(338a) Improved Non-Oxidative Butane Dehydrogenation Via RF Induction Heating

Induction heating paired with magnetically susceptible catalysts has emerged as an efficient method to perform high-temperature endothermic reactions. By targeting the magnetic catalysts with radio waves (RF), heat is quickly produced at the catalyst surface. Heat generation at the surface allows for quick energy replenishment due to its consumption in highly endothermic reactions such as alkane dehydrogenation. Furthermore, the increased heat transfer efficiency minimizes the catalyst temperature gradient and suppresses hot spot formation. By utilizing RF heating to create a more uniform catalyst surface temperature, improved alkene selectivity and longer catalyst life are expected.

Magnetically suspectable materials were made by synthesizing a γ-Al₂O₃ (20 wt. %) shell around Fe₃O₄ nanoparticle cores (~75 nm). Platinum (0.5 wt.%), tin (1.0 wt. %), or vanadium (up to 6.0 wt.%) were impregnated on the core-shell material to create three catalysts. Preliminary butane dehydrogenation results for the supported Pt-Sn and VO_x using conventional heating showed ~80% butane conversion for Pt-Sn and 20 and 40 % conversion for 3 and 6 wt. % vanadium, respectively. After one hour time on-stream, all catalysts experienced significant deactivation, to ~15 % conversion.

A RF-induction heated continuous flow reactor was then designed and constructed to determine if RF energy input can affect selectivity to 1-butene, cis/trans-2-butene, and isobutene selectivity and improve catalyst stability. The RF field strength was controlled to mimic thermal conditions for direct comparisons of the reaction kinetics to conventional butane dehydrogenation processes. Simultaneously, microkinetic models of both processes are under development, informed by the experimental results, to uncover and quantify differences in the rate-determining steps, surface coverages of the reaction intermediates, reaction orders, and apparent activation energies, necessary for the RF optimization.