Synergistic interface between Co3O4 and MgAl2O4 in CO2 assisted continuous vapour phase oxidative dehydrogenation of ethylbenzene to styrene monomer

Abstract

A Series of Co3O4/MgAl2O4 spinel catalysts were prepared by conventional co-precipitation method with various Co loadings (0.5, 0.75, 1.0 and 1.25) keeping Mg/Al atomic ratio of 1.0 with over all Co + Mg + Al concentration at 3.0. Catalysts characteristics were throughly obtained by X ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR), UV–Vis Diffuse reflectance spectra, Temperature programmed reduction (H2-TPR), Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA), NH3 and CO2 Temperture programmed desorption (TPD), CO2 pulse chemisorption, CHNS elemental analysis, and Surface area techniques. The superior catalytic activity accomplished by the catalyst with Co concentration of 1.0 (Co3O4/MgAl2O4), for an oxidative dehydrogenation of ethylbenzene can be ascribed to the presence of more number of active Co species. Co-precipitation method seems to be a excellent method in maintaining better synergistic influence, more number of active solid solution species such as MgCo2O4 or MgxCo(1−x)Al2O4 which were advantageous role for better catalytic efficiency. Suitable number of optimized acidic-basic properties measured by NH3 and CO2-TPD analysis was another property influencing the activity with respect to desired product contribution. Higher, 81.2% ethylbenzene conversion (81.2%) with 98% styrene selectivity was attained on 1.0Co3O4/MgAl2O4 in comparision to Co3O4/MgO, and Co3O4/γ-Al2O3 catalysts. According to the CO2 pulse chemisorption reaction with dehydrogenation of ethylbenzene over 1.0Co3O4/MgAl2O4 resulted to get superior CO yield which was promised to get higher ethylbenzene conversion as well as styrene selectivity. Keywords: Ethylbenzene, Styrene, Soft oxidant, Oxidative dehydrogenation, Reverse water gas shift reaction (RWGSR)