Ethylene Yield Research Articles

Protonic ceramic fuel cells for power-ethylene cogeneration: A modelling study on structural parameters

Protonic ceramic fuel cells (PCFCs) are promising electrochemical devices to achieve power-ethylene cogeneration. A model of a tubular C2H6-fed PCFC, including an internal reforming section (IRS) and an electrochemical reaction section (ERS), is constructed to investigate the effects of structural parameters on the cogeneration performance. Increasing cell length and ERS markedly enhance the ethylene yield. The highest ethylene yield of 44% is obtained in a 10 cm PCFC at 973 K. The positive effect of thickening the entire anode or IRS on yield is not as pronounced as extending the cell length or ERS. Except that the increase of IRS thickness leads to the decrease of the current density, the increase of other structural parameters causes the current density to increase first and then decrease. By decreasing the ERS ratio, the current density can be enhanced up to 14% and reaches the highest value of 2235 A m−2 at 973 K in an 8 cm PCFC with a 30% ERS ratio. This model provides an insightful understanding of the interrelationship between the structural parameters and the cogeneration performance of PCFC. This model can also serve as a valuable tool for the PCFC fuelled with other hydrocarbons.

A CuZn-BTC derived stable Cu/ZnO@SiO2 catalyst for ethanol dehydrogenation

Cu-based catalysts play pivotal role in many industrial processes, however, its application under high temperature is restricted due to the low Tammann temperature of Cu. Improving the stability and activity of Cu-based catalysts at high temperature is a challenge. In this work, a stable Cu/ZnO@SiO2 catalyst was prepared, in which silicon was introduced into CuZn-BTC precursor via a steam-assisted hydrolysis method before calcination and reduction. Characterizations found that Cu/ZnO@SiO2 catalyst prepared via above strategy possesses increased surface area, more exposed active sites and excellent stability for ethanol dehydrogenation than Cu/ZnO (prepared from CuZn-BTC without SiO2). It was confirmed that the space-time yield of acetaldehyde reached 9.0 g-acetaldehyde/g-cat/h, and Cu/ZnO@SiO2 could maintain its activity within 200 h at 350 °C due to the ZnO decorated Cu particles (Cu/ZnO) were encapsulated in the octahedral shaped SiO2 hollow.

Increased Light Olefin Production by Sequential Dehydrogenation and Cracking Reactions

In this study, a sequential reaction using selected metal oxides, followed by ZSM-5-based catalysts, was employed to demonstrate a promising route for enhancing light olefin production in the catalytic cracking of naphtha. The rationale for the reaction is based on the induction of alkenes into hydrocarbon feeds prior to cracking. The optimum olefin induction was achieved by carefully optimizing the dehydrogenation active sites Mo/Al2O3 catalyst. The formed alkenes have a lower activation energy for C-H/C-C bond breaking compared to alkanes. This could accelerate the formation of carbenium ions, thus promoting the conversion of n-octane to produce light olefins. Detailed product distribution and DFT calculation indicated a remarkable increase in ethylene and propylene production in the final product through a modified reaction pathway. Compared with the common metal-promoted zeolite catalysts, the new route could avoid the block of zeolite channels and corresponding decreased catalytic cracking activity. The feasibility of the proposed route was confirmed with different ratios of dehydrogenation catalyst to the reactant. The highest yields of ethylene and propylene reached 13.22% and 33.12% with ratios of Mo/Al2O3 and ZSM-5-based catalyst to n-octane both 10:1 at 600 °C. Stability tests showed that the catalytic activity of the double-bed system was stable over 10 cycles.

Mechanistic origin of transition metal modification on ZSM-5 zeolite for the ethylene yield enhancement from the primary products of n-octane cracking

In this work, n-octane has been selected to represent the alkane content in the naphtha for the catalytic cracking over Mn-ZSM-5 and Fe-ZSM-5 catalysts. Various characterization techniques are applied to quantify the possible active sites. The introduction of transition metal cations does not influence the strength of BAS. Therefore, the change on kinetic behavior is the contribution from newly generated LAS. Upon the elucidation of their roles in different adsorption scenarios, it is found that the new LAS establishes new adsorption equilibrium with olefin molecule formed from the thermal cracking, making the remaining alkane molecules adsorb and react on the BAS with minimum coverage of olefin. It is therefore favorable for the enhancement of ethylene yield in the primary cracking products. Furthermore, the unfavorable energy requirement of the carbonium ion pathway is compensated by the boosted activation entropy via the pathway change, as suggested by the kinetic analysis.

