Oxidative Dehydrogenation Process Research Articles

Electrochemical oxidative dehydrogenation of ethane to ethylene in a solid oxide electrolysis cell with in situ grown metal-oxide interface active electrodes

The shale gas revolution bolsters ethane supply, thereby enhancing the economic viability of ethylene production from ethane. Presently, catalytic ethane dehydrogenation technology exhibits immense potential in the realm of ethylene production. This study achieves the electrochemical oxidative dehydrogenation conversion of ethane to ethylene via a solid oxide electrolysis cell (SOEC), effectively circumventing the issue of excessive oxidation during the ethane oxidative dehydrogenation process. An active electrode with an in situ grown metal-oxide interface significantly promotes the activation of the ethane C–H bond, leading to efficient ethylene production. Under the co-electrolysis mode of ethane with CO2, the Co@CeO2 electrode demonstrates exceptional performance, achieving an ethane conversion rate of 33.1% and an ethylene selectivity of 88.9% at an applied voltage of 1.0 V. Moreover, the metal-oxide interface constructed via an in situ exsolved method effectively prevents the agglomeration of nanoparticles at high temperatures, thus enhancing the catalyst's resistance to coking and stability. Notably, the electrode's performance does not exhibit significant degradation even after 100 h of electrochemical reaction.

Experimental Combustion and Flame Characterization of a Chemical Looping-Based Oxidative Dehydrogenation Byproduct Fuel Mixture Containing High CO2 Dilution

Abstract This study investigates the combustion performance of a CO2-rich fuel mixture containing ethane and methane as active species using a constant volume combustion chamber. This fuel is obtained as a byproduct of a chemical looping-based oxidative dehydrogenation (Cl-ODH) process ethylene production. The byproduct gas mixture has 40.79% CO2, 39.49% ethane, and 4.88% methane by weight with other minor compounds. Using this fuel for energy extraction would improve the process efficiency of the ethane to ethylene conversion. After initial combustion modeling, the gas fuel mixture was reduced to just the major species: CO2, ethane, and methane. The mixture was then tested for flammability limits and combustion performance under spark-ignition conditions. Effects of ambient conditions like temperatures between 300 and 400 K with initial pressures from 1 to 10 bar were tested. The effects of stoichiometry were tested to understand flame velocities and heat release. The fuel mixture showed an overall reduced flame velocity compared to gasoline. Instability in combustion was believed to be caused by the dissociation of ethane under elevated conditions. At higher pressures, the flame produces lower cumulative heat release. Simulations were also performed using a model tuned to replicate the operations of the combustion chamber used in the experiments. Heat release and unburnt fuel mass data were calculated to identify the discrepancies in the combustion completeness at elevated pressures. The effects of CO2 quenching the flame coupled with the increased dissociation of the fuel species can lead to up to more than 75% of the fuel mixture being unburnt. Data from this study were used to modify a small-scale spark-ignition engine to use this fuel and produce usable energy.

Gas-Phase Oxidative Dehydrogenation of n-Octane over Metal Oxide Catalysts: A Review

The oxidative dehydrogenation (ODH) of alkanes, whereby hydrogen is removed to form unsaturated compounds, is an important process, particularly in the petrochemical industry. The ODH of lighter alkanes (C3–C6) is well-reported in the literature, and while there are several reports on the ODH of n-octane (C8), there is no reported review of the important findings in the literature. This review discusses the gas-phase ODH of n-octane occurring at high temperatures (300–550 °C). The mechanisms via which the n-octane ODH of occurs are also briefly discussed. The oxidants (mainly O2 and CO2) and catalysts (supported and unsupported metal oxides) are discussed as well as the effect of these and the temperature on the type of products formed and their various distributions. Furthermore, the review looks at the acid–base and redox properties of the catalysts and how they affect product formation. Some challenges as well as perspectives of the ODH process are also highlighted.

