Ethane Dehydrogenation Reaction Research Articles

Boosting the Stability of Subnanometer Pt Catalysts by the Presence of Framework Indium(III) Sites in Zeolite.

Subnanometer metal clusters show advantages over conventional metal nanoparticles in numerous catalytic reactions owing to their high percentage of exposed surface sites, abundance of under-coordinated metal sites and unique electronic structures. However, the applications of subnanometer metal clusters in high-temperature catalytic reactions (>600 °C) are still hindered, because of their low stability under harsh reaction conditions. In this work, we have developed a zeolite-confined bimetallic PtIn catalyst with exceptionally high stability against sintering. A combination of experimental and theoretical studies shows that the isolated framework In(III) species serve as the anchoring sites for Pt species, precluding the migration and sintering of Pt species in the oxidative atmosphere at ≥650 °C. The catalyst comprising subnanometer PtIn clusters exhibits long-term stability of >1000 h during a cyclic reaction-regeneration test for ethane dehydrogenation reaction.

Boosting the Stability of Subnanometer Pt Catalysts by the Presence of Framework Indium(III) Sites in Zeolite

AbstractSubnanometer metal clusters show advantages over conventional metal nanoparticles in numerous catalytic reactions owing to their high percentage of exposed surface sites, abundance of under‐coordinated metal sites and unique electronic structures. However, the applications of subnanometer metal clusters in high‐temperature catalytic reactions (>600 °C) are still hindered, because of their low stability under harsh reaction conditions. In this work, we have developed a zeolite‐confined bimetallic PtIn catalyst with exceptionally high stability against sintering. A combination of experimental and theoretical studies shows that the isolated framework In(III) species serve as the anchoring sites for Pt species, precluding the migration and sintering of Pt species in the oxidative atmosphere at ≥650 °C. The catalyst comprising subnanometer PtIn clusters exhibits long‐term stability of >1000 h during a cyclic reaction‐regeneration test for ethane dehydrogenation reaction.

Isolated Pt Atoms Stabilized by Ga2O3 Clusters Confined in ZSM-5 for Nonoxidative Activation of Ethane.

Selective activation of light alkanes is an essential reaction in the petrochemical industry for producing commodity chemicals, such as light olefins and aromatics. Because of the much higher intrinsic activities of noble metals in comparison to non-noble metals, it is desirable to employ solid catalysts with low noble metal loadings to reduce the cost of catalysts. Herein, we report the introduction of a tiny amount of Pt (at levels of hundreds of ppm) as a promoter of the Ga2O3 clusters encapsulated in ZSM-5 zeolite, which leads to ∼20-fold improvement in the activity for ethane dehydrogenation reaction. A combination of experimental and theoretical studies shows that the isolated Pt atoms stabilized by small Ga2O3 clusters are the active sites for activating the inert C-H bonds in ethane. The synergy of atomically dispersed Pt and Ga2O3 clusters confined in the 10MR channels of ZSM-5 can serve as a bifunctional catalyst for the direct ethane-benzene coupling reaction for the production of ethylbenzene, surpassing the performances of the counterpart catalysts made with PtGa nanoclusters and nanoparticles.

The types of metal M and crystal surface in the PtM (M = Co, Ni, Zn) IMCs catalysts to regulate catalytic performance of ethane direct dehydrogenation

