scholarly journals Preparation of bimetallic Ni–Fe/MCM-41 catalysts and their catalytic activity for CO methanation

2019 ◽  
Vol 45 ◽  
pp. 146867831987032
Author(s):  
Zhang Jiaying
Keyword(s):  
Bimetallic Catalysts ◽  
Space Velocity ◽  
Molar Ratio ◽  
Incipient Wetness Impregnation ◽  
Impregnation Method ◽  
Activity Increase ◽  
Co Methanation ◽  
Weight Hourly Space Velocity ◽  
Temperature Programmed ◽  
Mcm 41

A series of Ni–Fe/MCM-41 bimetallic catalysts and also Ni/MCM-41 and Fe/MCM-41 catalysts were prepared by the incipient-wetness impregnation method and tested for their activity for CO methanation in a continuous-flow microreactor. The results showed that the catalytic activities of the Ni–Fe/MCM-41 bimetallic catalysts were much higher than those of the Ni/MCM-41 and Fe/MCM-41 catalysts at low temperatures (200°C–325°C). The 10%Ni–5%Fe/MCM-41 catalyst showed the best activity with a CO conversion of almost 100% and a CH4 selectivity of 98% at 350°C under a pressure of 1.5 MPa with a 3:1 molar ratio of H2 to CO and a weight hourly space velocity of 12,000 mL h−1 g−1. The catalysts were characterized by N2 physisorption measurements, X-ray diffraction, and H2-temperature-programmed reduction. The results showed that the addition of Fe will lead to the formation of finer Ni particles and Ni–Fe alloy, which were the main reasons for the activity increase in the Ni–Fe/MCM-41 catalysts.

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

Catalysts ◽  
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.

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

Catalysts ◽  
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.

Effect of Fe and Co promoters on CO methanation activity of nickel catalyst prepared by impregnation – co-precipitation method

2020 ◽  
Vol 18 (5-6) ◽  
Author(s):  
Buyan-Ulzii Battulga ◽  
Tungalagtamir Bold ◽  
Enkhsaruul Byambajav
Keyword(s):  
Synergetic Effect ◽  
Space Velocity ◽  
Catalytic Performance ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Alumina Support ◽  
Co Methanation ◽  
Temperature Range ◽  
Co Precipitation ◽  
Catalyst Distribution

AbstractNi based catalysts supported on γ-Al2O3 that was unpromoted (Ni/γAl2O3) or promoted (Ni–Fe/γAl2O3, Ni–Co/γAl2O3, and Ni–Fe–Co/γAl2O3) were prepared using by the impregnation – co-precipitation method. Their catalytic performances for CO methanation were studied at 3 atm with a weight hourly space velocity (WHSV) of 3000 ml/g/h of syngas with a molar ratio of H2/CO = 3 and in the temperature range between 130 and 350 °C. All promoters could improve nickel distribution, and decreased its particle sizes. It was found that the Ni–Co/γAl2O3 catalyst showed the highest catalytic performance for CO methanation in a low temperature range (<250 °C). The temperatures for the 20% CO conversion over Ni–Co/γAl2O3, Ni–Fe/γAl2O3, Ni–Fe–Co/γAl2O3 and Ni/γAl2O3 catalysts were 205, 253, 263 and 270 °C, respectively. The improved catalyst distribution by the addition of cobalt promoter caused the formation of β type nickel species which had an appropriate interacting strength with alumina support in the Ni–Co/γAl2O3. Though an addition of iron promoter improved catalyst distribution, the methane selectivity was lowered due to acceleration of both CO methanation and WGS reaction with the Ni–Fe/γAl2O3. Moreover, it was found that there was no synergetic effect from the binary Fe–Co promotors in the Ni–Fe–Co/γAl2O3 on catalytic activity for CO methanation.

Influence Factors of Denitration Study on Catalyst Mn-Ce/TiO2

2013 ◽  
Vol 634-638 ◽  
pp. 526-530
Author(s):  
Chun Xiang Geng ◽  
Qian Qian Chai ◽  
Wei Yao ◽  
Chen Long Wang
Keyword(s):  
Reaction Temperature ◽  
Catalytic Reduction ◽  
Removal Rate ◽  
Load Capacity ◽  
Fixed Bed ◽  
Influence Factors ◽  
Space Velocity ◽  
Molar Ratio ◽  
Impregnation Method ◽  
Ammonia Gas

Selective Catalytic Reduction (SCR) processes have been one of the most widely used denitration methods at present and the property of low tempreture catalyst becomes a hot research. The Mn-Ce/TiO2 catalyst was prepared by incipient impregnation method. The influence of load capacity, reaction temperature, O2 content, etc. on denitration were studied by a fixed bed catalyst reactor with ammonia gas. Results showed that catalyst with load capacity 18% performed high NO removal rate of 90% at conditions of reaction temperature 160°C, low space velocity, NH3/NO molar ratio 1: 1, O2 concentration 6%.

