Catalytic reforming of volatiles from co-pyrolysis of lignite blended with corn straw over three different structures of iron ores

Abstract

As pyrolysis and tar lightening are fundamentally intertwined, understanding the mechanism of integrated co-pyrolysis of lignite blended with corn straw and tar decomposition-carbon deposition over low-grade iron ores via unveiling terminal products is important for both eliminating heavy tar generation and improving renewable energy utilization efficiency. Here we report the effects of three iron ores with different structures as catalytic beds on the distribution of co-pyrolysis products. We elucidate that the goethite undergoes a phase transition to generate a structured tunnel, thus the subsequent tar upgrading and carbon deposition are more acceptable during the integrated co-pyrolysis and tar decomposition. In combination with tar yield and deposited carbon content, we identify that a synergistic effect existed in the co-pyrolysis process. The Optimum conditions were a co-pyrolysis temperature of 600 °C, an added corn straw proportion of 50% and a tar decomposition temperature of 650 °C. The whole coupling process exhibits that the formation rate of H2 is always higher than that of the consumption of H2 in the iron ore reduction, while the opposite trend was observed for CO. The content of light oil components with simulated distillation temperatures below 170 °C in tar was in the order of goethite > specularite> hematite. The changes of benzene, phenol, p-cresol and naphthalene in tar obtained by volatile matter over goethite exhibit significant differences. This paper provides insight on the effects of natural iron ore on products evolution during co-pyrolysis of lignite and corn stalk.