Catalysts For Conversion Of Methane Research Articles

In situ generation of active ⋅OH on Co-SrTiO3 tandem catalyst for conversion of methane to methanol

Recently in <i>Chem Catalysis</i>, He and co-workers proposed the efficient conversion of methane to methanol under moderate conditions via the active O species <i>in situ</i> generated from photo-splitting of H₂O over Co-SrTiO₃ tandem catalysts. Using characterization techniques, the authors determined the intermediates and mechanism of the reaction.

Understanding the CH4 Conversion over Metal Dimers from First Principles.

Inspired by the advantages of bi-atom catalysts and recent exciting progresses of nanozymes, by means of density functional theory (DFT) computations, we explored the potential of metal dimers embedded in phthalocyanine monolayers (M2-Pc), which mimics the binuclear centers of methane monooxygenase, as catalysts for methane conversion using H2O2 as an oxidant. In total, 26 transition metal (from group IB to VIIIB) and four main group metal (M = Al, Ga, Sn and Bi) dimers were considered, and two methane conversion routes, namely *O-assisted and *OH-assisted mechanisms were systematically studied. The results show that methane conversion proceeds via an *OH-assisted mechanism on the Ti2-Pc, Zr2-Pc and Ta2-Pc, a combination of *O- and *OH-assisted mechanism on the surface of Sc2-Pc, respectively. Our theoretical work may provide impetus to developing new catalysts for methane conversion and help stimulate further studies on metal dimer catalysts for other catalytic reactions.

Conversion of CH4 Catalyzed by Gas Phase Ions Containing Metals.

Methane is an abundant and cheap feedstock to produce valuable chemicals. The catalytic reaction of methane conversion generally requires the participation of multiple molecules (such as two or three CH4 molecules, O2 , CO2 , etc.). Such complex process includes the cleavage of original chemical bonds, formation of new chemical bonds, and desorption of products. The gas phase study provides a unique arena to gain molecular-level insights into the detailed mechanisms of bond-breaking and bond-forming involved in complicated catalytic reactions. In this Review, we introduce the methane conversion catalyzed by gas phase ions containing metals and three topics will be discussed: (1) the direct coupling of methane molecules, (2) the conversion of CH4 with O2 , O3 and N2 O, and (3) the conversion of CH4 with CO2 and H2 O. The obtained mechanistic aspects may provide new clues for rational design of better-performing catalysts for conversion of methane to value-added products.

Study of Double Perovskites A2mgmoo6 (A=Sr, Ba) as Catalysts for Methane Conversion

Study of Double Perovskites A2mgmoo6 (A=Sr, Ba) as Catalysts for Methane Conversion

Tailoring trimetallic CoNiFe oxide nanostructured catalysts for the efficient electrochemical conversion of methane to methanol

The electrochemical conversion of methane to methanol and other oxygenates is of considerable importance to address pressing environmental and energy issues.

Direct oxidation of methane to oxygenates on supported single Cu atom catalyst

Catalytically converting CH4 to chemicals and fuels is of paramount importance but remains a major challenge to simultaneously obtain high activity and selectivity. Here, we report Cu1/ZSM-5 single atom catalyst is highly active (C1 oxygenates productivity of 4800 μmol⋅gcat−1 at 50 °C and 12,000 μmol⋅gcat-1 at 70 °C within 30 min) and selective (C1 oxygenates selectivity of 99 % at 50 °C) for direct CH4 oxidation, comparable to most of those state-of-the-art noble metal catalysts. The combined DFT calculation, electronic microscope, X-ray absorption and electron paramagnetic resonance results confirm that each isolated Cu atom stabilized by four O moieties on the ZSM-5 support possesses uniform Cu1-O4 entity as active site and preferentially activates CH4 instead of CH3OH that is advantageous for highly selective C1 oxygenates production, especially for methanol. Our molecular-level finding on the atomic structure of Cu active site paves the way to design better catalysts for methane conversion.