The Effect of Zinc Content on n-Pentane Isomerisation Over Zn–S2O82–/ZrO2–Al2O3 Catalyst

2017 ◽  
Vol 42 (1) ◽  
pp. 23-29
Author(s):  
Hua Song ◽  
Shengnan Li ◽  
Hualin Song ◽  
Feng Li ◽  
Huapeng Cui
Keyword(s):  
Zinc Content ◽  
Space Velocity ◽  
X Ray Diffraction ◽  
Sulfate Ions ◽  
X Ray ◽  
Weight Hourly Space Velocity ◽  
Mass Fractions ◽  
Crystallite Sizes ◽  
Temperature Programmed ◽  
Al2o3 Catalyst

A number of Zn–S2O82–/ZrO2–Al2O3 (Zn( x)–SZA) catalysts with different Zn mass fractions were synthesised and characterised by using X-ray diffraction, the Brunauer–Emmett–Teller method, and H2 temperature-programmed reduction. The structure and isomerisation performance of Zn( x)–SZA catalysts were studied using n-pentane as a probe reaction. The results showed that a pure tetragonal ZrO2 phase was formed on Zn( x)–SZA, and the ZrO2 crystallite sizes of the tetragonal phase increased in the order: Zn(0.5)–SZA < Zn(1.0)–SZA < Zn(1.5)–SZA < Zn(2.0)–SZA < SZA. Zn can strengthen the interaction between persulfate ions and the support, promote the formation of stronger acidity, lead to a better dispersion of sulfate ions on the surface, and improve the redox performance of the catalysts. The Zn(1.0)–SZA catalyst exhibited the best catalytic activity for n-pentane isomerisation. At a temperature of 170 °C, a reaction pressure of 2.0 MPa, a molar H2/ n-pentane ratio of 4:1, and a weight hourly space velocity of 1.0 h−1, the isopentane yield reached 58.0%.

scholarly journals Low Temperature NH3-SCR over Mn-Ce Oxides Supported on MCM-41 from Diatomite

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3654 ◽  
Author(s):  
Mingxuan Ma ◽  
Xiaoyu Ma ◽  
Suping Cui ◽  
Tingting Liu ◽  
Yingliang Tian ◽  
...  
Keyword(s):  
Molecular Sieves ◽  
Synthesis Method ◽  
Molar Ratio ◽  
Impregnation Method ◽  
Catalyst Carrier ◽  
Nh3 Scr ◽  
Catalytic Material ◽  
Lewis Acidic Sites ◽  
Acidic Sites ◽  
Mcm 41

A series of MCM-41 molecular sieves with different molar ratio of template to silicon were synthesized through hydrothermal synthesis method by using cetyltrimethylammonium bromide (CTAB) as the template, diatomite as the silicon source. By using impregnation method, the Mn-Ce/MCM-41 SCR molecular sieve-based catalysts were prepared. The results observed that when the molar ratio of template to silicon was 0.2:1, the MCM-41 as catalyst carrier has the highest surface area and largest pore volume, it also presented typically ordered hexagonal arrays of uniform channels. The denitration catalytic material based on this carrier has a high number of Lewis acidic sites, and the denitration efficiency can reach more than 93%.

scholarly journals Kinetics of Fischer–Tropsch Synthesis in a 3-D Printed Stainless Steel Microreactor Using Different Mesoporous Silica Supported Co-Ru Catalysts

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 872 ◽  
Author(s):  
Mohammad ◽  
Bepari ◽  
Aravamudhan ◽  
Kuila
Keyword(s):  
Stainless Steel ◽  
Mesoporous Silica ◽  
Photoelectron Spectroscopy ◽  
Space Velocity ◽  
Fischer Tropsch ◽  
One Pot ◽  
Ru Catalysts ◽  
Weight Hourly Space Velocity ◽  
Ft Synthesis ◽  
Mcm 41

