Highly Durable C2 Hydrocarbon Production via the Oxidative Coupling of Methane Using a BaFe0.9Zr0.1O3−δ Mixed Ionic and Electronic Conducting Membrane and La2O3 Catalyst

Analysis of oxidative coupling of methane in dense oxide membrane reactors

Performance of Zn-Al co-doped La2O3 catalysts in the oxidative coupling of methane

Catalyst-modified perovskite hollow fiber membrane for oxidative coupling of methane

Atomically dispersed SrOx species on exposed {2 2 2} facets of pyrochlore La2Zr2O7 nanocrystals for boosting low-temperature oxidative coupling of methane

Oxidative coupling of methane (OCM) on a conventional fixed-bed reactor (FBR) and a ceramic dense membrane reactor (DMR) packed with Li/MgO catalyst is analyzed using plug-flow reactor models. The validity of OCM kinetic equations employed in the modeling is confirmed by excellent agreement between the simulation and experimental data for OCM on FBR. For FBR, a high methane to oxygen feed ratio favors the OCM reaction, with a low C2 yield because of insufficient oxygen supply. The highest C2 yield achieved with a feed mixture consisting of 70% methane and 30% oxygen is 20.7% at a selectivity of 53% and operating temperature of 750 °C. The C2 yield and selectivity increase slightly at a higher operating temperature. The optimal feed ratio does not change with temperature. DMR is made of a mixed-conducting ceramic membrane tube packed with an OCM catalyst. The membrane tube separates the methane and oxygen feed. The oxygen concentration in the DMR is much lower and more uniform than that in the FBR because ...

Monolithic composites with geometry controlled by polymeric 3D printed templates: Characterization and catalytic performance in OCM

A new and very promising application of auto-thermal reactors is the coupling of endothermic and exothermic reactions where the product of the endothermic reaction is the desired one. Therefore, in this work, a reactor in which oxidative coupling of methane (OCM) and steam re-forming of methane (SRM) reactions take place simultaneously was modeled. The results were obtained in a wide range of different conditions such as inlet feed, inlet temperature, portions of OCM and SRM catalysts, and inlet velocity. In selection of the catalysts, more attention was drawn to prevent re-forming of OCM products. The main parameters of each reaction under different conditions such as conversion of the feed components, products selectivity and yield, temperature in the length of reactor, and component's concentration in the reactor were considered in course of this study. The results revealed that simultaneous OCM and SRM reactions in one reactor will tend to be auto-thermal, and the waste of energy will be reduced. The results also show that complete conversion of water and majority of methane and oxygen will decrease the amount of unwanted products at the reactor's discharge-a constraint that exists in single reactors of each reaction specially OCM.

To enhance CH4 conversion values in oxidative coupling of methane (OCM) reactions under an O2-lean condition (CH4/O2 = 6.0), a support vector regression (SVR) and one-hot encoding manner implemented machine learning (ML) is examined. From an open-source high-throughput screening (HTS) database of 300 OCM catalysts made by random sampling from a materials space, the top 10 three-element-supported catalysts with C2 yield higher than 11.0% and C2 selectivity higher than 80.0% at CH4/O2 = 6.0 were selected as targets for modification. Then, ML-aided investigation of an additive fourth element as a promoter was performed at the SVR field based on the HTS database among 350 catalysts (40,330 data points). Application of one-hot encoding to ascertain positive elements for CH4 conversion revealed that manganese (Mn) frequently appears at CH4 conversion higher than 44.0%. After the 10 selected catalysts were prepared with the Mn additive, their OCM performance was compared with those of pristine three-element-supported catalysts. Results show that four catalysts represent positive features on C2 yield in the presence of additive Mn working as a promoter. Consequently, 5 wt % Mn-loaded LiFeBa/La2O3 and LiBaLa/La2O3, respectively, show attractive OCM performance of 16.3% C2 yield with 88.4% selectivity and 13.8% C2 yield with 71.9% selectivity, even under an O2-lean condition (CH4/O2 = 6.0).

Oxidative Coupling of Methane (OCM) processes have been investigated as an alternative promising approach for ethylene production for the last three decades. Having considered the performance of the state-of-the-art OCM catalysts and the OCM reaction mechanism, improving the performance of the OCM membrane reactor could be considered as an important contribution to address such a complicated reactor engineering task. In this context, a systematic methodology implementing inorganic membranes, properly modified via silica-based materials, and the thereby achieved outstanding OCM membrane reactor performances are reported here. Moreover, the most important aspects of the performance analysis of OCM membrane reactors, especially in the context of the thermal-engineering characteristics of these systems, are discussed. Such analysis, for the most part, can be applied similarly to analyze other highly exothermic reaction systems in membrane reactors. Interactions between the membrane and the benchmark Mn–Na2WO4/SiO2 catalyst are also discussed. Furthermore, along with reviewing the general aspects of the model-based analysis of OCM membrane reactors, the potential of integrated OCM membrane reactors, such as dual-membrane reactors, is also highlighted. The special characteristics of modeling such non-isothermal reaction systems with significant mass and heat integration in both radial and axial dimensions are also reviewed.

Performance and reaction mechanism of Mg-doped and Li-doped La2O3 catalysts in oxidative coupling of methane: DFT and experiment study

The enhancement effects of BaX2 (X = F, Cl, Br) on SnO2-based catalysts for the oxidative coupling of methane (OCM)

Surface coupling of methyl radicals for efficient low-temperature oxidative coupling of methane

Conceptual Process Design and Economic Analysis of Oxidative Coupling of Methane

Oxidative coupling of methane using catalysts synthesized by solution combustion method: Catalyst optimization and kinetic studies

One of the great challenges in the field of heterogeneous catalysis is the conversion of methane to more useful chemicals and fuels. A chemical of particular importance is ethene, which can be obtained by the oxidative coupling of methane. In this reaction CH4 is first oxidatively converted into C2H6, and then into C2H4. The fundamental aspects of the problem involve both a heterogeneous component, which includes the activation of CH4 on a metal oxide surface, and a homogeneous gas‐phase component, which includes free‐radical chemistry. Ethane is produced mainly by the coupling of the surface‐generated CH radicals in the gas phase. The yield of C2H4 and C2H6 is limited by secondary reactions of CH radicals with the surface and by the further oxidation of C2H4, both on the catalyst surface and in the gas phase. Currently, the best catalysts provide 20% CH4 conversion with 80% combined C2H4 and C2H6 selectivity in a single pass through the reactor. Less is known about the nature of the active centers than about the reaction mechanism; however, reactive oxygen ions are apparently required for the activation of CH4 on certain catalysts. There is spectroscopic evidence for surface O− or O ions. In addition to the oxidative coupling of CH4, cross‐coupling reactions, such as between methane and toluene to produce styrene, have been investigated. Many of the same catalysts are effective, and the cross‐coupling reaction also appears to involve surface‐generated radicals. Although a technological process has not been developed, extensive research has resulted in a reasonable understanding of the elementary reactions that occur during the oxidative coupling of methane.