The selective oxidation of methane to ethane and ethylene over doped and un-doped rare earth oxides

Korf, S.J.; Roos, J.A.; Diphoorn, J.M.; Veehof, R.H.J.; Ommen, J.G. van; Ross, J.R.H.

doi:10.1016/0920-5861(89)85024-2

Cited by 64 publications

(24 citation statements)

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“…Thus, the higher performance of Gd2O3-2 was attributed to the presence of both cubic and monoclinic crystal structures in the sample. Similar results were observed for Sm2O3 catalysts in the literature which supported the obtained conclusion [17]. Additionally, the presence of two phase seem to be beneficial for the dehydrogenation of C2H6 as could be seen from the results.…”

Section: Resultssupporting

confidence: 91%

PREPARATION of Gd2O3 NANOMATERIALS via SOLUTION COMBUSTION SYNTHESIS FOR OXIDATIVE COUPLING OF METHANE

Özdemi̇r

2020

Eskişehir Technical University Journal of Science and Technology a - Applied Sciences and Engineering

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In this study, in the production of Gd2O3 material which has many usage areas, solution combustion synthesis was used and the changes in the physical and structural properties of the material were investigated by changing the oxidant/fuel ratio. The resulting metal oxide powders were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, Thermogravimetric-Differential thermal analysis (TG-DTA) and scanning electron microscopy (SEM) analysis and tested in oxidative coupling of methane. Cubic and monoclinic phases were observed in Gd2O3 crystal structure at fuel-rich and stoichiometric conditions, and only cubic phase was determined at fuel-lean conditions. It was determined that the obtained powders were mesoporous and the highest BET surface area was obtained at stoichiometric oxidant/fuel ratio (18.6 m 2 /g). It was determined that the powders were formed from rather small particles (<35 nm) and with layered or stacked structure. The catalytic performance of Gd2O3 nanoparticles was found to be dependent on the BET surface area and crystal structure. The highest C2 yield (8.5%) was obtained at 720°C with the Gd2O3 that was synthesized using the equivalence ratio of 0.5.

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Section: Resultssupporting

confidence: 91%

PREPARATION of Gd2O3 NANOMATERIALS via SOLUTION COMBUSTION SYNTHESIS FOR OXIDATIVE COUPLING OF METHANE

Özdemi̇r

2020

Eskişehir Technical University Journal of Science and Technology a - Applied Sciences and Engineering

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“…XRD results of the Sm 2 O 3 catalysts synthesized in different morphologies were presented in Figure 1. It was determined that all catalysts crystallized well and have cubic Sm 2 O 3 (JCPDS 43‐1029) crystal structures, which are known to perform better than other phases [10,11] . Average crystallite sizes, lattice parameters and BET surface areas of the catalysts were given in Table 1.…”

Section: Resultsmentioning

confidence: 99%

Detailed Investigation of Sm₂O₃ Catalysts with Different Morphologies for Oxidative Coupling of Methane

Özdemi̇r

2021

ChemistrySelect

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Sm 2 O 3 catalysts with different morphologies (nanoparticle, nanorod, hollow nanosphere, nanofiber, flower-like) were synthesized and tested for the oxidative coupling of methane. The results obtained showed that increasing specific surface area reduced the activity, C 2 selectivity and, thus the yield. It was observed that the reaction initiation temperature was dependent on the total or partial oxidation of methane, which produced the heat for the initiation of the reaction. The effect of temperature on catalytic performance was relatively low at lower temperatures (< 600°C) than at higher temperatures (> 700°C). High reaction temperatures (> 700°C) decreased the C 2 selectivity, lower temperatures were found beneficial to achieve higher C 2 selectivity and yield as expected. Hollow nanosphere morphology showed the highest activity and selectivity at 450°C and yielded 10.5 % C 2 under high space velocity. The highest C 2 yield (11.8 %) was obtained at 600°C with nanoparticle morphology. Considering the results at the conditions that full oxygen conversion was attained, it was found that the C 2 selectivity and yield decreased with the nanoparticle > flower-like > nanorod and nanosphere > nanofiber sequence.

