Hydrophobic zeolite modification for in situ peroxide formation in methane oxidation to methanol

Science ◽  
2020 ◽  
Vol 367 (6474) ◽  
pp. 193-197 ◽  
Author(s):  
Zhu Jin ◽  
Liang Wang ◽  
Erik Zuidema ◽  
Kartick Mondal ◽  
Ming Zhang ◽  
...  
Keyword(s):  
Methane Oxidation ◽  
Active Sites ◽  
Catalyst System ◽  
Oxidation Of Methane ◽  
Conversion Of Methane ◽  
Low Efficiency ◽  
Mild Temperature ◽  
Diffusion Of Hydrogen ◽  
Zeolite Modification

Selective partial oxidation of methane to methanol suffers from low efficiency. Here, we report a heterogeneous catalyst system for enhanced methanol productivity in methane oxidation by in situ generated hydrogen peroxide at mild temperature (70°C). The catalyst was synthesized by fixation of AuPd alloy nanoparticles within aluminosilicate zeolite crystals, followed by modification of the external surface of the zeolite with organosilanes. The silanes appear to allow diffusion of hydrogen, oxygen, and methane to the catalyst active sites, while confining the generated peroxide there to enhance its reaction probability. At 17.3% conversion of methane, methanol selectivity reached 92%, corresponding to methanol productivity up to 91.6 millimoles per gram of AuPd per hour.

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

2001 ◽  
Vol 08 (06) ◽  
pp. 627-632 ◽  
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.

In Situ X-ray Photoelectron Spectroscopy Detects Multiple Active Sites Involved in the Selective Anaerobic Oxidation of Methane in Copper-Exchanged Zeolites

ACS Catalysis ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 6728-6737 ◽  
Author(s):  
Luca Artiglia ◽  
Vitaly L. Sushkevich ◽  
Dennis Palagin ◽  
Amy J. Knorpp ◽  
Kanak Roy ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
X Ray ◽  
Oxidation Of Methane

Catalytic cycle of the partial oxidation of methane to methanol over Cu-ZSM-5 revealed using DFT calculations

2021 ◽  
Vol 23 (8) ◽  
pp. 4963-4974
Author(s):  
Xi Yu ◽  
Liangshu Zhong ◽  
Shenggang Li
Keyword(s):  
Dft Calculations ◽  
Methane Oxidation ◽  
Partial Oxidation ◽  
Active Sites ◽  
Partial Oxidation Of Methane ◽  
Catalytic Cycle ◽  
Oxidation Of Methane

Methane oxidation to methanol over Cu-ZSM-5 is found using DFT calculations to involve both [Cu2(O2)]2+ and [Cu2(μ-O)]2+ active sites.

scholarly journals Copper-Modified Zeolites and Silica for Conversion of Methane to Methanol

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 545 ◽  
Author(s):  
Xueting Wang ◽  
Natalia Martin ◽  
Johan Nilsson ◽  
Stefan Carlson ◽  
Johan Gustafson ◽  
...  
Keyword(s):  
Active Sites ◽  
Copper Ions ◽  
Ambient Pressure ◽  
Direct Conversion ◽  
Minor Amount ◽  
Powder Materials ◽  
Methanol Production ◽  
Conversion Of Methane ◽  
First Time

Powder materials containing copper ions supported on ZSM-5 (Cu-Zeolite Socony Mobil-5) and SSZ-13 (Cu-Standard Oil synthesised zeolite-13), and predominantly CuO nanoparticles on amorphous SiO 2 were synthesised, characterised, wash-coated onto ceramic monoliths and, for the first time, compared as catalysts for direct conversion of methane to methanol (DCMM) at ambient pressure (1 atm) using O 2 , N 2 O and NO as oxidants. Methanol production was monitored and quantified using Fourier transform infrared spectroscopy. Methanol is formed over all monolith samples, though the formation is considerably higher for the copper-exchanged zeolites. Hence, copper ions are the main active sites for DCMM. The minor amount of methanol produced over the Cu/SiO 2 sample, however, suggests that zeolites are not the sole substrate that can host those active copper sites but also silica. Further, we present the first ambient pressure in situ infrared spectroscopic measurements revealing the formation and consumption of surface methoxy species, which are considered to be key intermediates in the DCMM reaction.

scholarly journals Oscillatory Behaviour of Ni Supported on ZrO2 in the Catalytic Partial Oxidation of Methane as Determined by Activation Procedure

