Highly selective photocatalytic conversion of methane to liquid oxygenates over silicomolybdic-acid/TiO2 under mild conditions

Kaedah peminimuman jumlah tenaga Gibbs sangat berguna untuk menganalisis kemungkinan penukaran metana kepada hidrokarbon dan syngas pada suhu dan tekanan tertentu secara teoritikal. Keputusan numerik menunjukkan penukaran metana meningkat dengan peningkatan kepekatan oksigen dan suhu tindak balas. Bagaimanapun, kehadiran oksigen merencat pembentukan hidrokarbon tinggi yang kebanyakannya mengandungi aromatik, tetapi menggalakkan pembentukan hidrogen. Apabila tekanan sistem bertambah, hasil aromatik, olefin dan hidrogen berkurang, tetapi hasil parafin meningkat. Karbon monoksida menjadi produk mengandungi oksigen yang utama daripada pengoksidaan metana sementara hampir tiada H2O, CH3OH and HCOH yang dikesan walaupun sejumlah kecil karbon dioksida terbentuk pada suhu yang agak rendah dan tekanan tinggi. Kata kunci: Keseimbangan kimia termodinamik, peminimuman jumlah tenaga Gibbs, penukaran metana, hidrokarbon tinggi The total Gibbs energy minimization method is useful to theoretically analyze the feasibility of methane conversion to higher hydrocarbons and syngas at the selected temperature and pressure. Numerical results showed that the conversion of methane increased with oxygen concentration and reaction temperature, but decreased with pressure. Nevertheless, the presence of oxygen suppressed the formation of higher hydrocarbons that mostly consisted of aromatics, but enhanced the formation of hydrogen. As the system pressure increased, the aromatics, olefins and hydrogen yields diminished, but the paraffin yield improved. Carbon monoxide seemed to be the major oxygen-containing equilibrium product from methane oxidation whilst almost no H2O, CH3OH and HCOH were detected although traces amount of carbon dioxide were formed at relatively lower emperature and higher pressure. Key words: Thermodynamic chemical equilibrium, Gibbs energy minimization, methane conversion, higher hydrocarbons

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Methane Conversion Under Mild Conditions Using Semiconductors and Metal-Semiconductors as Heterogeneous Photocatalysts: State of the Art and Challenges

Frontiers in Chemistry ◽

10.3389/fchem.2021.685073 ◽

2021 ◽

Vol 9 ◽

Author(s):

Eliane Ribeiro Januario ◽

Patrícia Ferreira Silvaino ◽

Arthur Pignataro Machado ◽

Jorge Moreira Vaz ◽

Estevam Vitorio Spinace

Keyword(s):

High Temperatures ◽

Chemical Industry ◽

Methane Conversion ◽

State Of The Art ◽

Extreme Conditions ◽

Mild Conditions ◽

Photochemical Conversion ◽

Conversion Of Methane ◽

Challenges And Opportunities ◽

Fuels And Chemicals

The processes currently used in the chemical industry for methane conversion into fuels and chemicals operate under extreme conditions like high temperatures and pressures. In this sense, the search for methane conversion under mild conditions remains a great challenge. This review aims to summarize the use semiconductors and metal-semiconductors as heterogeneous photocatalysts for methane conversion under mild conditions into valuable products. First, a brief presentation of photochemical conversion of methane is provided and then the focus of this review on the use of heterogeneous photocatalysts for methane conversion are described. Finally, the main challenges and opportunities are discussed.

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Engineering PdAu Nanowires for Highly Efficient Direct Methane Conversion to Methanol under Mild Conditions

The Journal of Physical Chemistry C ◽

10.1021/acs.jpcc.1c04252 ◽

2021 ◽

Author(s):

Mingjun Zhong ◽

Yueshan Xu ◽

Jing Li ◽

Zi-Xin Ge ◽

Chunman Jia ◽

...

Keyword(s):

Methane Conversion ◽

Mild Conditions ◽

Highly Efficient

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Genomic and Transcriptomic Analyses of the Facultative Methanotroph Methylocystis sp. Strain SB2 Grown on Methane or Ethanol

Applied and Environmental Microbiology ◽

10.1128/aem.00218-14 ◽

2014 ◽

Vol 80 (10) ◽

pp. 3044-3052 ◽

Cited By ~ 40

Author(s):

Alexey Vorobev ◽

Sheeja Jagadevan ◽

Sunit Jain ◽

Karthik Anantharaman ◽

Gregory J. Dick ◽

...

