In-depth investigation of the effect of MgAl2O4 and SiO2 support on sulfur promoted nickel catalysts for the dehydrogenation of propane

Abstract

Sulfur promoted nickel catalysts supported on MgAl2O4 and SiO2 were investigated for the dehydrogenation of propane. The catalysts were prepared by the impregnation method using ammonium sulfate as the sulfiding agent. The catalysts were evaluated in both the sulfated form, NiO/MgAl2O4-20 wt%SO4 and NiO/SiO2-20 wt%SO4, in addition to the reduced form, Ni/MgAl2O4-20 wt%SO4 and Ni/SiO2-20 wt%SO4, which contained the sulfided species. Physicochemical properties of the catalysts were characterised by XRD, BET, TEM, TGA, NH3-TPD, FTIR and TPR techniques to investigate the particle size, surface area, morphology, acidic properties and stability of the catalysts on both MgAl2O4 and SiO2 supports. Structural and textural characterization of the catalysts revealed that NiO/MgAl2O4-20 wt%SO4 and Ni/MgAl2O4-20 wt%SO4 displayed highly dispersed particles in comparison to the catalysts on the SiO2 support. H2-TPR analysis showed that the reducibility of the smaller particles on the MgAl2O4 support was hindered. In addition, the stronger metal-support interactions on MgAl2O4 enhanced the stability of the catalyst which enables increased activity and facilitated the desorption of olefins, leading to a high selectivity of above 70 % for propylene.