Fischer–Tropsch (FT) synthesis was carried out in a 3D printed stainless steel (SS) microchannel microreactor using bimetallic Co-Ru catalysts on three different mesoporous silica supports. CoRu-MCM-41, CoRu-SBA-15, and CoRu-KIT-6 were synthesized using a one-pot hydrothermal method and characterized by Brunner–Emmett–Teller (BET), temperature programmed reduction (TPR), SEM-EDX, TEM, and X-ray photoelectron spectroscopy (XPS) techniques. The mesoporous catalysts show the long-range ordered structure as supported by BET and low-angle XRD studies. The TPR profiles of metal oxides with H2 varied significantly depending on the support. These catalysts were coated inside the microchannels using polyvinyl alcohol and kinetic performance was evaluated at three different temperatures, in the low-temperature FT regime (210–270 °C), at different Weight Hourly Space Velocity (WHSV) in the range of 3.15–25.2 kgcat.h/kmol using a syngas ratio of H2/CO = 2. The mesoporous supports have a significant effect on the FT kinetics and stability of the catalyst. The kinetic models (FT-3, FT-6), based on the Langmuir–Hinshelwood mechanism, were found to be statistically and physically relevant for FT synthesis using CoRu-MCM-41 and CoRu-KIT-6. The kinetic model equation (FT-2), derived using Eley–Rideal mechanism, is found to be relevant for CoRu-SBA-15 in the SS microchannel microreactor. CoRu-KIT-6 was found to be 2.5 times more active than Co-Ru-MCM-41 and slightly more active than CoRu-SBA-15, based on activation energy calculations. CoRu-KIT-6 was ~3 and ~1.5 times more stable than CoRu-SBA-15 and CoRu-MCM-41, respectively, based on CO conversion in the deactivation studies.

Effect of Supports on the Properties of Co-Mo Nitride Catalysts for Ammonia Decomposition

2011 ◽  
Vol 391-392 ◽  
pp. 1215-1219 ◽  
Author(s):  
Zhao Hui Zhao ◽  
Han Bo Zou ◽  
Wei Ming Lin
Keyword(s):  
Elevated Temperatures ◽  
Active Species ◽  
Ammonia Decomposition ◽  
Zeolite Catalysts ◽  
Incipient Wetness Impregnation ◽  
Impregnation Method ◽  
5A Zeolite ◽  
Temperature Programmed ◽  
Temperature Programmed Reaction ◽  
Effect Of Support

Supported Co–Mo nitride catalysts have been synthesized by incipient-wetness impregnation method and temperature-programmed reaction in N2-H2 mixed gases. The effect of support types, namely carbon nanotubes(CNTs), active carbon(AC), 5A zeolite and Al2O3 on the properties of the prepared catalysts for ammonia decomposition has been investigated by XRD, H2–TPR and SEM techniques. The results showed that CNTs was the optimum support for Co–Mo nitride catalyst. At 550 , NH3 conversions over CoMoNx/AC, CoMoNx/Al2O3 and CoMoNx/5A Zeolite catalysts were only 14.7%, 65.4% and 68.7%, respectively, while NH3 conversion over CoMoNx/CNTs catalyst was up to 84.4%. XRD and H2–TPR results indicated that the active species consist of CoMoO4, MoO3, γ-Mo2N and Co3Mo3N crystallites, which can be reduced at elevated temperatures at H2 atmosphere. The SEM characterization demonstrated that Co-Mo nitrides particles disperse uniformly on the CNTs.

Comparison of Cobalt Based Catalysts Supported on MWCNT and SBA-15 Supporters for Fischer-Tropsch Synthesis by Using Autoclave Type Reactor

2011 ◽  
Vol 364 ◽  
pp. 70-75 ◽  
Author(s):  
Adkham Yakubov ◽  
M.G. Kutty ◽  
Pei Lee Siew ◽  
Maizatul S. Shaharun ◽  
S.B. Abd Hamid ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Multiwall Carbon Nanotubes ◽  
Incipient Wetness Impregnation ◽  
Impregnation Method ◽  
Santa Barbara ◽  
X Ray ◽  
Transmission Electron ◽  
Temperature Programmed ◽  
Multiwall Carbon ◽  
Autoclave Reactor

10 and 40 wt% Co/Multiwall Carbon Nanotubes (MWCNT) and 10 and 40 wt% Co/Santa Barbara Amorphous-15 (SBA-15) catalysts were prepared via incipient wetness impregnation method. It was characterized by Scanning Electron Microscopy, BET, X-ray Diffractometry (XRD), Transmission Electron Microscopy (TEM), Temperature-Programmed Reduction and H2Desorption. A 200 ml hastelloy autoclave reactor was implemented to see the performance of the catalysts. It was observed that the performance of 40 wt% Co/SBA-15 was higher that other catalysts in terms of production of longer chain paraffins.

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