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“…The addition of Ti and Mg into the Na 2 WO 4 –MnO x /SiO 2 catalyst was also reported to improve the OCM activity when Na 2 WO 4 and MnO x were on the external surface of the silica, but it was unclear how these two additives improved the activation . Oxides of alkali or alkali earth metals (e.g., Li 2 O, ,,− Na 2 O, , K 2 O, , Rb 2 O, Cs 2 O, MgO, ,,− CaO, ,,, SrO, ,,,− and/or BaO) have been used as additives for various catalysts for the OCM reaction and were found to enhance the OCM activity because of their basicity property. In other words, they are unlike oxides of acidic metals, which prefer the complete oxidation of methane .…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Value-Added Chemicals via Oxidative Coupling of Methanes over Na₂WO₄–TiO₂–MnO_x/SiO₂ Catalysts with Alkali or Alkali Earth Oxide Additives

et al. 2020

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Na 2 WO 4 −TiO 2 −MnO x /SiO 2 (SM) catalysts with alkali (Li, K, Rb, Cs) or alkali earth (Mg, Ca, Sr, Ba) oxide additives, which were prepared using incipient wetness impregnation, were investigated for oxidative coupling of methane (OCM) to value-added hydrocarbons (C 2+ ). A screening test that was performed on the catalysts revealed that SM with Sr (SM−Sr) had the highest yield of C 2+ . X-ray photoelectron spectroscopy analyses indicated that the catalysts with a relatively low binding energy of W 4f 7/2 facilitated a high CH 4 conversion. A combination of crystalline MnTiO 3 , Mn 2 O 3 , α-cristobalite, Na 2 WO 4 , and TiO 2 phases was identified as an essential component for a remarkable improvement in the activity of the catalysts in the OCM reaction. In attempts to optimize the C 2+ yield, 0.25 wt % Sr onto SM−Sr achieved the highest C 2+ yield at 22.9% with a 62.5% C 2+ selectivity and a 36.6% CH 4 conversion. A stability test of the optimal catalyst showed that after 24 h of testing, its activity decreased by 18.7%.

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The selective oxidation of methane to ethane and ethylene over doped and un-doped rare earth oxides

Cited by 64 publications

References 10 publications

PREPARATION of Gd2O3 NANOMATERIALS via SOLUTION COMBUSTION SYNTHESIS FOR OXIDATIVE COUPLING OF METHANE

PREPARATION of Gd2O3 NANOMATERIALS via SOLUTION COMBUSTION SYNTHESIS FOR OXIDATIVE COUPLING OF METHANE

Detailed Investigation of Sm₂O₃ Catalysts with Different Morphologies for Oxidative Coupling of Methane

Synthesis of Value-Added Chemicals via Oxidative Coupling of Methanes over Na₂WO₄–TiO₂–MnO_x/SiO₂ Catalysts with Alkali or Alkali Earth Oxide Additives

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The selective oxidation of methane to ethane and ethylene over doped and un-doped rare earth oxides

Cited by 64 publications

References 10 publications

PREPARATION of Gd2O3 NANOMATERIALS via SOLUTION COMBUSTION SYNTHESIS FOR OXIDATIVE COUPLING OF METHANE

PREPARATION of Gd2O3 NANOMATERIALS via SOLUTION COMBUSTION SYNTHESIS FOR OXIDATIVE COUPLING OF METHANE

Detailed Investigation of Sm2O3 Catalysts with Different Morphologies for Oxidative Coupling of Methane

Synthesis of Value-Added Chemicals via Oxidative Coupling of Methanes over Na2WO4–TiO2–MnOx/SiO2 Catalysts with Alkali or Alkali Earth Oxide Additives

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Detailed Investigation of Sm₂O₃ Catalysts with Different Morphologies for Oxidative Coupling of Methane

Synthesis of Value-Added Chemicals via Oxidative Coupling of Methanes over Na₂WO₄–TiO₂–MnO_x/SiO₂ Catalysts with Alkali or Alkali Earth Oxide Additives