Methane Oxidation by H2O2 over Different Cu-Species of Cu-ZSM-5 Catalysts

Yashnik, S. A.; Boltenkov, Vadim V.; Babushkin, Dmitrii E.; Taran, Oxana P.; Parmon, Valentin N.

doi:10.1007/s11244-020-01247-6

Cited by 19 publications

(15 citation statements)

References 45 publications

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“…It is consistent with the experimental observation of Yashnik et al. 89 Nevertheless, since the Z[Cu(OH)2] + and Z[CuOH] + sites would mainly catalyze the self-decomposition of hydrogen peroxide, the rate of methanol oxidation would be significantly suppressed, preventing methane from the deep oxidation. Hence, the reported high selectivity toward methanol for DMTM using hydrogen peroxide at copper-zeolites may be related to the low methane conversion.…”

Section: Kinetic Analysissupporting

confidence: 92%

Advantages and Limitations of Hydrogen Peroxide for Direct Oxidation of Methane to Methanol at Mono-Copper Active Sites in Cu-Exchanged Zeolites

Cheng

Chen

et al. 2022

Preprint

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The oxidant is a crucial factor affecting the performance of direct oxidation of methane to methanol (DMTM). It is still extremely challenging to realize one-pot DMTM using dioxygen. So far, hydrogen peroxide is still the most frequently reported green oxidant for DMTM with high selectivity of methanol. Aiming to achieve insights into the influence of oxidants on the DMTM performance and to improve catalysts, we computationally investigated the reaction mechanisms of DMTM using hydrogen peroxide at mono-copper sites in three kinds of Cu-exchanged zeolites with different sizes of the micropores. We identified the common advantage and limitations of hydrogen peroxide as the oxidant. In contrast to molecular oxygen, the O-O bond of hydrogen peroxide could be easily broken to produce reactive surface oxygen species, enabling the facile C-H bond activation of methane at a lower temperature. However, the radical-like mechanism for the C-H bond activation in DMTM using hydrogen peroxide makes the C-H bond breaking of methanol ineluctably superior to methane. This leads to the inevitable trade-off between selectivity and activity for DMTM. Moreover, the lower O-H bonding energy of hydrogen peroxide would also result in the significant self-decomposition of hydrogen peroxide. Despite the existence of these bottlenecks, the kinetic analysis manifests that it is still promising to improve catalysts to boost the performance of DMTM using hydrogen peroxide.

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Section: Kinetic Analysissupporting

confidence: 92%

Advantages and Limitations of Hydrogen Peroxide for Direct Oxidation of Methane to Methanol at Mono-Copper Active Sites in Cu-Exchanged Zeolites

Cheng

Chen

et al. 2022

Preprint

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“…6,7 In contrast, hydrogen peroxide (H 2 O 2 ) is a highly effective, green oxidant to generate hydroperoxy species to catalyze methane at mild conditions. Many highly dispersed transition metals (such as Cu, Fe, and Cr) supported on zeolites, 8,9 MOF, 10 graphene, 11 carbon nitride, 12 and TiO 2 13 as well as precious metals including AuPd and Rh catalysts, 14,15 have been applied for the selective oxidation of methane under mild conditions by simulating the structure of natural methane monooxygenase (MMO). 16 The activation of a carbon− hydrogen bond in methane and the effective utilization of H 2 O 2 are considered to be the two main bottleneck problems during the methane oxidation process.…”

Section: Introductionmentioning

confidence: 99%

“…Currently, utilization of methane is mainly through indirect conversion into syngas under high temperature and high pressure, which was further converted into methanol or various hydrocarbons. , Direct conversion of methane to value-added products is of crucial importance to reduce the cost of transport and storage but still remains a major challenge. , Selective oxidation of methane with molecular oxygen and N 2 O as oxidants generally requires high temperature of more than 100 °C. , In contrast, hydrogen peroxide (H 2 O 2 ) is a highly effective, green oxidant to generate hydroperoxy species to catalyze methane at mild conditions. Many highly dispersed transition metals (such as Cu, Fe, and Cr) supported on zeolites, , MOF, graphene, carbon nitride, and TiO 2 as well as precious metals including AuPd and Rh catalysts, , have been applied for the selective oxidation of methane under mild conditions by simulating the structure of natural methane monooxygenase (MMO) . The activation of a carbon–hydrogen bond in methane and the effective utilization of H 2 O 2 are considered to be the two main bottleneck problems during the methane oxidation process.…”

