Design of Reduction Process of SnO₂ by CH₄ for Efficient Sn Recovery

We design a novel method for the CH₄ reduction of SnO₂ for the efficient recovery of Sn from SnO₂ through a study combining theory and experiment. The atomic-level process of CH₄-SnO₂ interaction and temperature-dependent reduction behavior of SnO₂ were studied with a combination of a multi-scale computational method of thermodynamic simulations and density functional theory (DFT) calculations. We found that CH₄ was a highly efficient and a versatile reducing agent, as the total reducing power of CH₄ originates from the carbon and hydrogen of CH₄, which sequentially reduce SnO₂. Moreover, as a result of the CH₄ reduction of SnO₂, a mixture of CO and H₂ was produced as a gas-phase product (syngas). The relative molar ratio of the produced gas-phase product was controllable by the reduction temperature and the amount of supplied CH₄. The laboratory-scale experimental study confirmed that CH₄ actively reduces SnO₂, producing 99.34% high-purity Sn and H₂ and CO. Our results present a novel method for an efficient, green, and economical recycling strategy for Sn with economic value added that is held by the co-produced clean energy source (syngas).