CoMo sulfide catalysts studies by metal solid NMR: The question of the existence of the chemical synergy
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Cited by (59)
First in situ temperature quantification of CoMoS species upon gas sulfidation enabled by new insight on cobalt sulfide formation
2021, Catalysis TodayCitation Excerpt :Their characterization evidenced four different cobalt sites after sulfidation with two of them corresponding to the regular octahedral and tetrahedral Co9S8 sites found regardless the studied cobalt loading that ranged from 38.3 to 2.5 wt % and two additional sites corresponding to a distorted tetrahedral site and a distorted octahedral site, only observed for the lowest loadings. The distorted octahedral site which was surmised by Ledoux et al. to be related to the CoS phase [29] is ascribed, considering our results, to the defective CoS2 which is reformed during cooling for dispersed species on silica and alumina. As Ledoux could not study alumina-supported catalysts under the NMR conditions they used, our study enlarges their conclusions to alumina support.
Relationship between the hydrodesulfurization of thiophene, dibenzothiophene, and 4,6-dimethyl dibenzothiophene and the local structure of Co in Co-Mo-S sites: Infrared study of adsorbed CO
2012, Journal of CatalysisCitation Excerpt :For example, an important issue like the local structure of the cobalt atoms on the edges of the MoS2 crystallites is still under debate. Based on nuclear magnetic resonance (NMR) and X-ray Absorption Near Edge Structure (XANES) analysis of promoted catalysts supported on different materials, several local structures of the Co atoms in the Co–Mo–S phase have been proposed: distorted octahedral and tetrahedral structures [13,14]; octahedral, distorted octahedral, distorted trigonal prismatic structures with 6-fold coordination, or distorted square pyramidal structure (5-fold coordination) [15–17]; tetragonal pyramidal structure (5-fold coordination) [18]. With a bulk technique like XANES, a coordination number greater than 5 is obtained, leading to the belief that in the promoted catalyst, the Co atoms are bonded to five and/or six sulfur atoms.
Unsupported transition metal sulfide catalysts: 100 years of science and application
2009, Catalysis TodayResearch perspectives during 40 years of the Journal of Catalysis
2003, Journal of CatalysisCitation Excerpt :Their concept of a “Co–Mo–S phase,” as it was termed, began to hold sway and various physical techniques (Mössbauer, IR, 59Co NMR, and X-ray absorption spectroscopy) and theoretical treatments were brought to bear on the problem. A consistent view emerged that cobalt was bonded as atoms on the edges of very small crystallites of MoS2 [73–76]. Cited here are only a few of the dozens of articles published in the Journal of Catalysis on this catalyst and its HDS activity in the 1980s and 1990s.
Periodic trends in hydrodesulfurization: In support of the Sabatier principle
2002, Applied Catalysis A: General