Conversion of ethanol to acetaldehyde using (NiO/Al2O3) as a catalyst

The conversion of ethanol to acetaldehyde in an atmospheric integral up flow reactor (inside diameter and height equal to 2.0 and 80 cm respectively)which was studied in order to find the optimum reaction temperature, the effect of ethanol concentration and flow rate according to the type of catalyst used. The proposed dehydrogenation method offers several advantages over the various production processes advantages are cheap raw (ethyl alcohol) and the reaction occur at atmospheric pressure. The (NiO/Al2O3) catalyst was prepared in laboratory using ten gram of catalyst in the reaction, the studied temperature range was 250-325° C at atmospheric pressure, the ethanol mole Concentration ranging between 90% - 100% mole and the flow rate was 1-4 ml/min Where (NiO/Al2O3) catalyst was employed the maximum yield of acetaldehyde is 43% mole and the conversion of ethyl alcohol at the optimum reaction conditions is 74% mole.

A novel strategy for rapid identification of pyrolytic synergy and prediction of product yield: Insight into co-pyrolysis of xylan and polyethylene

The distributions of biomass and plastic co-pyrolysis products are complicated by abundant component combinations, pyrolysis conditions, and synergies. Herein, the hierarchical clustering analysis (HCA) and response surface methodology (RSM) were used to rapidly determine synergies and predict product yields of xylan and polyethylene (PE) co-pyrolysis at 500–700 °C. The results showed that co-pyrolysis promoted liquid production and suppressed solid and char formation. Pyrolytic interactions improved the decomposition of the PE-derived wax, resulting in 1.5–1.9- and 1.7–2.1-fold higher yields of heavy gas oil and C≥26 hydrocarbons compared to the theoretical values. HCA classified pyrolyzates with similar synergy into the same cluster, which reflected the suppressed carbonyl compound production, enhanced furfural and phenols yields at 700 °C, and greater C17–C30 hydrocarbon production. The quadratic model of RSM predicted the yields of gas, CO, C3Hn, C4Hn, liquid, ethanol, acetaldehyde, hydrocarbon oil, gasoline, solid, and char influenced by synergies. Owing to complex interactions, the cubic model fitted the CH4 and C2H4 yields. The linear model described the CO2 yield without synergy. This work illustrates the utility of combining RSM and HCA to predict product distributions of various waste co-treatment processes.

Enhanced Isopropyl Alcohol Conversion over Acidic Nickel Phosphate-Supported Zeolite Catalysts.

In this preliminary research, the catalytic activity of isopropyl alcohol conversion to diisopropyl ether through dehydration reaction catalyzed by zeolite-Ni and zeolite-Ni(H2PO4)2 was comparatively described. The natural zeolite was treated with 1% HF and 6 N HCl prior to modifications using the impregnation method. Isopropyl alcohol conversion was examined at a mild temperature of 150 °C for 3.5 h on the reflux system with various catalyst loadings. X-ray diffraction and Fourier transform infrared analysis confirmed the successful impregnation of nickel and nickel phosphate into the zeolite. Scanning electron microscopy analysis revealed a cubic-like structure on zeolite-Ni(H2PO4)2, whereas homogenously distributed nickel species were observed on the zeolite-Ni catalyst. Energy-dispersive X-ray spectroscopy analysis reinforced the accomplishment of zeolite modifications. The N2 physisorption isotherms showed a decline in the surface area and total pore volume of the zeolite because of the blocking of pores. The zeolite-Ni(H2PO4)2 catalyst had higher acidity than unmodified zeolite and zeolite-Ni catalysts, which inherently suggested that the presence of phosphate groups results in higher catalytic activity toward isopropyl alcohol. The highest catalytic activity was attained by 8 mEq/g metal loading zeolite-Ni(H2PO4)2 with isopropyl alcohol conversion of 81.51%, diisopropyl ether yield, and selectivity of 40.77 and 33.16%. The reusability study suggested that the zeolite-Ni(H2PO4)2 catalyst was still active and had sufficient catalytic activity stability toward isopropyl alcohol after the third cycle was reused. This nickel phosphate-based modified zeolite was adequately potential for diisopropyl ether production through isopropyl alcohol dehydration.

