Synthesis, Characterization, and Catalytic Activity of Nickel Sulfided Catalysts for the Dehydrogenation of Propane: Effect of Sulfiding Agent and Sulfidation Temperature

The effect of sulfiding agent and sulfidation temperature on nickel catalysts supported on MgAl2O4 were investigated for propane dehydrogenation. The catalysts were prepared by reduction of NiO/MgAl2O4, followed by sulfidation using (NH4)2SO4 (S1), (NH4)2S (S2), and DMSO (S3) as sulfiding agents. The catalysts were sulfided at 200 °C, 400 °C, and 550 °C to form Ni/MgAl2O4-Sx-y, where x and y represent the sulfiding agent and sulfidation temperature, respectively. Physiochemical properties of the catalysts were characterized by XRD, BET, SEM, TEM, and TGA to investigate the type of nickel-sulfur species, surface area, morphology, particle size, and stability of the catalysts. Structural and textural properties revealed that the anion present on the sulfiding agent as well as the sulfidation temperature affect both the type and the strength of the Ni-S species. For the S1 catalysts, the SO42− ion interacted with the support to form MgSO4, while the S2− ion on the S2 and S3 catalysts was responsible for the formation of the Ni3S2 phase. The sulfidation temperature contributed to the %S present on each catalyst. Although the catalysts sulfided by S3 contained the least %S, Ni/MgAl2O4-S3-550 displayed the best catalytic performance as a result of the higher particle dispersion and stronger Ni-S interaction compared to S1 and S2 catalysts.