Oxidative Dehydrogenation Of Ethane Research Articles

Defect-Rich TiO2 In Situ Evolved from MXene for the Enhanced Oxidative Dehydrogenation of Ethane to Ethylene

Defect-Rich TiO₂ <i>In Situ</i> Evolved from MXene for the Enhanced Oxidative Dehydrogenation of Ethane to Ethylene

Oxidative Dehydrogenation of Ethane in the Presence of СО2 on CrOx/SiO2 Catalysts

Oxidative Dehydrogenation of Ethane in the Presence of СО2 on CrOx/SiO2 Catalysts

Screening of Adsorbent/Catalyst Composite Monoliths for Carbon Capture-Utilization and Ethylene Production.

Combining CO2 adsorption and utilization in oxidative dehydrogenation of ethane (ODHE) into a single bed is an exciting way of converting a harmful greenhouse gas into marketable commodity chemicals while reducing energy requirements from two-bed processes. However, novel materials should be developed for this purpose because most adsorbents are incapable of capturing CO2 at the temperatures required for ODHE reactions. Some progress has been made in this area; however, previously reported dual-functional materials (DFMs) have always been powdered-state composites and no efforts have been made toward forming these materials into practical contactors. In this study, we report the first-generation of structured DFM adsorbent/catalyst monoliths for combined CO2 capture and ODHE utilization. Specifically, we formulated M-CaO/ZSM-5 monoliths (M = In, Ce, Cr, or Mo oxides) by 3D-printing inks with CaCO3 (CaO precursor), insoluble metal oxides, and ZSM-5. The physiochemical properties of the monoliths were vigorously characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 physisorption, elemental mapping, pyridine Fourier transform infrared spectroscopy (Py-FTIR), H2-temperature-programmed reduction (H2-TPR), and NH3-temperature-programmed desorption (NH3-TPD). Their performances for combined CO2 adsorption at 600 °C and ODHE reaction at 700 °C under 25 mL/min of 7% C2H6 were then investigated. The combined adsorption/catalysis experiments revealed the best performance in Cr-CaO/ZSM-5, which achieved 56% CO2 conversion, 91.2% C2H4 selectivity, and 33.8% C2H4 yield. This exceptional performance, which was improved from powdered-state DFMs, was attributed to the high acidity and numerous oxidation states of the Cr2O3 dopant which were verified by NH3-TPD and H2-TPR. Overall, this study reports the first-ever proof-of-concept for 3D-printed DFM adsorbent/catalyst materials and furthers the area of CO2 capture and ODHE utilization by providing a simple pathway to structure these composites.

Ce-modified SrFeO3-δ for ethane oxidative dehydrogenation coupled with CO2 splitting via a chemical looping scheme

The current study investigates Ce-modified SrFeO3-δ oxygen carriers for oxidative dehydrogenation (ODH) of ethane coupled with CO2 splitting in a chemical looping manner. During 39 cycles of redox testing over the sample of 0.2Ce/SrFeO3, up to 29% ethane conversion and 82% ethylene selectivity are achieved, and the CO generation in the subsequent CO2 splitting step is 0.25 mmol/g. XPS characterization results indicate decreased Fe2+/(Fe3++Fe4+) ratio as well as increased active oxygen species proportion on the near-surface of Ce-modified samples, which are responsible for the improved activity of the 0.2Ce/SrFeO3 in ethane ODH reaction. DFT calculations further reveal that the increased ODH activity of 0.2Ce/SrFeO3 is due to the lower surface oxygen vacancy formation energy upon Ce promotion. Moreover, the higher resistance of lattice oxygen diffusion from the bulk to the surface is the main reason for the superior ethylene selectivity attained by the CO2-regenerated sample than that by O2 regeneration.

Tuning the properties of NiO supported on silicon-aluminum oxides: Influence of the silica amount in the ODH of ethane

Nickel-based catalysts (40 wt% Ni) with commercial silicon-aluminum oxides as supports were prepared. The variation of the silica amount (10%, 20% and 40%) was studied. These catalytic formulations were characterized by N2 adsorption, SEM/EDX, HR-TEM, XRD, LRS and XPS, and tested in the oxidative dehydrogenation of ethane (ODHE) to produce ethylene. Besides, they were compared with a nickel-based silica-supported catalyst (NiO/SiO2). The effect of the proportion of silica in the supports on the generated Ni species, and consequently on the respective catalytic performances, was investigated. The results showed that, despite of the same NiO loading in all catalysts, different NiO-support interactions and surface amounts of non-selective oxygen species were obtained. These features had an impact on the catalytic behavior of each formulation. Remarkably, while ethylene selectivity was high and almost the same, ethane conversion increased with the silica amount in the supports. On the other hand, as expected, pure silica as a support resulted in high conversion but markedly low selectivity, favoring the total ethane oxidation to carbon dioxide. This work demonstrates that it is possible to increment the alkane conversion without sacrificing the alkene selectivity by tuning the active species properties through the increase of the amount of silica in the supports.

