An Efficient Cr-TUD-1 Catalyst for Oxidative Dehydrogenation of Propane to Propylene with CO2 as Soft Oxidant

A series of Cr-TUD-1 catalysts with various loadings of chromium (3, 5, 7, and 9 wt%) were prepared by microwave irradiation and explored for oxidative dehydrogenation of propane to propylene utilizing CO2 as soft oxidant. The microwave irradiation reduced the synthesis time and the resulting Cr-TUD-1 catalysts exhibited a high specific surface area of more than 600 m(2) g(-1). The synthesized catalysts were characterized by various techniques including XRD, XPS, TEM, UV-vis DRS, BET surface area, and pore size distribution to understand the physicochemical properties, and to correlate with the catalytic activity. Among various compositions, the 7% Cr-TUD-1 catalyst exhibited a high propane conversion (similar to 45%) with better propylene product selectivity (similar to 75%). The Cr-TUD-1 catalyst was also found to be quite stable up to 8 h of time-on-stream investigated. As revealed by the characterization techniques, the inter-convertible Cr6+ to Cr3+/2+ species are very crucial for the observed better catalytic activity of these materials. The TUD-1 enables to encapsulate the chromium nanoparticles in the porous silica structure with high dispersion which help in maintaining the better catalytic performance. Graphical Abstract [GRAPHICS] .