Study on the mechanism and reaction characteristics of red-mud-catalyzed pyrolysis of corn stover

Abstract

With catalytic pyrolysis gradually becoming the most efficient thermal treatment for biomass, the search for catalysts with high economic and catalytic performances has attracted widespread attention from scholars. In this study, the use of red mud as a catalyst for the pyrolysis of biomass to produce high-quality pyrolysis gas was investigated. The effects of the three components of red mud (Fe2O3, Al2O3, and CaCO3) on pyrolysis and the catalytic effect and mechanism of red mud on pyrolysis were analyzed. Fe2O3 was the most dominant catalytically active ingredient in red mud, which had a good contribution to the improvement of carbon conversion and hydrogen yield. Specifically, Fe2O3-catalyzed corn stover pyrolysis at a 40 % addition ratio increased the hydrogen yield by 82 %. Because of the stable pore structure provided by Al2O3 and SiO2 as carriers and the chimeric structure of the catalyst particles, the specific surface area of the red mud reached 25.88 m2/g, and the specific surface area of the magnetic separation product reached 42.41 m2/g, which greatly improved the catalytic performance. Red-mud-catalyzed corn stover pyrolysis with a red mud addition ratio of 40 wt% could achieve an H2 yield of 108 ml/g, representing a rise of 79 %. The phase composition and crystal structure of the red mud and magnetic separation products were analyzed; the components in the red-mud catalyst doped with each other at the lattice level in the form of a solid solution, which improved the catalytic activity.