Reaction Kinetics and Mechanism of the Catalytic Oxidation of Propane over Co–ZSM-5 Zeolites

The complete oxidation of propane over Co-containing ZSM-5 zeolites having different Si/Al ratios (23, 40 and 100) was studied. It was observed that the applied preparation procedure ensured a fine dispersion of Co3O4. Regarding the surface composition, both Co2+ and Co3+ were present on the surface. The oxo cations containing Co2+ and/or CoOx stabilized inside the zeolite and Co2+ ions at the exchange sites are also formed. It was found out that the complete oxidation of propane proceeds at catalyst bed temperatures above 240 °C and the needed temperature to achieve 30% conversion of propane (T30) at gas hourly space velocity of 100,000 h−1 is 314–338 °C. The high catalytic activity of Co–ZSM-5 (Si/Al = 23) is explained by the high reducibility as result of lower interaction of the cobalt oxide with the support. Based on the study of the reaction kinetics, the mechanism of Mars–van Krevelen was considered to be the most probable. Based on the observed activity of the prepared Co–ZSM-5 materials, one could expect further development of these new catalytic systems for real application in the reduction of greenhouse gas emissions.