Dehydrogenation Of Ethane Research Articles

Quantitative Evidence to Challenge the Traditional Model in Heterogeneous Catalysis: Kinetic Modeling for Ethane Dehydrogenation over Fe/SAPO-34.

The production of ethylene from ethane dehydrogenation (EDH) is of great importance in the chemical industry, where zeolites are reported to be promising catalysts and kinetic simulations using the energetics from quantum mechanical calculations might provide an effective approach to speed up the development. However, the kinetic simulations with rigorous considerations of the zeolite environment are not yet advanced. In this work, EDH over Fe/SAPO-34 is investigated using quantum mechanical calculations with kinetic simulations. We show that an excellent agreement between the reaction rates from the self-consistent kinetic simulations using the coverage-dependent kinetic model developed in this work and the experimental ones can be achieved. We demonstrate that the adsorbate-adsorbate interactions are of paramount importance to the accuracy of kinetic calculations for zeolite catalysts. Our self-consistent kinetic calculations illustrate that the CH3CH2• radical rather than CH3CH2* is a favored intermediate. Perhaps more importantly, we reveal that the traditional model to describe catalytic reactions in heterogeneous catalysis cannot be used for the kinetics of the system and it may not be appropriate for many real catalytic systems. This work not only builds a framework for accurate kinetic simulations in zeolites, but also emphasizes an important concept beyond the traditional model.

Microwave Heating of the Catalyst Bed as a Way of Energy-Saving Oxidative Dehydrogenation of Ethane on a Mo-V-Te-Nb-Ox Catalyst.

In search of a more effective process of ethane oxidative hydrogenation, different operation modes (thermal and microwave heating) are compared. The catalyst Mo1-V0.3-Te0.13-Nb0.11-Ox was prepared by hydrothermal synthesis and characterized by a set of physicochemical methods (XRD, N2 adsorption, SEM, EDX). The direct microwave heating of the catalyst layer is proposed as an alternative way of energy-saving ethane-to-ethylene oxidation by a Mo-V-Te-Nb-Ox system. A substantial decrease in the reactor temperature upon the microwave-assisted process is accompanied by extremely high catalyst selectivity, which remains at a very high level of 98+%.

Construction of flower spherical Cr–Ce/ZSM-5 catalyst with rich surface structure and study on CO2-assisted ethane dehydrogenation performance

In this paper, we used kaolinite tailings as raw materials to design and prepare ZSM-5 zeolite with “flower ball” morphology. Through the functional design of the material, Cr–Ce/ZSM-5 catalysts were prepared for CO2-assisted ethane oxidative dehydrogenation reaction (CO2-ODH). The folds and grooves on the surface of the “flower ball” ZSM-5 carrier act as a good anchor site for the loading of the active components, thus better anchoring Cr and Ce metal oxides, and leading to a strong interaction between the active component and the carrier. The 5%Cr–10%Ce/ZSM-5 catalyst exhibited the best catalytic performance, the conversion rate of C2H6 and the selectivity of C2H4 can always maintain the initial 64% and 80% within 30 h stability test at 800 °C. The existence of abundant Cr6+ species in catalyst strengthens the binding ability of the catalyst and active oxygen species and promotes the formation-gasification process of carbon deposits on surface of the catalyst.

Ethane dehydrogenation over the g-C3N4 supported metal single-atom catalysts to enhance reactivity and coking-resistance ability

Ethane dehydrogenation over the g-C3N4 supported metal single-atom catalysts to enhance reactivity and coking-resistance ability

Deactivation origins and stability-enhancing strategies of Sn/SiO2 catalysts for ethane dehydrogenation

A low-cost and environment-friendly Sn/SiO2 catalyst, highly active and selective for ethane dehydrogenation, is an effective alternative for high-cost Pt and toxic CrOx-based catalysts. While the catalyst deactivates fast due to the loss and aggregation of Sn species. In order to solve the problem, complexation impregnation method and in-situ synthesis approach have been tried to enhance the stability of Sn-based catalyst. As for the former one, a relatively stable performance of 5Sn/SiO2 catalyst can be achieved due to depressed Sn loss and coke deposition, while there is still room for improvement. When the latter strategy is applied, 5Sn-MCM-41 catalyst demonstrates the optimal dehydrogenation performance, with 44.0% of ethane conversion and 98.8% of ethylene selectivity, and no obvious decreasing trend is observed in the progress of 18 h reaction due to the well dispersion and anchoring of Sn species on the framework of MCM-41.

