The selective oxidation of methane to methanol using in situ generated H2O2 over palladium-based bimetallic catalysts

Carter, James H.; Lewis, Richard J.; Demetriou, Nikolas; Williams, Christopher; Davies, Thomas E.; Qin, Tian; Dummer, Nicholas F.; Morgan, David J.; Willock, David J.; Liu, Xi; Taylor, Stuart H.; Hutchings, Graham J.

doi:10.1039/d3cy00116d

Cited by 8 publications

(5 citation statements)

References 65 publications

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“…The best-performing catalyst (0.2Au0.5FeHS, further written as AuFeHS) had an optimum Fe concentration of 0.46 wt % and an Au concentration of 0.23 wt %, confirmed by inductively coupled plasma-optical emission spectrometry (ICP-OES). Hydrophobic support is important in oxidation reactions involving H 2 O 2 because it helps peroxide to be close to the active sites of Au and Fe, where incoming methane can react with peroxide efficiently. , Further, it is known that the active sites get blocked in the hydrophilic conditions because of the presence of moisture, and it is also known that the Au particle size increases in the aqueous conditions, which further lowers the activity of the catalyst. − A hydrophobic environment also facilitates easy desorption of the methanol from the surface, preventing overoxidation. , The hydrophobicity of silica was confirmed by contact angle analysis with an observed angle of 118° (Figures S1 and S2). The C–H vibration from silica confirmed hydrophobic functionalization from HS (Figure S3).…”

Section: Resultsmentioning

confidence: 99%

“…Hydrophobic support is important in oxidation reactions involving H 2 O 2 because it helps peroxide to be close to the active sites of Au and Fe, where incoming methane can react with peroxide efficiently. 31,32 Further, it is known that the active sites get blocked in the hydrophilic conditions because of the presence of moisture, and it is also known that the Au particle size increases in the aqueous conditions, which further lowers the activity of the catalyst. 33−35 A hydrophobic environment also facilitates easy desorption of the methanol from the surface, preventing overoxidation.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Atmospheric-Pressure Continuous-Flow Methane Oxidation to Methanol and Acetic Acid Using H₂O₂ over the Au–Fe Catalyst

Jagtap,

Kumar,

Gupta

et al. 2024

ACS Sustainable Chem. Eng.

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An enormous value proposition exists when molecules such as acetic acid and methanol are derived from natural gas. With abundant worldwide resources, the conversion of methane to methanol (M2M) by partial oxidation or to acetic acid through C-insertion is considered one of the most enterprising chemical transformations in catalysis. Methane partial oxidation using H 2 O 2 as the oxidant is reported at high-pressure conditions with an excess of oxidant. In this work, significant catalytic challenges successfully tackled are the continuous partial oxidation of methane to methanol and acetic acid at atmospheric pressure. Under continuous flow and at atmospheric pressure, a modified silica-supported bimetallic (AuFeHS) catalyst catalyzed the conversion of methane to methanol using H 2 O 2 with an impressive yield of 224 mmol/g Fe+Au . Cofeeding of CO in the stream produces acetic acid, demonstrating a selectivity switch from methanol with an overall yield of 92 mmol/g Fe+Au .

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Atmospheric-Pressure Continuous-Flow Methane Oxidation to Methanol and Acetic Acid Using H₂O₂ over the Au–Fe Catalyst

Jagtap,

Kumar,

Gupta

et al. 2024

ACS Sustainable Chem. Eng.

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“…These include poor selective H 2 utilization, rapid catalyst deactivation, and the formation of complex product mixtures, necessitating extensive purification and the inclusion of promoters. Indeed, in many cases, it is the presence of H 2 , required to generate H 2 O 2 in situ, that largely promotes the formation of such byproducts. , Such concerns are not limited to alkene epoxidation, with product distributions for a range of transformations influenced by competitive unselective hydrogenation pathways. , It is the overcoming of these challenges that has motivated extensive research from our laboratory, with particular focus placed on the application of Pd-based catalysts for (i) alkane upgrading, − (ii) alcohol oxidation, ,− and recently (iii) the ammoximation of cyclohexanone (and other cyclic ketones) to the corresponding oxime. ,, Regarding alkane oxidation, we direct the reader to our recent Account on methane valorization for an extensive discussion of our contribution to this field …”

Section: Challenging Current Industrial Processesmentioning

confidence: 99%

Selective Oxidation Using In Situ-Generated Hydrogen Peroxide

Lewis,

Hutchings

2023

Acc. Chem. Res.

