A facile MnSO4 surface coated NiMnFeOx catalyst with enhanced SO2 resistance for SCR reaction：a dual-protection mechanism

The SO2 resistance under low-temperature conditions remains a pivotal challenge in the industrial application of NH3-SCR catalysts. This work develops a facile and effective strategy of constructing a surface MnSO4 coating layer on catalysts in combination with Ni doping, which significantly boosts the SO2 resistance and stability of the conventional MnFeOx catalyst. Advanced characterizations including Synchrotron XAS analysis coupled with density functional theory (DFT) calculations, were utilized to further elucidate the underlying mechanism. The findings corroborate that the remarkable SO2 resistance of the MnSO4 surface-coated NiMnFeOx catalyst originates from a dual-protection mechanism. The doping of Ni effectively restricts the diffusion of SO2 within the catalyst, thereby confining sulfation to the surface of the catalyst. Subsequently, the MnSO4 coating layer provides further protection to the surface of the catalyst, inhibiting SO2 adsorption and safeguarding the active metal from poisoning. Importantly, this facile strategy can be implemented without any alterations to the catalyst preparation process, making it applicable to existing commercial catalysts, thus having outstanding industrial application potential.