Techno-economic analysis of bromine mediated propane oxidative dehydrogenation to produce propylene

The production of propylene from propane is becoming increasingly important. Catalytic propane dehydrogenation (PDH) is the major on-purpose propylene production process today. The conventional PDH process has a relatively high energy consumption (6.1–9.4 kWh/kg C3H6) which results in high direct CO2 emissions and modest propylene yield (0.8–0.9 kg C3H6/kg C3H8). A bromine-mediated propane oxidative dehydrogenation process (Br-ODH) is evaluated in this techno-economic study which can potentially improve both the process energy efficiency and product yield. To investigate the Br-ODH process feasibility, a heat integrated process model was designed using Aspen Plus® V12 for a 450 kta propylene facility using reaction data from the literature. The partial oxidation of propane under bromine limited conditions selectively produces a propylbromide intermediate which can be readily separated from propane. Propylbromide undergoes dehydrobromination under relatively mild conditions to produce the propylene product in a second step. Bromine is regenerated by conversion of the hydrogen bromide byproduct either thermochemically or electrochemically. Due to the current interest in use of renewable electricity in chemical processes, the electrochemical regeneration process was evaluated in this study. Based on the model, the Br-ODH process can achieve approximately 10% higher propylene yield with 37% lower utilities than conventional PDH. However, the use of high-cost electrolyzers resulted in the capital investment increasing by approximately 11%. Capital cost was also increased due to the requirements of high alloy materials of construction for the potentially corrosive halogen containing equipment. The sensitivity analysis showed that the production cost was most sensitive to the propane price. For the electrolyzer-based regeneration process the capital cost was found to be key parameter that might limit competition with conventional PDH; however, the development of a commercial thermochemical HBr oxidation process analogous to the Deacon process for chlorine would likely bring significant cost savings.

Efficient Catalytic Oxidative Dehydrogenation of Tetrahydroisoquinolines via Copper Catalysis

AbstractAn efficient copper‐catalyzed oxidative dehydrogenation of tetrahydroisoquinolines has been developed, giving a general and convenient strategy from amines toward imines in excellent yields. A series of tetrahydroisoquinolines bearing electron‐donating/withdrawing groups proceeded smoothly with air (O2) as oxidant. The oxidative dehydrogenation proved to be an atom‐economical and environmentally friendly strategy, which could effectively avoid generating stoichiometric hazardous wastes. In addition, this methodology provides a convenient and effective approach to the reutilization of amines, especially for the synthesis of enantiomerically pure substances, such as (+)‐Solifenacin, in industrial process. Preliminary experimental results revealed that the reaction was carried out via a process of oxidative dehydrogenation.

Support Effect of Ga-Based Catalysts in the CO2-Assisted Oxidative Dehydrogenation of Propane

Carbon dioxide (CO2) assisted oxidative dehydrogenation of propane over Ga-modified catalysts is highly sensitive to the identity of support, but the underlying cause of support effects has not been well established. In this article, SSZ-13, SSZ-39, ZSM-5, silica and γ-Al2O3 were used to load Ga species by incipient wet impregnation. The structure, textural properties, acidity of the Ga-based catalysts and the process of CO2-assisted oxidative dehydrogenation of propane were examined by X-ray diffraction (XRD), nitrogen physisorption (N2 physisorption), ammonia temperature-programmed desorption (NH3-TPD), pyridine chemisorbed Fourier transform infrared spectra (Py-FTIR), OH-FTIR and in situ FTIR. Evaluation of the catalytic performance combined with detailed catalyst characterization suggests that their dehydrogenation activity is positively associated with the number of acid sites in middle strength, confirming that the Lewis acid sites generated by Ga cations are the active species in the reaction. Ga/Na-SSZ-39(9) also has feasible acidic strength and a unique channel structure, which is conducive to the dissociative adsorption of propane and desorption of olefins. The Ga/Na-SSZ-39(9) catalysts showed superior olefins selectivity and catalytic stability at 600 ℃ compared to any other catalysts. This approach to quantifying support acid strength, and channel structure and applying it as a key catalytic descriptor of support effects is a useful tool to enable the rational design of next-generation CO2-assisted oxidative dehydrogenation catalysts.

