Morphology, Dispersion and Catalytic Functions of Supported Molybdenum Sulfide Catalysts for Hydrotreating Petroleum Fractions

Abstract

The relationships between the morphologies and dispersion of supported Mo sulfide catalysts and their catalytic functions evaluated by model test reactions are reviewed. The catalyst support had large effects on the morphologies through the electronic interaction and geometrical relationship between the catalyst and the support surface. High hydrogenation activities were obtained for Al2O3 supported catalysts due to high dispersion, whereas high hydrogenolysis activities were obtained for TiO2-supported catalysts due to the electronic interaction. Relatively large single-layered MoS2 structures were formed on the {110} γ-Al2O3 surface, whereas microclusters and multilayered MoS2 structures were more favorably formed on the {111} and {100} γ-Al2O3 surfaces. Multi-layered MoS2 structures had the edge-bonding orientation on anatase-TiO2 with an epitaxial relationship by sulfidation in H2S/N2. Single-layered MoS2 catalysts exhibited relatively hydrogenation-oriented function, whereas multilayered MoS2 catalysts had relatively hydrogenolysis-oriented function. Steric hindrance affected the catalytic functions, particularly in hydrogenation that required η 6 adsorption of aromatic rings. Long-term uses in hydrotreating caused growth of the MoS2 structures in the lateral direction, which decreased the number of active sites. Simultaneously, the aging caused deep sulfiding of the catalysts, which weakened the interaction with the support and increased the intrinsic activities of the catalysts.

Synthesis and characterization of Mo-blue-based sulfided CoMo catalysts for guaiacol HDO

“…Finally, it should be also considered that Mo-blue formation in solids prepared with saccharose could produce organic acids (by oxidation of fructose and glucose from saccharose hydrolysis) that could play the aforementioned role of chelating agents as Co sulfiding retardant (Nicosia & Prins, 2005b). SAI was the solid of the highest MoS 2 phase aspect ratio (Ar MoS2 , equation (3), Table 3) due to having the shortest average slab length (Shimada et al, 2016) that also provoked the lowest (f e /f c ) MoS2 = (Mo e /Mo c ) ratio pointing out to enhanced number of corner sites in molybdenum sulfide slabs. Interestingly, it has been proposed that under HDS conditions, exposed metal atoms in corner sites could be resistant to inhibition by strongly adsorbed nitrogen-bearing compounds (Rangarajan et al, 2017).…”

Self-Assembly Preparation of Al2O3/MoS2 Bifunctional Catalyst for Highly Efficient Reduction of SO2 to Elemental Sulfur

“…The bottom layer limited by steric hindrance may show poor catalytic performance . Several material properties of the catalyst determine the catalytic performance of reducing SO 2 to sulfur, such as particle size, surface area, and dispersion of MoS 2 . , Shimada studied the effect of dispersion, stacking of MoS 2 , and morphology on the reduction of SO 2 . The decreases of size and stacking of MoS 2 were instrumental in the dispersion of active sites, which can benefit hydrogenation performance.…”

Enhanced activity of Co–Mo–S catalysts towards hydrodesulfurization and hydrogen evolution reaction via NaBH4 assisted formation

“…11–18 Considering that HDS and HER involve hydrogenation and dehydrogenation processes, which are inverse reactions, the activity and correlation of Co–Mo–S based catalysts between these two reactions are worthy of in-depth investigation. 19,20…”