Reaction Kinetics Study and Analysis of Reaction Schemes for Isobutane Conversion over USY Zeolite

Reaction kinetics studies were conducted for isobutane conversion over a USY zeolite catalyst at a total pressure of 1 atm and for temperatures of 523 and 573 K. The catalyst is inactive for isobutane conversion in the absence of feed olefins at these temperatures; however, a stable catalyst performance was achieved for levels of isobutylene in the feed ranging from approximately 50 to 400 ppm. The rates of production of n-butane, propane, isopentane, propylene, 1-butylene, cis-2-butylene, and trans-2-butylene were measured for the aforementioned temperatures and isobutylene feed concentrations at isobutane inlet concentrations of 20 and 80%. A kinetic model for isobutane conversion over USY zeolite was developed based on the following families of reactions: adsorption/desorption steps, oligomerization/β-scission processes, isomerization steps, hydride transfer processes, and initiation steps. This kinetic model describes the reaction kinetics data collected in the present study of isobutane conversion at low temperatures, and it also describes reaction kinetics data collected at higher temperatures (733–773 K) over a USY zeolite catalyst, where the reaction was initiated by the activation of isobutane.