Abstract
Unmodified and sulfate-modified SBA-15-supported Cr2O3 catalysts were prepared by impregnation method. The physico-chemical properties of the supports and catalysts were determined by nitrogen adsorption/desorption, powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), laser-Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance spectroscopy (UV-DRS), inductively coupled plasma optical emission spectroscopy (ICP-OES), transmission electron microscopy (TEM) and temperature-programmed reduction (TPR) techniques. Oxidative dehydrogenation of ethane to ethylene (ODE) with CO2 as oxidant was carried out on these catalysts in a fixed-bed reactor at temperatures in the range of 600–700 °C and at atmospheric pressure. The changes in structural and textural properties because of sulfate modification were identified. Sulfate modification affected the nature of interaction of CrOx species with the SBA-15 support. During the evaluation, it was observed that sulfate modification enhances ethane conversion and ethylene selectivity of the catalyst. Better dispersion of CrOx and the increase in Cr6+/Cr3+ ratio seem to be the reasons for the higher performance of the sulfate-modified catalysts compared to that of the unmodified catalyst.
Highlights
Ethylene is an important raw material for the synthesis of plastics, fibers and other organic chemicals
The physico-chemical properties of the supports and catalysts were determined by nitrogen adsorption/ desorption, powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), laser-Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance spectroscopy (UV-DRS), inductively coupled plasma optical emission spectroscopy (ICP-OES), transmission electron microscopy (TEM) and temperature-programmed reduction (TPR) techniques
We report the effect and the reasons for the enhanced activity and selectivity in the case of Cr2O3 supported on sulfatemodified SBA-15 catalyst
Summary
Ethylene is an important raw material for the synthesis of plastics, fibers and other organic chemicals. Sulfate modification affected the nature of interaction of CrOx species with the SBA-15 support. Wang et al reported that sulfate modification of the silica support is advantageous for the preparation of highly active chromia catalysts for the ODE reaction in the presence of CO2 [14].
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