PtM IMCs have improved catalytic performance of ethane dehydrogenation (EDH), however, identifying the functions of the types of metal M and crystal surface for the PtM IMCs catalysts in regulating EDH catalytic performance are still a challenge in experiment. This work fully investigated catalytic performance of EDH over three crystal surfaces (110), (111) and (200) of PtM IMCs (M = Co, Ni, Zn) by using density functional theory (DFT) calculations and kinetic Monte Carlo (kMC) simulations. The results show that the catalytic performance of EDH over PtM IMCs strongly depend on the types of metal M and crystal surfaces, the PtZn(111) catalyst is screened out as the most promising in EDH reaction with the optimal reaction temperature of 773.15 K. The geometrically isolated Pt site in the [PtM3] assembly of PtZn(111) could catalyze the CH cleavage, and C2H4* exhibits weak π-adsorption model at the individual Pt sites, promoting C2H4* desorption. Compared to (110) and (200) surfaces, the (111) surface with moderate Bader charge transfer showed the highest C2H4(g) production activity, and Zn atoms transferred more electrons to Pt atoms, which greatly weakened the charge transfer between C2H4* and the catalyst surface, favoring C2H4* desorption to inhibit C2H4* deep dehydrogenation. Moreover, the catalytic performance of PtZn(111) catalyst is superior to the industrially used PtSn catalyst. This work provides valuable structure clue for the design of high-performance catalyst in alkane direct dehydrogenation.

Non-oxidative ethane dehydrogenation reaction over molybdenum and chromium incorporated MgO encapsulated carbon-core catalysts in microwave reactor

Chromium and molybdenum incorporated MgO and MgO–C catalysts were synthesized for hydrogen production from a non-oxidative ethane dehydration reaction. Hydrogen production studies were carried out using a microwave-heated reactor system. The study investigated the effects of reaction temperature, type of active metal, and catalyst preparation method (physical mixture or core–shell structure) on hydrogen selectivity and ethane conversion during dehydrogenation reactions. The results showed that the optimal reaction temperature for the non-oxidative ethane dehydration reaction was 450 °C. Above this temperature, the selectivity of undesired byproducts increased. Catalysts containing molybdenum exhibited higher ethane conversion. Moreover, a comparison of MgO–C-supported catalysts with MgO-supported catalysts revealed that the core–shell catalysts exhibited superior ethane conversion. Notably, the 5Mo@MgO–C catalyst demonstrated exceptional catalytic activity, achieving a high ethane conversion rate of 72% along with excellent stability.

An active and stable catalyst of Zn modified Pt nanoparticles encapsulated within silicalite-1 zeolite for dehydrogenation of ethane

The rapid deactivation of catalysts for ethane dehydrogenation (EDH) at considerably higher temperature and the relatively inert feature of ethane makes it urgent to develop highly active and stable catalysts. Herein, a Zn modified Pt nanoparticles confined within silicalite-1 (S-1) zeolite catalyst for EDH reaction was synthesized by hydrothermal synthesis using the PtZn/SiO2 precursor without any protective ligands, which achieved extremely high catalytic performance (e.g., 15.9 % conversion which was close to the thermodynamic equilibrium limitation, 99.5 % ethylene selectivity, and 0.001 h−1 the deactivation rate). Multiple characterizations with XPS, in situ CO-DRIFTS, in situ C2H6-DRIFTS, TG-DTA, and Raman techniques on these catalysts revealed that the electron-rich Pt sites with stable electronic environment formed by Zn promoter introduced, resulting in enhanced anti-reduction and coke-resistance abilities. Furthermore, characterizations with XRD, HRTEM, Py-IR, hydroxyl vibration region of DRIFT spectra and 1H MAS NMR spectroscopic analysis showed that the dilution effect of Zn and the trapping of zinc and platinum species by Si-OH groups in the form of (≡Si-O-Zn)xPt complex could inhibit migration and aggregation, resulting in smaller metal particles and increase anti-sintering ability. The superior catalytic performance as well as the environmental benign preparation route with no-ligand will further contribute to the advantages for future applications.