A low carbon route to ethylene: Ethane oxidative dehydrogenation with CO2 on embryonic zeolite supported Mo-carbide catalyst

The study reports a novel catalyst based on supported molybdenum-carbide (Mo2C) phase for oxidative dehydrogenation of ethane with CO2 (ODH-CO2). The optimal result is obtained with MoS2-precursor as the intermediate supported on a non-acidic embryonic zeolite, which is transformed in situ to Mo2C (Mo2C@EZ). The ultimate catalyst and its intermediates are characterized. 66% conversion of ethane, 58% of ethylene yield, and 56% conversion of CO2 to CO with the in situ co-produced hydrogen obtained from ethane to ethylene transformation are the achievements of utilizing Mo2C@EZ. The performed techno-economic study on Mo2C@EZ results in a potentially CO2 negative route for ethylene production with 109% of CO2 reduction per ton of produced ethylene in comparison with a conventional ethane cracker. The process is expected to be cheaper in capital expenditure (CAPEX) and operating expenses (OPEX) thanks to a simpler product slate, lower energy demand, and no requirement for steam dilution.

Immobilization of HPW on UiO-66-NH2 MOF as efficient catalyst for synthesis of furfuryl ether and alkyl levulinate as biofuel

Phosphotungustic Acid (HPW) is an inorganic super acid, that is highly soluble in polar solvents limiting its applicability as acid catalysis. To overcome these limitations immobilization of HPW was carried out at room temperature by protonation of -NH2 group of UiO-66-NH2 MOF to UiO-66-NH2HPW. ATR-FTIR spectroscopy and XPS results confirmed the protonation and chemical interaction between HPW and UiO-66-NH2. STEM-EDS mapping showed homogeneous distribution of HPW on UiO-66-NH2. BET and NH3-TPD confirmed the reduction in specific surface area, total pore volume, and increase in total acidity for UiO-66-NH2HPW. Further, powder XRD, SEM, and HR-TEM prevailed that there is no change in phase and morphology after post-synthetic modification of UiO-66-NH2. The prepared catalyst is found to be effective for etherification and alcoholysis of furfuryl alcohol (FALc) to Furfuryl ether (FE) and Alkyl levulinate (AL). UiO-66-NH2HPW has shown 97 mol% FALc conversions in ethanolic media and 31 mol% Ethyl furfuryl ether (EFE) yield and 29 mol% Ethyl levulinate (EL) yield. UiO-66-NH2HPW is also found to be efficient for the multistep conversion of Furfural (FFR) to FALc, FE, and AL.

Main-Group Catalysts with Atomically Dispersed In Sites for Highly Efficient Oxidative Dehydrogenation

Transition metal oxides are well-known catalysts for oxidative dehydrogenation thanks to their excellent ability to activate alkanes. However, they suffer from an inferior alkene yield due to the trade-off between the conversion and selectivity induced by more reactive alkenes than alkanes, which obscures the optimization of catalysts. Herein, we attempt to overcome this challenge by activating a selective main-group indium oxide considered to be inactive for oxidative dehydrogenation in conventional wisdom. Atomically dispersed In sites with the local structure of [InOH]2+ anchored by substituting the protons of supercages in HY are enclosed to be active centers that enable the activation of ethane with a metal-normalized turnover number of almost one magnitude higher than those of their supported In2O3 counterparts. Furthermore, the structure of isolated [InOH]2+ sites could be stabilized by in situ formed H2O from the selective oxidation of hydrogen by In2O3 nanoparticles. As a result, the as-designed main-group In catalysts exhibit 80% ethene selectivity at 80% ethane conversion, thus achieving 60% ethene yield due to active isolated [InOH]2+ sites and selective In2O3 nanoparticles, outperforming state-of-the-art transition metal oxide catalysts. This study unlocks new opportunities for the utilization of main-group elements and could pave the way toward a more rational design of catalysts for highly efficient selective oxidation catalysis.

Influence of hydrotalcite/rosasite precursors over Cu/Zn/Al mixed oxides on ethanol dehydrogenation

