Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Observation of induction period and oxygenated intermediates in methane oxidation over Pt catalyst.

ABSTRACT: Selective oxidation of methane is one of the most attractive routes for methane to chemicals. However, mechanistic understanding and avoiding over-oxidation have great challenges because of its very rapid reaction rate. Herein, a capillary micro-reaction system was introduced to monitor the initial stage of methane oxidation over platinum. For the first time, an induction period is observed, during which oxygenated intermediates, such as methanol, acetone, methyl methoxy acetate, etc., are detected. Induction period can be shortened by methane pretreatment at 600°C, which generates highly active species containing unsaturated bonds. Combined these findings and observations of in situ characterizations, the evolution route of methane oxidation over Pt is prosed, i.e., the reaction starts from the formation of initial species containing Pt-C bond, followed by the generation of oxygenated intermediates, and ended with the over-oxidation of the intermediates to CO/CO₂.

SUBMITTER: Yang K

PROVIDER: S-EPMC10391729 | biostudies-literature | 2023 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Observation of induction period and oxygenated intermediates in methane oxidation over Pt catalyst.

Yang Kuo K Li Jinzhe J Zhao Zhongkui Z Liu Zhongmin Z

iScience 20230608 7

Selective oxidation of methane is one of the most attractive routes for methane to chemicals. However, mechanistic understanding and avoiding over-oxidation have great challenges because of its very rapid reaction rate. Herein, a capillary micro-reaction system was introduced to monitor the initial stage of methane oxidation over platinum. For the first time, an induction period is observed, during which oxygenated intermediates, such as methanol, acetone, methyl methoxy acetate, etc., are detec ...[more]

PMID: 37534163

Similar Datasets

Operando Observation of Oxygenated Intermediates during CO Hydrogenation on Rh Single Crystals.

Project description:The CO hydrogenation reaction over the Rh(111) and (211) surfaces has been investigated operando by X-ray photoelectron spectroscopy at a pressure of 150 mbar. Observations of the resting state of the catalyst give mechanistic insight into the selectivity of Rh for generating ethanol from CO hydrogenation. This study shows that the Rh(111) surface does not dissociate all CO molecules before hydrogenation of the O and C atoms, which allows methoxy and other both oxygenated and hydrogenated species to be visible in the photoelectron spectra.

| S-EPMC9052753 | biostudies-literature

Active site localization of methane oxidation on Pt nanocrystals.

Project description:High catalytic efficiency in metal nanocatalysts is attributed to large surface area to volume ratios and an abundance of under-coordinated atoms that can decrease kinetic barriers. Although overall shape or size changes of nanocatalysts have been observed as a result of catalytic processes, structural changes at low-coordination sites such as edges, remain poorly understood. Here, we report high-lattice distortion at edges of Pt nanocrystals during heterogeneous catalytic methane oxidation based on in situ 3D Bragg coherent X-ray diffraction imaging. We directly observe contraction at edges owing to adsorption of oxygen. This strain increases during methane oxidation and it returns to the original state after completing the reaction process. The results are in good agreement with finite element models that incorporate forces, as determined by reactive molecular dynamics simulations. Reaction mechanisms obtained from in situ strain imaging thus provide important insights for improving catalysts and designing future nanostructured catalytic materials.

| S-EPMC6109038 | biostudies-literature

Photocatalytic methane oxidation over a TiO<sub>2</sub>/SiNWs p-n junction catalyst at room temperature.

Project description:Rapid recombination of charge carriers in semiconductors is a main drawback for photocatalytic oxidative coupling of methane (OCM) reactions. Herein, we propose a novel catalyst by developing a p-n junction titania-silicon nanowires (TiO2/SiNWs) heterostructure. The structure is fabricated by atomic layer deposition of TiO2 on p-type SiNWs. The TiO2/SiNWs heterostructure exhibited an outstanding OCM performance under simulated solar light irradiation compared to the single components. This enhanced efficiency was attributed to the intrinsic electrical field formed between n-type TiO2 and p-type SiNWs, which forces generated charge carriers to move in opposite directions and suppresses charge recombination. Besides, surface morphology and optical properties of the the p-n TiO2/SiNWs catalyst are also beneficial for the photocatalytic activity. It is expected that the results of this study will provide massive guidance in synthesizing an efficient photocatalyst for CH4 conversion under mild conditions.

| S-EPMC11403797 | biostudies-literature

High Coke-Resistance Pt/Mg1-xNixO Catalyst for Dry Reforming of Methane.

