Elucidating the structure of the W and Mn sites on the Mn-Na2WO4/SiO2 catalyst for the oxidative coupling of methane (OCM) at real reaction temperatures

Ortiz-Bravo, Carlos A.; Figueroa, Santiago; Portela, Raquel; Chagas, Carlos Alberto; Bañares, Miguel Á.; Toniolo, Fabio Souza

doi:10.1016/j.jcat.2021.06.021

Cited by 32 publications

(41 citation statements)

References 63 publications

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“…A study of electronic properties and structure of Mn and W in the Mn–Na 2 WO 4 /SiO 2 catalyst demonstrated the absence of correlation of OCM activity with the crystallinity. 221 Thus, heating of catalysts leads to the transformation of W oxide to molten Na 2 WO 4 with significant distortion of bond orders and a switch of the tetrahedral T d to octahedral O h symmetry. The authors concluded that the O h -W 6+ species were inactive in OCM reaction, however, T d -W 6+ activated methane in the presence of Mn 3+ octahedral sites.…”

Section: Light Olefin Synthesis From Hydrocarbonsmentioning

confidence: 99%

Light olefin synthesis from a diversity of renewable and fossil feedstocks: state-of the-art and outlook

et al. 2022

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Section: Light Olefin Synthesis From Hydrocarbonsmentioning

confidence: 99%

Light olefin synthesis from a diversity of renewable and fossil feedstocks: state-of the-art and outlook

et al. 2022

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“…Ortiz-Bravo et al [64] showed better C2 selectivity but were slightly less active. The bi-component system (Na and Mn oxide) is 100% selective but has poor conversion, while, the three-component system (Mn-Na-W oxide supported on SiO2) shows significantly higher selectivity than bicomponent (Na-W, Na-Mn and, and Mn-W) catalysts, although it is slightly less active than the Na-W oxide catalyst.…”

Section: Modified Transition Metal Oxide Catalystsmentioning

confidence: 97%

“…OCM reaction mechanism for the supported Mn2O3/Na2WO4/SiO2 catalyst is shown in Figure 6. Ortiz-Bravo et al [64] systematically elucidate the electronic and molecular structure of the W and Mn sites on the Mn-Na2WO4/SiO2 catalyst of the corresponding OCM reaction temperature by using different analytical techniques. The Mn-Na2WO4/SiO2 catalyst's structure is highly temperature-dependent; thus, the association of any OCM activity with crystalline phases observed at room temperature is inadequate.…”

Section: Modified Transition Metal Oxide Catalystsmentioning

confidence: 99%

Oxidative Coupling of Methane: Perspective for High-Value C2 Chemicals

Murthy

Liu

et al. 2021

Crystals

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The oxidative coupling of methane (OCM) to C2 hydrocarbons (C2H4 and C2H6) has aroused worldwide interest over the past decade due to the rise of vast new shale gas resources. However, obtaining higher C2 selectivity can be very challenging in a typical OCM process in the presence of easily oxidized products such as C2H4 and C2H6. Regarding this, different types of catalysts have been studied to achieve desirable C2 yields. In this review, we briefly presented three typical types of catalysts such as alkali/alkaline earth metal doped/supported on metal oxide catalysts (mainly for Li doped/supported catalysts), modified transition metal oxide catalysts, and pyrochlore catalysts for OCM and highlighted the features that play key roles in the OCM reactions such as active oxygen species, the mobility of the lattice oxygen and surface alkalinity of the catalysts. In particular, we focused on the pyrochlore (A2B2O7) materials because of their promising properties such as high melting points, thermal stability, surface alkalinity and tunable M-O bonding for OCM reaction.

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“…The process OCM is a process working due to [66,67] like in reactions ( 9) and (10) (s subscript in reaction stands for surface)…”

Section: Commented [Km1]: Add From Colcot Amentioning

confidence: 99%

Analysis of Biogas Component Production during Anaerobic Digestion of Sour Cabbage in Microaeration Conditions under Different pH Conditions

Sołowski¹

2021

Preprint

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In the article, were checked influences of microaeration, pH, and VSS (Volatile Suspended Solid) for sour cab-bage anaerobic digestion. Results fermentation of sour cabbage under the condition of small oxygen addition are presented in this research can be classified as dark fermentation or hydrogenotrophic anaerobic digestion. The investigations were carried out for two concentrations 5 g VSS /L and 10 g VSS /L of sour cabbage at pH 6.0. The oxygen flow rates (OFR) for 5 g VSS /L were in the range of 0.53 to 3.3 mL/h for obtaining 2% to 8% of oxygen. In cases of low pH and microaeration, ethylene production was observed at a level below 0.05% in biogas. The highest volume of hydrogen for 5 g VSS/L was obtained for flow rate 0.58 O2 mL/h, giving hydrogen concentration in biogas in the range of 0 to 20%. For VSS 5 g/L and oxygen flow rate 0.58 mL/h; 0.021 L of hydrogen is produced per gram of VSS. In this case, VSS 10 g/L and oxygen flow rate 1.4 mL/h at pH 6.0, 0.03 L of hydrogen is generated per gram. Microaeration from 0.58 mL/h to 0.87 mL/h was propitious for hydrogen production at 5 g VSS/L of sour cabbage and 1.4 mL/h for 10 g/L. Another relevant factor is the volatile suspended solid factor of sour cabbage that caused optimal hydrogen production at VSS 89.32%.

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Elucidating the structure of the W and Mn sites on the Mn-Na2WO4/SiO2 catalyst for the oxidative coupling of methane (OCM) at real reaction temperatures

Cited by 32 publications

References 63 publications

Light olefin synthesis from a diversity of renewable and fossil feedstocks: state-of the-art and outlook

Light olefin synthesis from a diversity of renewable and fossil feedstocks: state-of the-art and outlook

Oxidative Coupling of Methane: Perspective for High-Value C2 Chemicals

Analysis of Biogas Component Production during Anaerobic Digestion of Sour Cabbage in Microaeration Conditions under Different pH Conditions

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