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2495
Author(s):  
Daniela Pietrogiacomi ◽  
Maria Cristina Campa ◽  
Ida Pettiti ◽  
Simonetta Tuti ◽  
Giulia Luccisano ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Partial Oxidation ◽  
Active Sites ◽  
Direct Reduction ◽  
Partial Oxidation Of Methane ◽  
Catalytic Partial Oxidation ◽  
Oxidation Of Methane ◽  
Short Contact Time ◽  
Oxidation Reduction ◽  
Ni Species

Ni/ZrO2 catalysts, active and selective for the catalytic partial oxidation of methane to syngas (CH4-CPO), were prepared by the dry impregnation of zirconium oxyhydroxide (Zhy) or monoclinic ZrO2 (Zm), calcination at 1173 K and activation by different procedures: oxidation-reduction (ox-red) or direct reduction (red). The characterization included XRD, FESEM, in situ FTIR and Raman spectroscopies, TPR, and specific surface area measurements. Catalytic activity experiments were carried out in a flow apparatus with a mixture of CH4:O2 = 2:1 in a short contact time. Compared to Zm, Zhy favoured the formation of smaller NiO particles, implying a higher number of Ni sites strongly interacting with the support. In all the activated Ni/ZrO2 catalysts, the Ni–ZrO2 interaction was strong enough to limit Ni aggregation during the catalytic runs. The catalytic activity depended on the activation procedures; the ox-red treatment yielded very active and stable catalysts, whereas the red treatment yielded catalysts with oscillating activity, ascribed to the formation of Niδ+ carbide-like species. The results suggested that Ni dispersion was not the main factor affecting the activity, and that active sites for CH4-CPO could be Ni species at the boundary of the metal particles in a specific configuration and nuclearity.

scholarly journals Electrokinetic and in situ spectroscopic investigations of CO electrochemical reduction on copper

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jing Li ◽  
Xiaoxia Chang ◽  
Haochen Zhang ◽  
Arnav S. Malkani ◽  
Mu-jeng Cheng ◽  
...  
Keyword(s):  
Mass Transport ◽  
Active Sites ◽  
Gas Diffusion ◽  
Reduction Reaction ◽  
Adsorbed Hydrogen ◽  
Diffusion Type ◽  
Proton Coupled Electron Transfer ◽  
Alkaline Electrolytes ◽  
Reaction Orders

AbstractRigorous electrokinetic results are key to understanding the reaction mechanisms in the electrochemical CO reduction reaction (CORR), however, most reported results are compromised by the CO mass transport limitation. In this work, we determined mass transport-free CORR kinetics by employing a gas-diffusion type electrode and identified dependence of catalyst surface speciation on the electrolyte pH using in-situ surface enhanced vibrational spectroscopies. Based on the measured Tafel slopes and reaction orders, we demonstrate that the formation rates of C2+ products are most likely limited by the dimerization of CO adsorbate. CH4 production is limited by the CO hydrogenation step via a proton coupled electron transfer and a chemical hydrogenation step of CO by adsorbed hydrogen atom in weakly (7 < pH < 11) and strongly (pH > 11) alkaline electrolytes, respectively. Further, CH4 and C2+ products are likely formed on distinct types of active sites.

Diffuse Reflectance FT-IR Characterization of Active Sites under Reaction Conditions: The Production of Oxygenates in the CO/H2 Reaction

1994 ◽  
Vol 48 (10) ◽  
pp. 1208-1212 ◽  
Author(s):  
J. J. Benítez ◽  
I. Carrizosa ◽  
J. A. Odriozola
Keyword(s):  
Infrared Spectra ◽  
Active Sites ◽  
Diffuse Reflectance ◽  
Reaction Conditions ◽  
In Situ Drifts ◽  
Ft Ir

The reactivity of a Lu2O3-promoted Rh/Al2O3 catalyst in the CO/H2 reaction is reported. Methane, heavier hydrocarbons, methanol, and ethanol are obtained. In situ DRIFTS has been employed to record the infrared spectra under the actual reaction conditions. The structure of the observed COads DRIFTS bands has been resolved into its components. The production of oxygenates (methanol and ethanol) has been correlated with the results of the deconvolution calculation. Specific sites for the production of methanol and ethanol in the CO/H2 reaction over a Rh,Lu2O3/Al2O3 catalyst are proposed.

In situ mercaptosilane-assisted confinement of Pd nanoparticles in Beta for high-efficient methane oxidation

2021 ◽  
Author(s):  
Liling Zhang ◽  
Junfei Chen ◽  
Haolin Yang ◽  
Xiaohan Wang ◽  
Zebao Rui
Keyword(s):  
Methane Oxidation ◽  
Pd Nanoparticles ◽  
High Efficient

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

2014 ◽  
Vol 80 (10) ◽  
pp. 3044-3052 ◽  
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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