Comparison of single-bed oxidative dehydrogenation of ethylbenzene with double-bed using CO2

Abstract

The present study highlights the catalytic performance of 5 wt% Fe2O3 supported on sodium chromosilicate (5F/NCS) in a single-bed reactor for dehydrogenation of ethylbenzene with CO2 and compares it with the catalytic performance of two subsequent catalysts (5F/NCS + industrial oxidation catalyst) in a double-bed reactor. The support of the target nanocomposite catalyst was obtained by hydrothermal treatment and subsequently was loaded with a medium amount of 5 wt% γ-Fe2O3. Structural and textural characterizations of the catalysts were performed by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 physical adsorption analysis, and Fourier-transform infrared spectroscopy. The catalytic tests revealed that 5F/NCS in the single-bed reactor had a high ethylbenzene conversion (> 54%) and a low styrene selectivity (> 70%). In comparison with this observation, in the double-bed reactor with the presence of oxidation catalysts, styrene selectivity increased significantly (> 91%), however; ethylbenzene conversion indicated a minor decrease (> 50%). The high styrene selectivity (> 91%) and styrene yield (> 46%) in the double-bed reactor were ascribed to the coupling reaction of ethylbenzene dehydrogenation and RWGS as well as the synergistic effect of Pt–Sn in the structure of oxidation catalyst.