Industrially potential MoVNbTeOx@FoamSiC structured catalyst for oxidative dehydrogenation of ethane

Oxidative dehydrogenation of ethane (ODHE) is a highly exothermic process. Structured catalyst is one of the potential methods to achieve industrial applications. The main hurdles are heat removal and coating stability. Here we adopt highly thermal conductive Foam SiC as the structured support and propose three strategies to intensify the coating stability. The prepared structured catalysts present excellent heat transfer and the catalytic performance (i.e., 1.77 kgC2H4/kgcat/h) has reached the industrial goal. A “Dual Interfaces” coating stability mechanism is proposed. The mechanism provides fundamental guidelines for successful development of three strategies of preparing stable coating. The results indicate that proper calcination treatment facilitates good coating adhesion without activity loss, and adding the binding agent, or the strategy of “stabilize the coating, then activate the catalyst” can achieve both robust coating and fair catalytic performance. Briefly, these results pave the way for industrial applications of ODHE and enlighten other heterogeneous catalysis processes.

On the dynamics of the catalytic surface of a bimetallic mixed-oxide formulation during the oxidative dehydrogenation of ethane

This work aims to evaluate the dynamic performance of a highly selective Ni-based surface during the oxidative dehydrogenation of ethane (ODH-C2). The catalyst comprises an in-house bimetallic mixed-oxide formulation with a Ni/Sn atomic ratio of 10. To corroborate its proper synthesis, it is characterized by TGA, AES, XRD, physisorption of N2 and TEM. The catalytic evaluation of the mixed oxide under dynamic conditions allows the proposition of a redox surface mechanism whose reliability is evaluated through a rigorous analysis, which is based on the development of a kinetic model and a robust experimentation program using a fully-automated micro-reaction unit and registering in-situ surface temperatures and continuous inline monitoring of oxygen and carbon dioxide. Experiments are carried out using a mixture of ethane or ethylene, oxygen and nitrogen as feedstock, at temperatures from 360 to 480 °C, total pressures from 100 to 500 kPa, and space-time values from 8.1 to 133.1 kgcat s molC2H6−1. Oxygen conversion ranges from 5% to 100% while the one for ethane varies from 5% to 60%. Besides, the selectivity and yield to ethylene vary from 30% to 90% and from 2% to 40%, respectively. The suitability of the redox mechanism is here assessed by evaluating statistical and phenomenological foundations, including Boudart’s criteria. Kinetic parameters, estimated by non-linear regression and using the reparametrized form of the Arrhenius and van’t Hoff equations, are phenomenologically well founded, such that changes of entropy and enthalpy of adsorption correctly describe the loss of mobility due to adsorption and the exothermic nature of the adsorption processes. Ethylene formation is the reaction demanding the lowest activation energy (Ea1= 61.94 kJ mol−1), while the total oxidation of ethane is the path requiring the largest activation energy (Ea2= 132.6 kJ mol−1). Concerning the adsorption enthalpy, ethylene exhibits the largest value (−ΔHC2H4° = 123.39 kJ mol−1), while carbon dioxide presents the lowest one (−ΔHCO2° = 42.00 kJ mol−1). Additional findings can be summarized as follows: activity and selectivity are recovered after the dynamic operation under oxidative conditions of the catalytic surface; carbon dioxide is identified as the only no desired byproduct; and hydroxyl surface species lead to the formation of water which affects the selectivity to ethylene, as well as the reaction rates. These findings are of interest for future studies directed at elucidating the performance of the Ni-based catalyst at larger scales, paving the way for the efficient design of the industrial reactor for the ODH-C2.

Mo–V–O nanocrystals synthesized in the confined space of a mesoporous carbon

Ternary Mo–V oxide nanocrystals (Nano-MoVO) were hydrothermally synthesized in the confined space of a mesoporous carbon template and tested in the oxidative dehydrogenation (ODH) of ethane and propane. The synthesized nanocrystals are approximately 60 nm in length, 20 nm in diameter on average, and possess a structure resembling orthorhombic MoVO (Orth-MoVO) as indicated by spectroscopic and microscopy characterization. The Nano-MoVO catalyst has a 5-fold higher mesopore volume and a 4-fold larger external surface area than an Orth-MoVO synthesized by a conventional method (Orth-MoVO) as characterized through N2 adsorption analysis. Nano-MoVO shows similar activation energy in the ODH of ethane compared with other conventional MoVO catalysts. However, Nano-MoVO exhibits significantly higher propane/ethane activation rate ratio and higher propene selectivity even in the absence of elements such as Te and Nb that suppress overoxidation of propane-derived species to COx. The results suggest the benefits of the nanocrystalline morphology to limit overoxidation.

