Selective Oxidation of Methane to Methanol over Ceria‐Zirconia Supported Mono and Bimetallic Transition Metal Oxide Catalysts

Lyu, Yimeng; Jocz, Jennifer N.; Xu, Rui; Williams, Olivia C.; Sievers, Carsten

doi:10.1002/cctc.202100268

Cited by 25 publications

(18 citation statements)

References 103 publications

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“…The obtained maximum rate of methane oxidation over Pt/Al 2 O 3 was lower at 16 μmol g −1 cat h −1 (albeit at a lower inlet molar ratio of H 2 O/CH 4 of 136). The role of water in the aerobic, selective oxidation of methane was highlighted previously, [9, 13–17, 20] but here we show unequivocally the need to perform the reaction in the presence of liquid water to accelerate the aerobic oxidation of methane. The increase in the activity upon entering the trickle bed regime changes gradually, possibly due to the incomplete wetting of the catalyst by liquid water [28] .…”

Section: Resultssupporting

confidence: 75%

“…Water facilitates the selective oxidation of methane [9, 13–17, 20] . The mechanism for the observed enhancement may be system specific.…”

Section: Introductionmentioning

confidence: 99%

“…Some success in the selective oxidation of methane has been achieved using sulfuric acid, [6] H 2 O 2 [7] or N 2 O [8] as the oxidant. However, the use of oxygen [9][10][11][12][13][14][15][16][17][18][19] or even air as the oxidant is necessary to make the process economically viable. It should be noted further that heat is an important side product in the selective methane oxidation (the oxidation of methane to formaldehyde releases 34 % of the lower heating value of methane), which will need to be recovered to obtain an energy-efficient process.…”

Section: Introductionmentioning

confidence: 99%

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Platinum‐Catalysed Selective Aerobic Oxidation of Methane to Formaldehyde in the Presence of Liquid Water

et al. 2022

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The aerobic, selective oxidation of methane to C1‐oxygenates remains a challenge, due to the more facile, consecutive oxidation of formed products to CO2. Here, we report on the aerobic selective oxidation of methane under continuous flow conditions, over platinum‐based catalysts yielding formaldehyde with a high selectivity (reaching 90 % for Pt/TiO2 and 65 % over Pt/Al2O3) upon co‐feeding water. The presence of liquid water under reaction conditions increases the activity strongly attaining a methane conversion of 1–3 % over Pt/TiO2. Density‐functional theory (DFT) calculations show that the preferential formation of formaldehyde is linked to the stability of the di‐σ‐hydroxy‐methoxy species on platinum, the preferred carbon‐containing species on Pt(111) at a high chemical potential of water. Our findings provide novel insights into the reaction pathway for the Pt‐catalysed, aerobic selective oxidation of CH4.

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Section: Resultssupporting

confidence: 75%

“…Water facilitates the selective oxidation of methane [9, 13–17, 20] . The mechanism for the observed enhancement may be system specific.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Platinum‐Catalysed Selective Aerobic Oxidation of Methane to Formaldehyde in the Presence of Liquid Water

et al. 2022

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“…The metal oxides can also be employed as a cocatalyst being strong electrophilic metal oxides with extraordinary capacity to promote the C–H bond cleavage of CH 4 ( Fuller et al, 2016 ). The synergistic effect of bimetallic oxides offers an alternative route for the design and synthesis of novel catalysts for the direct conversion of CH 4 into methanol ( Lyu et al, 2021 ). In addition, the mechanism by which H 2 O promotes the high selectivity of direct CH 4 conversion also needs to be continuously explored.…”

