Alternative Oxidants for the Catalytic Oxidative Coupling of Methane

Arinaga, Allison M.; Ziegelski, Morgan C.; Marks, Tobin J.

doi:10.1002/ange.202012862

Cited by 4 publications

(7 citation statements)

References 138 publications

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“…In addition to catalyst characterization studies, the usage of N 2 O instead of O 2 for performing the OCM reaction is helpful for deriving insights into the kind and the role of different oxygen species. − N 2 O has often been reported to improve the selectivity to C 2 hydrocarbons over different catalysts. The improvement is related to the kind of surface oxygen species formed from this oxidant; monatomic oxygen species were suggested to lead to higher selectivity than biatomic oxygen species, which are formed from O 2 . − It is especially worth mentioning that there is only one study where N 2 O was used as an oxidant for the OCM reaction over Na 2 WO 4 /SiO 2 .…”

Section: Introductionmentioning

confidence: 97%

Effects of N₂O and Water on Activity and Selectivity in the Oxidative Coupling of Methane over Mn–Na₂WO₄/SiO₂: Role of Oxygen Species

et al. 2022

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The understanding of the reaction mechanism of product formation in the oxidative coupling of methane (OCM) is the prerequisite for designing catalysts with improved selectivity to the desired products, i.e., C 2 H 6 and C 2 H 4 (C 2 hydrocarbons). One step in this direction is to understand the kind of oxygen species involved in the selective and nonselective reactions. Against this background, a series of kinetic and mechanistic tests of the OCM reaction with N 2 O (N 2 O−OCM) were carried out over the Mn−Na 2 WO 4 /SiO 2 system in the absence and the presence of cofed water. The usage of N 2 O instead of O 2 was proven to suppress the direct oxidation of CH 4 to CO 2 in favor of the formation of C 2 hydrocarbons. This inhibition was explained by a lower concentration of surface biatomic oxygen species participating in the formation of CO 2 . The formation of such species from O 2 was supported by oxygen isotopic exchange and electron paramagnetic resonance (EPR) tests. As proven by in situ UV−vis tests under various reaction conditions at 750 °C, N 2 O−OCM and O 2 −OCM mainly proceed through a Mars van Krevelen sequence. As MnO x is reduced faster than Na 2 WO 4 , it should be primarily involved in oxidant activation. In comparison with O 2 , N 2 O was proven to reoxidize reduced catalysts significantly slower. This results in reducing surface density (spatial separation) of lattice oxygen species in N 2 O−OCM that is unfavorable for the undesired oxidation reactions leading to carbon oxides. As a result, the selectivity to C 2 hydrocarbons increases. This knowledge is essential for catalyst design through controlling the rates of generation and consumption of oxygen species. A further aspect of this work is the positive effect of H 2 O on the rate of methane conversion and the selectivity to C 2 hydrocarbons in N 2 O−OCM. The strength of this effect on the activity is lower than in O 2 −OCM. The enhancing effect was related to H 2 O-mediated transformation of surface biatomic oxygen species into monatomic ones.

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Section: Introductionmentioning

confidence: 97%

Effects of N₂O and Water on Activity and Selectivity in the Oxidative Coupling of Methane over Mn–Na₂WO₄/SiO₂: Role of Oxygen Species

et al. 2022

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“…However, OCM has limited industrial implementation due to the poor selectivity of the C 2 products. The predominant dry reforming or partial oxidation is a competing reaction that can form the undesired product of CO and H 2 . Additionally, the formed ethane and ethylene can also become oxidized back into CO 2 , lowering the overall yield.…”

Section: Co2 Utilization For Hydrocarbon and Lower Olefin Productionmentioning

confidence: 99%

“…The predominant dry reforming or partial oxidation is a competing reaction that can form the undesired product of CO and H 2 . 204 Additionally, the formed ethane and ethylene can also become oxidized back into CO 2 , lowering the overall yield. Nevertheless, OCM is an essential reaction for the direct utilization of CO 2 and CH 4 into ethane and ethylene, a valuable intermediate for the chemical industry.…”

Section: Co 2 Utilization For Hydrocarbon and Lower Olefin Productionmentioning

confidence: 99%

“…212 In summary, the use of CO 2 as the oxidizing gas for OCM, either substituting or supplementing oxygen, has seen several instances of either improving selectivity or having no effect at all. The presence of carbon dioxide increases surface O ads species and reduces exothermicity of reaction, either of which could be a factor affecting the selectivity 204…”

Section: Co 2 Utilization For Hydrocarbon and Lower Olefin Productionmentioning

confidence: 99%

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Perspective on Sorption Enhanced Bifunctional Catalysts to Produce Hydrocarbons

Cruz

Shah

et al. 2022

ACS Catal.