Cu/Zn/Al mixed oxides catalysts were obtained from their corresponding layered precursors synthesized by coprecipitation of components varying M(II)/M(III) molar ratios of 2, 3, and 4 while maintaining Cu2+/Zn2+ molar ratio at 1.0. Crystalline phases concentration in the precursors was determined by Rietveld refinement analysis. Hydrotalcite (HTLc) phase concentration decreased from 79 to 32 wt % as M(II)/M(III) molar ratio increased from 2 to 4, respectively. A constant value of M(II)/M(III) molar ratio of 1.3–1.4 was determined for HTLc formation independently of the M(II)/M(III) molar ratio used for the synthesis. The excess of M(II), Cu and Zn components, segregate as Rosasite phase. Therefore, mixed oxides with different surface properties were obtained depending on the precursor crystalline phase component. Precursor with mainly HTLc phase generates mostly a homogenous Cu/Zn/Al mixed oxide where Al atoms hinder Cu reduction. On that sample no Cu0 was detected by XPS, then, hydrogen consumption during its reduction process was related to the presence of anionic vacancies, where H2 can be heterolytically dissociated and stored in its hydric form, generating highly active hydro/dehydrogenation sites, with highest Lewis acidity. When the mixed oxides come from a precursor with mainly Rosasite phase, mixed oxides decompose into Cu0, ZnO, and Al2O3 during reduction, where metallic Cu0 acts as dehydrogenating sites during ethanol dehydrogenation to acetaldehyde. In fact, higher Cu surface concentration favors the dehydrogenation route, increasing the yield towards acetaldehyde, whereas a high Al surface concentration enhances the dehydration path increasing diethyl ether yield.

Shock Tube/Laser Absorption Measurements of Cyclopentadiene Pyrolysis.

High-temperature cyclopentadiene pyrolysis was examined behind reflected shock waves in a heated shock tube using several laser absorption diagnostic schemes. A two-color, online-offline sensor near 3335 cm-1 was used to measure time histories of acetylene, while a three-color scheme of diagnostics at 10.532, 10.675, and 11.345 μm yielded measurements of cyclopentadiene and ethylene. Species time histories of cyclopentadiene decomposition and acetylene formation as well as ethylene yields are reported from 1319 to 1678 K at 1.2-1.5 atm. In addition, the overall decomposition rate of cyclopentadiene is reported, and comparisons are made to a number of kinetic models.

Direct grafting synthesis of bi-functional Zr–Al-MWW zeolites and their catalytic characteristics in Lewis-Brønsted cascade reaction

A series of Zr–Al-MWW zeolites with different Zr state and layer-stacking structure are successfully synthesized via direct grafting zirconocene dichloride onto the external silanols of three kinds of MWW zeolites, i.e. MCM-22 with multilayered structure, ITQ-2 (through layer delaminated route) and OL-MWW (by direct hydrothermal synthesis) with oligolayered structure. The structure, porosity and state of grafted Zr species are distinctly different among the three Zr–Al-MWW zeolites. Zr-OL-MWW possesses the highest content of single Zr atoms with an ideal micro-meso-macro pore system, while Zr-MCM-22 and Zr-ITQ-2 contain two kinds of Zr species (ZrO2 clusters and single Zr atoms) coexisting in various proportions. The high dispersion of single Zr atoms on OL-MWW can be assigned to the large amount of external silanols of OL-MWW. The as-prepared three bi-functional Zr–Al-MWW zeolites are used for the cascade Meerwein-Ponndorf-Verley (MPV) reduction and etherification (ETH) reaction. Among them, Zr-OL-MWW shows dramatically higher conversion of cinnamaldehyde and yield of 1-cinnamyl 2-propyl ether than Zr-MCM-22 and Zr-ITQ-2, owing to the higher catalytic activity of Lewis acid centers from single Zr atoms, as well as more integrated framework Al sites as Brønsted acid centers with good accessibility. This study offers a simple and efficient strategy to construct Lewis-Brønsted acidic zeolites with exposed heteroatom sites and integrated framework structure, which will provide especial potential in the catalytic conversion of macromolecules.

Ethylene production over A/B-site doped BaCoO3 perovskite by chemical looping oxidative dehydrogenation of ethane

Ethylene is a valuable and widely used platform inindustrial chemical. Herein, we report a potential route for selective and efficient ethylene production via chemical looping oxidative dehydrogenation of ethane using alkaline, rare earth and transition metals modified BaCoO3 perovskite as the circulative redox catalyst. The catalysts were characterized by XRD, XPS, SEM, TEM, N2 adsorption-desorption, H2-TPR, and O2-TPD analyses. Results showed that ethane conversion and ethylene selectivity were mainly regulated by lattice oxygen and Co valence of the catalysts, respectively. Doping of La to A-site of BaCoO3 promoted ethane conversion while doping of Cu to B-site contributed to ethylene selectivity. Both ethane conversion and ethylene selectivity were enhanced by the co-doping of La and Cu to A/B-site of BaCoO3, obtaining the highest selectivity of 81.2% at ethane conversion of 67.6%. The ethylene yield over Ba0.7La0.3Co0.8Cu0.2O3 was 7.9% higher than that over patent BaCoO3 (53.7% versus 45.8%). In addition, the Ba0.7La0.3Co0.8Cu0.2O3 catalyst also exhibited a stable catalytic performance during 12 redox recycles.