Oxidative Dehydrogenation of Ethane with CO2 as a Soft Oxidant over a PtCe Bimetallic Catalyst

Oxidative Dehydrogenation of Ethane with CO₂ as a Soft Oxidant over a PtCe Bimetallic Catalyst

Molten-salt-mediated carbon dioxide capture and superequilibrium utilization with ethane oxidative dehydrogenation

Existing CO2-mediated oxidative dehydrogenation (CO2-ODH) of ethane has yet to demonstrate >60% single-pass CO yield due to the intrinsic equilibrium limitations. We report a unique approach with mixed molten carbonates as a reaction medium for CO2-ODH, which strategically partitions the CO2-ODH reactions into gas and molten-salt phases and facilitates integrated CO2 capture from power plant flue gases. An 89% CO yield was achieved at 770°C, doubling the equilibrium limitation of conventional CO2-ODH. The high CO yield in turn enhances ethylene formation. Further characterizations confirmed that molten-salt mediated ODH (MM-ODH) proceeds through a gas-phase cracking and molten-salt mediated reverse water-gas-shift reaction pathway. Based on this understanding, thermodynamic analysis and ab initio molecular dynamics simulations were conducted to develop general principles to optimize the molten-salt reaction medium. Process analyses confirm that MM-ODH has the potential to be significantly more efficient for CO2 capture and utilization than conventional CO2-ODH.

Porous Silica Coated Ceria as a Switch in Tandem Oxidative Dehydrogenation and Dry Reforming of Ethane with CO2

AbstractThe oxidative dehydrogenation of ethane using CO2 as soft oxidant for the production of ethylene, possesses the features of valorization of light alkane and utilization of greenhouse gas. Although a significant challenge, the control of the reaction extent can provide a potential on‐purpose ethylene technology. In the present paper, CeO2 is proposed to be a promising catalyst, while the deep oxidation process of dry reforming is preferred. The SiO2 coated CeO2 catalyst can render the reaction more selective towards ethylene. Through high sensitivity low energy ion scattering spectroscopy, findings were made that SiO2 only partially covered CeO2 in the Si0.1CeO2 sample, in which the ethylene selectivity was 2.7 times as high as that of the bulk CeO2 based on the same conversion level. Further, density functional theory calculations also demonstrated that the presence of the SiO2 layer was more conducive to the desorption of ethylene.

The nickel-support interaction as determining factor of the selectivity to ethylene in the oxidative dehydrogenation of ethane over nickel oxide/alumina catalysts

Nickel oxides supported on γ-alumina (Ni-loading from 5 to 30 wt% NiO) have been synthesized and tested in the oxidative dehydrogenation (ODH) of ethane in order to determine the importance of the NiO-support interaction. The best performance was achieved by the catalyst with 15 wt% NiO; higher NiO-loadings lead to the formation of unselective bulk-like NiO and lower Ni-loadings present high proportion of free alumina surface sites. The presence of oxalic acid and/or niobium in the synthesis gel resulted in the formation of NiO particles with similar size, but higher crystallinity and reducibility than the standard 15 wt% NiO catalyst. The obtained results have revealed that, in addition to NiO crystal size, the nickel oxide-support interaction determines the catalytic performance of these catalysts.

Unveiling the Role of Active Oxygen Species in Oxidative Dehydrogenation of Ethane with CO2 over NiFe/CeO2

AbstractThe oxidative dehydrogenation of ethane (ODH) assisted by CO2 to produce ethylene is inevitably accompanied by the side reaction of dry reforming (DRE) to produce carbon monoxide. However, the key factor determining the dehydrogenation selectivity is still ambiguous. In this paper, four different NiFe/CeO2 catalysts were synthesized via an impregnation method over four types of CeO2. The dehydrogenation selectivity of the four catalysts ranged from 40 % to 83 %. Temperature‐programmed surface reaction and transient response experiments reveal the existence of two types of oxygen species over NiFe/CeO2 catalysts. FeOx layers exist as an oxygen species supply buffer over CeO2 supports. Weakly electrophilic oxygen species supplied by FeOx overlayers could participate in producing C2H4 while strong electrophilic oxygen species supplied by CeO2 supports could participate in producing CO. The content of weakly electrophilic oxygen species is identified to be a rational descriptor of C2H4 selectivity.