Two-Component Ni–Mg–O/V–Mg–O Catalytic System: II. The Dehydrogenation of Ethane

Two-Component Ni–Mg–O/V–Mg–O Catalytic System: II. The Dehydrogenation of Ethane

Effect of Gadolinium Additives on the Active Phase Morphology and Physicochemical and Catalytic Properties of MoVSbNbGdOx/SiO2 Catalysts in the Oxidative Dehydrogenation of Ethane to Ethylene

Effect of Gadolinium Additives on the Active Phase Morphology and Physicochemical and Catalytic Properties of MoVSbNbGdOx/SiO2 Catalysts in the Oxidative Dehydrogenation of Ethane to Ethylene

The Effect of Pressure on the Oxidative Dehydrogenation of Ethane with Molecular Oxygen over a MoVNbTeOx Mixed Oxide Catalyst

The Effect of Pressure on the Oxidative Dehydrogenation of Ethane with Molecular Oxygen over a MoVNbTeOx Mixed Oxide Catalyst

Plasma-Catalysis of Nonoxidative Methane Coupling: A Dynamic Investigation of Plasma and Surface Microkinetics over Ni(111).

A heterogeneous catalytic microkinetic model is developed and implemented in a zero-dimensional (0D) plasma model for the dynamic study of methane nonoxidative coupling over Ni(111) at residence times and power densities consistent with experimental reactors. The microkinetic model is thermodynamically consistent and is parameterized based on the heats of chemisorption of surface species on Ni(111). The surface network explicitly accounts for the interactions of plasma species, namely, molecules, radicals, and vibrationally excited states, with the catalyst active sites via adsorption and Eley-Rideal reactions. The Fridman-Macheret model is used to describe the enhancement of the rate of the dissociative adsorption of vibrationally excited CH4, H2, and C2H6. In combination with a previously developed detailed kinetic scheme for nonthermal methane plasma, 0D simulation results bring insights into the complex dynamic interactions between the plasma phase and the catalyst during methane nonoxidative coupling. Differential turnover frequencies achieved by plasma-catalysis are higher than those of equivalent plasma-only and catalysis-only simulations combined; however, this performance can only be sustained momentarily. Hydrogen produced from dehydrogenation of ethane via electron collisions within the plasma is found to quickly saturate the surface and even promote the conversion of surface CH3* back to methane.

Rivet of cobalt in siliceous zeolite for catalytic ethane dehydrogenation

•A catalyst with isolated cobalt in siliceous zeolite was prepared •This catalyst catalyzed the EDH at thermodynamically limited conversion levels •Superior productivity of ethylene was achieved •The catalyst was coking resistant with constant performances over a long period Catalytic dehydrogenation of ethane (EDH) is promising for the utilization of shale gas to produce ethylene, but the current processes mostly exhibit space-time productivity of ethylene lower than 1.5 KgC2H4 Kgcat−1 h−1 because of the insufficient catalyst activity in the non-oxidative route. We reported a catalyst with isolated cobalt in siliceous zeolite derived from a mechanically assisted spontaneous dispersion. This material can operate as a non-oxidative EDH catalyst at thermodynamically limited conversion levels under rapid gas feeding, resulting in ethylene productivity at 13.4 KgC2H4 Kgcat−1 h−1. This result is superior to that of the previous non-noble metal catalysts and even outperforms the precious PtSn/Al2O3 catalyst. The isolated cobalt sites are preserved upon calcination at high temperatures and during EDH operation under harsh conditions, resulting in superior durability in a long reaction period with negligible coke formation. Catalytic dehydrogenation of ethane (EDH) is promising for the utilization of shale gas to produce ethylene, but the current processes mostly exhibit space-time productivity of ethylene lower than 1.5 KgC2H4 Kgcat−1 h−1 because of the insufficient catalyst activity in the non-oxidative route. We reported a catalyst with isolated cobalt in siliceous zeolite derived from a mechanically assisted spontaneous dispersion. This material can operate as a non-oxidative EDH catalyst at thermodynamically limited conversion levels under rapid gas feeding, resulting in ethylene productivity at 13.4 KgC2H4 Kgcat−1 h−1. This result is superior to that of the previous non-noble metal catalysts and even outperforms the precious PtSn/Al2O3 catalyst. The isolated cobalt sites are preserved upon calcination at high temperatures and during EDH operation under harsh conditions, resulting in superior durability in a long reaction period with negligible coke formation.

