Role of CO2 During Oxidative Dehydrogenation of Propane Over Bulk and Activated-Carbon Supported Cerium and Vanadium Based Catalysts
Petar Djinović, Janez Zavašnik, Janvit Teržan, Ivan Jerman
Abstract
Abstract CeO 2 , V 2 O 5 and CeVO 4 were synthesised as bulk oxides, or deposited over activated carbon, characterized by XRD, HRTEM, CO 2 -TPO, C 3 H 8 -TPR, DRIFTS and Raman techniques and tested in propane oxidative dehydrogenation using CO 2 . Complete oxidation of propane to CO and CO 2 is favoured by lattice oxygen of CeO 2 . The temperature programmed experiments show the ~ 4 nm AC supported CeO 2 crystallites become more susceptible to reduction by propane, but less prone to re-oxidation with CO 2 compared to bulk CeO 2 . Catalytic activity of CeVO 4 /AC catalysts requires a 1–2 nm amorphous CeVO 4 layer. During reaction, the amorphous CeVO 4 layer crystallises and several atomic layers of carbon cover the CeVO 4 surface, resulting in deactivation. During reaction, V 2 O 5 is irreversibly reduced to V 2 O 3 . The lattice oxygen in bulk V 2 O 5 favours catalytic activity and propene selectivity. Bulk V 2 O 3 promotes only propane cracking with no propene selectivity. In VO x /AC materials, vanadium carbide is the catalytically active phase. Propane dehydrogenation over VC proceeds via chemisorbed oxygen species originating from the dissociated CO 2 . Graphic Abstract