Section: Introductionmentioning

confidence: 99%

IrFe/ZSM-5 Synergistic Catalyst for Selective Oxidation of Methane to Formic Acid

Huang

et al. 2021

Energy Fuels

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Selective conversion of methane to value-added products with high activity and high selectivity to the target products under mild reaction condition remains a great challenge. Herein, bicomponent IrFe supported on ZSM-5 (IrFe/Z-5) was investigated for the selective oxidation of methane. Compared with the 0.7Fe/Z-5 catalyst, the 0.1Ir-0.6Fe/Z-5 exhibited much higher oxygenate yield (3192 vs 971 μmol/g/h). In addition, higher H 2 O 2 utilization efficiency was obtained, and the selectivity toward formic acid was enhanced from 54% to 71.3%. It was found that the activation of the C−H bond was improved by the introduction of Ir single atoms. The superior catalytic performance of 0.1Ir-0.6Fe/Z-5 can be attributed to the synergistic effect between Ir and Fe species with high C−H bond activation capacity and high H 2 O 2 utilization efficiency.

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“…The former can provide the complete destruction of phenol and high mineralization of total organic compounds without leaching of a considerable quantity of copper to the solution [ 5 ]. Cu-modified MFIs catalyze the oxidation of methane with hydrogen peroxide [ 14 , 15 , 16 ] or oxygen [ 17 , 18 , 19 ] to methanol and other valuable products, although these catalysts have not yet found practical applications in this area.…”

Section: Introductionmentioning

confidence: 99%

Leaching Stability and Redox Activity of Copper-MFI Zeolites Prepared by Solid-State Transformations: Comparison with Ion-Exchanged and Impregnated Samples

et al. 2023

Self Cite

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The catalyst preparation route is well known to affect the copper loading and its electronic state, which influence the properties of the resulting catalyst. Electronic states of copper ions in copper-containing silicalites with the MFI-framework topology obtained by a solid-state transformation S (SST) were studied with using EPR, UV-Vis DR, XRD, H2-TPR and chemical differentiating dissolution. They were compared with Cu-ZSM-5 and Cu-MFI (silicalite) prepared via the ion-exchange and incipient wetness impregnation. SST route was shown to provide the formation of MFI structure and favor clustering of Cu-ions near surface and subsurface of zeolite crystals. The square-planar oxide clusters of Cu2+-ions and the finely dispersed CuO nanoparticles with the size down to 20 nm were revealed in Cu-MFI-SST samples with low (0.5–1.0 wt.%) and high (16 wt.%) Cu-content. The CuO nanoparticles were characterized by energy band gap 1–1.16 eV. The CuO-like clusters were characterized by ligand-to-metal charge transfer band (CTB L → M) at 32,000 cm−1 and contain EPR-visible surface Cu2+-ions. The low Cu-loaded SST-samples had poor redox properties and activity towards different solvents due to decoration of copper-species by silica; whereas CuO nanoparticles were easily removed from the catalyst by HCl. In the ion-exchanged samples over MFI-silicalite and ZSM-5, Cu2+-ions were mainly CuO-like clusters and isolated Cu2+ ions inside MFI channels. Their redox properties and tendency to dissolve in acidic solutions differed from the behavior of SST-series samples.

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Methane Oxidation by H2O2 over Different Cu-Species of Cu-ZSM-5 Catalysts

Cited by 19 publications

References 45 publications

Advantages and Limitations of Hydrogen Peroxide for Direct Oxidation of Methane to Methanol at Mono-Copper Active Sites in Cu-Exchanged Zeolites

Advantages and Limitations of Hydrogen Peroxide for Direct Oxidation of Methane to Methanol at Mono-Copper Active Sites in Cu-Exchanged Zeolites

IrFe/ZSM-5 Synergistic Catalyst for Selective Oxidation of Methane to Formic Acid

Leaching Stability and Redox Activity of Copper-MFI Zeolites Prepared by Solid-State Transformations: Comparison with Ion-Exchanged and Impregnated Samples

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