scholarly journals Effect of Alumina Support on the Formation of the Active Phase of Selective Hydrodesulfurization Catalysts Co-Mo/Al2O3

2011 ◽  
Vol 32 (1-2) ◽  
pp. 240-249 ◽  
Author(s):  
Qiherima ◽  
Huifeng LI ◽  
Hui YUAN ◽  
Yunhong ZHANG ◽  
Guangtong XU
1992 ◽  
Vol 46 (3) ◽  
pp. 489-497 ◽  
Author(s):  
Douglas P. Hoffmann ◽  
Marwan Houalla ◽  
Andrew Proctor ◽  
David M. Hercules

ESCA, Mössbauer spectroscopy, XRD, and CO chemisorption were used to study the reduction and sulfidation reactions of a series of 1 to 24 wt % Fe/Al2O3 catalysts. The speciation and particle size of the active phase were correlated with CO hydrogenation activity data. Two phases were previously identified in all oxidic catalysts: Fe2O3 and Fe+3 in solid solution with the alumina support. The Fe2O3 phase was found to reduce to Fe0 and sulfide to Fe1- xS. For the reduced and sulfided catalysts, Mössbauer was able to identify two iron species which were detected as a single solid solution species in the oxidic catalysts. The two species were found to differ by their location in the alumina support. One species is incorporated within the alumina matrix [Fe+2(A)] and the other species [Fe+2(B)] is present at the alumina surface. Both ESCA and CO chemisorption indicate that the Fe particle size increases with increasing iron loading. The turnover frequency (TOF) for CO hydrogenation appears to be a function of the extent of reduction and particle size of the metallic iron phase.


2017 ◽  
Vol 197 ◽  
pp. 87-99 ◽  
Author(s):  
Tracey van Heerden ◽  
Eric van Steen

It is challenging to isolate the effect of metal–support interactions on catalyst reaction performance. In order to overcome this problem, inverse catalysts can be prepared in the laboratory and characterized and tested at relevant conditions. Inverse catalysts are catalysts where the precursor to the catalytically active phase is bonded to a support-like ligand. We can then view the metal–support interaction as a ligand interaction with the support acting as a supra-molecular ligand. Importantly, laboratory studies have shown that these ligands are still present after reduction of the catalyst. By varying the quantity of these ligands present on the surface, insight into the positive effect SMSI have during a reaction is gained. Here, we present a theoretical study of mono-dentate alumina support based ligands, adsorbed on cobalt surfaces. We find that the presence of the ligand may significantly affect the morphology of a cobalt crystallite. With Fischer–Tropsch synthesis in mind, the CO dissociation is used as a probe reaction, with the ligand assisting the dissociation, making it feasible to dissociate CO on the dense fcc Co(111) surface. The nature of the interaction between the ligand and the probe molecule is characterized, showing that the support-like ligands’ metal centre is directly interacting with the probe molecule.


2006 ◽  
Vol 32 (9) ◽  
pp. 857-870 ◽  
Author(s):  
Seung Tae Hong ◽  
Dal Ryung Park ◽  
Seung-Joon Yoo ◽  
Jae-Duck Kim ◽  
Hyung Sang Park

2021 ◽  
Vol 266 ◽  
pp. 02016
Author(s):  
R.R. Konoplin ◽  
N.K. Kondrasheva

The article presents bibliographic knowledgeof the world-scaleinventions that formed the basis ofHDS-catalysts for the development of variousoil products. Extensive studies were conductedon optimizationof carrier properties, active-phase chemical-mass composition, and basictech-nological parameters of transformation of initial components into active six-sided MoS2 groups which are decorated by CoS2 molecules, involving stages of desulfurization ofoxide formsof the catalyst. Differences in the microstructure of Al2O3supportsderived from aluminum hydroxide of vari-ous genesis are described. Comparative possibilitiesof binding properties of aluminum hydroxide raw materials in laboratory tests and molding of-waterpeptidized pastesare presented.


Author(s):  
J. Cruz-Reyes ◽  
M. Avalos-Borja ◽  
M. H. Farias ◽  
S. Fuentes

Applications of transition metal sulfides for hydroprocessing catalysts have included a variety of reactions. It is generally believed that an interaction between the active phase (Mo or W) and the promoter (Co or Ni) takes place. Several models have been suggested to explain the enhanced catalytic activity. The catalytic properties of the unsupported sulfides are dependent on the catalyst preparation methods . In this work we study by electron microscopy two sets of unsupported samples ranging from molybdenum sulfide to cobalt sulfide. The specimens were prepared by the following methods, a slight variation of the classical homogeneous sulfide precipitation (HSP) method, and a new method called impregnated thiosalt decomposition (ITD).


2020 ◽  
Vol 6 (19) ◽  
pp. eaax5331 ◽  
Author(s):  
Manuel F. Wagenhofer ◽  
Hui Shi ◽  
Oliver Y. Gutiérrez ◽  
Andreas Jentys ◽  
Johannes A. Lercher

Unsupported Ni-Mo sulfides have been hydrothermally synthesized and purified by HCl leaching to remove Ni sulfides. Unblocking of active sites by leaching significantly increases the catalytic activity for dibenzothiophene hydrodesulfurization. The site-specific rates of both direct (hydrogenolytic) and hydrogenative desulfurization routes on these active sites that consist of coordinatively unsaturated Ni and sulfhydryl groups were identical for all unsupported sulfides. The hydrogenative desulfurization rates were more than an order of magnitude higher on unsupported Ni-Mo sulfides than on Al2O3-supported catalysts, while they were similar for the direct (hydrogenolytic) desulfurization. The higher activity is concluded to be caused by the lower average electronegativity, i.e., higher base strength and polarity, of Ni-Mo sulfides in the absence of the alumina support and the modified adsorption of reactants enabled by multilayer stacking. Beyond the specific catalytic reaction, the synthesis strategy points to promising scalable routes to sulfide materials broadly applied in hydrogenation and hydrotreating.


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