Role of CO2 During Oxidative Dehydrogenation of Propane Over Bulk and Activated-Carbon Supported Cerium and Vanadium Based Catalysts

Abstract

CeO2, V2O5 and CeVO4 were synthesised as bulk oxides, or deposited over activated carbon, characterized by XRD, HRTEM, CO2-TPO, C3H8-TPR, DRIFTS and Raman techniques and tested in propane oxidative dehydrogenation using CO2. Complete oxidation of propane to CO and CO2 is favoured by lattice oxygen of CeO2. The temperature programmed experiments show the ~ 4 nm AC supported CeO2 crystallites become more susceptible to reduction by propane, but less prone to re-oxidation with CO2 compared to bulk CeO2. Catalytic activity of CeVO4/AC catalysts requires a 1–2 nm amorphous CeVO4 layer. During reaction, the amorphous CeVO4 layer crystallises and several atomic layers of carbon cover the CeVO4 surface, resulting in deactivation. During reaction, V2O5 is irreversibly reduced to V2O3. The lattice oxygen in bulk V2O5 favours catalytic activity and propene selectivity. Bulk V2O3 promotes only propane cracking with no propene selectivity. In VOx/AC materials, vanadium carbide is the catalytically active phase. Propane dehydrogenation over VC proceeds via chemisorbed oxygen species originating from the dissociated CO2. Graphic Abstract

Recent progress in the development of catalysts for propane dehydrogenation in the presence of CO2

“…Balogun et al 126 The catalytic activity of surface VO x can also be further regulated by doping with metal oxides such as CeO x , FeO x and CrO x . By using active carbon as a support, Djinović et al 132 prepared a series of nVO x /AV and nCeVO 4 /AC catalysts and tested their activity in CO 2 -OPDH. They found that the CeVO 4 content was positively correlated with the catalytic activity and propene selectivity.…”

Research progress of CO2 oxidative dehydrogenation of propane to propylene over Cr-free metal catalysts

“…species by CO 2 at 750 °C. Subsequently, Djinovic ´et al [59] utilized an electron-rich active carbon (AC) to adjust the electron environment of CeO 2 and prepared a CeO 2 /AC catalyst, which could achieve the CO 2 -ODHP. The catalyst was found to be susceptible to the dehydrogenation of propane, and especially a catalyst with large CeO 2 size was beneficial for re-oxidation with CO 2 .…”

Metallic Catalysts for Oxidative Dehydrogenation of Propane Using CO2

“…The UV-Vis analysis showed that CO 2 addition may have retained the higher oxidation state of vanadium species. Further investigations were conducted from different catalyst design, such as surface doped vanadia catalysts (7 V7 W, 7 V5Mo, and 7 V4Cr), [56] mixed oxides (WO x -VO x /SiO 2 [57] and CeVO x [58] ), modified supports (VO x /La 2 O 3 -g-Al 2 O 3 , [59] nV-MSNSs, [60] and nV-MCM-41 [61] ), and the specific preparation method using 3D printing. [44,[62][63][64] However, designing an efficient vanadium-based catalyst remains challenging due to the controversy over the active site (oxidized vanadium, oligomeric vanadium, and V 2 O 5 crystallite) in various complex systems.…”