Efficient Oxidative Dehydrogenation of Ethylbenzene over K/CeO2 with Exceptional Styrene Yield

Oxidative dehydrogenation (ODH) is an alternative for styrene (ST) production compared to the direct dehydrogenation process. However, ODH with O2 or CO2 suffers from either over-oxidation or endothermic property/low ethylbenzene conversion. Herein, we proposed an ODH process with a CO2-O2 mixture atmosphere for the efficient conversion of ethylbenzene (EB) into styrene. A thermoneutral ODH is possible by the rationalizing of CO2/O2 molar ratios from 0.65 to 0.66 in the temperature range of 300 to 650 °C. K modification is favorable for ethylbenzene dehydrogenation, and 10%K/CeO2 achieved the highest ethylbenzene dehydrogenation activity due to the enhanced oxygen mobility and CO2 adsorbability. The catalyst achieved 90.8% ethylbenzene conversion and 97.5% styrene selectivity under optimized conditions of CO2-4O2 oxidation atmosphere, a temperature of 500 °C, and a space velocity of 5.0 h−1. It exhibited excellent catalytic and structural stability during a 50 h long-term test. CO2 induces oxygen vacancies in ceria and promotes oxygen exchange between gaseous oxygen and ceria. The ethylbenzene dehydrogenation in CO2-O2 follows a Mars-van Krevelen (MvK) reaction mechanism via Ce3+/Ce4+ redox pairs. The proposed ODH strategy by using oxygen vacancies enriched catalysts offers an important insight into the efficient dehydrogenation of ethylbenzene at mild conditions.

Coupling acid catalysis and selective oxidation over MoO3-Fe2O3 for chemical looping oxidative dehydrogenation of propane

Redox catalysts play a vital role in chemical looping oxidative dehydrogenation processes, which have recently been considered to be a promising prospect for propylene production. This work describes the coupling of surface acid catalysis and selective oxidation from lattice oxygen over MoO3-Fe2O3 redox catalysts for promoted propylene production. Atomically dispersed Mo species over γ-Fe2O3 introduce effective acid sites for the promotion of propane conversion. In addition, Mo could also regulate the lattice oxygen activity, which makes the oxygen species from the reduction of γ-Fe2O3 to Fe3O4 contribute to selectively oxidative dehydrogenation instead of over-oxidation in pristine γ-Fe2O3. The enhanced surface acidity, coupled with proper lattice oxygen activity, leads to a higher surface reaction rate and moderate oxygen diffusion rate. Consequently, this coupling strategy achieves a robust performance with 49% of propane conversion and 90% of propylene selectivity for at least 300 redox cycles and ultimately demonstrates a potential design strategy for more advanced redox catalysts.

A DFT study of the catalytic ODH of n-hexane over a cluster model of vanadium oxide

