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A series of NiMo/FDU-12 catalysts with tunable pore diameters and mesostructures have been controllably synthesized by adjusting the synthetic hydrothermal temperature and applied for the hydrodesulfurization of dibenzothiophene and its derivative. The state-of-the-art electron tomography revealed that the pore sizes of FDU-12 supports were enlarged with the increase in the hydrothermal temperature and the mesostructures were transformed from ordered cage-type pores to locally disordered channels. Meanwhile, the MoS2 morphology altered from small straight bar to semibending arc to spherical shape and finally to larger straight bar with the change of support structures. Among them, FDU-12 hydrothermally treated at 150 °C possessed appropriate pore diameter and connected pore structure and was favorable for the formation of highly active MoS2 with curved morphology; thus, its corresponding catalyst exhibited the best HDS activity. Furthermore, it was indicated that the isomerization pathway could be significantly improved for HDS of 4,6-dimethyldibenzothiophene after the addition of aluminum, which was expected to be applied to the removal of the macromolecular sulfur compounds. Our study sheds lights on the relationship between support effect, active sites morphology and HDS performance, and also provides a guidance for the development of highly active HDS catalysts. [ABSTRACT FROM AUTHOR]

In this work, a series of Mo/γ-Al 2 O 3 catalysts have been prepared by using Mo species enwrapping with dodecyltrimethylammonium bromide (DTAB) as the novel precursors for the hydrodesulfurization (HDS) of dibenzothiophene (DBT). The objective of this work is to get a deep insight into the effect of the Mo precursors on the size and morphology of the active phases and HDS activity. DTAB as the organic additive for the preparation of Mo precursors can dominate the nature of precursor solution and adjust the metal-support interaction so as to control the dispersion and morphology of the active phases. It is clearly shown that the addition of DTAB can effectively decrease the strong interaction between the Mo species and γ-Al 2 O 3 support and favor to tune the size and morphology of MoS 2 nanoparticles. The optimum molar ratio of DTAB/Mo is 3/5 and the corresponding catalyst shows the highest sulfidation degree with the most suitable stacking layer numbers and the shortest length of MoS 2 and thus exhibits the best HDS performance. Our work explores the important roles of organic additive to adjust the metal-support interaction and control the morphology of active phases and provides an effective precursor which can be used widely to prepare supported catalysts. [ABSTRACT FROM AUTHOR]

Silica hollow microspheres with moonscape-like rough surface (RS) and macroporous surface (MS) have been controllably synthesized by a water–oil–water three-phase emulsion method, which are used as supports of the heterogeneous catalysts for the catalytic hydrogenation of nitrile-butadiene rubber (NBR). It is found that Pd can be uniformly dispersed on both amino-functionalized RS and MS supports and both the catalysts show high hydrogenation activity with 100% selectivity to C=C bonds. However, the reusability of Pd/N-RS is much better than that of Pd/N-MS, maintaining 92% of activity without any regeneration treatment after five times of recycling experiment. The high activity retention is because the moonscape-like surface of the RS support is favorable for the contact of NBR macromolecules with the active sites, and more importantly, the NBR macromolecules do not need to diffuse into the interior of the catalyst, leading to fast desorption of the hydrogenated NBR from the surface of catalyst and re-exposure of the active sites. [ABSTRACT FROM AUTHOR]

Supported Pd catalyst with an enhanced catalytic performance for polystyrene hydrogenation was successfully prepared by using macroporous silica microspheres (MSM) as the support. In order to eliminate the macromolecular diffusion limitation and improve the metal utilization, MSM was treated with steam at 800 °C first to remove mesopores and then refluxed with aqueous solutions to increase Si OH groups on the surface for Pd immobilization. The optimum support was obtained after the steam treatment for 2 h and using ammonia solution as reflux liquors, and the corresponding catalyst showed superior hydrogenation activity with a high conversion of 95%. [ABSTRACT FROM AUTHOR]

To realize the efficient and complete removal of organic pollutants in waste water, it is highly urgent for scalable synthesis of either self-supported bimetallic nanocatalysts or anchored on carbon-based materials. In this study, a simple one-pot coreduction method was developed for preparing well-dispersed AgPd alloyed nanoclusters uniformly dispersed on reduced graphene oxide (AgPd NCs/rGO) at room temperature by utilizing 5-azacytosine as the capping agent. The nanocomposites were characterized by a set of physical characterizations. The formation mechanism and catalytic mechanism were discussed in some details. Moreover, the prepared AgPd NCs/rGO exhibited dramatically increased catalytic properties towards the reduction of 4-nitrophenol (4-NP) in the presence of NaBH 4 when compared to commercial Pd/C (20  wt .%). [ABSTRACT FROM AUTHOR]

Abstract: Hierarchically macro–mesoporous titania was synthesized by the simple dropwise addition of tetrabutyl titanate to an ammonia solution in the absence of surfactant molecules, and then calcined at different temperatures. The as-prepared titania was characterized by X-ray diffraction, N2 adsorption–desorption analysis and scanning electron microscopy. The results showed that the hierarchically marcro–mesoporous structure of the titania was well preserved after calcination at 650°C, indicating high thermal stability. The 500°C calcined titania with the hierarchically bimodal pore network was impregnated with 0.5wt.% of palladium and compared with 0.5wt.% Pd/TiO2 catalyst without such macrochannels. The novel macro–mesostructured Pd/TiO2 catalyst exhibited higher catalytic activity for styrene hydrogenation due to the lower diffusion resistance of species inside the catalyst caused by the hierarchically macro–mesoporous bimodal structure. [Copyright &y& Elsevier]