Influence of Co2 on the Catalytic Performance Of La2O3/CeO2 and CaO/CeO2 Catalysts in the Oxidative Coupling of Methane

In this work the La2O3/CeO2 (33 mol % of La) and CaO/CeO2 (33 mol % of Ca) catalysts were prepared by the impregnation method and characterized by XRD and CO2-TPD. The catalytic properties of the catalysts were tested in the OCM process at 1073 K using the methane/oxygen mixture of the mole ratio 3.7 or 2.5 additionally containing CO2 and helium balance. It was found that in the presence of both catalysts an addition of CO2 enhances the selectivity to the ethylene and ethane and it does not have any negative influence on methane conversion. In the case of the CaO/CeO2 catalyst the promoting effect of CO2 was the highest. When the partial pressure of CO2 equals to 39 kPa the increase in selectivity from 36 to 41% was noted while the conversion of methane equal to 19.4-19.7 %.

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Raw Biogas as Feedstock for the OCM Process

Catalysts ◽

10.3390/catal12010054 ◽

2022 ◽

Vol 12 (1) ◽

pp. 54

Author(s):

Barbara Michorczyk ◽

Jakub Sikora ◽

Bogusława Kordon-Łapczyńska ◽

Dorota Gaweł ◽

Izabela Czekaj

Keyword(s):

Photoelectron Spectroscopy ◽

Oxidative Coupling ◽

Methane Conversion ◽

Catalytic Performance ◽

Oxidative Coupling Of Methane ◽

Raw Material ◽

Plant Materials ◽

X Ray ◽

Poisoning Effect ◽

Negative Effect

The paper presents the research results obtained in the process of oxidative coupling of methane, in which unpurified biogas was used as the feedstock. Biogas obtained from two kinds of biomass materials, i.e., plant materials (potato and beet pulp, Corn-Cob-Mix—biogas 1) and animal waste (waste from fish filleting—biogas 2) was considered. The influence of temperature, the ratio of methane/oxygen and total flows of feedstock on the catalytic performance in oxidative coupling of methane process was investigated. Comparative tests were carried out using pure methane and a mixture of methane-carbon dioxide to simulate the composition of biogas 2. The process was carried out in the presence of an Mn-Na2WO4/SiO2 catalyst. Fresh and used catalysts were characterised by means of powder X-ray diffraction, X-ray photoelectron spectroscopy, and low-temperature nitrogen adsorption techniques. In oxidative coupling of methane, the type of raw material used as the source of methane has a small effect on methane conversion (the differences in methane conversion are below 3%), but a significant effect on the selectivity to C2. Depending on the type of raw material, the differences in selectivity to C2 reach as high as 9%. However, the Mn-Na2WO4/SiO2 catalyst operated steadily in the tested period of time at any feedstock composition. Moreover, it was found that CO2, which is the second main component of biogas in addition to methane, has an effect on catalytic performance. Comparative results of catalytic tests indicate that the CO2 effect varies with temperature. Below 1073 K, CO2 exerts a small poisoning effect on methane conversion, while above this temperature the negative effect of CO2 disappears. In the case of selectivity to C2+, the negative effect of CO2 was observed only at 1023 K. At higher temperatures, CO2 enhances selectivity to C2+. The effect of CO2 was established by correlating the catalytic results with the temperature programmed desorption of CO2 investigation. The poisoning effect of CO2 was connected with the formation of surface Na2CO3, whose concentration depends on temperature.

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

Frontiers in Chemistry ◽

10.3389/fchem.2018.00581 ◽

2018 ◽

Vol 6 ◽

Cited By ~ 2

Author(s):

Masaaki Haneda ◽

Yuya Katsuragawa ◽

Yuichiro Nakamura ◽

Atsuya Towata

Keyword(s):

Cerium Oxide ◽

Yttrium Oxide ◽

Oxidative Coupling ◽

Catalytic Performance ◽

Oxidative Coupling Of Methane ◽

Promoting Effect

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Catalytic performance of Na-Mn2O3-based catalysts towards oxidative coupling of methane

Catalysis Today ◽

10.1016/j.cattod.2020.12.024 ◽

2021 ◽

Author(s):

P. Saychu ◽

M. Thanasiriruk ◽

C. Khajonvittayakul ◽

R. Viratikul ◽

V. Tongnan ◽

...

Keyword(s):

Oxidative Coupling ◽

Catalytic Performance ◽

Oxidative Coupling Of Methane

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Nanosheet-Like Ho2O3 and Sr-Ho2O3 Catalysts for Oxidative Coupling of Methane

Catalysts ◽

10.3390/catal11030388 ◽

2021 ◽

Vol 11 (3) ◽

pp. 388

Author(s):

Yuqiao Fan ◽

Changxi Miao ◽

Yinghong Yue ◽

Weiming Hua ◽

Zi Gao

Keyword(s):

Oxidative Coupling ◽

Temperature Programmed Desorption ◽

Oxidative Coupling Of Methane ◽

Molar Ratio ◽

Impregnation Method ◽

Oxygen Species ◽

N2 Adsorption ◽

Basic Sites ◽

Chemisorbed Oxygen ◽

Temperature Programmed

In this work, Ho2O3 nanosheets were synthesized by a hydrothermal method. A series of Sr-modified Ho2O3 nanosheets (Sr-Ho2O3-NS) with a Sr/Ho molar ratio between 0.02 and 0.06 were prepared via an impregnation method. These catalysts were characterized by several techniques such as XRD, N2 adsorption, SEM, TEM, XPS, O2-TPD (temperature-programmed desorption), and CO2-TPD, and they were studied with respect to their performances in the oxidative coupling of methane (OCM). In contrast to Ho2O3 nanoparticles, Ho2O3 nanosheets display greater CH4 conversion and C2-C3 selectivity, which could be related to the preferentially exposed (222) facet on the surface of the latter catalyst. The incorporation of small amounts of Sr into Ho2O3 nanosheets leads to a higher ratio of (O− + O2−)/O2− as well as an enhanced amount of chemisorbed oxygen species and moderate basic sites, which in turn improves the OCM performance. The optimal catalytic behavior is achievable on the 0.04Sr-Ho2O3-NS catalyst with a Sr/Ho molar ratio of 0.04, which gives a 24.0% conversion of CH4 with 56.7% selectivity to C2-C3 at 650 °C. The C2-C3 yield is well correlated with the amount of moderate basic sites present on the catalysts.

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