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Sorption-enhanced catalysts are bifunctional materials consisting of a heterogeneous catalyst affixed to a solid sorbent with a combined capacity to selectively capture and convert CO2 directly to value-added fuels and chemicals in the same reactor. The benefits of facile separation of CO2, directly from air or from flue gas, and conversion to chemical commodities is appealing for developing an integrated carbon capture and utilization scheme. The growth of this area is rapidly expanding with interest from catalysis, materials design, and life-cycle analysis researchers. However, the promise of sorption-enhanced catalysts is limited by their reduced thermal stability, CO2 capture capacity, and restricted product streams to C1 hydrocarbons. The prime issue is that the reaction conditions for the capture of CO2, regeneration of the sorbent, and utilization can be vastly different. It remains a challenge to optimize both the properties of the sorbent support material and the heterogeneous catalyst used. This perspective summarizes the current state-of-the-art for the properties of solid sorbents, heterogeneous catalysts, and the combined sorbent-enhanced catalysts for producing hydrocarbons from CO2. Lastly, the perspective discusses challenges and future areas for improving the performance and capture efficiency of sorption-enhanced catalysts.

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“…Table 2 shows a compilation of the main reactions that can take place in CO 2 –OCM 8 . The catalysts that presented the best results for CO 2 –OCM are composed of binary basic metal oxides; however, due to thermodynamic constraints, the average results of C 2 yield are still below 10% 9 …”

Section: Introductionmentioning

confidence: 99%

Ethylene production by partial oxidation of biogas using lime as catalyst

May,

Perez‐Lopez

2023

J of Chemical Tech & Biotech

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The oxidative coupling of methane (OCM) is an interesting route for direct conversion of methane into ethylene and ethane. Nevertheless, COx is a secondary product of this route, which decreases the selectivity of hydrocarbons. In this work it is proposed to overcome this drawback by using biogas as source of methane. In addition to being a renewable source of methane, the presence of CO2 in biogas may shift the balance of the methane combustion. For this purpose, it was evaluated how process conditions such as O2 and CO2 flow rates and temperature affect biogas‐based OCM, in the temperature range of 650 – 800 °C, using lime as catalyst. The increase in CO2 flow from 0 to 15 mL.min‐1 increased the ethylene selectivity from 25.9% to 44.5% at 800 °C. As consequence, CO2 formation dropped from 53.9% to 18.3%. Methane conversion was not affected significantly by CO2 flow rate, remaining in the range of 22 – 25%. O2 flow was essential to activate the OCM reaction and the presence of higher concentrations of O2 favored the selectivity of ethylene, but also increased the CO2 produced through methane combustion. In the OCM experiments with variable flow of CO2, the highest C2 yield of 18% was obtained for the highest flow of co‐fed CO2, whereas the experiments with biogas and variable O2 flow showed the highest yield of ethylene for the highest flow of air co‐fed. Thus, biogas‐based OCM was shown to be a promising route to improve C2 selectivity, since the CO2 present in the biogas minimizes the formation of CO2 in the reaction. The use of lime as a low‐cost catalyst proved to be viable for the OCM reaction, presenting results compatible with those obtained for catalysts with more complex composition.This article is protected by copyright. All rights reserved.

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Alternative Oxidants for the Catalytic Oxidative Coupling of Methane

Cited by 4 publications

References 138 publications

Effects of N₂O and Water on Activity and Selectivity in the Oxidative Coupling of Methane over Mn–Na₂WO₄/SiO₂: Role of Oxygen Species

Effects of N₂O and Water on Activity and Selectivity in the Oxidative Coupling of Methane over Mn–Na₂WO₄/SiO₂: Role of Oxygen Species

Perspective on Sorption Enhanced Bifunctional Catalysts to Produce Hydrocarbons

Ethylene production by partial oxidation of biogas using lime as catalyst

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Alternative Oxidants for the Catalytic Oxidative Coupling of Methane

Cited by 4 publications

References 138 publications

Effects of N2O and Water on Activity and Selectivity in the Oxidative Coupling of Methane over Mn–Na2WO4/SiO2: Role of Oxygen Species

Effects of N2O and Water on Activity and Selectivity in the Oxidative Coupling of Methane over Mn–Na2WO4/SiO2: Role of Oxygen Species

Perspective on Sorption Enhanced Bifunctional Catalysts to Produce Hydrocarbons

Ethylene production by partial oxidation of biogas using lime as catalyst

Contact Info

Product

Resources

About

Effects of N₂O and Water on Activity and Selectivity in the Oxidative Coupling of Methane over Mn–Na₂WO₄/SiO₂: Role of Oxygen Species

Effects of N₂O and Water on Activity and Selectivity in the Oxidative Coupling of Methane over Mn–Na₂WO₄/SiO₂: Role of Oxygen Species