Metal phenanthroline-based porous polymeric hybrid catalysts for direct conversion of methane

The direct conversion of tremendous greenhouse gas methane into various value-added chemical products or energy fuels is not only a concern associated with an economic interest but also related to environmental protection. However, neither industry nor academia has an effective or low-cost way to directly achieve this result. Herein, a high specific area (962 m2 g−1) porous organic polymer was designed and used as a substance to support catalytic active sites, including PdBr2, Pd(OAc)2, and well-dispersed AuPd bimetallic nanoparticles which were reduced via hydrogen flow. The as-synthesized catalysts (HNU-2 and HNU-3) can not only maintain the porous and stable structure of their pristine matrix but also show extremely high catalytic performance in methane direct transformation systems for preparing methanol derivative methyl trifluoroformate. Our simple strategy provides a complementary alternative to application of methane via an efficient one-step conversion procedure in order to reduce its impact on climate change and obtain value-added chemicals.

Nature of Cu active sites in zeolite-based catalysts for selective catalytic oxidation of methane

Though copper-containing zeolites (Cu–zeolites) have shown great potential in the direct conversion of methane to methanol under low temperature, the yields of methanol and the catalytic efficiency remain far behind the necessary level for industrialization. The recent progress in Cu–zeolites catalysts for the direct conversion of methane to methanol by selective oxidation, especially in the investigation on the nature of Cu active species presented in zeolites, was summarized in this mini-review.

Use of Surfactants in Manufacture of Catalysts for Conversion of Methane

Effects are compared of various surfactants on the properties of an impregnating solution of nickel and aluminum nitrates in the condensate, used in manufacture of supported catalysts for conversion of methane. It was shown that use of synthanols (oxyethylated alcohols, which are nonionogenic surfactants) makes it possible to significantly (by three orders of magnitude) reduce the necessary content of surfactants in solution, which is confirmed by many years of industrial experience. Results are presented of quantum-chemical calculations of the interaction of synthanol molecules with nickel ions. The use of synthanol can substantially reduce the probability of carbonization of the catalyst surface and the possible carryover of a part of metal ions with the impregnating solution and also diminish the toxicity and the explosion hazard in the production area.

Catalytically active coatings for steam reforming systems: synthesis and catalytic properties

The paper considers science and engineering aspects of catalytically active compositions creation as regards immobilized catalysts for reforming hydrocarbon raw materials into hydrogen fuel. The authors investigate synthesis of catalytic powder mixtures and manufacturing of functional coatings by supersonic cold gas dynamic spraying. Research results in the field of creation of catalysts for steam conversion of methane to hydrogenous fuel on the metal support (Cr15Al15 tape support) are given. Composite powder mixtures (Ni–Al–Al(OH)3– Ca(OH)2–Mg(OH)2) were used as starting materials.

Development of a Ni–Pd/CeZrO2/Al2O3 catalyst for the effective conversion of methane into hydrogen-containing gas

The effects of the Pd content (0–1 wt %) and the synthesis method (joint impregnation with Ni + Pd and Pd/Ni or Ni/Pd sequential impregnation) on the physicochemical and catalytic properties of Ni–Pd/CeZrO2/Al2O3 were studied in order to develop an efficient catalyst for the conversion of methane into hydrogen-containing gas. It was shown that variation in the palladium content and a change in the method used for the introduction of an active constituent into the support matrix make it possible to regulate the redox properties of nickel cations but do not affect the size of NiO particles (14.0 ± 0.5 nm) and the phase composition of the catalyst ((γ + δ)-Al2O3, CeZrO2 solid solution, and NiO). It was established that the activity of Ni–Pd catalysts in the reaction of autothermal methane reforming depends on the method of synthesis and increases in the following order: Ni + Pd < Ni/Pd < Pd/Ni. It was found that, as the Pd content of the Ni–Pd/CeZrO2/Al2O3 catalyst was decreased from 1 to 0.05 wt %, the ability for self-activation, high activity, and operational stability of the catalyst under the conditions of autothermal methane reforming remained unaffected: at 850°C, the yield of hydrogen was ~70% at a methane conversion of ~100% during a 24-h reaction.