Porous Ni−Al−O Fabricated by a Facile Hydrothermal Method: Improved Catalytic Performance for the Oxidative Dehydrogenation of Ethane to Produce Ethylene

AbstractThe oxidative dehydrogenation of ethane (ODHE) to ethylene is a process with many advantages (such as energy conservation and coke resistance). Herein, flower‐like Ni−Al−O catalysts with hierarchical structure and high surface areas were fabricated through a hydrothermal route and were applied to ODHE using O2 as oxidant. Compared with NiO alone, the Al3+ insertion into NiO matrix not only increases the C2H4 selectivity by 3–4 times, but also prevents the generation of CO2 and CH4 above 500 °C. At 550 °C, all Ni−Al−O catalysts maintain approximately 50 % ethylene selectivity regardless of Al content. The ethylene yield of 29.5 % with C2H4 selectivity 55.7 % over Ni−Al0.8‐O sample can be reached at 500 °C. Moreover, the Ni−Al0.8‐O catalyst presents a good stability and has no loss of activity after 100 h continuous evaluation. The various characterizations were carried out for investigating the nature of as‐prepared Ni−Al−O catalysts with different Al loadings. Experimental results demonstrate that the addition of Al not only affects the structure and texture properties of NiO, but also impacts the reducibility of Ni species and the amount of active oxygen species. It is found that the Al3+ substitution results in: (1) smaller NiO size; (2) larger specific surface area; (3) weaker reducibility and (4) fewer non‐stoichiometric oxygen species. Therefore, the significant improvement of ethylene selectivity is observed in Ni−Alx‐O catalysts.

Enhancement of acetylene and ethylene yields in partially decoupled oxidation of ethane by changing the composition of heat carrier

In our previous work, a partially decoupled process (PDP) was proposed for efficient conversion of ethane to increase the ethylene yield and a new structural reactor called forward-impinging-back reactor (FIB) was proposed for scale-up. In this work, the influence of changing the composition and temperature of the heat carrier was investigated by simulations with detailed chemistry to further increase of the C2 (C2H2 + C2H4) yield in the PDP of ethane. At ideal mixing conditions, the C2 yield is 75.3% without steam addition and it is 82.9% at steam addition ratio of β = 1.4. In comparison, the C2 yield in an FIB reactor is 62.4% without steam addition and it increases to 78.5% with steam addition (β = 1.4). The requirement of high mixing efficiency is diminished by steam addition, which is favorable for reactor scale-up.

Optimization of ethylene dichloride (EDC) and ethane concentrations to maximize catalytic ethylene oxide production rate and yield: Experimental study and modeling

Simultaneous optimization of EDC and ethane concentrations to maximize ethylene oxide production rate (rEO) over a commercial catalyst at 17.4 bar, 213–240 °C and in the GHSV range of 3000–5000 h−1 was done in this study. The feed composition and operating conditions were chosen similar to those in the industry, so that the findings are practical. EDC and ethane concentrations in the feed are merged into a practical parameter referred to as equivalent EDC (EDCeq) in this study which is indicative of the chlorinating power of the gas mixture. It was noticed that the higher the temperature, the higher the optimum EDCeq to maximize rEO. Although rEO had a decreasing trend versus EDCeq for 213 °C, it showed a maximum with EDCeq for 225 and 240 °C. While CO2 production rate (rCO2) monotonically decreased with EDCeq, EO selectivity experienced an upward trend with EDCeq, approaching a horizontal asymptote.

