(625d) Propane Dehydrogenation on Different Platinum Surfaces and in the Presence of Al2O3 ALD Layer

Propylene is an important precursor for different industrial processes including polypropylene synthesis for various plastics. Propylene is mainly harvested as by-product from steam cracking and fluid catalytic cracking but direct dehydrogenation of propane has been proposed to be a viable route for propylene production. The catalytic dehydrogenation of propane generally carries out on Al₂O₃-supported Pt/Sn catalyst, which has shown promising reactivity and selectivity. Herein, we use DFT calculations and microkinetic modeling to assess how different surface structures and co-adsorbed Al₂O₃ affect the selectivity towards propylene of propane dehydrogenation (PDH) on Pt. We study PDH on different Pt facets including flat surfaces (Pt(100), Pt(111)) and stepped surfaces(Pt(211), Pt(511)) to see how reactivity and selectivity towards propylene change with surface arrangement, and find that Pt(100) poses highest reactivity while Pt(211) shows highest selectivity to propylene. Additionally, we find that on step and kink surfaces (Pt(211), Pt(321), Pt(533)), Al₂O₃ precursors form a one-dimensional ribbon type of structure, leaving open active sites on the upper terraces where PDH reaction intermediates can interact with both Pt surface atoms and the Al₂O₃-precursor; hence, postulates effects on the reactivity and selectivity of PDH. Our microkinetic model with modification from experimental finding show improved in selectivity towards propylene and reduction of coke formation on Pt surfaces in the presence of the alumina ALD.