scholarly journals Resistance against Carbon Deposition via Controlling Spatial Distance of Catalytic Components in Methane Dehydroaromatization

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 148
Author(s):  
Yan Zeng ◽  
Ayano Kimura ◽  
Peipei Zhang ◽  
Jiaming Liang ◽  
Jiaqi Fan ◽  
...  
Keyword(s):  
Mechanical Milling ◽  
High Selectivity ◽  
Carbon Deposition ◽  
Zeolite Catalysts ◽  
Spatial Distance ◽  
Product Selectivity ◽  
Active Components ◽  
Methane Dehydroaromatization

Molybdenum-zeolite catalysts always suffer from severe carbon deposition and rapid deactivation in the methane dehydroaromatization (MDA) process. Herein, we present a strategy that controls spatial distance between Mo species and HMCM-22 zeolite over Mo/HMCM-22 catalysts, to inhibit the severe carbon deposition. Our characterization analyses demonstrate that the Mo/HMCM-22 catalysts possess the same active components, but the spatial distance plays a key role in determining product selectivity in the MDA process. The MDA performance reveals that Mo/HMCM-22-MM (mechanical milling) catalyst, with a medium spatial distance between Mo species and HMCM-22 zeolite, significantly inhibits carbon deposition and produces high selectivity to benzene. This work shows that spatial distance between molybdenum and zeolite is an important property for suppressing carbon deposition and improving benzene selectivity in MDA process.

scholarly journals High selectivity of CO2 hydrogenation to CO by controlling the valence state of nickel using perovskite

2018 ◽  
Vol 54 (53) ◽  
pp. 7354-7357 ◽  
Author(s):  
Baohuai Zhao ◽  
Binhang Yan ◽  
Zhao Jiang ◽  
Siyu Yao ◽  
Zongyuan Liu ◽  
...  
Keyword(s):  
Valence State ◽  
High Selectivity ◽  
Co2 Hydrogenation ◽  
Product Selectivity

The product selectivity of CO2 hydrogenation can be significantly tuned by controlling the valence state of Ni using perovskites.

Towards the sustainable production of pyridines via thermo-catalytic conversion of glycerol with ammonia over zeolite catalysts

2015 ◽  
Vol 17 (4) ◽  
pp. 2426-2435 ◽  
Author(s):  
Lujiang Xu ◽  
Zheng Han ◽  
Qian Yao ◽  
Jin Deng ◽  
Ying Zhang ◽  
...  
Keyword(s):  
High Selectivity ◽  
Catalytic Conversion ◽  
Sustainable Production ◽  
Zeolite Catalysts ◽  
High Yield

Thermo-catalytic conversion of renewable glycerol with ammonia over HZSM-5 for producing pyridines with high yield and high selectivity.

The Influence of Temperature on the Degree of Bio-Oil Hydroupgrading over High-Loaded NiCu-SiO2 Catalyst at Low Hydrogen Content

2018 ◽  
Vol 18 (5) ◽  
pp. 53-62
Author(s):  
A. A. Smirnov ◽  
M. V. Alekseeva ◽  
O. A. Bulavchenko ◽  
V. A. Yakovlev
Keyword(s):  
Hydrogen Pressure ◽  
Carbon Deposition ◽  
Catalyst Surface ◽  
Sol Gel ◽  
Reaction Medium ◽  
Process Temperature ◽  
Active Components ◽  
Bio Oil ◽  
Liquid Products ◽  
Influence Of Temperature On

The process of upgrading of pyrolysis bio-oil via hydrodeoxygenation was studied at 0.6 MPa hydrogen pressure and 150–350 °C in the presence of the NiCu-SiO2catalyst prepared by the sol-gel method. The catalyst resistance to agglomeration of the active component and to the carbon deposition on its surface was examined. The oxygen content in the liquid products of lignocellulose pyrolysis was shown to decrease from 37 to 15 wt.% as the process temperature rose. A CHNS-O analyzer was used to establish that the coke quantity on the catalyst surface at 350 °C decreased to one fourth of that at 150 °C. XPS studies revealed that the elevation of the process temperature led to progressive agglomeration of the particles followed by a decrease in their size at high temperature due to dissolution of the active components of the catalyst in the reaction medium.

ChemInform Abstract: Metal/Zeolite Catalysts of Methane Dehydroaromatization

ChemInform ◽  
2014 ◽  
Vol 45 (38) ◽  
pp. no-no
Author(s):  
N. A. Mamonov ◽  
E. V. Fadeeva ◽  
D. A. Grigoriev ◽  
M. N. Mikhailov ◽  
L. M. Kustov ◽  
...  
Keyword(s):  
Zeolite Catalysts ◽  
Methane Dehydroaromatization

High-selectivity cobalt zeolite catalysts for the synthesis of isoparaffins from CO and H2

2007 ◽  
Vol 413 (2) ◽  
pp. 79-81 ◽  
Author(s):  
O. L. Eliseev ◽  
A. S. Volkov ◽  
V. S. Budtsov ◽  
A. L. Lapidus
Keyword(s):  
High Selectivity ◽  
Zeolite Catalysts

scholarly journals Production ofC3+Olefins and Propylene from Ethanol by Zr-Modified H-ZSM-5 Zeolite Catalysts

