biomass co-pyrolysis significantly reduced the char yield (0.9-2.7 wt%) and enhanced the gas yield (1.36-4.04 wt%). In the catalytic system, HZSM-5 promoted tar aromatization through acidic sites with 37.99 wt% of aromatics, and preferential deoxygenation of CuMgAl alkaline sites increased gas CO2 yield by 8.88 wt%. Tandem catalysis (HZSM-5/CuMgAl) optimizes product distribution through synergistic effects: tar aromatization content increased to 76.88 wt%, while char and moisture yields were reduced by 7.5 wt% and 3.9 wt%, respectively. Mechanistic studies have shown that, tandem catalysis involved CuMgAl cleaving macromolecules into intermediates, which diffused into HZSM-5 pores for cyclization and condensation. The findings underscore the viability of acid-base tandem catalysts for converting low-rank coal and biomass into high-value aromatics.