scholarly journals Well-dispersed nickel nanoparticles on the external and internal surfaces of SBA-15 for hydrocracking of pyrolyzed α-cellulose

RSC Advances ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 1230-1237 ◽  
Author(s):  
Wega Trisunaryanti ◽  
Endah Suarsih ◽  
Triyono Triyono ◽  
Iip Izul Falah

Ni/SBA-15c catalyst showed excellent catalytic activity, resistance towards coke formation, and selective production of 3-methyl-pentane in the hydrocracking of pyrolyzed α-cellulose.

1987 ◽  
Vol 52 (7) ◽  
pp. 1701-1707 ◽  
Author(s):  
Miloslav Křivánek ◽  
Nguyen Thiet Dung ◽  
Pavel Jírů

The catalytic activity of Na, H-Y zeolite samples with a varying Si/Al ratio (2·5 to 20) in the transformation of methanol was determined. The amounts of formed individual aliphatic hydrocarbons as function of reaction time were correlated with the amount of Bronsted and Lewis centres on the catalysts. The effect of coke formation on the over-all course of the reaction has been demonstrated.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yoottapong Klinthongchai ◽  
Seeroong Prichanont ◽  
Piyasan Praserthdam ◽  
Bunjerd Jongsomjit

AbstractMesocellular foam carbon (MCF-C) is one the captivating materials for using in gas phase dehydrogenation of ethanol. Extraordinary, enlarge pore size, high surface area, high acidity, and spherical shape with interconnected pore for high diffusion. In contrary, the occurrence of the coke is a majority causes for inhibiting the active sites on catalyst surface. Thus, this study aims to investigate the occurrence of the coke to optimize the higher catalytic activity, and also to avoid the coke formation. The MCF-C was synthesized and investigated using various techniques. MCF-C was spent in gas-phase dehydrogenation of ethanol under mild conditions. The deactivation of catalyst was investigated toward different conditions. Effects of reaction condition including different reaction temperatures of 300, 350, and 400 °C on the deactivation behaviors were determined. The results indicated that the operating temperature at 400 °C significantly retained the lowest change of ethanol conversion, which favored in the higher temperature. After running reaction, the physical properties as pore size, surface area, and pore volume of spent catalysts were decreased owing to the coke formation, which possibly blocked the pore that directly affected to the difficult diffusion of reactant and caused to be lower in catalytic activity. Furthermore, a slight decrease in either acidity or basicity was observed owing to consumption of reactant at surface of catalyst or chemical change on surface caused by coke formation. Therefore, it can remarkably choose the suitable operating temperature to avoid deactivation of catalyst, and then optimize the ethanol conversion or yield of acetaldehyde.


Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1875
Author(s):  
Prashanth Reddy Buchireddy ◽  
Devin Peck ◽  
Mark Zappi ◽  
Ray Mark Bricka

Amongst the issues associated with the commercialization of biomass gasification, the presence of tars has been one of the most difficult aspects to address. Tars are an impurity generated from the gasifier and upon their condensation cause problems in downstream equipment including plugging, blockages, corrosion, and major catalyst deactivation. These problems lead to losses of efficiency as well as potential maintenance issues resulting from damaged processing units. Therefore, the removal of tars is necessary in order for the effective operation of a biomass gasification facility for the production of high-value fuel gas. The catalytic activity of montmorillonite and montmorillonite-supported nickel as tar removal catalysts will be investigated in this study. Ni-montmorillonite catalyst was prepared, characterized, and tested in a laboratory-scale reactor for its efficiency in reforming tars using naphthalene as a tar model compound. Efficacy of montmorillonite-supported nickel catalyst was tested as a function of nickel content, reaction temperature, steam-to-carbon ratio, and naphthalene loading. The results demonstrate that montmorillonite is catalytically active in removing naphthalene. Ni-montmorillonite had high activity towards naphthalene removal via steam reforming, with removal efficiencies greater than 99%. The activation energy was calculated for Ni-montmorillonite assuming first-order kinetics and was found to be 84.5 kJ/mole in accordance with the literature. Long-term activity tests were also conducted and showed that the catalyst was active with naphthalene removal efficiencies greater than 95% maintained over a 97-h test period. A little loss of activity was observed with a removal decrease from 97% to 95%. To investigate the decrease in catalytic activity, characterization of fresh and used catalyst samples was performed using thermogravimetric analysis, transmission electron microscopy, X-ray diffraction, and surface area analysis. The loss in activity was attributed to a decrease in catalyst surface area caused by nickel sintering and coke formation.


