Improved Catalytic Performance of Ethane Dehydrogenation in the Presence of CO₂ over Zr-Promoted Cr/SiO₂

Abstract

The Zr-, Ce-, Sr-, and Sn-promoted Cr/SiO2 catalysts were prepared by the incipient wetness impregnation method, then characterized by N2 adsorption/desorption, X-ray diffraction, X-ray photoelectron spectroscopy, H2-TPR, CO2-TPD, UV–vis, high-angle annular dark-field imaging–scanning transmission electron microscopy—energy dispersive X-ray spectroscopy elemental mapping, Raman, and thermogravimetric techniques to study the structural evolution under the preparation/reaction conditions, and applied to catalyze ethane oxidative dehydrogenation with CO2. The results suggested that the Cr6+ species were indispensable for activating the dehydrogenation reaction thanks to the oxidation–reduction cycle between Cr6+ and Cr3+. The type of the promotor also affected significantly the ability of replenishing the lattice oxygen through the disassociation of CO2, leading to the different catalytic performances. The Zr-promoted sample had the best performance in converting the reactants as well as the catalytic stability.

Enhancing the Ethylene Yield over Hybrid Adsorbent Catalyst Materials in CO2-Assisted Oxidative Dehydrogenation of Ethane by Tuning Catalyst Support Properties

“…As indicated in the literature, the reducibility of Cr 6+ species greatly depends on the support nature, catalyst−support interaction, and catalyst dispersion. For instance, Li et al 36 investigated the stability of chromium-based silica and reported a 47.6% drop in the material's initial activity after 100 h time on stream, as a result of coke formation. In another study, 46 a better stability was reported for Cr-supported H-ZSM-5 catalyst with only 22% decline from its initial catalytic activity.…”

“…UVM-7 SiO 2 and H-ZSM-5 with high SiO 2 :Al 2 O 3 ratio of 280:1 were used as catalyst supports for Cr nanoparticles, whereas double salt K–Ca was selected as the CO 2 adsorbing constituent owing to its high adsorption efficacy . Cr particles were selected as a catalyst due to the high catalytic activity for this reaction and different oxidation states. , The amount of Cr was fixed at 10 wt % on the basis of our previous work, where we optimized Cr loading. The structural and physiochemical characteristics of the materials were assessed by N 2 physisorption, XRD, XPS, SEM, NH 3 -TPD, and H 2 -TPR.…”

“…35 Cr particles were selected as a catalyst due to the high catalytic activity for this reaction and different oxidation states. 6,36 The amount of Cr was fixed at 10 wt % on the basis of our previous work, 34 where we optimized Cr loading. The structural and physiochemical characteristics of the materials were assessed by N 2 physisorption, XRD, XPS, SEM, NH 3 -TPD, and H 2 -TPR.…”

Bimetallic-Derived Catalysts and Their Application in Simultaneous Upgrading of CO2 and Ethane

“…However, compared with the C-H bond (C 2 H 5 -H, 415 kJ mol À1 ) of ethane, cleavage of the C-C bond (CH 3 -CH 3 , 368 kJ mol À1 ) is thermodynamically favored, thereby imposing a challenge on promoting the product selectivity toward ethylene, which requires breaking the C-H bond while retaining the formed C=C bond. Recent advances in modified Cr/ Zr-based catalysts, [124][125][126] metal carbides, 18,127 MOs, 128,129 and especially bimetallic-derived catalysts 19,23,125,128,130 have demonstrated the feasibility of enhancing ethylene selectivity. However, few fundamental strategies are available to guide the development of ODHE catalysts due to their structural complexity under reaction conditions.…”

Synthesizing High‐Volume Chemicals from CO2 without Direct H2 Input

“…[109,114] It is possible, albeit inconclusive, that surface acidity also determines the reaction mechanism. For example, CrO x /γ-Al 2 O 3 reportedly favors the DDH + RWGS mechanism during CO 2 -ODHE, [115] whereas Zr-and Ce-doped CrO x / SiO 2 and CrO x /ZrO 2 favor the redox mechanism during CO 2 -ODHE [116] and CO 2 -ODHP, [117] respectively, as depicted in Figure 6a and b.…”