Supported vanadium oxides are one of the most widely reported catalysts for the selective oxidative dehydrogenation (ODH) of alkanes to alkenes. These vanadium oxide catalysts contain at least three distinct O species classified by their coordination to the vanadium cations. The involvement in ODH of the different oxygen species is thought to follow the coordination environment with singly coordinated vanadyl V(V)=O being the most reactive. A quantitative understanding of the relative activity of the different oxygen species in vanadium oxides could inform catalyst design to further enhance productivity and selectivity in the ODH reaction. Here we use computational models based on hybrid density functional theory to study the mechanistic pathway for n-hexane to 1- and 2-hexene. We compare the potential energy surfaces calculated for these reactions initiated by β-H abstraction with H transfer to the vanadyl oxygen, V(V)=O, with that involving H transfer to a two-coordinate bridging O atom. An isolated H4V2O7 cluster is used to represent the supported vanadium oxide catalyst so that the reactivity of oxygen species can be understood in the absence of support effects. Gibbs energy calculations were carried out at temperatures of 573, 673 and 773 K to mirror laboratory experimental conditions. We find that the rate-determining step (RDS) in the conversion of n-hexane to either alkene is associated with n-hexane interaction with H4V2O7 through a secondary CH bond. This leads to β-H abstraction with the calculated reaction barrier for abstraction by a V(V)=O (ΔE‡ = +32.7 kcal mol−1) significantly lower than that for the two-coordinate bridging O (ΔE‡ = +43.9 kcal mol−1). H-abstraction leads to reduction of one of the vanadium cations. Removal of the second H atom to form an alkene can follow several pathways. We have considered the second step leading to 2-hexene (γ-H abstraction) using either an adjacent V(V)=O on the reduced V(IV)-O-V(V) unit, a different active V(V)=O site on a fully oxidised cluster, or gas-phase molecular O2. Our results show that the ODH process is likely to proceed via a Mars-van Krevelen redox mechanism. In a practical catalyst the results imply that catalyst activity will depend on the surface coverage of V(V)=O active sites and the n-hexane to gas-phase molecular oxygen ratio. In addition to the pathways leading to alkene products we have noted the formation of CO bonds by the radical intermediate formed from the initial β-H abstraction. From this observation, we suggest that the low yields of 1- and 2-hexene (< 20%) obtained in our laboratory experiments with V2O5/MgO catalysts may be a result of the chemisorption properties of the radical intermediate (∙C6H13) on bridging or terminal O sites in the V(V)-O-V(V) units, leading to undesired products including oxygenates.

Unraveling the Surface State Evolution of IrO2 in Ethane Chemical Looping Oxidative Dehydrogenation

Based on the advantages of favorable thermodynamics and coking resistance of ethane oxidative dehydrogenation and the challenge of low ethylene selectivity, chemical looping oxidative dehydrogenation (CL-ODH) over the IrO2 catalyst was examined, including the dehydrogenation and regeneration processes. The stoichiometric S-IrO2 and reduced R-IrO2 catalysts as two extreme states of the IrO2 surface structure with dynamic changes were considered. Density functional theory (DFT) calculations and kinetic Monte Carlo simulations showed that the mechanisms of ethane dehydrogenation over S-IrO2 and R-IrO2 catalysts were quite different. Over the S-IrO2 catalyst, ethane oxidative dehydrogenation to C2H4(g) with H2O(g), CO(g), and CO2(g) taking away surface lattice oxygen, followed by lattice oxygen migration from the bulk to the surface, leads to the reduction of the S-IrO2 catalyst. Over the R-IrO2 catalyst, ethane directly dehydrogenates to C2H4(g) and H2(g). Furthermore, the oxidation degree in the regeneration process is greater than the Ov concentration in the dehydrogenation process, which can easily achieve oxygen replenishment in the regeneration process. More importantly, the IrO2 catalyst can be neither completely reduced in the dehydrogenation process nor completely oxidized in the regeneration process, both S-IrO2 and R-IrO2 simultaneously exist for the IrO2 catalyst, and both 750 K and 0.8 bar C2H6(g) pressure were obtained to be the optimal reaction conditions; thus, for ethane CL-ODH over the IrO2 catalyst, the proposed mechanism starts from the oxidative dehydrogenation process; with the consumption of surface lattice oxygen and the oxygen migration from the bulk to the surface, the oxidative and nonoxidative dehydrogenations occur simultaneously until the regeneration. The present study broadens the understanding of ethane CL-ODH over metal oxide catalysts and provides valuable information for the optimization of the CL-ODH process and the development of other high-performance metal oxide catalysts in other alkane CL-ODH processes.