Effect of Introducing Thallium in Microporous Vanado-molybdate with Orthorhombic or Trigonal Structures and Catalytic Properties

Thallium-containing mixed vanadium and molybdenum oxides have been synthesized using a microwave-assisted hydrothermal method. The pH, the nature of the metal precursors, and the use of a structuring agent were shown to be key parameters of the synthesis; depending upon these parameters, trigonal (Tri) or orthorhombic (M1) structures were obtained. Both structures have been characterized by X-ray diffraction (XRD) and scanning and transmission electron microscopies (SEM and TEM, respectively). The orthorhombic phase has lattice parameters of a = 2.108 nm, b = 2.656 nm, c = 0.3997 nm and space group Pba2, and the trigonal phase, lattice parameters of a = 2.143 nm, c = 0.4004 nm and space group P3. In the orthorhombic phase, both hexagonal and heptagonal channels are partially but consistently occupied by thallium cations. The trigonal phase also exhibited both hexagonal and heptagonal channels; hexagonal channels were occupied by thallium cations, whereas the heptagonal channels appeared almost empty. The catalytic properties of the solids have been studied for the oxidative dehydrogenation of ethane and the oxidation of propene to acrylic acid. The orthorhombic phase was inactive; the trigonal phase, while not very active, had a high selectivity to ethylene. Although the occupancy rate of the heptagonal sites is probably low in the later phase, it strongly attenuates its activity.

A pseudo-local heat transfer approach in a low tube to particle diameter ratio packed bed catalytic reactor: Oxidative dehydrogenation of ethane as a case study

A generalized approach to model heat transfer in an industrial-scale wall-cooled packed bed reactor with a low tube-to-particle diameter ratio (<8) is proposed and assessed in this work. The modeling approach rests on the realization of experiments carried out in absence of reaction in bench-scale as well as in industrial-scale packed beds. The approximation overcomes historical limitations identified when modeling radial heat transfer mechanisms by applying conventional approaches. The methodology leads to the reliable determination of the external wall heat transfer coefficient and pseudo-local radial effective thermal conductivity. The approach allows the quantification of heat transfer resistances through the core, the internal and the external wall of the bed indicating that approximately 30 % of the resistances are located along the internal side of the packed bed when it was operated at Particle Reynolds numbers ranging from 700 to 1400. Because of its complex impact on heat transfer, fluid dynamics is accounted for by implementing a methodology that uses pressure drop data and the mass conservation criterion to describe velocity profiles, including the determination of the viscous and inertial resistances caused by solid surfaces at the core and near the wall. Finally, the heat transfer information is transferred to a pseudo-heterogenous model to simulate the performance of an industrial-scale wall-cooled packed bed reactor for the highly exothermic oxidative dehydrogenation of ethane. Simulations demonstrate both the reliability of the proposed heat transfer approach and the limitations of the conventional approximations when describing temperature profiles in a packed bed reactor.

Preparation of Shaped Binder‐Free SSZ‐13 Zeolite and Its Application in CO2 Adsorption and Catalysis

AbstractSSZ‐13, small‐pore zeolite with chabazite (CHA) topology, exhibits outstanding performance in gas adsorption‐separation and catalysis. However, most of the studies on SSZ‐13 zeolite are limited to the powder form. In practical application, the SSZ‐13 zeolite should be shaped with a certain amount of inert binder into technical form resulting in reduced performance. Herein, shaped binder‐free SSZ‐13 zeolite was prepared by treating the extruded SSZ‐13/SiO2 sample with amantadine solution under hydrothermal conditions, to crystallize the SiO2 binder into the zeolite phase. The characterization and DFT calculation results point out that the recrystallization of SiO2 binder in shaped SSZ‐13 into zeolite crystal could improve the physical and chemical properties. Enhanced CO2 adsorption capacity and catalysis performance in CO2‐assisted oxidative dehydrogenation of ethane and propane were also found on the shaped binder‐free SSZ‐13 zeolite.

