Na2WO4-Mn/mullite Catalysts for Oxidative Coupling of Methane

The catalysts, 5 wt% Na2WO4-2 wt% Mn on mullites sintered at 1200°C, 1300°C, 1400°C, and 1500 °C, were prepared by incipient wetness impregnation method for the oxidative coupling of methane (OCM) reaction in a fixed-bed quartz tube reactor. These catalysts were characterized by XRD, XPS and BET method. The XRD pattern of Na2WO4-Mn/mullite indicated that the main crystal phase of metal oxide was MnWO4. From the XPS spectra, the results revealed the information on Na, W and Mn species distributed on the catalyst surface. For catalytic activity testing, Na2WO4-Mn/mullite sintered at 1300 °C showed the highest C2selectivity of 11.4% and Na2WO4-Mn/mullite sintered at 1400 °C showed the highest CH4conversion of 56.6%.

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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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Tungsten Oxide-Modified SSZ-13 Zeolite as an Efficient Catalyst for Ethylene-To-Propylene Reaction

Catalysts ◽

10.3390/catal11050553 ◽

2021 ◽

Vol 11 (5) ◽

pp. 553

Author(s):

Mansurbek Urol ugli Abdullaev ◽

Sungjune Lee ◽

Tae-Wan Kim ◽

Chul-Ung Kim

Keyword(s):

Tungsten Oxide ◽

Fixed Bed ◽

Acid Sites ◽

Fixed Bed Reactor ◽

Incipient Wetness Impregnation ◽

Impregnation Method ◽

Efficient Catalyst ◽

X Ray ◽

Propylene Selectivity ◽

Temperature Programmed

Among the zeolitic catalysts for the ethylene-to-propylene (ETP) reaction, the SSZ-13 zeolite shows the highest catalytic activity based on both its suitable pore architecture and tunable acidity. In this study, in order to improve the propylene selectivity further, the surface of the SSZ-13 zeolite was modified with various amounts of tungsten oxide ranging from 1 wt% to 15 wt% via a simple incipient wetness impregnation method. The prepared catalysts were characterized with several analysis techniques, specifically, powder X-ray diffraction (PXRD), Raman spectroscopy, temperature-programmed reduction of hydrogen (H2-TPR), temperature-programmed desorption of ammonia (NH3-TPD), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and N2 sorption, and their catalytic activities were investigated in a fixed-bed reactor system. The tungsten oxide-modified SSZ-13 catalysts demonstrated significantly improved propylene selectivity and yield compared to the parent H-SSZ-13 catalyst. For the tungsten oxide loading, 10 wt% loading showed the highest propylene yield of 64.9 wt%, which was 6.5 wt% higher than the pristine H-SSZ-13 catalyst. This can be related to not only the milder and decreased strong acid sites but also the diffusion restriction of bulky byproducts, as supported by scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDS) observation.

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Comparative Study on the Kinetic Modeling of the Oxidative Coupling of Methane in Laboratory and Bench Scales

Chemical Product and Process Modeling ◽

10.2202/1934-2659.1133 ◽

2008 ◽

Vol 3 (1) ◽

Cited By ~ 3

Author(s):

Nakisa Yaghobi ◽

Mir Hamid Reza Ghoreishy

Keyword(s):

Kinetic Models ◽

Oxidative Coupling ◽

Consumption Rate ◽

Linear Regression Analysis ◽

Fixed Bed ◽

Space Velocity ◽

Oxidative Coupling Of Methane ◽

Power Law Model ◽

Fixed Bed Reactors ◽

Rate Of Reaction

The aim of this work is to develop and compare kinetic models for the oxidative coupling of methane (OCM) based on the gas hourly space velocity (GHSV) value and CH4/O2 ratio in two scales: laboratory and bench. The experiments were carried out in tubular fixed bed reactors at 1023 K, using 0.7-1.5 g and 30 g of perovskite titanate as the reaction catalyst for laboratory and bench scales, respectively. The various GHSVs (8000, 12000, 17000 h-1) and (3400, 4300, 5200 h-1) and methane to oxygen ratios (1, 2, 3, 4, 7.5) and (2, 2.5, 3) were selected for laboratory and bench scales, respectively. We have proposed a mechanism in which the consumption rate of methane is always twice of production rate of C2. A power law model was assumed for rate of reaction in terms of partial pressure of oxygen and methane. Using a linear regression analysis, the kinetic models were determined. Comparison of the calculated rate of reaction with the experimentally measured data confirmed the accuracy and applicability of the developed model for both scales.

