Enhancing Propane Dehydrogenation: Insights into Oxidative Dehydrogenation and Total Oxidation Pathways

Abstract

The oxidative dehydrogenation and total oxidation of propane were studied using various Pt-based catalysts. In both reactions, supported platinum catalysts prepared by strong electrostatic adsorption (SEA) have higher propane activity than the supports. The high selectivity of desired products in both reactions (propene or CO2) and activity depends on different parameters such as the reaction temperature, the support nature (surface area, reducibility, acidity, etc.), the concentration of reactants especially oxygen, and the structure and chemistry of Pt (oxidation state and particle size). The study shows the relationship between these parameters and Pt catalyst activity, selectivity, and stability. In general, the reducible catalysts (Pt/CeO2) can be efficient in the cleavage of the C-H bond for propane in the oxidative dehydrogenation reaction using low oxygen concentration, because it can provide the lattice oxygen in the redox reaction that leads to the increase of activity of propane, while the partial reducible catalysts like (Pt/TiO2) and Pt/ZrO2) were selective to propene due to a decrease in the conversion, which is consistent with the typical conversion-selectivity trade-off observed in ODH-O2 catalytic reactions. However, the presence of enough oxygen in the reaction led to an increase in propane conversion and formation the COX compounds due to more oxygen promoting over-oxidation to CO and CO2. The study shows the difference between reducible catalysts and non-reducible catalysts in the structure-activity relationship and reaction rate (TOF) for Pt catalysts. In contrast, the study examines the impact of promoter additions such as Mn and K on supported Pt catalysts using CeO2 and SiO2. The reaction is operated under low concentrations of oxygen and promoter to avoid the overoxidation reaction and increase the dehydrogenation rate (TOF) which enhances propene selectivity. The study found that the support nature and the particle size can influence the performance of catalysts. For example, catalysts supported on reducible support CeO2 have a higher propene selectivity and efficiency (TOF) than catalysts supported by the non-reducible support SiO2. In addition, Mn-Pt/CeO2 and K-Pt/CeO2 show high selectivity, yield, and TOF in the reaction where Mn can supply oxygen to the PtOX active site and increase propene selectivity. In contrast, K addition to the Pt catalyst significantly decreases the acid sites on the catalyst. In addition, it may block the acid sites on the catalyst which improves propene selectivity.