Determination of highly active and selective surface for the oxidative dehydrogenation of ethane over phase-pure M1 MoVNbTeOx catalyst

The original phase-pure M1 MoVNbTeOx catalyst was mechanically treated with stirring water for several days under ambient conditions to obtain particles with different sizes. The catalytic performance was significantly improved and stabilized after about 7 days of treatment. Among all the catalysts, the sample treated in water for 7 days can obtain 57.6 % ethane conversion and 0.79 kgC2H4/kgcat/h ethylene productivity while the original phase-pure M1 catalyst was only 19.2 % and 0.27 kgC2H4/kgcat/h at reaction temperature of 400 °C and contact time of 18.5 gcat·h/molC2H6. Meanwhile, the catalyst was systematically characterized and the results showed that there was essentially no difference in microstructure between the original and treated catalysts. TEM and SEM morphological characterizations presented that the particle size and aspect ratio of the catalysts changed significantly, in which the particle size of the catalyst become smaller and the proportion of basal surface was enhanced. The activity and selectivity of the catalysts exhibited a correlation with the amount and proportion of basal surface. It can be deducted that the basal surface is the most active and selective surface during oxidative dehydrogenation of ethane (ODHE) process, and the intrinsic activity based on the basal (001) plane of the catalyst remains stable after the mechanical treatment. Samples treated in water for 7 days showed excellent long-term stability in a 200 h stability test at reaction temperature of 440 °C and contact time of 9.3 gcat·h/molC2H6. The present work demonstrated that the differences in the catalytic properties of different M1 samples depend mainly on the amount and proportion of exposed basal surface, and the possibility of enhancing the activity of orthorhombic M1 phase by fragmentation method.

Simultaneous generation of electricity, ethylene and decomposition of nitrous oxide via protonic ceramic fuel cell membrane reactor

Ethylene, one of the most widely produced building blocks in the petrochemical industry, has received intense attention. Ethylene production, using electrochemical hydrogen pump-facilitated nonoxidative dehydrogenation of ethane (NDE) to ethylene, is an emerging and promising route, promoting the transformation of the ethylene industry from energy-intensive steam cracking process to new electrochemical membrane reactor technology. In this work, the NDE reaction is incorporated into a BaZr0.1Ce0.7Y0.1Yb0.1O3−δ electrolyte-supported protonic ceramic fuel cell membrane reactor to co-generate electricity and ethylene, utilizing the Nb and Cu doped perovskite oxide Pr0.6Sr0.4Fe0.8Nb0.1Cu0.1O3−δ (PSFNCu) as anode catalytic layer. Due to the doping of Nb and Cu, PSFNCu was endowed with high reduction tolerance and rich oxygen vacancies, showing excellent NDE catalytic performance. The maximum power density of the assembled reactor reaches 200 mW cm−2 at 750 °C, with high ethane conversion (44.9%) and ethylene selectivity (92.7%). Moreover, the nitrous oxide decomposition was first coupled in the protonic ceramic fuel cell membrane reactor to consume the permeated protons. As a result, the generation of electricity, ethylene and decomposition of nitrous oxide can be simultaneously obtained by a single reactor. Specifically, the maximum power density of the cell reaches 208 mW cm−2 at 750 °C, with high ethane conversion (45.2%), ethylene selectivity (92.5%), and nitrous oxide conversion (19.0%). This multi-win technology is promising for not only the production of chemicals and energy but also greenhouse gas reduction.

The role of modified manganese perovskite oxide for selective oxidative dehydrogenation of ethane: Not only selective H2 combustion but also ethane activation

To break through the thermodynamic reaction limitation of ethane dehydrogenation to ethylene, the oxidative dehydrogenation in the presence of O2 and chemical looping oxidative dehydrogenation has been investigated with the oxygen storage oxide compound. LaMnO3 perovskite catalysts with large specific surface areas were prepared using citric acid-nitrate combustion. The oxygen vacancies and M4+ contents in the catalysts were improved by doping LaMnO3 as the active sites. The experimental results show that the catalyst not only promotes ethane dehydrogenation through selective hydrogen combustion but also promotes ethane conversion through activation of CH. The catalyst exhibits good stability in oxidative dehydrogenation reaction.