Keyword(s):

Methane Oxidation ◽

Coenzyme A ◽

Draft Genome ◽

Carbon Assimilation ◽

Tca Cycle ◽

Content Type ◽

The Tca Cycle ◽

Conversion Of Methane ◽

Oxidative Transformations ◽

Rate Limiting

ABSTRACTA minority of methanotrophs are able to utilize multicarbon compounds as growth substrates in addition to methane. The pathways utilized by these microorganisms for assimilation of multicarbon compounds, however, have not been explicitly examined. Here, we report the draft genome of the facultative methanotrophMethylocystissp. strain SB2 and perform a detailed transcriptomic analysis of cultures grown with either methane or ethanol. Evidence for use of the canonical methane oxidation pathway and the serine cycle for carbon assimilation from methane was obtained, as well as for operation of the complete tricarboxylic acid (TCA) cycle and the ethylmalonyl-coenzyme A (EMC) pathway. Experiments withMethylocystissp. strain SB2 grown on methane revealed that genes responsible for the first step of methane oxidation, the conversion of methane to methanol, were expressed at a significantly higher level than those for downstream oxidative transformations, suggesting that this step may be rate limiting for growth of this strain with methane. Further, transcriptomic analyses ofMethylocystissp. strain SB2 grown with ethanol compared to methane revealed that on ethanol (i) expression of the pathway of methane oxidation and the serine cycle was significantly reduced, (ii) expression of the TCA cycle dramatically increased, and (iii) expression of the EMC pathway was similar. Based on these data, it appears thatMethylocystissp. strain SB2 converts ethanol to acetyl-coenzyme A, which is then funneled into the TCA cycle for energy generation or incorporated into biomass via the EMC pathway. This suggests that some methanotrophs have greater metabolic flexibility than previously thought and that operation of multiple pathways in these microorganisms is highly controlled and integrated.

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On the Mechanism of Methane Conversion in the Nonсatalytic Processes of Its Thermal Pyrolysis and Steam and Carbon Dioxide Reforming

Petroleum Chemistry ◽

10.1134/s0965544121110037 ◽

2021 ◽

Author(s):

E. Busillo ◽

V. I. Savchenko ◽

V. S. Arutyunov

Keyword(s):

Carbon Dioxide ◽

Methane Conversion ◽

Carbon Dioxide Reforming ◽

Temperature Range ◽

Thermal Pyrolysis ◽

First Order Kinetics ◽

Initial Stage ◽

Conversion Of Methane ◽

Exponential Factors ◽

Kinetics Of

Abstract A detailed kinetic modeling of the noncatalytic processes of thermal pyrolysis and steam and carbon dioxide reforming of methane revealed almost completely identical kinetics of the methane conversion in these processes. This suggests that, in the temperature range 1400–1800 K, the initial stage of conversion of methane in all these processes is its thermal pyrolysis. The modeling results agree well with the experimental data on methane pyrolysis. For the temperature range examined, the Arrhenius expressions (pre-exponential factors and activation energy) were obtained in the first-order kinetics approximation for the rate of methane conversion in the processes studied. The expressions derived may be useful for making preliminary estimates and carrying out engineering calculations.

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Single Chromium Atoms Supported on Titanium Dioxide Nanoparticles for Synergic Catalytic Methane Conversion under Mild Conditions

Angewandte Chemie ◽

10.1002/ange.201913309 ◽

2019 ◽

Vol 132 (3) ◽

pp. 1232-1235 ◽

Cited By ~ 3

Author(s):

Qikai Shen ◽

Changyan Cao ◽

Runkun Huang ◽

Lei Zhu ◽

Xin Zhou ◽

...