Project description:A highly active and stable nano structured Pt/Mg1-xNixO catalysts was developed by a simple co-precipitation method. The obtained Pt/Mg1-xNixO catalyst exhibited cubic structure nanocatalyst with a size of 50-80 nm and realized CH4 and CO2 conversions as high as 98% at 900°C with excellent stability in the dry reforming of methane. The characterization of catalyst was performed using various kinds of analytical techniques including XRD, BET, XRF, TPR-H2, TGA, TEM, FESEM, FT-IR, and XPS analyses. Characterization of spent catalyst further confirms that Pt/Mg1-xNixO catalyst has high coke-resistance for dry reforming. Thus, the catalyst demonstrated in this study, offers a promising catalyst for resolving the dilemma between dispersion and reducibility of supported metal, as well as activity and stability during high temperature reactions.

| S-EPMC4706417 | biostudies-literature

Synthesis of MOF-supported Pt catalyst with high electrochemical oxidation activity for methanol oxidation.

Project description:Fuel cells, one of the clean energy sources, is quite remarkable for energy production. In this context, catalysts are needed for the electrochemical reactions of DMFCs (direct methanol fuel cells) to work efficiently. In this study, Pt and Pt@Ti-MOF (Pt@MIL-125) NPs (nanoparticles) catalysts were synthesized by chemical synthesis. The Ti-MOF (MIL-125) structure was synthesized using the solvothermal method, and the effect of Ti-MOF on methanol oxidation was investigated. The results showed that Pt@Ti-MOF NPs provided 9.45 times more electrocatalytic activity for methanol oxidation compared to Pt NPs. In addition, Ti-MOF doping was shown to increase the stability and durability by long-term tests. The study provides important results on how MOF-supported structures behave electrochemically. The results show that Ti-MOF provides very high potential in MOR applications and is promising for use as an anode catalyst in DMFC systems.

| S-EPMC11559627 | biostudies-literature

Unraveling the structure and chemical mechanisms of highly oxygenated intermediates in oxidation of organic compounds.

Project description:Decades of research on the autooxidation of organic compounds have provided fundamental and practical insights into these processes; however, the structure of many key autooxidation intermediates and the reactions leading to their formation still remain unclear. This work provides additional experimental evidence that highly oxygenated intermediates with one or more hydroperoxy groups are prevalent in the autooxidation of various oxygenated (e.g., alcohol, aldehyde, keto compounds, ether, and ester) and nonoxygenated (e.g., normal alkane, branched alkane, and cycloalkane) organic compounds. These findings improve our understanding of autooxidation reaction mechanisms that are routinely used to predict fuel ignition and oxidative stability of liquid hydrocarbons, while also providing insights relevant to the formation mechanisms of tropospheric aerosol building blocks. The direct observation of highly oxygenated intermediates for the autooxidation of alkanes at 500-600 K builds upon prior observations made in atmospheric conditions for the autooxidation of terpenes and other unsaturated hydrocarbons; it shows that highly oxygenated intermediates are stable at conditions above room temperature. These results further reveal that highly oxygenated intermediates are not only accessible by chemical activation but also by thermal activation. Theoretical calculations on H-atom migration reactions are presented to rationalize the relationship between the organic compound's molecular structure (n-alkane, branched alkane, and cycloalkane) and its propensity to produce highly oxygenated intermediates via extensive autooxidation of hydroperoxyalkylperoxy radicals. Finally, detailed chemical kinetic simulations demonstrate the influence of these additional reaction pathways on the ignition of practical fuels.

| S-EPMC5740676 | biostudies-literature

Oscillating syngas production on NiO/YSZ catalyst from methane oxidation.

