Direct methane conversion with oxygen and CO over hydrophobic dB-ZSM-5 supported Rh single-atom catalyst

Wang, Honglin; Xin, Wenyu; Wang, Quan; Zheng, Xiangdong; Lu, Zihan; Pei, Ruqin; He, Pimo; Dong, Xianjiang

doi:10.1016/j.catcom.2021.106374

Cited by 13 publications

(7 citation statements)

References 28 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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“…Supported Rh catalysts are widely used in numerous industrial processes, notably in catalytic carbonylation reactions, 1,2 CO 2 hydrogenation, 3,4 and catalytic CH 4 conversion. 5,6 The size sensitivity of active Rh species in those reactions has been well explored to have a profound influence on their catalytic activity and selectivity. 7−9 For instance, Rh nanoparticles (Rh NP ) often catalyzed methanation reaction at high CO 2 conversions, 4,10 whereas Rh single atoms (Rh SA ) favored high CO selectivity under the equivalent conditions.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Supported Rh catalysts are widely used in numerous industrial processes, notably in catalytic carbonylation reactions, , CO 2 hydrogenation, , and catalytic CH 4 conversion. , The size sensitivity of active Rh species in those reactions has been well explored to have a profound influence on their catalytic activity and selectivity. − For instance, Rh nanoparticles (Rh NP ) often catalyzed methanation reaction at high CO 2 conversions, , whereas Rh single atoms (Rh SA ) favored high CO selectivity under the equivalent conditions. , Recently, Rh single-atom catalysts (SACs) have also shown superior activity in mild methane oxidation to methanol, − but the specific size of active sites is still under debate. ,− Thus, precise control of Rh particle size and the determination of site-specific reactivity are highly desirable for the rational design of high-performance Rh catalysts.…”

Section: Introductionmentioning

confidence: 99%

Controlled-Release Mechanism Regulates Rhodium Migration and Size Redistribution Boosting Catalytic Methane Conversion

Shen

Xiao

et al. 2023

ACS Catal.

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The migration of Rh atoms under a gas/reactive environment has a great impact on the dynamic restructuring and size redistribution of Rh catalysts in a variety of structure-sensitive catalytic reactions. To date, regulating the size distribution of active Rh species via controlled atomic migration remains challenging. Here, we show a controlled-release mechanism to regulate Rh atom migration through two-dimensional (2D) zeolite nanosheets, enabling quasi-continuous size redistribution of active Rh species from a single atom to nanoparticles with reversibility. Utilizing state-of-the-art in situ characterizations, a reversible aggregation/redispersion of Rh catalysts in/out of the 2D zeolite was directly observed under H2 or CO environment. The interplay between gas environment and support confinement was disclosed that substantially restrained the dynamic migration of Rh species and enabled a quasi-continuous control of Rh size distribution over a wide temperature window and size range. The catalytic testing for mild oxidation of methane demonstrated a volcano correlation of methanol activity with increasing particle size. The sub-nanometer Rh clusters with an average diameter of 0.9 nm exhibited the highest methanol activity of 39.7 molCH3OOH·molRh –1·h–1 with remarkable selectivity as high as 73.2%, far beyond that of single atom species and larger particles. Density functional theory calculations and electron paramagnetic resonance spectroscopy further revealed that this size dependency is related to the preferential formation of •OH radicals on Rh clusters with different sizes, which acts as a key initiator for methane activation. Our results thus provide a practical approach to synthesize size-specific metal catalysts via controlled atomic migration.

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“…Early reports on the development of catalytic systems for single-pot transformation of methane to acetic acid are based on CuSO 4 /Pd(OCOEt) 2 , vanadium catalysts, − or CaCl 2 ·H 2 O in trifluoroacetic acid (TFA) with K 2 S 2 O 8 as the oxidant, RhCl 3 , Pd(II) in sulfuric acid, and Mo catalyst. − However, the commercialization of any such process on a large scale would have to use molecular oxygen (O 2 ) as a cheap and readily available oxidant. Several homogeneous catalysts based on Rh ,, and Pt, and heterogeneous catalytic systems such as ZSM-5-supported Rh, − IrCuPd, Ru, or Cu catalysts have also been developed for direct conversion of methane to acetic acid using O 2 and carbon monoxide (CO) as the reactants. ,, However, using toxic CO and precious metals, multiactive sites, poor selectivity, and very low acetic acid productivity require further research efforts in designing novel catalysts for economic and environmentally friendly production of acetic acid.…”

Section: Introductionmentioning

confidence: 99%

Selective Methane Oxidation to Acetic Acid Using Molecular Oxygen over a Mono-Copper Hydroxyl Catalyst

et al. 2023

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Acetic acid is an industrially important chemical, produced mainly via carbonylation of methanol using precious metal-based homogeneous catalysts. As a low-cost feedstock, methane is commercially transformed to acetic acid via a multistep process involving energy-intensive methane steam reforming, methanol synthesis, and, subsequently, methanol carbonylation. Here, we report a direct single-step conversion of methane to acetic acid using molecular oxygen (O 2 ) as the oxidant under mild conditions over a mono-copper hydroxyl site confined in a porous cerium metal−organic framework (MOF), Ce-UiO-Cu(OH). The Ce-UiO MOF-supported single-site copper hydroxyl catalyst gave exceptionally high acetic acid productivity of 335 mmolg cat −1 in 96% selectivity with a Cu TON up to 400 at 115 °C in water. Our spectroscopic and theoretical studies and controlled experiments reveal that the conversion of methane to acetic acid occurs via oxidative carbonylation, where methane is first activated at the copper hydroxyl site via σ-bond metathesis to afford Cu-methyl species, followed by carbonylation with in situ-generated carbon monoxide and subsequent hydrolysis by water. This work may guide the rational design of heterogeneous abundant metal catalysts for the activation and conversion of methane to acetic acid and other valuable chemicals under mild and environmentally friendly reaction conditions.

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Direct methane conversion with oxygen and CO over hydrophobic dB-ZSM-5 supported Rh single-atom catalyst

Cited by 13 publications

References 28 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

Controlled-Release Mechanism Regulates Rhodium Migration and Size Redistribution Boosting Catalytic Methane Conversion

Selective Methane Oxidation to Acetic Acid Using Molecular Oxygen over a Mono-Copper Hydroxyl Catalyst

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Direct methane conversion with oxygen and CO over hydrophobic dB-ZSM-5 supported Rh single-atom catalyst

Cited by 13 publications

References 28 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

Controlled-Release Mechanism Regulates Rhodium Migration and Size Redistribution Boosting Catalytic Methane Conversion

Selective Methane Oxidation to Acetic Acid Using Molecular Oxygen over a Mono-Copper Hydroxyl Catalyst

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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