Preparation of indole products from soybean protein pyrolysis catalyzed by Fe and Co modified zeolite

Protein-rich biomass is a promising feedstock for producing N-containing chemicals via catalytic pyrolysis, yet poor product selectivity remains a critical bottleneck. Therefore, it is of great significance to improve the catalyst activity and catalytic efficiency for the for the highly selective synthesis of N-containing chemicals. This study pioneered bottleneck the modification of HZSM-5 zeolite with Fe and Co for the catalytic pyrolysis of soybean protein to produce indoles. The results indicated that Fe and Co loading reduced the number of Brønsted acid sites on HZSM-5 while generating novel Lewis acid sites, such acid rearrangement improved the yield of liquid oil and facilitated indoles formation. Among monometallic Fe or Co modified HZSM-5, 1   wt% Fe/HZSM-5 obtained the maximum content and selectivity of total indoles (35.5% and 55.6%, respectively). Furthermore, Fe-Co bimetallic modification with Low Fe/Co ratio exists a synergistic effect on indole, but excess Fe is unfavorable for indoles production. Fe 1 Co 3 /HZSM-5 further increased total indoles content and selectivity (37.6% and 61.6%, respectively). The Lewis acid sites were conducive to the formation of indole, Fe 1 Co 3 /HZSM-5 had the highest content of Lewis acid sites. This work provides a novel technical pathway for indole production via catalytic pyrolysis of biomass with endogenous nitrogen.