Section: Perspectivesmentioning

confidence: 99%

Recent progress of catalytic methane combustion over transition metal oxide catalysts

et al. 2022

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Methane (CH4) is one of the cleanest fossil fuel resources and is playing an increasingly indispensable role in our way to carbon neutrality, by providing less carbon-intensive heat and electricity worldwide. On the other hand, the atmospheric concentration of CH4 has raced past 1,900 ppb in 2021, almost triple its pre-industrial levels. As a greenhouse gas at least 86 times as potent as carbon dioxide (CO2) over 20 years, CH4 is becoming a major threat to the global goal of deviating Earth temperature from the +2°C scenario. Consequently, all CH4-powered facilities must be strictly coupled with remediation plans for unburned CH4 in the exhaust to avoid further exacerbating the environmental stress, among which catalytic CH4 combustion (CMC) is one of the most effective strategies to solve this issue. Most current CMC catalysts are noble-metal-based owing to their outstanding C–H bond activation capability, while their high cost and poor thermal stability have driven the search for alternative options, among which transition metal oxide (TMO) catalysts have attracted extensive attention due to their Earth abundance, high thermal stability, variable oxidation states, rich acidic and basic sites, etc. To date, many TMO catalysts have shown comparable catalytic performance with that of noble metals, while their fundamental reaction mechanisms are explored to a much less extent and remain to be controversial, which hinders the further optimization of the TMO catalytic systems. Therefore, in this review, we provide a systematic compilation of the recent research advances in TMO-based CMC reactions, together with their detailed reaction mechanisms. We start with introducing the scientific fundamentals of the CMC reaction itself as well as the unique and desirable features of TMOs applied in CMC, followed by a detailed introduction of four different kinetic reaction models proposed for the reactions. Next, we categorize the TMOs of interests into single and hybrid systems, summarizing their specific morphology characterization, catalytic performance, kinetic properties, with special emphasis on the reaction mechanisms and interfacial properties. Finally, we conclude the review with a summary and outlook on the TMOs for practical CMC applications. In addition, we also further prospect the enormous potentials of TMOs in producing value-added chemicals beyond combustion, such as direct partial oxidation to methanol.

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“…The similarities in the direct partial oxidation chemistries of methane and benzene suggest that Lewis-acidic NiO clusters on redox active ceria-based supports, which can activate methane, − could also catalyze benzene hydroxylation. Indeed, experimental and theoretical studies have shown that Lewis-acidic NiO active centers can perform benzene activation and hydroxylation. , Because the oxidation state of cerium can easily shift between Ce(III) and Ce(IV), oxygen storage and removal within CeO 2 and CeO 2 –ZrO 2 (CZ) solid solutions occurs rapidly .…”

Section: Introductionmentioning

confidence: 99%

Characterization of Surface Species during Benzene Hydroxylation over a NiO-Ceria-Zirconia Catalyst

et al. 2021

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NiO/ceria-zirconia (CZ) is a promising catalyst for the selective oxidation of benzene, as the Lewis-acidic NiO clusters can activate C–H bonds and the redox-active CZ support can activate O2 and supply active oxygen species for the reaction. In this study, we used transmission in situ infrared (IR) spectroscopy to examine surface species formed from benzene, water, oxygen, phenol, and catechol on a NiO/CZ catalyst. The formation of surface species from benzene and phenol was compared at different temperatures in the range of 50–200 °C in the presence and absence of water vapor. We also examined the role of the NiO clusters and the CZ support during benzene activation by comparing the surface species formed on NiO-CZ with those formed on a Ni-free CZ support and on a NiO/SiO2 catalyst. The spectrum of surface species from dosing benzene at 180 °C provides evidence for C–H bond activation. Specifically, the observation of C–O stretching vibrations indicates the formation of phenolate species. Introduction of water enhances these IR signals and introduces several additional peaks, indicating that a variety of different surface species are formed. These results show that NiO/CZ could catalyze direct conversion of benzene to phenol.

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Selective Oxidation of Methane to Methanol over Ceria‐Zirconia Supported Mono and Bimetallic Transition Metal Oxide Catalysts

Cited by 25 publications

References 103 publications

Platinum‐Catalysed Selective Aerobic Oxidation of Methane to Formaldehyde in the Presence of Liquid Water

Platinum‐Catalysed Selective Aerobic Oxidation of Methane to Formaldehyde in the Presence of Liquid Water

Recent progress of catalytic methane combustion over transition metal oxide catalysts

Characterization of Surface Species during Benzene Hydroxylation over a NiO-Ceria-Zirconia Catalyst

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