(327g) Mechanistic Insights into Non-Oxidative Ethane Dehydrogenation on Pt-Based Catalysts Via First-Principles Microkinetic analysis

Recent advancements in large-scale shale-gas production has ignited renewed interest in the use of light alkanes as low-cost feedstock for the production of chemicals and fuels. Direct dehydrogenation of ethane has been achieved at relatively low temperatures (~600°C) on Pt based catalysts. However, the efficiencies of these catalysts are still not sufficiently high due to the low yield and selectivity and quick deactivation of the catalysts under reaction conditions. A detailed mechanistic knowledge of ethane dehydrogenation reaction on the catalyst surface and the identification of the key parameters that control the selectivity and stability of these catalysts are essential in the design of more efficient catalytic materials.

We utilize a first principles based microkinetic model to develop molecular level insights into the mechanisms that control the performance and selectivity of Pt-based catalysts in ethane dehydrogenation. A thorough mechanistic study is executed on Pt(111) catalyst surface, using a network of 139 elementary steps and 55 species, to address fundamental mechanistic questions and existing debates in literature regarding ethane dehydrogenation pathways and competing reactions toward side products and coke formation. Our model successfully predicts the experimentally observed activation barrier, selectivity and partial pressure dependency of non-oxidative ethane dehydrogenation on Pt catalysts.^1,2 Sensitivity analysis identifies kinetically relevant activity and selectivity steps. The results of our analysis are used to develop a reduced reaction system and a rate expression for ethane dehydrogenation.

References:

1. Wegener, E. C. et al. Structure and reactivity of Pt–In intermetallic alloy nanoparticles: Highly selective catalysts for ethane dehydrogenation. Catal. Today 299, 146–153 (2018).
2. Wu, J. et al. Ethane and propane dehydrogenation over PtIr/Mg(Al)O. Appl. Catal. A Gen. 506, 25–32 (2015).