Zongxuan Jiang

Oxidative desulfurization of dibenzothiophene with molecular oxygen using emulsion catalysis

Dibenzothiophene (DBT) is oxidized to the corresponding sulfoxide and sulfone in an emulsion system (W/O) composed of polyoxometalate anion [C(18)H(37)N(CH(3))3](5)[PV(2)Mo(10)O(40)] as both the surfactant and catalyst, using molecular oxygen as the oxidant and aldehyde as the sacrificial agent under mild conditions.

Photocatalytic oxidation of thiophene on BiVO4 with dual co-catalysts Pt and RuO2 under visible light irradiation using molecular oxygen as oxidant

Thiophene is one of the main sulfur-containing compounds in gasoline and difficult to be oxidized with the conventional oxidative processes. Herein for the first time we report that thiophene can be oxidized to SO3 on BiVO4 co-loaded with Pt and RuO2 co-catalysts (denoted as Pt-RuO2/BiVO4) under visible light irradiation with molecular oxygen as oxidant. The high activity of the catalyst can be achieved by only loading as low as 0.03 wt% of Pt and 0.01 wt% of RuO2 as dual co-catalysts on BiVO4. ESR measurements give the evidence that the active oxygen species (˙OH and O2˙−) generated by photocatalytic processes are involved in the photocatalytic oxidation of thiophene. The considerable enhancement of photocatalytic activity can be attributed to the simultaneous presence of the reduction and oxidation co-catalysts which are beneficial for the efficient separation and transfer of the photo-generated electrons and holes.

Oxidative Desulfurization of Fuel Oils

Abstract Several attractive approaches toward oxidative desulfurization of fuel oils, such as using H 2 O 2 /organic acids, H 2 O 2 /heteropolyacid, H 2 O 2 /Ti-containing zeolites, and other non-hydrogen peroxide systems (e.g., t -butyl hydroperoxide etc.) are reviewed. A new alternative oxidative desulfurization process using emulsion catalysts was developed mainly by our group, is introduced in detail. Limitations because of interphase mass transfer are greatly reduced in the emulsion reaction medium. The amphiphilic emulsion catalysts can selectively oxidize the sulfur-containing molecules present in diesel to their corresponding sulfones when using H 2 O 2 as the oxidant under mild conditions. The sulfones in the oxidized fuel oils can be removed by a polar extractant. The sulfur level of a prehydrotreated diesel can be lowered from a few hundred μg/g to 0.1 μg/g after oxidation and subsequent extraction whereas the sulfur level of a straight-run diesel can be decreased from 6000 to 30 μg/g after oxidation and extraction.

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.

The Synthesis of Chiral Isotetronic Acids with Amphiphilic Imidazole/Pyrrolidine Catalysts Assembled in Oil-in-Water Emulsion Droplets†

Drop it! A highly enantioselective catalytic cascade reaction of α-ketoacids and aldehydes is achieved using the title catalyst and water as the solvent. Fluorescence imaging shows that the catalyst is mainly distributed on the surface of emulsion droplets. Optically active isotetronic acids can be obtained with this method and the emulsion droplets are responsible for the high reactivity and enantioselectivity.

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.

Oxidation of refractory sulfur-containing compounds with molecular oxygen catalyzed by vanadoperiodate

A new vanadoperiodate [HIV9O28]3− has been synthesized by a simple, one-pot stoichiometric reaction of HIO4·2H2O with NaVO3 in aqueous solution and then isolated as [C8H17N(CH3)3]3HIV9O28 by cation exchange. We have found that [C8H17N(CH3)3]3HIV9O28 shows high catalytic activity in the oxidation of refractory sulfur-containing compounds to their corresponding sulfones using molecular oxygen as oxidant under mild reaction conditions.

Ultra-deep Oxidative Desulfurization of Fuel Oil Catalyzed by Dawson-Type Polyoxotungstate Emulsion Catalysts

Ultra-deep Oxidative Desulfurization of Fuel Oil Catalyzed by Dawson-type Polyoxotungstate Emulsion Catalysts

Preparation of Zn–Co–O mixed-metal oxides nanoparticles through a facile coordination polymer based process

This paper reports a facile process that starts from the coordination polymers (CPs) precursor for the preparation of mixed-metal oxides. Firstly, a series of CPs, Zn–Co–ptcda (ptcda = perylene-3,4,9,10-tetracarboxylic dianhydride) with different molar ratios of Zn2+ and Co2+, were prepared by self-assembly of metal ions and organic ligands at the molecular scale. Based on the scanning electron microscopy, X-ray diffraction and thermogravimetric analysis, Zn–Co–ptcda takes both the advantages of Zn–ptcda and Co–ptcda. After a simple thermal treatment, the mixed-metal CPs are transformed into mixed-metal oxides with morphology and composition inherited from the CPs precursor. Binary-phase oxide Co3O4/ZnO and single-phase spinel ZnxCo3−xO4 (0 < x < 1) can be successfully prepared by this strategy.