Investigation of the effect of microwave heated reactor on ethane dehydrogenation over KIT-6 supported catalysts

Abstract

Non-oxidative conversion of ethane to hydrogen and ethylene was carried out with Cr and Co-based KIT-6 supported catalysts in a conventional heated reactor (C-HRS) and microwave heated reactor (M-HRS) systems. The catalysts were synthesized by wet impregnation of hydrothermally prepared KIT-6 support. X-ray diffraction (XRD) and N2 adsorption–desorption studies showed that the well-ordered three-dimensional mesoporous structure of the KIT-6 support was preserved after 10wt% metal loading. The pyridine adsorbed diffuse reflectance FT-IR (DRIFT) spectroscopy results revealed the presence of Lewis acid sites on the catalysts. The incorporation of Co into the structure slightly increased the Lewis acid sites. The Cr@KIT-6 catalyst exhibited the highest ethylene and hydrogen selectivity with a C2H4/H2 ratio of 1.00 at 650 °C in C-HRS. To compare the effect of active metal on the catalytic activity, Co@KIT-6 catalyst was tested at 650 °C in C-HRS. Although, the ethane conversion values of Cr and Co-based catalysts were similar, Co@KIT-6 catalyst exhibited lower C2H4/H2 ratio (0.51). The characterization studies of the spent catalysts confirmed higher amount of coke deposited on the Co@KIT-6 catalyst. The effect of microwave-assisted heating on the catalytic activity was investigated with Cr and Co-based catalysts at 450 °C in M-HRS. It was determined that much higher ethane conversion and yield values were obtained even at lower temperatures in M-HRS compared to the C-HRS. While the H2 yield was 0.15 at 650 °C in C-HRS, this value increased to 0.37 at 450 °C in M-HRS.