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Two-Dimensional Modeling of the Oxidative Coupling of Methane in a Fixed Bed Reactor: A Comparison among Different Catalysts

Engineering Journal ◽

10.4186/ej.2017.21.3.77 ◽

2017 ◽

Vol 21 (3) ◽

pp. 77-99 ◽

Cited By ~ 1

Author(s):

Salamah Manundawee ◽

Amornchai Arpornwichanop ◽

Suttichai Assabumrungrat ◽

Wisitsree Wiyaratn

Keyword(s):

Oxidative Coupling ◽

Fixed Bed ◽

Oxidative Coupling Of Methane ◽

Fixed Bed Reactor ◽

Two Dimensional ◽

Dimensional Modeling

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On efficiency of vanadium-oxide promoter in cobalt Fischer – Tropsch catalysts

Kataliz v promyshlennosti ◽

10.18412/1816-0387-2021-1-2-15 ◽

2021 ◽

Vol 1 (1-2) ◽

pp. 15

Author(s):

Elham Yaghoobpour ◽

Yahya Zamani ◽

Saeed Zarrinpashne ◽

Akbar Zamaniyan

Keyword(s):

Vanadium Oxide ◽

Active Sites ◽

Fixed Bed ◽

Fixed Bed Reactor ◽

Bet Surface Area ◽

Incipient Wetness Impregnation ◽

Impregnation Method ◽

Fischer Tropsch ◽

Co Conversion ◽

Loading Amount

Promoters and their loading amount have crucial roles in cobalt Fischer – Tropsch catalysts. In this regard, the effects of vanadium oxide (V2O5) as a proposed promoter for Co catalyst supported on TiO2 have been investigated. Three catalysts with 0, 1, and 3 wt.% of V2O5 promoter loading are prepared by the incipient wetness impregnation method, and characterized by the BET surface area analyzer, XRD, H2-TPR, and TEM techniques. The fixed-bed reactor was employed for their evaluations. It was found that the catalyst containing 1 wt.% V2O5 has the best performance among the evaluated catalysts, demonstrating remarkable selectivity: 92 % C5+ and 5.7 % CH4, together with preserving the amount of CO conversion compared to the unpromoted catalyst. Furthermore, it is reported that the excess addition of V2O5 promoter (> 1 wt.%) in the introduced catalyst leads to the detrimental effect on the CO conversion and C5+ selectivity, mainly owing to diminished active sites by V2O5 loading.

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Real-time multi-length scale chemical tomography of fixed bed reactors during the oxidative coupling of methane reaction

Journal of Catalysis ◽

10.1016/j.jcat.2020.03.027 ◽

2020 ◽

Vol 386 ◽

pp. 39-52 ◽

Cited By ~ 2

Author(s):

Antonis Vamvakeros ◽

Dorota Matras ◽

Simon D.M. Jacques ◽

Marco di Michiel ◽

Stephen W.T. Price ◽

...

Keyword(s):

Real Time ◽

Oxidative Coupling ◽

Fixed Bed ◽

Oxidative Coupling Of Methane ◽

Length Scale ◽

Fixed Bed Reactors

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

Polish Journal of Chemical Technology ◽

10.2478/pjct-2013-0005 ◽

2013 ◽

Vol 15 (1) ◽

pp. 22-26 ◽

Cited By ~ 5

Author(s):

Barbara Litawa ◽

Piotr Michorczyk ◽

Jan Ogonowski

Keyword(s):

Oxidative Coupling ◽

Methane Conversion ◽

Catalytic Properties ◽

Catalytic Performance ◽

Negative Influence ◽

Oxidative Coupling Of Methane ◽

Oxygen Mixture ◽

Impregnation Method ◽

Promoting Effect ◽

Conversion 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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What is the Effect of Promoter Loading on Alkalized Bimetallic Co-Mo Catalyst for Higher Alcohols Synthesis from Syngas?

Kataliz v promyshlennosti ◽

10.18412/1816-0387-2019-2-86-94 ◽

2019 ◽

Vol 19 (2) ◽

pp. 86-94

Author(s):

R. G. Moqadam ◽

A. Tavasoli ◽

M. Salimi

Keyword(s):

Fixed Bed ◽

Fixed Bed Reactor ◽

Incipient Wetness Impregnation ◽

Operating Pressure ◽

Impregnation Method ◽

Higher Alcohol Synthesis ◽

Higher Alcohol ◽

Alcohol Synthesis ◽

Higher Alcohols Synthesis ◽

Methanol Formation

Manganese and nickel co-modified K/Co/MoS2 catalysts supported on graphene were prepared by incipient wetness impregnation method for application in higher alcohol synthesis (HAS). All catalysts were characterized by X-ray diffraction (XRD), nitrogen adsorptiondesorption, temperature-programmed reduction (TPR) and transmission electron microscopy (TEM). The effect of promoters, as well as supports on higher alcohol synthesis production from syngas, was investigated in a fixed bed reactor. The process was performed with an molar ratio H2 : CO = 1 : 1, operating pressure and temperature of 4 MPa and 330 °C, respectively, and gas hourly space velocity (GHSV) 3.84 m3 (STP)/(kgcat.·h) as reaction conditions (STP – standard temperature and pressure). Results originated from practical works showed that the addition of Ni to the graphene-based catalyst increased HAS production and decreased methanol formation. The total alcohols space-time yield (STY) and alcohol selectivity on Ni/Mn/Co/Mo/K/graphene catalyst reached a maximum at 0.41 galc./(gcat.·h) and 63.51 %, respectively, which is higher than the same composition over alumina supported catalyst.

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