Boosting the propylene selectivity over embryonic borosilicate zeolite catalyst for oxidative dehydrogenation of propane

Boron-containing zeolites have been proven potential in catalyzing the oxidative dehydrogenation (ODH) process and the boron sites in open coordination are considered as the active center. By considering the diversity and adjustability in the crystal structure of zeolite, there is a great opportunity to further tune the activity and selectivity. Herein, the embryonic borosilicate zeolite with abundant defective sites and developed large porosity is prepared for catalyzing ODH of propane reaction. An ∼ 20 % improvement in propylene selectivity is achieved at propane conversion of 21.5 % at 540 °C, with propylene productivity nearly an order of magnitude higher compared with crystalline MFI-type borosilicate zeolite. Solid-state NMR reveals the formation of boron sites in open coordination derived from the defect-rich structure of embryonic borosilicate zeolite, guaranteeing ample exposure of the active center. Combined with kinetic measurements, the reaction in the gas phase initiated by the active boron sites is mainly responsible for the high catalytic performance in ODH of propane reaction. The designed experiment indicates the strengthened gas-phase reaction facilitates the activation of propane, consequently resulting in the increase of reaction order of propane from 1.06 to 2.30. This work reveals the significant role of gas-phase reactions during the ODH of propane reaction and provides a new insight for boosting the propylene selectivity of zeolite-based catalysts.

Mechanistic Interpretations and Insights for the Oxidative Dehydrogenation of Propane via CO2 over Cr2O3/Al2O3 Catalysts

Oxidative dehydrogenation (ODH) of alkanes using carbon dioxide as a soft oxidant has recently emerged as a potentially attractive alternative to steam cracking for the production of light olefins. To elucidate reaction pathways and their dependence on the operating conditions, CO2-assisted propane dehydrogenation over a redox-active Cr2O3/Al2O3 catalyst was examined in a packed bed reactor as a function of temperature, Cr2O3/CO2 feed ratio, and residence time. Previous ODH studies have largely focused on CO2-rich conditions with the aim of preventing coke formation. However, at T = 600 °C the present study finds that the use of propane-rich conditions (1 ≤ C3H8/CO2 ≤ 2.5) maximizes propylene production and selectivity while maintaining catalyst stability. It is postulated that the selective Mars van Krevelen dehydrogenation process is optimized at these ratios. Excess CO2 apparently promotes nonselective dehydrogenation and dry reforming pathways that generate additional CO, adversely impacting catalyst stability via the Bouduard reaction. This hypothesis is supported by complementary investigations of the reverse water gas shift reaction and thermodynamic analysis. The findings and methodology presented here are likely applicable to related ODH processes with other alkanes and redox-active catalysts.

Insight into highly efficient FeOx catalysts for the selective catalytic reduction of NOx by NH3: Experimental and DFT study

Fe3O4, α-Fe2O3 and γ-Fe2O3 catalysts were synthesized and showed excellent activities for the selective catalytic reduction (SCR) of NOx by NH3 in the temperature range that was between 433 K and 653 K in the presence of excess oxygen. Physical and chemical properties of catalysts were tested to investigate the effect of the iron oxides on the NH3-SCR activities by a series of characterization methods that were XRD, H2-TPR, NH3-TPD, BET and XPS. The related results indicated that the species of iron oxides had significant effects on oxidation–reduction ability, surface acidity distribution, BET surface area and surface adsorbed oxygen. Meanwhile, DRIFTS tests were carried out to further investigate the reduction process over α-Fe2O3, γ-Fe2O3 and Fe3O4 catalysts, supporting the DFT calculations. The adsorption energy of ammonia and nitric oxide on α-Fe2O3 (001), γ-Fe2O3 (001) and Fe3O4 (111) surfaces are calculated by the Density Functional Theory (DFT) calculations, suggesting that ammonia and nitric oxide are easily adsorbed on the Fe3O4 (111) surface. Moreover, it is reasonable to draw a conclusion that more surface chemisorbed oxygen, easier adsorption of reaction gases (NO, NH3 and O2) and more effortless oxidative dehydrogenation process can promote NH3-SCR.