Project description:Synthesis gas was produced by methane oxidation on a NiO/YSZ cermet by interrupting the oxygen flow. Stopping the oxygen flow provoked the diffusion of lattice oxygen in the cermet, which in turn replenished the Ni-O bond that was consumed by methane. Resuming the oxygen flow brought about the activation of oxygen on the extrinsic vacancy site of YSZ. The activation, followed by the diffusion of oxygen and a Ni/NiO redox cycle, led to oscillatory syngas production. The infrared and mass spectroscopy results provide the reaction mechanism that governs the oxidation of methane on the NiO/YSZ cermet. This study presents a technique that can be applied to the catalysis of other metal/anion or cation conductor systems.

| S-EPMC9055530 | biostudies-literature

Simultaneous nitric oxide and toluene reduction over Pt-based catalyst.

Project description:This research investigates the simultaneous reduction of nitric oxide (NOx) and toluene using Pt-based catalysts, aiming at applications in small-scale industrial environmental processes. Catalysts with varying Pt loadings from 0.01 to 3 % were synthesized through wet impregnation, and their dispersion was assessed across several characterizations, revealing effective Pt dispersion even at loadings above 1 %. Under conditions of high toluene feed, the 3 % Pt-loaded catalyst emerged as the most efficient, achieving significant NOx and toluene conversion rates. The performance of this catalyst was thoroughly examined under various operational parameters including NO, toluene, O2 concentrations, gas hourly space velocity (GHSV) and reaction temperature. A short-stress test further underscored its effectiveness, with NOx and toluene conversions reaching 89.7 % and 97.6 %, respectively. Additionally, a preliminary process simulation of the NOx reduction by toluene indicated an energy efficiency improvement of over 8 % compared to conventional RCO and de-NOx processes. The findings suggest the catalyst's potential for NOx reduction in industrial settings, utilizing toluene present in flue gas without the need for additional commercial reducing agents.

| S-EPMC11626009 | biostudies-literature

Fully oxygenated water columns over continental shelves before the Great Oxidation Event.

Project description:Late Archaean sedimentary rocks contain compelling geochemical evidence for episodic accumulation of dissolved oxygen in the oceans along continental margins before the Great Oxidation Event. However, the extent of this oxygenation remains poorly constrained. Here we present thallium and molybdenum isotope compositions for anoxic organic-rich shales of the 2.5 billion-year-old Mount McRae Shale from Western Australia, which previously yielded geochemical evidence of a transient oxygenation event. During this event, we observe an anti-correlation between thalium and molybdenum isotope data, including two shifts to higher molybdenum and lower thalium isotope compositions. Our data indicate pronounced burial of manganese oxides in sediments elsewhere in the ocean at these times, which requires that water columns above portions of the ocean floor were fully oxygenated: all the way from the air-sea interface to well below the sediment-water interface. Well-oxygenated continental shelves were likely the most important sites of manganese oxide burial and mass-balance modeling results suggest that fully oxygenated water columns were at least a regional-scale feature of early-Earth's oceans 2.5 billion years ago.

| S-EPMC6398953 | biostudies-literature

Direct observation of reaction intermediates for a well defined heterogeneous alkene metathesis catalyst.

Project description:Grafting of [W([triple bond]NAr)(=CHtBu)(2,5-Me(2)NC(4)H(2))(2)] on a silica partially dehydroxylated at 700 degrees C (SiO(2- (700))) generates the corresponding monosiloxy complex [([triple bond]SiO)W([triple bond]NAr)(=CHtBu)(2,5-Me(2)NC(4)H(2))] as the major species (approximately 90%) along with [([triple bond]SiO)W([triple bond]NAr)(CH(2)tBu)(2,5-Me(2)NC(4)H(2))(2)], according to mass balance analysis, IR, and NMR studies. This heterogeneous catalyst displays good activity and stability in the metathesis of propene. Very importantly, solid state NMR spectroscopy allows observation of the propagating alkylidene as well as stable metallacyclobutane intermediates. These species have the same reactivity as the initial surface complex [([triple bond]SiO)W([triple bond]NAr)(=CHtBu)(2,5-Me(2)NC(4)H(2))], which shows that they are the key intermediates of alkene metathesis.

| S-EPMC2527876 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data