Yongna Zhang

Aerobic oxidative desulfurization of benzothiophene, dibenzothiophene and 4,6-dimethyldibenzothiophene using an Anderson-type catalyst [(C18H37)2N(CH3)2]5[IMo6O24]

Benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) are oxidized to their corresponding sulfones by an Anderson-type catalyst [(C18H37)2N(CH3)2]5IMo6O24 using molecular oxygen as the oxidant under mild reaction conditions. These refractory sulfur-containing compounds can be oxidized completely in the absence of any sacrificial agent. Solvents such as acetonitrile and water play a negative effect on the oxidative desulfurization system. The catalytic activities of the amphiphilic Anderson catalysts depend on the quaternary ammonium cations. The reactivity of the sulfur-containing compounds follows the order 4,6-DMDBT > DBT > BT.

Ultra‐Deep Hydrodesulfurization of Diesel Fuels on Trimetallic NiMoW Sulfide Catalysts

Developing ultra-deep hydrodesulfurization (HDS) catalysts with super high activity has been one of the most challenging and important subjects because of the increasingly stringent environmental regulations for the sulfur content in diesel fuels being enforced throughout the world. Furthermore, it is more difficult to process the residual oil resources remaining in the earth because the residual oil usually has high sulfur content and more refractory sulfur-containing compounds. Currently, the most commonly used HDS catalysts are molybdenum or tungsten sulfide catalysts promoted by cobalt or nickel and supported on porous-alumina, Co(Ni)Mo(W)/Al2O3. These catalysts have been extensively investigated in the last few decades and the room to further improve the HDS performance of the conventional catalysts is very limited. Therefore, the development of novel HDS catalysts with super high activity remains a promising but challenging subject. In recent years, it has been reported in several patents that a new NiMoW trimetallic HDS catalyst without a support, called NEBULA, could achieve much higher HDS activity than conventional catalysts. In striking contrast with the recognition from industry, the preparation and catalytic performance of such catalysts have been rarely reported in the literature. For the conventional supported NiMo catalyst, the active phase is the so-called Ni-Mo-S phase, which consists of sulfide Ni atoms decorating the edges of MoS2 slabs. In the supported NiW catalyst, Ni-W-S phases have also been detected similar to the Ni-Mo-S phases. However, the preparation, structure, and the active phase of unsupported NiMoW catalysts have been rarely reported. In this work we prepared an unsupported trimetallic NiMoW sulfide catalyst by a novel method. The new catalyst can achieve catalytic activity up to 7.5 times that of the commercial catalysts in the HDS of diesel. Characterization of the NiMoW catalyst reveals that the unique multilayered structure of the NiMoW sulfide catalyst is most possibly responsible for the super high HDS activity. The precursor of the NiMoW sulfide catalyst was prepared by a surfactant-assisted co-precipitation method from the starting materials (see Experimental Section) including basic nickel carbonate followed by a sulfidation process to obtain the final sulfide catalyst. Different solvents, including alcohols, and a surfactant were used in the preparation to improve the morphology of the catalyst. The synthesis reaction was conducted in a liquid–solid phase, involving a soluble tungsten source, a soluble molybdenum source, and an insoluble nickel source, so the structure of the Ni precursor could be maintained in the final sulfide catalyst. Different kinds of basic nickel carbonate were also used to prepare the NiMoW catalysts. Basic nickel carbonate was used as the nickel source to prepare the NiMoW precursors with hydrotalcite-like structures, which were composed of layered sheets with positive charge and exchangeable anions located in the galleries between the sheets. Molybdate and tungstate anions can be exchanged with OH and CO3 2 bonded to nickel hydroxyl sheets in the interlayer galleries of the NiMoW catalysts. The introduction of mixed solvents and basic nickel carbonate prepared by the co-precipitation method in this work greatly affect the morphology of the NiMoW catalyst. The TEM and SEM images (see Figure S1 in the Supporting Information) of the NiMoW-3 sulfide catalyst show a uniformly distributed nanoparticle with a particle size of about 20 nm and the species with small sheets of the catalysts, respectively. 4,6-Dimethyldibenzothiophene (4,6-DMDBT) was used as a model sulfur-containing molecule in decalin (sulfur content of 500 ppm) to test the HDS performance of the NiMoW-3 and the commercial CoNiMoW/Al2O3 catalysts. The sulfur content of the model compound was reduced from 500 ppm to 1.5 ppm when the HDS reaction was per[a] Dr. L. Wang, Dr. Y. Zhang, Dr. Y. Zhang, Prof. Z. Jiang, Prof. C. Li State Key Laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences 457 Zhongshan Road, Dalian,116023 (China) Fax: (+86) 411-84694447 E-mail : zxjiang@dicp.ac.cn canli@dicp.ac.cn Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.200901997.

A direct imaging of amphiphilic catalysts assembled at the interface of emulsion droplets using fluorescence microscopy

An amphiphilic fluorescent catalyst Q9[EuW10O36] (Q = [(C18H37)2N+ (CH3)2]), assembled in the interface of emulsion systems, was directly imaged by fluorescence microscopy; the catalyst shows high selectivity and activity in the oxidation of alcohols using H2O2 as oxidant and the catalyst can be easily separated and recycled by demulsifying.

The modification of molybdenum nitrides : the effect of the second metal component

A set of Mo2N-based bimetallic catalysts with high surface area around 140 m 2 /g have been successfully prepared from precursors obtained using the coprecipitation method. Both the precursors and the end-catalysts were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The nitriding processes were monitored by differential thermal analysis (TDA). The catalytic properties of Co-Mo bimetallic catalyst under mediumpressure (3.0 MPa) are much better for the hydrodenitrogenation of pyridine than those of pure γ-Mo2N and a commercially used sulfided CoMo/Al2O3 catalyst. The introduction of the second metal component has been shown to disrupt the morphology of the nitride phase with a greater concentration of (111) planes being present compared to (200) planes, a situation that is reversed compared to γ-Mo2N.

Synthesis, characterization and catalytic properties of bimetallic ZrMo2Nx–Mo2N nitrides of high surface area

Abstract A set of bimetallic nitrides, ZrMo 2 N x –Mo 2 N, of high specific surface area up to 132 m 2 /g has been synthesized by temperature programmed nitriding (TPN) mixtures of Zr- and Mo-containing compounds with ammonia. Two series of precursors have been studied using XRD, SEM and FT-IR. It is found that the structure and composition of the end-products depend on the properties of the precursors and these, in turn, are influenced to a large extent by the preparation method of the precursor, i.e. using impregnation or using coprecipitation. The end-catalysts obtained from precursors prepared by impregnation are composed of ZrO 2 –Mo 2 N while those from precursors prepared by coprecipitation consist of ZrMo 2 N x –Mo 2 N. XRD and SEM results reveal that the characteristic platelet structure of MoO 3 is damaged upon the introduction of the second metal component by coprecipitation, but is retained when using impregnation. The catalytic activities of the bimetallic nitrides for the hydrogenation of cyclohexene and the hydrodesulfurization of thiophene are found, under medium pressures (3.0 MPa), to compare favourably with those of a commercial sulfided NiCoMo/Al 2 O 3 catalyst and unsupported γ -Mo 2 N. H 2 -TPD results indicate that the bimetallic nitrides possess a more extensive capacity for hydrogen adsorption in low temperature states.