Effect of Zn–Brønsted acid in zeolites on ethane dehydrogenation with tandem reverse water gas shift reaction

The abundant hydroxyl groups and tunable Brønsted acid sites (BAS) of MWW zeolites were used to introduce and anchor zinc active sites, preventing the volatilization and deactivation of ZnOx due to its reduction to Zn0. Fabricated Zn/MWW catalysts effectively promoted ethane dehydrogenation (EDH) and tandem complex reaction of dehydroaromatization and CO2 oxidative dehydrogenation at high temperatures. Brønsted Zn/MWW catalysts containing [ZnOH]+ were prepared via incipient wetness impregnation using liquid ion exchange whereas those containing [ZnOx]2+ were prepared via atom planting using the gas dechlorination reaction. Additionally, the different acidic sites in MWW zeolites effectively affected the interaction between ZnCl2 and hydroxyl groups during the dechlorination reaction. The catalytic EDH performance of [ZnOx]2+ active sites generated using stronger BASs was higher than that of [ZnOx]2+ active sites generated via weaker BASs and silanol. The synergetic effect of Zn and BASs in zeolites catalyzed dehydroaromatization can be suppress by control the [ZnOH]+ location in the external surface of zeolite or by homogenous consumption of the BAS by [ZnOx]2+. Furthermore, [ZnOH]+ and [ZnOx]2+ catalyzed the reverse water gas shift reaction, accelerated the rate-limiting step of EDH via the CO2 oxidative EDH reaction, inhibited the selectivity of aromatics, and consumed coke via the Boudouard reaction.

Cobalt catalyzed ethane dehydrogenation to ethylene with CO2: Relationships between cobalt species and reaction pathways

TiO2, ZrO2 and a series of TiO2-ZrO2 (TxZ1, x means the atomic ratio of Ti/Zr = 10, 5, 1, 0.2 and 0.1) composite oxide supports were prepared through co-precipitation, and then 3 wt% Co was loaded through wetness impregnation methods. The obtained 3 wt% Co/TiO2 (3CT), 3 wt% Co/ZrO2 (3CZ) and 3 wt% Co/TxZ1 (3CTxZ1) catalysts were evaluated for the oxidative ethane dehydrogenation reaction with CO2 (CO2-ODHE) as a soft oxidant. 3CT1Z1 catalyst exhibits excellent catalytic properties, with C2H4 yield, C2H6 conversion and CO2 conversion about 24.5 %, 33.8 % and 18.0 % at 650 °C, respectively. X-Ray Diffraction (XRD), in-situ Raman, UV–vis diffuse reflectance spectra (UV–vis DRS), H2 temperature-programmed reduction (H2-TPR), Electron paramagnetic resonance (EPR) and quasi in-situ X-ray Photoelectron Spectroscopy (XPS) have been utilized to thoroughly characterize the investigated catalysts. The results revealed that 3CT1Z1 produced TiZrO4 solid solution with more metal defect sites and oxygen vacancies (Ov), promoting the formation of Co2+-TiZrO4 structure. Furthermore, the presence of Ov and Ti3+can facilitate the high dispersion and stabilization of Co2+, as well as suppressing the severe reduction of Co2+, leading to superior ethane oxidative dehydrogenation activity. Besides, less Co0 is beneficial to ODHE reaction, because of its promotion effects for reverse water gas shift reaction; however, more Co0 results in dry reforming reaction (DRE). This work will shed new lights for the design and preparation of highly efficient catalysts for ethylene production.

Role of active oxygen species in Fe-doped ZrO2 catalyst during CO2 assisted ethane dehydrogenation reaction

CO2 assisted ethane dehydrogenation provides a promising route for the utilization of shale gas and greenhouse gas. This study investigates the role and evolution of active oxygen species over Fe-doped ZrO2 catalysts in distinct dehydrogenation reactions via Mars-van Krevelen mechanism. Fe doping led to an increase in active oxygen species (from 12.9% to 23.4%) benefitted from the phase transformation of ZrO2. This enhancement significantly boosted ethane dehydrogenation activity from 5.0 to 16.1 mmolEthene/gCat/h. In the absence of CO2, the ethane conversions rapidly decreased with a deactivation rate constant (kd) of 0.930 h−1 due to the irreversible oxygen species loss and coke deposition. Although the catalytic stability of the optimal catalyst was greatly improved (kd = 0.006 h−1) after CO2 introduction, a decrease in ethane conversion occurred when CO2 could not supplement oxygen species due to the formation of coke layers. A simple O2 oxidation can effectively restore stable activity during 5 reaction-regeneration cycles for 3600 mins.