Exploration of Optical, Redox, and Catalytic Properties of Vanadia-Mayenite Nanocomposites

The present paper continues the exploration of the physicochemical and catalytic properties of vanadia-mayenite composites. The samples were prepared by an impregnation of calcium aluminate Ca12Al14O33 (mayenite, C12A7) with a solution of vanadium precursor. Pure mayenite and V/C12A7 nanocomposites were characterized by Raman and diffuse reflectance UV–Vis spectroscopies. The reducibility of the samples was examined in temperature-programmed reduction experiments performed in a hydrogen atmosphere. The catalytic performance of vanadium-containing systems was studied in the non-oxidative dehydrogenation of ethane. As found, the low-loaded sample (5%V/C12A7 sample) contains vanadium predominantly in the form of Ca3(VO4)2, while for the 10%V/C12A7 sample, two types of calcium vanadates (Ca2V2O7 and Ca3(VO4)2) are registered. The presence of these phases defines the spectroscopic characteristics and the redox properties of nanocomposites. Both the samples, 5%V/C12A7 and 10%V/C12A7, exhibit comparable catalytic activity, which is mainly connected with the amount of the Ca3(VO4)2 phase. The uniqueness of the studied catalysts is their excellent tolerance toward coke formation under the reaction conditions.

Synthesis and characterization of (Mo0.52V0.38W0.1)2O5 used as a catalyst in the oxidative dehydrogenation of ethane

This work presents a study of mixed molybdenum vanadium and tungsten oxides applied to oxidative dehydrogenation of ethane (ODE). Different oxides were prepared by a microwave-assisted hydrothermal method using oxalic acid as a reducing agent to obtain a crystalline phase of composition (Mo0.52V0.38W0.1)2O5. The materials were studied by XRF, BET, X-ray powder diffraction (XRD), transmission electron microscopy, IR, UV–Vis, TPR-H2 and XPS spectroscopy. The structure with space group C2/m is closely related to that of R–Nb2O5 with cell parameters a ​= ​1215.1 p.m., b ​= ​374.2 p.m., c ​= ​402.0 p.m., and β ​= ​90.70°. This phase is stable under reaction and active and selective to ethylene in the ODE reaction. Comparison with the literature indicates that R–Nb2O5-type matrices constitute an alternative to Mo5O14-type oxides to control the selectivity of active species in ODE.

Identification of the Intrinsic Active Site in Phase-Pure M1 Catalysts for Oxidation Dehydrogenation of Ethane by Density Functional Theory Calculations

Heterogeneous catalysts for alkane conversion reactions are required to possess both high activity for C–H bond cleavage and selectivity to target products. This work employed an atomic substitution strategy to investigate the active site of the phase-pure M1 MoVNbTeOx catalyst for the oxidation dehydrogenation of ethane (ODHE) reaction. Density of states and crystal orbital Hamilton population (COHP) based on density functional theory calculations indicated that the transition metal–O (M–O) bonds were weakened after H adsorption. Both integrated COHP and Bader charge were useful descriptors to correlate the electronic structure with catalytic performance. The results showed that the content of V in phase-pure M1 catalysts had a linear relationship with ethane conversion. Synergetic interactions between Te–O and V–O sites were accordingly considered as the intrinsic active sites for the ODHE reaction.

Catalytic Dehydrogenation of Ethane over Mn Oxide Supported on Zeolite Chabazite

AbstractA new class of Mn‐containing zeolites prepared by incipient wetness impregnation (IWI) have been found to catalyze the ethane dehydrogenation reaction with high selectivity (98 %+). Preparation by IWI leads to the formation of Mn2O3 nanoparticles on the external surface of the zeolite crystals and herein is shown that the primary active sites for the reaction are located on the surface of these particles. Propane dehydrogenation is also successfully catalyzed by this catalyst. Other Mn‐zeolites (MFI and BEA) also have high reactivity and selectivity towards light alkane dehydrogenation.