Structure sensitivity of propane partial oxidation over chromium-manganese binary oxides

Catalytically active chromium-manganese oxides (CMO) were synthesized by the sol-gel route for the par-tial oxidation of propane to propene. The effects of calcination temperature and time on the catalytic per-formance of the CMO were examined in a fixed bed reactor within 300-600 & DEG;C at a gas hourly space velocity (GHSV) of 6,000 mL & BULL;g-1 cat & BULL;h -1. Structural and morphological analysis disclosed nano-crystallite sizes and spherical shapes with smooth and tiny particles. The introduction of Cr tends to increase the specific surface area, decrease the pore diameter and crystallite size, as well as the bandgap energy of the obtained samples, which promoted the movement of abundant lattice oxygen. Based on the light-off curves, the catalyst CM32 (CMO calcined at 300 & DEG;C@2 h), with low calcination temperature and long calcination time, achieved the best performance and stability. CM32 exhibited the highest selectivity and yield, 79.35% and 29.80%, respec-tively. CM32 owned a reaction rate of 2.93 mol & BULL;g-1 cat & BULL;s-1 and apparent activation energy of 49.52 kJ mol-1, which could be related to not only its higher quantity of lattice oxygen (O2-) and Cr6 + /Cr3+ ratio, but also to the decrement in pore diameter size and bandgap energy. The reaction pathway was proposed based on the MvK mechanism for the propane partial oxidation. Moreover, CM32 maintained its catalytic performance after a stability test of 100 h' time-on-stream. The highly stable and active CM32 catalyst obtained shows good potential for partial oxidation of propane to propene.& COPY; 2022 The Combustion Institute. Published by Elsevier Inc. All rights reserved.