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Megumu Inaba ◽  
Kazuhisa Murata ◽  
Isao Takahara ◽  
Ken-ichiro Inoue
Keyword(s):  
Carbon Deposition ◽  
Aqueous Ethanol ◽  
Zeolite Catalysts ◽  
Ethanol Conversion ◽  
Initial Yield ◽  
Zeolite Support ◽  
Propylene Yield ◽  
Zr Modification ◽  
Catalytic Deactivation

Ethanol conversion to C3+olefins, especially propylene, using Zr-modified H-ZSM-5 catalysts was investigated. Zr-modification to H-ZSM-5 zeolite could improve the initial yield of C3+olefins and propylene and could reduce the initial yield of ethylene. In general, catalysts exhibiting the higher initial yield of propylene showed the steeper decrease in propylene yield as the reaction proceeded. However, Zr-modification to H-ZSM-5 could depress the decrease in propylene yield for aqueous ethanol. As cause of catalytic deactivation, carbon deposition on catalyst and framework collapse of zeolite support can be considered. The addition of water to Zr-modified H-ZSM-5 catalyst could depress carbon deposition in some degree, and, as a result, the decrease in propylene yield could be depressed.

scholarly journals Promoting Light Hydrocarbons Yield by Catalytic Hydrodechlorination of Residual Chloromethanes Using Palladium Supported on Zeolite Catalysts

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 199 ◽  
Author(s):  
Carlos Fernandez-Ruiz ◽  
Jorge Bedia ◽  
Javier Mario Grau ◽  
Ana Clara Romero ◽  
Daniel Rodríguez ◽  
...  
Keyword(s):  
Surface Properties ◽  
High Selectivity ◽  
Surface Acidity ◽  
Zeolite Catalysts ◽  
Ionic Exchange ◽  
Light Hydrocarbons ◽  
Reaction Conditions ◽  
Catalytic Hydrodechlorination ◽  
Pd Dispersion ◽  
Zeolite Supports

Gas catalytic hydrodechlorination (HDC) of trichloromethane (TCM) and dichloromethane (DCM) was analyzed using Pd (1 wt.%) on different zeolites as catalysts. The aim of this study was to know the surface properties of the catalysts and reaction conditions that promote the yield to light hydrocarbons in this reaction. Five different zeolite supports were used from three commercial zeolites (KL, L-type; NaY, Faujasite; H-MOR, Mordenite). KL and NaY were submitted to ionic exchange treatments in order to increase their acidity and analyze the effect of the acidity in the activity and selectivity of the HDC reaction. Exchanged zeolites (HL and HY) showed the highest Pd dispersion due to their higher surface acidity. The best TCM/DCM conversion and selectivity to light hydrocarbons was obtained using the two non-exchanged zeolite-catalysts, KL and NaY. Low surface acidity seems to be the key aspect to promote the formation of light hydrocarbons. The formation of these products is favored at high reaction temperatures and low H2: chloromethane ratios. KL showed the highest selectivity to olefins (60%), although with a lower dechlorination degree. Non-exchanged NaY catalyst showed high selectivity to paraffins (70% and 95% for the HDC of DCM and TCM, respectively).

scholarly journals Dehydroaromatization of methane over noble metal loaded Mo/H-ZSM-5 zeolite catalysts

2021 ◽  
Author(s):  
Themba E. Tshabalala ◽  
Neil J. Coville ◽  
James A. Anderson ◽  
Michael S. Scurrell
Keyword(s):  
Comparative Study ◽  
Noble Metal ◽  
Methane Conversion ◽  
Catalytic Performance ◽  
Zeolite Catalysts ◽  
Product Selectivity ◽  
Total Reduction

AbstractDehydroaromatization of methane (MDA) reaction was investigated over platinum modified Mo/H-ZSM-5 catalysts which were pre-carbided at 750 °C. The influence of platinum on the catalytic performance and product selectivity of Mo/H-ZSM-5 catalysts for the MDA reaction at 700 °C were studied. The presence of platinum led to a slight decrease in methane conversion from 7.5 to 4.2%. Aromatic selectivities above 90% were obtained with catalysts containing low platinum loadings (0.5 and 1.0 wt.%), with benzene being the most prominent product. A decrease in coke selectivity and coke deposits was noted with the platinum modified Mo/H-ZSM-5 zeolite catalysts. A comparative study was performed to compare platinum, palladium and ruthenium promoted Mo/H-ZSM-5 zeolite catalysts with un-promoted Mo/H-ZSM-5. The ruthenium promoted catalyst proved to be superior in catalytic performance, with a higher methane conversion obtained than that found for platinum promoted and palladium promoted Mo/H-ZSM-5 catalysts. Benzene selectivity of about 60% was obtained for ruthenium and palladium promoted Mo/H- ZSM-5 catalysts and the total aromatic selectivity was maintained at 90%. TGA results showed a total reduction of 50% by weight of carbon deposited on the promoted Mo/H-ZSM-5 catalyst. Graphic abstract

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