Characterization and mechanism of red-mud-catalyzed steam gasification of corn stover

Abstract

Catalytic biomass gasification has received extensive attention from scholars worldwide. This study proposes steam gasification of corn stover using red mud (RM), an industrial solid waste, as a catalyst to produce high-quality reducing gas. Experiments were conducted at different reaction temperatures and gasification times. Characterization of RM and its three main components, Fe2O3, CaCO3, and Al2O3, in the catalytic steam gasification process of corn stover, was performed and its catalytic mechanism was explored by characterizing magnetic separation products. Results show that an increase in reaction temperature significantly promotes the production of CO, CO2, and H2. The promotion of steam to H2 production is caused by the gas-phase reaction and gasification of fixed carbon (FC). Fe2O3 promotes gas-phase reactions, such as the water–gas shift reaction, and effectively catalyzes the steam gasification of FC as an intermediate reactant. The addition of Al2O3 is beneficial for the production of CH4 and H2. The CO2 produced by the decomposition of CaCO3 inhibits the water–gas shift and methane-steam reforming reactions, thus reducing H2 output. The addition of RM is beneficial for the production of H2 and CO2 and inhibits the production of CO. Compared with pure Fe2O3, the superior pore structure and unique solid solution structure of RM provide Fe2O3 with more active surface lattice oxygen, higher redox performance, larger gas–solid contact area, superior ability to prevent carbon deposition, and better catalytic ability.