OPTIMAL DESIGN OF THE OXIDATIVE DEHYDROGENATION OF METHYLCYCLOHEXANE INTO METHYLCYCLOHEXADIENE ON A MODIFIED ZEOLITE CATALYST

Selection and theoretical optimization of the reactor type was carried out on the basis of a kinetic model of the process of selective oxidative dehydrogenation of methylcyclohexane into methylcyclohexadiene on a modified active metal-zeolite catalyst. It was determined that it was more expedient to carry out the process in an ideal tubular ( packed-bed ) type reactor. As a result of theoretical optimization of the process, optimal technological regimes were determined and the optimal design dimensions of the reactor element for a given capacity calculated. A complete mathematical model of the process was developed with regard to the effect of heat and pressure drop.

New approach for enhancement of light olefin production through oxidative dehydrogenation of propane over doped Mo/TiO2 nanotubes

Using promoters in different types of catalysts can positively affect the yield of oxidative dehydrogenation process and the selectivity of propylene as the main product Titania nanotubes containing distinct promoters including silver, nitrogen and cerium have been synthesized with high specific area by the hydrothermal technique and used as a support in oxidative dehydrogenation of propane. The incipient wetness impregnation method was applied for catalysts preparation Mo/Ce-TNT, Mo/Ag-TNT and Mo/N-TNT were characterized by various techniques such as XRD, TEM, SEM, EDS, BET, H2-TPR. The presence of these promoters lead to enhancement of propylene yield among which the Mo/Ce-TNT catalyst was of great efficiency. From the results, it is considered to be quite evident that the oxygen capacity of the catalyst containing Ce can contribute to the oxidation state and redox reactions. In comparison to Mo/TNT, the yield to propylene in the Mo/Ce-TNT sample increased from 9.3% to 14.8% and propylene selectivity substantially surged from 39% to 66.3%.

A study of molybdena catalysts in ethanol oxidation. Part 1. Unsupported and silica‐supported MoO3

AbstractBackgroundAcetaldehyde is a main organic intermediate for manifold chemical products. In the near future, its production using renewable raw materials is rapidly becoming highly desirable. In this paper, investigations on pure and silica‐supported molybdenum oxide (MoO3) as catalysts for the ethanol oxidative dehydrogenation process to acetaldehyde are reported.ResultsAcicular pure α‐MoO3 crystals and silica‐gel supported MoO3 (1, 5 and 12% wtMoO3/wtsupport) were prepared by the thermal decomposition method and by incipient wetness impregnation, respectively. Catalysts were studied and extensively characterized assessing structural, morphological and chemical properties. The samples were tested in ethanol oxidative dehydrogenation through Temperature Programmed Surface Reaction (TPSR) and steady‐state measurements. MoO3/SiO2 samples were constituted by MoO3 particles weakly interacting with the support, but also by some molybdate species entering the silica framework and significantly modifying the silica morphology. High catalyst acidity limits oxydehydrogenation yield, catalyzing the competitive dehydration reaction to ethylene. Thus, the highest obtained acetaldehyde yield was ≈60%. Molybdenum loss by MoO3 volatilization was found on MoO3/SiO2.ConclusionThe produced and characterized catalysts are active, and allow quite a high yield to acetaldehyde. Slight deactivation was observed and also investigated. © 2021 Society of Chemical Industry (SCI).

A study of molybdena catalysts in ethanol oxidation. Part 2. Alumina‐supported and silica‐doped alumina‐supported MoO3