Electroreductive C[sbnd]O coupling of benzaldehyde over SACs Au–NiMn2O4 spinel synergetic composites

Electroreductive CO coupling provides a prospective strategy for biomass derivative upgrading via reducing the number of oxygen-containing functional groups and increasing their molecular weight. However, exploring superior electrocatalysts with effective reactivity and high selectivity for target products are still a challenge. In this work, single atom Au surface derived NiMn2O4 (SACs Au−NiMn2O4) spinel synergetic composites were fabricated by a versatile adsorption-deposition method and applied in electroreductive self-coupling of benzaldehyde to dibenzyl ether. The SACs Au–NiMn2O4 spinel synergetic composites enhanced electroreductive coupling of benzaldehyde, significantly improved the yield and selectivity of dibenzyl ether. Systematic characterizations and density functional theory calculation revealed that atomically dispersed Au occupied surface Ni2+ vacancies, which played a dominated role in CO coupling of benzaldehyde. Detailed calculation results showed that benzaldehyde preferred to adsorb on Ni octa-hedral sites of NiMn2O4 spinel synergetic structure, single atom Au surficial derivation over NiMn2O4 further reduced the adsorption energy (Eads) of benzaldehyde on SACs Au−NiMn2O4, thus the CO coupling of benzaldehyde to dibenzyl ether was promoted. Moreover, single atom Au surficial derivation lowered the energy barrier of rate-determining step, facilitated the formation of dibenzyl ether species. Our work also paves an avenue for rational design single atom materials using spinel as support.

Modulation effects of Cu modification and ligands (oxalate and borohydride) functionalization on Pt d-band center, upper d-band edge, and alloyed PtCe support acidity on semihydrogenation of acetylene

The modulating effects of Cu modification and oxalate or borohydride ligands functionalization on the structure, catalyst d-band center (εd), upper d-band edge (εu), and acetylene partial hydrogenation of expediently synthesized Ce alloyed Pt supported catalysts were investigated. Firstly, a 5 wt% Pt alloyed Ce was synthesized via flame spray pyrolysis. The PtCe sample was further supported on zeolite Y, ZY, (PtCe/ZY) and copper modified ZY (PtCe/Cu-ZY). Furthermore, the PtCe was supported on two other oxalate and borohydride ligands functionalized copper modified ZY (PtCe/CuX-ZY and PtCe/CuB-ZY, respectively). The high-angle annular darkfield scanning transmission electron microscopy (HAADF/STEM) data showed a reduction in the PtO average particle size from 2.65 nm in PtCeO2 to average 1.73, 0.64, and 0.30 nm in PtCe/Cu-ZY, PtCe/CuX-ZY, and PtCe/CuB-ZY, which was corroborated by the electron energy-loss spectroscopy (EELS) results wherein nonhomogeneous mixing of elements was seen with segregated Pt clusters in the non-functionalized samples. Conversely, both PtCe/CuX-ZY and PtCe/CuB-ZY samples showed near-perfect homogeneity with no distinct Pt signals. The measured εu values for PtCe, PtCe/Cu-ZY, PtCe/CuX-ZY, and PtCe/CuB-ZY are +1.85, +0.40, −0.15, and −0.19 eV, respectively. The positive values indicated strong metal-adsorbate bonding typical of large Pt sizes while the negative values indicated weak metal-adsorbate bonding due to highly downsized Pt sizes. The ethylene yield (YC2H4) over the PtCe sample showed depletion as the reaction temperature increased, while it reflected maxima at 120 °C with 55.3% YC2H4 over PtCe/ZY. The maxima shifted to 180 °C with enhanced YC2H4 of 71.4% in PtCe/Cu-ZY. On the contrary, both PtCe/CuX-ZY and PtCe/CuB-ZY exhibited a monotonous increase in YC2H4 up to the maximum C2H2 conversion with YC2H4 of 81.9% and 92.1% at 180 and 160 °C, respectively. These results showed that both the Cu modification and ligands functionalization were highly invaluable to enhance the properties and activities of the semihydrogenation of acetylene (SHA) catalysts.

Effect of the particle blending-shaping method and silicon carbide crystal phase for Mn-Na-W/SiO2-SiC catalyst in oxidative coupling of methane

Supported Mn-Na-W on silica is a benchmark catalyst for oxidative coupling of methane due to its appropriate ethylene yields. Here we compare eight catalysts with the same active phase (Mn-Na-W) and variable support composition or particle blending-shaping method to evaluate the effect of the support. First, we explore the different preparation methods (impregnation, ball milling, and spray-drying), concluding that spray-drying leads to a promising selective catalyst. Then, we compare different SiC crystal phases (α+β and β), keeping the same composition and shaping method (spray-drying). The catalyst with α+βSiC crystal phase has significantly more activity than the β one in 30 h reaction runs. Finally, we assess the effect of process conditions to improve the yields (15 % at 800°C) of the most promising catalyst: spray-dried and with α+βSiC. The roles of the blending-shaping method and SiC crystal phase are explained by the induced differences in oxidation behavior and active phase distributions.