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Metrics & MoreArticle Recommendations CONSPECTUS: Hydrogen peroxide (H 2 O 2 ) for industrial applications is manufactured through an indirect process that relies on the sequential reduction and reoxidation of quinone carriers. While highly effective, production is typically centralized and entails numerous energyintensive concentration steps. Furthermore, the overhydrogenation of the quinone necessitates periodic replacement, leading to incomplete atom efficiency. These factors, in addition to the presence of propriety stabilizing agents and concerns associated with their separation from product streams, have driven interest in alternative technologies for chemical upgrading. The decoupling of oxidative transformations from commercially synthesized H 2 O 2 may offer significant economic savings and a reduction in greenhouse gas emissions for several industrially relevant processes. Indeed, the production and utilization of the oxidant in situ, from the elements, would represent a positive step toward a more sustainable chemical synthesis sector, offering the potential for total atom efficiency, while avoiding the drawbacks associated with current industrial routes, which are inherently linked to commercial H 2 O 2 production. Such interest is perhaps now more pertinent than ever given the rapidly improving viability of green hydrogen production.The application of in situ-generated H 2 O 2 has been a long-standing goal in feedstock valorization, with perhaps the most significant interest placed on propylene epoxidation. Until very recently a viable in situ alternative to current industrial oxidative processes has been lacking, with prior approaches typically hindered by low rates of conversion or poor selectivity toward desired products, often resulting from competitive hydrogenation reactions. Based on over 20 years of research, which has led to the development of catalysts for the direct synthesis of H 2 O 2 that offer high synthesis rates and >99% H 2 utilization, we have recently turned our attention to a range of oxidative transformations where H 2 O 2 is generated and utilized in situ. Indeed, we have recently demonstrated that it is possible to rival state-of-the-art industrial processes through in situ H 2 O 2 synthesis, establishing the potential for significant process intensification and considerable decarbonization of the chemical synthesis sector.We have further established the potential of an in situ route to both bulk and fine chemical synthesis through a chemo-catalytic/ enzymatic one-pot approach, where H 2 O 2 is synthesized over heterogeneous surfaces and subsequently utilized by a class of unspecific peroxygenase enzymes for C−H bond functionalization. Strikingly, through careful control of the chemo-catalyst, it is possible to ensure that competitive, nonenzymatic pathways are inhibited while also avoiding the regiospecific and selectivity concerns associated with current energy-intensive industrial processes, with further cost savings associated with the operation of the chemo-enzymatic appr...

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“…14,15,16,17,18 To address the issue of overoxidation by excessive amount of H2O2, the in situ synthesis of H2O2 from H2/O2 mixtures, catalyzed by AuPd bimetallic nanoparticles, has been integrated into CH4 oxidation processes. 19,20,21,22,23,24,25 Nonetheless, the cost of catalysts/oxidants and the employment of hazardous chemicals have limited the utility of those process.Recently, electrocatalytic conversion of CH4 has been reported, bringing advantages like mild reaction condition and innovative reaction pathway. 26,27 Studies have demonstrated that CH4 can be directly activated on the electrocatalyst surface such as NiO/Ni 28 and TiO2/RuO2/V2O5 29 , showing 13-97%CH3OH selectivity (Table S1).…”

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confidence: 99%

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Electrothermal Conversion of Methane to Methanol at Room-Temperature with Phosphotungstic Acid

Yan,

Chang,

Wang

et al. 2023

Preprint

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Traditional methods for anerobic oxidation of methane to methanol frequently require the use of noble metal catalysts or flammable H2-O2 mixtures. While electrochemical methods enhance safety and may avoid the use of noble metals, these processes suffer from low yields due to limited current density and/or low selectivity. Here, we design an electrothermal process to conduct aerobic oxidation of methane to methanol at room temperature using phosphotungstic acid (PTA) as a redox mediator. When electrochemically reduced, PTA activates methane with O2 to produce methanol selectively. The optimum productivity reaches 29.45 μmol gPTA-1 h-1 with approximately 10% overall Faradic efficiency. Under continuous operation, we achieved 19.90 μmol gPTA-1 h-1 catalytic activity, over 88.6% methanol selectivity, and 10 hours durability. This approach leverages reduced PTA to initiate thermal catalysis in solution phase, addressing slow methane oxidation kinetics and preventing overoxidations on electrode surfaces. The current density towards methanol production increased over 40 times compared with direct electrochemical processes. The in-situ generated hydroxyl radical, from the reaction of reduced PTA and oxygen, plays an important role in the selective methane conversion. This study demonstrates reduced polyoxotungstate as a viable platform to integrate thermo- and electrochemical methane oxidation at ambient conditions.

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The selective oxidation of methane to methanol using in situ generated H₂O₂ over palladium-based bimetallic catalysts

Abstract: The selective oxidation of methane to methanol, using H2O2 generated in situ from H2 and O2 has been investigated using a series of TS-1 supported bimetallic palladium-based catalysts. The alloying...

Cited by 8 publications

References 65 publications

Atmospheric-Pressure Continuous-Flow Methane Oxidation to Methanol and Acetic Acid Using H₂O₂ over the Au–Fe Catalyst

Atmospheric-Pressure Continuous-Flow Methane Oxidation to Methanol and Acetic Acid Using H₂O₂ over the Au–Fe Catalyst

Selective Oxidation Using In Situ-Generated Hydrogen Peroxide

Electrothermal Conversion of Methane to Methanol at Room-Temperature with Phosphotungstic Acid

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The selective oxidation of methane to methanol using in situ generated H2O2 over palladium-based bimetallic catalysts

Abstract: The selective oxidation of methane to methanol, using H2O2 generated in situ from H2 and O2 has been investigated using a series of TS-1 supported bimetallic palladium-based catalysts. The alloying...

Cited by 8 publications

References 65 publications

Atmospheric-Pressure Continuous-Flow Methane Oxidation to Methanol and Acetic Acid Using H2O2 over the Au–Fe Catalyst

Atmospheric-Pressure Continuous-Flow Methane Oxidation to Methanol and Acetic Acid Using H2O2 over the Au–Fe Catalyst

Selective Oxidation Using In Situ-Generated Hydrogen Peroxide

Electrothermal Conversion of Methane to Methanol at Room-Temperature with Phosphotungstic Acid

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The selective oxidation of methane to methanol using in situ generated H₂O₂ over palladium-based bimetallic catalysts

Atmospheric-Pressure Continuous-Flow Methane Oxidation to Methanol and Acetic Acid Using H₂O₂ over the Au–Fe Catalyst

Atmospheric-Pressure Continuous-Flow Methane Oxidation to Methanol and Acetic Acid Using H₂O₂ over the Au–Fe Catalyst