Effect of the conditions of thermal pretreatment on the properties of Mo/ZSM-5 catalyst of the nonoxidative conversion of methane

Mo-containing zeolite catalysts for the nonoxidative conversion of methane are produced via solid-phase synthesis, followed by thermal treatment at different temperatures. The state of nanosized Mo powders is investigated by means of X-ray diffraction and thermal analysis. The effect the temperature of Мо/ZSM-5 catalyst annealing has on its acidic characteristics and activity in the process of methane dehydroaromatization is established.

Materials and technologies for gas feedstock processing: Challenges, prospects, and solutions

The Russian Federation has large gas resources, and an increase in the share of their chemical processing is a topical problem, solution of which involves many scientific teams. This paper describes innovative achievements of the author and his colleagues in developing highly efficient catalysts for methane conversion into ethylene and synthesis gas—key large-tonnage semiproducts of the chemical industry. The prospects of creating corresponding technologies and their practical implementation are discussed. In particular, for the most active catalysts of ethylene production, technical conditions and a production technology have been developed and introduced at the Baltic Enterprise (Baltiiskaya Manufaktura) research and production company. Within the framework of cooperation with the Gazprom public joint-stock company, technical conditions for catalysts for synthesis gas production have been developed and approved, mathematical modeling has been conducted, and options of reactor units and a process flowsheet have been proposed.

Catalytic Upgrading of Methane to Higher Hydrocarbon in a Nonoxidative Chemical Conversion

Discovery of large shale gas reserves in recent years resulted in the reduction of natural gas price. In order to convert methane in a direct and energy efficient route, nonoxidative catalytic conversion is a potentially attractive option which includes an activation of methane molecules at low temperature. The oxide of transition metals such as Mo, Fe, V, W, Cr, Zn, and Cu have been studied as catalysts for methane conversion, where usually the conversion is lower than 20% and the operating temperature needed is above 800 °C which causes coking, thus resulting in an early catalyst deactivation. In this work, a noble transition metal, ruthenium, has been chosen as the catalyst with the objective to decrease the methane activation temperature, increase the stability, and also achieve higher conversion than other transition metal catalysts. The catalyst was prepared as 1.5 or 3.0 wt % ruthenium loading on zeolite (i.e., ZSM-5) and silica supports separately to compare the effect of metal loading and metal–s...

Synthesis of Urchin‐Like FeF2 Nanoarchitectures and Their Conversion into Three‐Dimensional Urchin‐Like Mesoporous α‐Fe2O3 Nanoarchitectures for Methane Activation

AbstractNovel urchin‐like FeF2 nanoarchitectures have been fabricated by an unconventional nonhomogeneous ionic liquid/diphenyl ether solvothermal method. Subsequent solid‐state thermal annealing was utilized to convert the FeF2 nanoarchitectures into 3D urchin‐like mesoporous α‐Fe2O3 nanoarchitectures. The reaction system and temperature played important roles in the morphology of FeF2 and the growth of the 3D urchin‐like α‐Fe2O3. A study of methane activation over the 3D urchin‐like mesoporous α‐Fe2O3 nanoarchitectures revealed that methane was activated and converted into carbon dioxide at a low temperature (230 °C). Compounds containing C–C bonds were produced at 600 °C. This 3D urchin‐like mesoporous α‐Fe2O3 shows excellent potential as a catalyst for methane conversion in the chemical industry.

Application of BaTiO3 as anode materials for H2S-containing CH4 fueled solid oxide fuel cells

Undoped BaTiO3 perovskite oxide is more effective than SrTiO3 and La2Ti2O7 oxide as anode catalyst in SOFC fueled with H2S-containing methane. Electrochemical performance, impedance spectroscopy and other characterizations show that pure BaTiO3 is a good anode catalyst for conversion of methane in SOFC, especially in H2S-containing atmospheres. Compared with SrTiO3 and La2Ti2O7 samples, the BaTiO3−based fuel cell has higher resistance to carbon deposition, better electrochemical performance and much higher stability during long term operation. A maximum power density of 135 mW cm−2 was achieved at 900 °C with 0.5% H2S–CH4 in a fuel cell having a 300 μm thick YSZ electrolyte. High catalytic activity for methane conversion, mixed electronic and ionic conductivity, and the surface basicity of BaTiO3 unexpectedly provides promising performance as anodes in SOFC.

