Dehydrogenation of propane over Pt/KL catalyst: Investigating the role of L-zeolite structure on catalyst performance using isotope labeling

[Display omitted] ▶ An NKIE exists during propane (H and D labeled) dehydrogenation over Pt/KL. ▶ Catalyst deactivation occurred from carbon deposition due to bimolecular reactions. ▶ The unique structure of Pt/KL did not enhance performance with C 3 as with C 6. Dehydrogenation of propane using an equimolar mixture of propane- d 0 and propane- d 8 was investigated over 1%Pt/KL and 1%Pt/SiO 2 at atmospheric pressure and different reaction temperatures. A normal kinetic isotope effect exists ( k H/ k D = 1.4–1.5) when the reaction is conducted on Pt/KL at different temperatures (400, 500, and 600 °C), suggesting that C–H bond activation is involved in the kinetically relevant steps. Furtheremore, there is hardly any H–D exchange in the recovered propane during dehydrogenation at temperatures above 400 °C, suggesting that adsorption and subsequent dehydrogenation of propane are essentially irreversible and that C–H bond activation is the rate determining step. Unlike the case of hexane aromatization, the unique structure of L-zeolite does not help in controlling the entry of propane molecules into the lobes of the L-zeolite containing the active sites; hence, bimolecular reactions do occur, leading to coke formation and catalyst deactivation.