Light-enabled coupling of tandem ethane dehydrogenation and CO2 hydrogenation

The integration of electromagnetic energy into a thermal reaction is beneficial in catalytic performance and product distribution. To date, such a photothermal strategy has mainly been applied to relatively low-temperature reactions, such as CO2 hydrogenation, and its application to high-temperature reactions has yet to be explored. Herein, electromagnetic energy is successfully introduced into a tandem ethane dehydrogenation and CO2 hydrogenation system over a Zn-based catalyst. According to the experiments and theoretical simulations, light enables a new reverse water-gas shift reaction, which consumes the produced H2 and thus right shifts the ethane dehydrogenation reaction and enhances the catalytic performance. The resulting ethylene rate could achieve 11.5 mmol g−1 h−1 with a selectivity of 96%, and the estimated external quantum efficiency is up to 18.85% under weak light intensity (2 sun). In the meantime, the ethylene rate could be improved by about 600-fold with higher light intensities.

Single‐Atom Fe Catalyst for Catalytic Ethane Dehydrogenation to Ethylene

AbstractThe single atom catalysts (SACs) show unique catalytic performance in heterogeneous reactions owing to unsaturated coordination sites and high metal atom dispersion. Herein, a simple wet impregnation method was utilized to synthetize of Fe−Al2O3 catalysts. The Fourier transformation infrared spectroscopy (FTIR) revealed that abundant OH group attached to the support (Al2O3) surface facilitating formation of isolated Fe single atom. High resolution transmission electron microscope (HR‐TEM) and extended X‐ray absorption fine structure (EXAFS) confirmed the Fe single atom architecture. Fe−Al2O3 (4.5 wt %) performed enhanced stability and activity on ethane dehydrogenation reaction.

Ethane dehydrogenation over manganese oxides supported on ZSM-5 zeolites

Mn-ZSM5 catalysts are shown to have high reaction rates, C2H4 selectivity and stability for ethane dehydrogenation 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.

Comparative investigation of Ga- and In-CHA in the non-oxidative ethane dehydrogenation reaction

Ga- and In-exchanged chabazite (CHA) zeolites with same Si/Al and metal/Al ratios were prepared via the incipient wetness impregnation method, were characterized using N2 adsorption, electron microscopy, temperature-programed reactions and were evaluated for the ethane dehydrogenation reaction using flow microreactors. Ga-CHA has higher reaction rates and a lower activation energy of 107 kJ/mol than In-CHA (Ea = 175 kJ/mol). Rietveld refinement of the X-ray powder diffraction pattern shows that the In+ cation is predominantly located above the 6-ring of the CHA cage. It is proposed that the reaction proceeds through the alkyl mechanism based on stability of alkyl hydride intermediates as determined using DFT calculations. The oxidative addition of ethane to the metal shows much lower Gibbs free energy for Ga-CHA (+27.95 kJ/mol) vs In-CHA (+124.85 kJ/mol). These results indicate that oxidative addition may be the rate-limiting step of ethane dehydrogenation in these materials.

Influence of ZrO2 crystal structure on the catalytic performance of Fe-Ni catalysts for CO2-assisted ethane dehydrogenation reaction

The catalytic reaction of ethane with CO2 promotes the value-added conversion of natural gas and the resource utilization of greenhouse gases. In this work, the CO2-assisted ethane dehydrogenation reaction characteristics on Fe1.5Ni0.5/ZrO2(M, T, Mix) catalyst with different crystal plane structure were studied through catalyst activity test, catalytic reaction kinetics study and catalyst characterization analysis. It is found that the exposed crystal faces of the ZrO2-supported catalyst has a significant effect on the CO2-assisted ethane oxidative dehydrogenation reaction. The monoclinic phase Fe1.5Ni0.5/ZrO2-M catalyst exhibits the largest conversion of ethane (21.8%) and CO2 (25.2%) and the maximum selectivity to C2H4 (80.5%). Monoclinic phase of ZrO2 selectively exposes the (−111) and (111) low-index surfaces with higher oxygen vacancy (Ov) density and stronger metal-support interaction, which leads to the formation of more FexZr1-xO2 structures with high catalytic activity. The reductive oxygen vacancy Ov and Fe2+-O-Zr3+ sites promote the activation of CO2 through the cleavage of C=O bond to supplement O* species. The O* species on the oxidative Fe3+-O-Zr4+ site are captured and combined with H* species derived from the selective cleavage of ethane C–H bond to generate H2O.