Ionic liquids as novel catalysts for methane conversion under a DC discharge plasma

Nine imidazolium-based ionic liquids were investigated as novel catalysts for methane conversion in a direct current (DC) discharge plasma reactor. The conversion of methane increased from 21.2% to 43.6% in the plasma system when the C6MIMHSO4 IL was used as a catalyst, C6MIMBF4 successfully achieved 91.0% selectivity for C2 hydrocarbons. The results of the optical emission spectroscopy indicate that the intensity of the C2, CH, H, C+, and C active species from methane decomposition increased when C6MIMHSO4, C6MIMCF3COO, and C6MIMBF4 were introduced into the plasma system. FTIR analysis indicates that C6MIMBF4 is steady in the DC discharge plasma.

Metal–Organic Frameworks of Vanadium as Catalysts for Conversion of Methane to Acetic Acid

A catalytic system combining the high activity of homogeneous catalysts and the ease of use of heterogeneous catalysts for methane activation is reported. The vanadium-containing metal-organic frameworks (MOFs) MIL-47 and MOF-48 are found to have high catalytic activity and chemical stability. They convert methane selectively to acetic acid with 70% yield (490 TON) based on K(2)S(2)O(8) as an oxidant. Isotopic labeling experiments showed that two methane molecules are converted to the produced acetic acid. The MOF catalysts are reusable and remain catalytically active for several recycling steps without losing their crystalline structures.

Silica-supported tantalum clusters: catalysts for conversion of methane with n-butane to give ethane, propane, and pentanes

Si02-supported tantalum clusters were prepared by adsorption of the precursor Ta(CH2Ph)5 (Ph is phenyl) on the support followed by treatments in H2 at 523, 623, and 723 K. The resultant clusters, had approximate average diameters of 0.3, 0.8, and 2 nm, as determined by extended X-ray absorption fine structure (EXAFS) spectroscopy. The samples were tested as catalysts for conversion of methane with n-butane in a once-through flow reactor operated at atmospheric pressure and 523 K, and EXAFS spectroscopy was used to characterize the used catalysts. The results show that (a) the catalysts are active for the conversion of methane with n-butane to give ethane, propane, and pentanes; (b) catalytic activity decreased to nearly zero over a time on stream of 22 h; (c) the catalyst incorporating the smallest clusters exhibited the highest initial activity and that incorporating the largest clusters exhibited the lowest activity; (d) each used catalyst contained clusters of approximately the same nuclearity as the respective fresh catalyst, but with Ta–Ta bond lengths approximately 0.17 A longer than those found in the fresh catalysts. The data are consistent with catalysis by the supported clusters, and the product distributions are consistent with disproportionation of n-butane accompanied by the reaction of methane with propane to give other alkanes.

Research On a Ceramics Membrane Reactor for Natural Gas Conversion

We explore the new concept for a ceramics membrane reactor including the investigation of the nickel-based catalysts for methane conversion into synthesis gas and the exploitation of an oxide ionic and electronic mixed conductor. When Ca0.8Sr0.2Ti1−xFe x O3−α exhibiting the ionic and electronic mixed conduction was used as a support material of Ni based catalyst, coke formation over the catalyst under the methane conversion with air or carbon dioxide was strongly depended on the iron (III) ion contents, x. From the relationship between the amount of carbon deposited on the catalyst and the mixed conduction in support oxide materials, it was suggested that the self-migration of lattice oxygen inside the support regulated by the balance between the oxide ionic and electronic conductivities played an important role to prevent from accumulating the deposited carbon over the catalysts. In addition, we demonstrated the methane conversion into synthesis gas at 1173 K with one component ceramics membrane reactor constructed with the same type of perovskite-type oxide for both the catalyst supported and mixed conductor.