AbstractBACKGROUNDγ‐Al2O3 and silica‐doped aluminas are largely used supports for industrial catalysts. The addition of silica to alumina modifies its acid–base properties, also affecting its dispersion ability of supported species. In this paper, investigations on the silica doping effect in alumina‐supported MoO3 catalysts, developed for the oxidative dehydrogenation process of ethanol to acetaldehyde, are reported.RESULTSMoO3 (1÷12% wtMoO3/wtsupport) supported over pure γ‐Al2O3, SiO2 (1 and 5 wt.%) doped γ‐Al2O3 were prepared by incipient wetness impregnation. Catalysts were studied and extensively characterized structurally, morphologically, and chemically. All samples were tested in ethanol oxidative dehydrogenation in Temperature Programmed Surface Reaction conditions. Best performing catalysts were also tested in steady‐state and time‐on‐stream experiments. At 573 K, the best acetaldehyde yield (60% in steady state conditions) was found on 12 wt.% MoO3 over 1 wt.% SiO2 on alumina. The slight deactivation after 8 h on stream (10% activity loss) is attributed to a limited MoO3 loss by volatilization.CONCLUSIONThe investigated catalysts are active and allow quite a high yield to acetaldehyde. The addition of silica to alumina increases both the conversion of ethanol and the selectivity to acetaldehyde, and reduces MoO3 volatilization, due to the higher activity of monomeric molybdates with respect to polymeric ones. The high acidity of the catalysts limits oxydehydrogenation yield, catalyzing competitive reaction to ethylene. © 2021 Society of Chemical Industry (SCI).

Experimental data supported techno-economic assessment of the oxidative dehydrogenation of ethane through chemical looping with oxygen uncoupling

Ethylene is an essential building block in the petrochemical industry and it is almost exclusively produced via ethane steam cracking, a well-established albeit highly energy and carbon dioxide intensive process. The oxidative dehydrogenation of ethane is a promising alternative to steam cracking reactions due to its exothermic nature, which decreases the overall energy requirements and carbon footprint. The need of a capital intensive air separation unit for producing oxygen limits its potential for industrial application. The current study investigates an alternative route, i.e. the production of oxygen via chemical looping, where oxygen is released in-situ by suitable oxygen carriers. The chemical looping oxidative dehydrogenation, supported by original experimental data, and the steam cracking processes are simulated with ASPEN Plus®. A comprehensive analysis of the energy requirements and an economic assessment are carried out for both processes. Compared with state-of-the-art ethane steam cracking, the proposed process provides ~28% energy savings per tonnes of ethylene produced and ~21% reduction in the resulting ethylene price. Sensitivity analysis show that the economy of the chemical looping oxidative dehydrogenation process is strongly sensitive to the feedstock price.

Oxidative dehydrogenation of ethane: catalytic and mechanistic aspects and future trends.

Ethene is a commodity chemical of great importance for manufacturing diverse consumer products, whose synthesis via crude oil steam cracking is one of the most energy-intensive processes in the petrochemical industry. Oxidative dehydrogenation (ODH) of ethane is an attractive, low energy, alternative route to ethene which could reduce the carbon footprint for its production, however, the commercial implementation of ODH requires catalysts with improved selectivity. This review critically assesses recent developments in catalytic technologies for ethane ODH, and discusses how insight into proposed mechanisms from computational studies, and CO2 assisted ethane dehydrogenation (CO2-DHE), provide opportunities for economically viable processes to meet growing demands for ethene while reducing carbon emissions. Future trends and emerging technologies for ethane ODH are also discussed.

Regularities of Oxidative Dehydrogenation of Ethane Over MoVNbTeOx Catalyst Under Supercritical Conditions

One of the most active and high-selective catalytic systems for oxidative dehydrogenation of ethane is the MoVNbTeOx catalyst. However, this catalytic system has the low thermal stability and is prone to deactivation at temperatures above 350 °C. At the first time it was proposed to use oxygen ((Tcr = –119 °C, Pcr = 48 atm) and ethane (Tcr = 32 °C, Pcr = 51 atm) in supercritical state in the oxidative dehydrogenation process. Carrying out the process at supercritical conditions (T = 240–300 °C, P = 60–100 atm) leads to high selectivity up to 90% for ethylene under growth conversion of ethane and oxygen. At the same time, it manages to keep M1 phase crystallinity unchanged throughout the experiment (more than 40 h). Dependences of ethylene productivity on pressure (Reaction conditions: T = 280 °C, C2H6:O2:N2 = 31:23:46, 2 g of catalyst, the density of the reagent mixture varies from 0.65 (at 1 atm ) to 63.15 kg/m3 (at 100 atm )