Effects of alkali and alkaline-earth metal dopants on magnesium oxide supported rare-earth oxide catalysts in the oxidative coupling of methane

Elkins, Trenton W.; Roberts, Samantha J.; Hagelin‐Weaver, Helena E.

doi:10.1016/j.apcata.2016.09.011

Cited by 58 publications

(45 citation statements)

References 68 publications

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“…Evidently, aggregation of catalyst particles results in the significant drop in surface area. A similar phenomena was reported by Elkins during OCM investigations . During OCM reaction, and despite the notable decrease in surface area, the CH 4 conversion per unit mass of catalyst is the same or higher over the magnesium oxide supported rare‐earth oxide catalysts.…”

Section: Resultssupporting

confidence: 84%

“…A similar phenomena was reported by Elkins during OCM investigations. 49 During OCM reaction, and despite the notable decrease in surface area, the CH 4 conversion per unit mass of catalyst is the same or higher over the magnesium oxide supported rare-earth oxide catalysts. It is unusual to observe a significant decrease in surface area of a catalyst and for that catalyst to maintain its intrinsic activity.…”

Section: Characterization Of the Fresh And Spent Catalysts Textual Prmentioning

confidence: 93%

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Catalytic coupling of CH₄ with CHF₃ for the synthesis of VDF over LaOF catalyst

et al. 2018

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The oxidative coupling of methane (OCM) with CHF3 facilitates the synthesis of vinylidene fluoride (VDF). The aim is to utilize CHF3, which is otherwise considered a waste with a very high global warming potential. This study focuses on the effect of a LaOF catalyst on OCM occurring in the presence of CHF3, which engenders a promoting effect of O2 on CH4 activation. It examines the structural and phase changes of the lanthanum catalyst during the reaction and then speculates on the reaction mechanism. In combining OCM with CHF3, both the conversion of CH4 and the formation rate of VDF are almost tripled at 700°C. However, at higher temperatures, gas‐phase reactions play a dominating role in the conversion of CH4 and LaOF catalyst plays a very minor role in the reaction system at elevated temperatures. Irrespective of the reaction temperature, VDF is produced via the gas‐phase coupling of CH3 radicals with CF2. During pretreatment or during the reaction itself, La2O3 is fluorinated by CHF3 and HF, yielding the formation of surface LaOF and LaF3 species. LaF3 is a relatively inactive catalyst for CH4 conversion, whereas, in comparison LaOF appears to play a very important role in the activation of CH4 at low temperatures. The activation mechanism of CH4 at relatively low temperatures is similar with that postulated to occur during the OCM. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.

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Section: Resultssupporting

confidence: 84%

Section: Characterization Of the Fresh And Spent Catalysts Textual Prmentioning

confidence: 93%

Catalytic coupling of CH₄ with CHF₃ for the synthesis of VDF over LaOF catalyst

et al. 2018

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“…They explained the promoting effect of CeO 2 by oxygen activation caused via the electron transfer between Ce 4+ /Ce 3+ and Li/MgO. A similar promoting effect of CeO 2 was reported for Na/CaO (Pacheco Filho et al, 2000) and Li/MgO (Elkins et al, 2016). In case of alkali-doped catalysts, Li + O − and Na + O − sites are proposed to participate in oxygen activation (Ito et al, 1985; Lin et al, 1986).…”

Section: Introductionsupporting

confidence: 55%

Promoting Effect of Cerium Oxide on the Catalytic Performance of Yttrium Oxide for Oxidative Coupling of Methane

et al. 2018

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The promoting effect of CeO2 on the catalytic performance of Y2O3, which is moderately active catalyst, for the oxidative coupling of methane (OCM) reaction was investigated. The addition of CeO2 into Y2O3 by coprecipitation method caused a significant increase in not only CH4 conversion but also C2 (C2H6/C2H4) selectivity in the OCM reaction. C2 yield at 750 °C was increased from 5.6% on Y2O3 to 10.2% on 3 mol% CeO2/Y2O3. Further increase in the CeO2 loading caused an increase in non-selective oxidation of CH4 to CO2. A good correlation between the catalytic activity for the OCM reaction and the amount of H2 consumption for the reduction of surface/subsurface oxygen species in the H2-TPR profile was observed, suggesting the possibility that highly dispersed CeO2 particles act as catalytically active sites in the OCM reaction. The 16O/18O isotopic exchange reaction suggested that the beneficial role of CeO2 in the OCM reaction is to promote the formation of active oxygen species via the simple hetero-exchange mechanism, resulting in the promotion of CH4 activation.

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“…There are also significant demands of magnesium in oxide form. The oxide form of magnesium is needed to make drugs, slow release fertilizer, fire retardant materials, catalyst, etc [9,10,11,12]. The process to produce magnesium oxide obviously consumes less energy than the process to produce magnesium metal.…”

Section: Proceedings Of the International Seminar On Metallurgy And Mmentioning

confidence: 99%

Dissolution profile of dolomite in chloric acid solution: The effect of chloric acid concentration and pulp density

Solihin¹,

Indriani²,

Mubarok³

2018

AIP Conference Proceedings

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Abstract. Dolomite is one of carbonate minerals that contain magnesium. Magnesium is important element used in many aspects of life such as cofactor of many enzymes in human body, nutrient for plants, and raw material in automotive industry. Dolomite can be processed through low temperature process to obtain magnesium and calcium oxide that is needed in important applications such as base material for making drugs, raw material in the synthesize slow release fertilizer, materials for fire retardant, component for catalyst, etc. One of the important step of this low temperature process is dissolution of dolomite. Optimizing the dissolution process determines the % extraction of magnesium and calcium oxide from dolomite. The dissolution of dolomite from Gresik, East Java Provence Indonesia, in chloric acid solution has been conducted. Chloric acid concentration and pulp density are the variables that were observed. The dissolution of magnesium and calcium from Gresik dolomite was found to be very fast. The stable stage of dissolution can be reached for 5-10 seconds. The % extraction is mainly determined by the molar ratio of chloric acid / dolomite. At molar ratio of chloric acid / dolomite equal or above stoichiometric of dolomite dissolution, % extraction of magnesium is almost 100 %.

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Effects of alkali and alkaline-earth metal dopants on magnesium oxide supported rare-earth oxide catalysts in the oxidative coupling of methane

Cited by 58 publications

References 68 publications

Catalytic coupling of CH₄ with CHF₃ for the synthesis of VDF over LaOF catalyst

Catalytic coupling of CH₄ with CHF₃ for the synthesis of VDF over LaOF catalyst

Promoting Effect of Cerium Oxide on the Catalytic Performance of Yttrium Oxide for Oxidative Coupling of Methane

Dissolution profile of dolomite in chloric acid solution: The effect of chloric acid concentration and pulp density

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Effects of alkali and alkaline-earth metal dopants on magnesium oxide supported rare-earth oxide catalysts in the oxidative coupling of methane

Cited by 58 publications

References 68 publications

Catalytic coupling of CH4 with CHF3 for the synthesis of VDF over LaOF catalyst

Catalytic coupling of CH4 with CHF3 for the synthesis of VDF over LaOF catalyst

Promoting Effect of Cerium Oxide on the Catalytic Performance of Yttrium Oxide for Oxidative Coupling of Methane

Dissolution profile of dolomite in chloric acid solution: The effect of chloric acid concentration and pulp density

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Catalytic coupling of CH₄ with CHF₃ for the synthesis of VDF over LaOF catalyst

Catalytic coupling of CH₄ with CHF₃ for the synthesis of VDF over LaOF catalyst