Synthesis, properties, and activity of MoVTeNbO catalysts modified by zirconia-pillared clays in oxidative dehydrogenation of ethane

Abstract Composites comprising MoVTeNbO mixed oxide and zirconia-pillared montmorillonite clays (PilCs) were prepared. XRD and TEM with EDX studies confirmed the preservation of M1 MoVTeNbO phase in these composites responsible for high activity and selectivity in ethane oxidative dehydrogenation into ethylene. For composites with PilC content of 10 wt%, the best ethylene yield exceeding that of bulk MoVTeNbO oxide was demonstrated for clays with zirconia pillars doped with Ce and Al possessing the highest specific surface area. This is explained by optimized chemical interaction of these clays with MoVTeNbO mixed oxide improving its bulk oxygen mobility and reactivity by structure disordering while blocking surface sites responsible for combustion due to the stabilization of the reactive terminal oxygen species.

Physico-Chemical Changes in the KCl-MgCl2/La-FAU Composite Catalyst Induced by Oxidative Dehydrogenation of Ethane

In this research, a binary eutectic composition of KCl and MgCl2 supported over lanthanum exchanged FAU (faujasite) zeolite has been investigated for the oxidative dehydrogenation (ODH) of ethane. The catalyst was prepared by the thermal treatment of La-FAU with a mechanical mixture of alkali chlorides under a flow of helium at 500 °C. The eutectic mixture of alkali chlorides formed at this temperature and a molten layer were spread over the support. Synthesized fresh and spent catalysts were characterized to obtain information about changes in crystallinity, textural properties, phase content, chemical composition, and morphology of the catalyst over the reaction time. The initial conversion of ethane was 80% with ethene as the main product (65% yield). The catalyst deactivation has been demonstrated over time on the stream (TOS). The characterization methods confirmed that the chlorine was being removed from the catalyst. The side products detected by mass spectroscopy, including chlorinated hydrocarbons, have been found as a key pathway of chlorine removal from the catalyst. The exchange of chlorine for oxygen in the catalyst led to a significant decrease in the activity and production of higher hydrocarbons and their oxygenates as side products of the ODH reaction.

Autothermal Gas-Phase Oxidative Dehydrogenation of Ethane to Ethylene at Atmospheric Pressure

The autothermal gas-phase oxidative dehydrogenation of ethane (ODHE) in a tubular reactor was analyzed by one-dimensional (1D) and two-dimensional (2D) reactor simulations coupling with a detailed ...

Surface Characterization of Composite Catalysts Prepared by Sol‐Gel Route

AbstractThe aim of this work is to synthesize Nb‐V oxide catalysts by sol gel route starting from metal alkoxides using different H2O/V ratios. Dried samples are characterized by X‐ray diffraction (XRD), atomic absorption, and Brunauer‐Emmett‐Teller (BET) analysis. Calcination of dried materials up to 600°C in flowing air has been followed with Thermogravimetry‐Fourier‐transform infrared spectroscopy (TG‐FTIR) spectroscopic analysis. The catalytic properties of calcined materials are tested in the oxidative dehydrogenation of ethane at 600°C. An improvement of the catalytic performances of vanadium for the gel prepared with the higher H2O/V ratio is found with respect to those of the supported catalyst due to the better interaction between vanadium and niobium.

Oxidative dehydrogenation of ethane over mixed metal oxide catalysts: Autothermal or cooled tubular reactor design?

AbstractA kinetic model consistent with experimentally measured reaction orders for the oxidative dehydrogenation of ethane (ODHE) over a MoVTeNbO catalyst is developed and applied to compare autothermal and multi‐tubular reactor designs for the same. The results suggest that autothermal reactor configurations are more favorable compared to multi‐tubular ones for this highly exothermic reaction, and become even more so with increasing active site density. A bifurcation analysis based on ignition and extinction behavior is presented as a function of adiabatic temperature rise (varied by altering the feed ethane to oxygen molar ratio) and catalyst active site density (varied by altering the pre‐exponential factor), thereby providing additional insights into strategies for successful scale‐up of ODHE reactors. These strategies for the design of viable reactor configurations may be more broadly applicable to high temperature catalytic partial oxidation reactions currently in practice or under consideration in the context of large‐scale processes for chemical production.

Oxidative Dehydrogenation of Ethane and Subsequent Co2 Activation on Ce-Incorporated Fetiox Metal Oxides

Oxidative Dehydrogenation of Ethane and Subsequent Co2 Activation on Ce-Incorporated Fetiox Metal Oxides

CO2-assisted ethane oxidative dehydrogenation over MoOx catalysts supported on reducible CeO2–TiO2

Supported MoOx catalysts on mixed CeO2–TiO2 were investigated for the oxidative dehydrogenation of ethane (ODHE) using CO2 as a mild oxidant. The reducibility of the support and nature of MoOx affect the relative dehydrogenation pathways.