A Kinetic Model for Catalytic N-Butane Oxidative Dehydrogenation under Oxygen-Free Reaction Conditions in a Fluidized CREC Riser Simulator

Abstract

This study considers the development of a kinetic model for the n-butane oxidative dehydrogenation (ODH) to C4-olefins using a VOx/MgO−γAl2O3 catalyst. The prepared catalyst contained 5 wt% V on an MgO modified γAl2O3 support. The developed catalyst exhibited both weak and medium acid sites, as revealed by NH3-temperature-programmed desorption. TPR/TPO analyses also indicated that 73% of the loaded VOx was reducible. Kinetic experiments were conducted in a fluidized CREC Riser Simulator at temperatures ranging from 475–550 °C and residence times of 5–20 s. An optimal C4-olefin selectivity of 86% was achieved at 500 °C and 10 s, with this selectivity then decreasing at higher temperatures and longer residence times. The kinetic model developed involved a Langmuir–Hinshelwood-type of kinetics that incorporated cracking, oxydehydrogenation, and complete oxidation reactions. Model parameters were determined by fitting experimental data with kinetic parameters established with narrow 95% confidence intervals and low cross-correlation.