Pure silica-supported transition metal catalysts for the non-oxidative dehydrogenation of ethane: confinement effects on the stability

All-silica MFI zeolite was used as a support for the synthesis of promoter-free robust transition metal catalysts. Effects of different physical parameters and catalyst deactivation mechanism were studied for the ethane dehydrogenation reaction.

Comparative Investigation of Ga- and In-Cha in the Non-Oxidative Ethane Dehydrogenation Reaction

Comparative Investigation of Ga- and In-Cha in the Non-Oxidative Ethane Dehydrogenation Reaction

Exploring bimetallic alloy catalysts of Co, Pd and Cu for CO2 reduction combined with ethane dehydrogenation

First principles theoretical analysis, employing the age-old Sabatier principle and microkinetic modelling, is undertaken to rationally design bimetallic alloy catalysts of Co, Pd and Cu for CO2 assisted ethane dehydrogenation reaction. Using CO2 as a mild oxidant, the reaction aims to convert a part of natural gas and meet the increasing demand of ethylene, while also mitigating the growing levels of CO2 in the atmosphere. The in silico mean field microkinetic model (MKM) facilitates the selection of bimetallic alloy catalysts based on several criteria which include; equal or enhanced conversion of CO2 and ethane, higher yield of ethylene and reduced coke formation. Catalyst compositions are evaluated at the reaction temperature of 873 K and an inlet composition of ethane and carbon dioxide as 1:1. Six bimetallic alloy catalysts are proposed as potential candidates for CO2 assisted ethane dehydrogenation reaction – CoFe, CoPd, PdNi, CuNi, CuSn and CuPt. Out of these, three alloys (CoFe, CuNi, and CuSn) consist of cheaper metals and hold considerable potential for experimental testing and scale-up studies.

CO2reduction and ethane dehydrogenation on transition metal catalysts: mechanistic insights, reactivity trends and rational design of bimetallic alloys

Reactivity trends of transition metal catalysts, studied for the ethane dehydrogenation reaction using CO2as a mild oxidant.

Non-oxidative dehydrogenation of ethane to ethylene over ZSM-5 zeolite supported iron catalysts

The shale gas boom has stimulated tremendous interests in ethylene production using ethane as the feedstock. Catalytic non-oxidative ethane dehydrogenation (EDH) to ethylene represents a viable strategy to improve the process energy efficiency and to minimize the environmental impact. The breakthroughs in catalyst design play a key role in the successful development of this process. Herein, we demonstrate that iron supported on ZSM-5 zeolite (Fe/ZSM-5) is a highly efficient catalyst for the EDH reaction. Under comparable conditions, Fe/ZSM-5 exhibits superior activity and stability over various metal (Pt) or metal oxide catalysts (Zn, Ga, Cr, Mo) supported on ZSM-5. The use of ZSM-5 instead of conventional γ-Al2O3 as the support for Fe catalysts is critical to achieve high activity and selectivity in the EDH reaction. Detailed structure characterizations combined with density functional calculations indicate that iron oxides in the as-prepared Fe/ZSM-5 catalysts are reduced to iron metal and then carburized under reaction condition, which accounts for the excellent activity and stability for the EDH reaction. Compared with Fe/Al2O3, the relatively weaker binding strength of ethylene and the weaker surface acidity on Fe/ZSM-5 allow facile desorption of ethylene, which suppresses its consecutive transformation into higher hydrocarbons and carbon deposits, resulting in higher ethylene selectivity.