2010 ◽  
Vol 34 (4) ◽  
pp. 708 ◽  
Author(s):  
Aili Wang ◽  
Hengbo Yin ◽  
Min Ren ◽  
Huihong Lu ◽  
Jinjuan Xue ◽  
...  

2020 ◽  
Vol 44 (3) ◽  
pp. 1082-1089
Author(s):  
Alejandro A. Rodríguez ◽  
Jorge A. Garduño ◽  
Juventino J. García

The use of nickel(ii) and nickel(0) complexes as precursors of nickel nanoparticles with catalytic activity in the hydrogenation of benzonitrile is reported.


Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 828 ◽  
Author(s):  
Hyunjoung Kim ◽  
Young-Hee Lee ◽  
Hongjin Lee ◽  
Jeong-Cheol Seo ◽  
Kyubock Lee

Ni catalysts are most suitable for a steam methane reforming (SMR) reaction considering the activity and the cost, although coke formation remains the main problem. Here, Ni-based spinel catalysts with various Mg contents were developed through the synthesis of mesoporous Mg-aluminate supports by evaporation-induced self-assembly followed by Ni loading via incipient wetness impregnation. The mesoporous Ni/Mg-aluminate spinel catalysts showed high coke resistance under accelerated reaction conditions (0.0014 gcoke/gcat·h for Ni/Mg30, 0.0050 gcoke/gcat·h for a commercial catalyst). The coke resistance of the developed catalyst showed a clear trend: the higher the Mg content, the lower the coke deposition. The Ni catalysts with the lower Mg content showed a higher surface area and smaller Ni particle size, which originated from the difference of the sintering resistance and the exsolution of Ni particles. Despite these advantageous attributes of Ni catalysts, the coke resistance was higher for the catalysts with the higher Mg content while the catalytic activity was dependent on the reaction conditions. This reveals that the enhanced basicity of the catalyst could be the major parameter for the reduction of coke deposition in the SMR reaction.


2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Seokju Seo ◽  
Gabriela Alvarez Perez ◽  
Ketan Tewari ◽  
Xavier Comas ◽  
Myeongsub Kim

2000 ◽  
Vol 31 ◽  
pp. 634-635
Author(s):  
M. Seipenbusch ◽  
A.P. Weber ◽  
G. Kasper

Catalysts ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 25
Author(s):  
Su-Un Lee ◽  
You-Jin Lee ◽  
Soo-Jin Kwon ◽  
Jeong-Rang Kim ◽  
Soon-Yong Jeong

With the growing global propylene demand, propane dehydrogenation (PDH) has attracted great attention for on-purpose propylene production. However, its industrial application is limited because catalysts suffer from rapid deactivation due to coke deposition and metal catalyst sintering. To enhance metal catalyst dispersion and coke resistance, Pt-based catalysts have been widely investigated with various porous supports. In particular, zeolite can benefit from large surface area and acid sites, which favors high metal dispersion and promoting catalytic activity. In this work, we investigated the PDH catalytic properties of Beta zeolites as a support for Pt-Sn based catalysts. In comparison with Pt-Sn supported over θ-Al2O3 and amorphous silica (Q6), Beta zeolite-supported Pt-Sn catalysts exhibited a different reaction trend, achieving the best propylene selectivity after a proper period of reaction time. The different PDH catalytic behavior over Beta zeolite-supported Pt-Sn catalysts has been attributed to their physicochemical properties and reaction mechanism. Although Pt-Sn catalyst supported over Beta zeolite with low acidity showed low Pt dispersion, it formed a relatively lower amount of coke on PDH reaction and maintained a high surface area and active Pt surfaces, resulting in enhanced stability for PDH reaction. This work can provide a better understanding of zeolite-supported Pt-Sn catalysts to improve PDH catalytic activity with high selectivity and low coke formation.


Sign in / Sign up

Export Citation Format

Share Document