SO 2 adsorption and transformation on calcined NiAl hydrotalcite-like compounds surfaces: An in situ FTIR and DFT study

Abstract

Flower-like hydrotalcite-based NiAl mixed oxides with high surface area were synthesized by urea hydrolysis approach, and employed for SO 2 removal. The catalyst was well characterized by TGA, ICP, XRD, SEM, TEM and N 2 adsorption/desorption isotherm analyses. The calcined NiAlO showed excellent SO 2 adsorption and its adsorption equilibrium was of a type I isotherm, which significantly improved the adsorption performance for low-concentration SO 2. XPS and TPD methods were conducted to identify the sulfate species. Specifically, in situ Fourier transform infrared spectroscopy revealed that adsorbed SO 2 molecules formed surface bidentate binuclear sulfate. Density functional theory based computations interpreted the vibrational data associated with the NiAlO surface and confirmed that sulfate species adopted a binuclear bidentate binding configuration on the surface of NiAlO catalyst.