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Propane dehydrogenation is a highly efficient and selective route to produce propylene. The development of transition-metal-based catalysts, especially cobalt oxide−Co(II) for propane dehydrogenation reaction has gained momentum in the past few years. However, the formation of bulk metallic cobalt is a major drawback of cobalt oxide-based catalysts, which need to be circumvented to maintain the high propylene selectivity. In this study, a facile route is proposed to prepare stable Co(II) on a mesoporous silica matrix (Co-mSiO 2 ) via a simple synthesis procedure using the neutral templating method. The cobalt content in the silica is varied to optimize the activity and stability during the reaction. The physicochemical properties of the catalyst measured using X-ray diffraction, N 2 adsorption−desorption, and transmission electron microscopy revealed the high surface area and well-dispersed cobalt oxide present in the mesoporous silica matrix. The coordination geometry found from the UV−vis and extended X-ray absorption fine structure analysis showed that Co(II) is highly dispersed with tetrahedral coordination in the mesoporous silica. The Co-mSiO 2 catalyst with the lowest cobalt content of 2 wt % tested for the propane dehydrogenation reaction at the operating temperature of 600 °C showed 36% propane conversion with 94% propylene selectivity. 2Co-mSiO 2 showed the nonredox properties of Co(II) with negligible metallic cobalt formed and a lower coke deposition rate (4 mg carbon /g cat. •h) after the reaction supported by X-ray absorption near-edge structure and thermogravimetric analysis. The source for the side reaction (coke formation) can be assigned to the strong adsorption of propylene, which was unraveled using Fourier transform infrared analysis, and a nonredox mechanism is proposed for propane dehydrogenation reaction over the 2Co-mSiO 2 catalyst.

Developing an economically viable and eco-friendly catalyst is essential for the dehydrogenation reaction. In this context, cobalt-based catalysts supported on different morphologies of γ-Al 2 O 3 , nano-sheet (Al 2 O 3 À NS), nano-fiber (Al 2 O 3 À NF) and nanoplate (Al 2 O 3 À NP) were synthesized using wetness impregnation method and tested for non-oxidative propane dehydrogenation reaction. Metal support interaction and Lewis acidic center play a crucial role in propane dehydrogenation reaction; therefore this study focuses on investigating the role of these parameters on the catalytic activity for cobalt-based catalysts. A higher metal support interaction was observed in Co/Al 2 O 3 À NS as compared to Co/Al 2 O 3 À NF and Co/Al 2 O 3 À NP. The presence of tetrahedral coordinated Co + 2 in Co/Al 2 O 3 À NS leads to higher selectivity towards propylene. The formation of metallic cobalt from Co 3 O 4 precursor present in Co/Al 2 O 3 À NP promoted side reactions to form lower hydrocarbons and carbon, which caused catalyst deactivation. In-situ DRIFTS analysis revealed the interaction of propane and propylene gases with the catalyst, which was an important revelation to find the source of carbon deposition.

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