Keyword(s):

Titanium Dioxide ◽

Methane Conversion ◽

Titanium Dioxide Nanoparticles ◽

Mild Conditions

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Influence of Co2 on the Catalytic Performance Of La2O3/CeO2 and CaO/CeO2 Catalysts in the Oxidative Coupling of Methane

Polish Journal of Chemical Technology ◽

10.2478/pjct-2013-0005 ◽

2013 ◽

Vol 15 (1) ◽

pp. 22-26 ◽

Cited By ~ 5

Author(s):

Barbara Litawa ◽

Piotr Michorczyk ◽

Jan Ogonowski

Keyword(s):

Oxidative Coupling ◽

Methane Conversion ◽

Catalytic Properties ◽

Catalytic Performance ◽

Negative Influence ◽

Oxidative Coupling Of Methane ◽

Oxygen Mixture ◽

Impregnation Method ◽

Promoting Effect ◽

Conversion Of Methane

In this work the La2O3/CeO2 (33 mol % of La) and CaO/CeO2 (33 mol % of Ca) catalysts were prepared by the impregnation method and characterized by XRD and CO2-TPD. The catalytic properties of the catalysts were tested in the OCM process at 1073 K using the methane/oxygen mixture of the mole ratio 3.7 or 2.5 additionally containing CO2 and helium balance. It was found that in the presence of both catalysts an addition of CO2 enhances the selectivity to the ethylene and ethane and it does not have any negative influence on methane conversion. In the case of the CaO/CeO2 catalyst the promoting effect of CO2 was the highest. When the partial pressure of CO2 equals to 39 kPa the increase in selectivity from 36 to 41% was noted while the conversion of methane equal to 19.4-19.7 %.

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XPS AND FTIR STUDIES OF Mo/ZSM-5 CATALYSTS FOR NONOXIDATIVE CONVERSION OF METHANE TO AROMATICS

Surface Review and Letters ◽

10.1142/s0218625x0100152x ◽

2001 ◽

Vol 08 (06) ◽

pp. 627-632 ◽

Cited By ~ 3

Author(s):

H. Y. CHEN ◽

S. TANG ◽

Z. Y. ZHONG ◽

J. LIN ◽

K. L. TAN

Keyword(s):

Methane Conversion ◽

Active Sites ◽

Reaction Times ◽

Initial Reaction ◽

Oxygen Treatment ◽

Conversion Of Methane ◽

Xps Study ◽

Nonoxidative Conversion ◽

First Time

In this investigation, several Mo/ZSM-5 catalysts with various Mo loadings and various reaction times were prepared, and methane conversion to aromatics without the presence of oxygen was studied by microreactor evaluation, FTIR and XPS. It was found, for the first time, that oxygen treatment before the reaction could shorten the induction period of this reaction. In situ FTIR study indicated the formation of [Formula: see text] species ( 888 cm -1) and O–Al ( 670 cm -1) on the surface of the catalyst as a result of the oxygen treatment. The two IR bands shifted to 854 and 659 cm -1 respectively when 18 O 2 was used. These oxygen species may take part in the initial reaction and shorten the induction time. The XPS study revealed the coexistence of Mo 2 C and MoO 3 species on working catalyst surfaces, and a proper Mo 2 C/MoO 3 ratio (~0.38) was identified for the best aromatization Mo/ZSM-5 catalyst. The active sites for methane conversion to aromatics should include Mo oxide as well as Mo carbide.

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Stimulation of Methanotrophic Growth in Cocultures by Cobalamin Excreted by Rhizobia

Applied and Environmental Microbiology ◽

10.1128/aem.05834-11 ◽

2011 ◽

Vol 77 (24) ◽

pp. 8509-8515 ◽

Cited By ~ 53

Author(s):

Hiroyuki Iguchi ◽

Hiroya Yurimoto ◽

Yasuyoshi Sakai

Keyword(s):

Methane Oxidation ◽

Microbial Consortium ◽

Growth Stimulation ◽

Microbial Interactions ◽

Content Type ◽

Positive Effects ◽

Conversion Of Methane ◽

Consortium Culture ◽

Global Carbon ◽

Stimulating Factor

ABSTRACTMethanotrophs play a key role in the global carbon cycle, in which they affect methane emissions and help to sustain diverse microbial communities through the conversion of methane to organic compounds. To investigate the microbial interactions that cause positive effects on methanotrophs, cocultures were constructed usingMethylovulum miyakonenseHT12 and each of nine nonmethanotrophic bacteria, which were isolated from a methane-utilizing microbial consortium culture established from forest soil. Three rhizobial strains were found to strongly stimulate the growth and methane oxidation ofM. miyakonenseHT12 in cocultures. We purified the stimulating factor produced byRhizobiumsp. Rb122 and identified it as cobalamin. Growth stimulation by cobalamin was also observed for three other gammaproteobacterial methanotrophs. These results suggest that microbial interactions through cobalamin play an important role in methane oxidation in various ecosystems.

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