This paper reports a sustainable,water-assisted,solid-state method for synthesizing ammonium nickel molybdate（（NH4）HNi2（OH）2（MoO4）2,ANM）,a precursor for an unsupported hydrodesulfurization（HDS） catalyst.The associated ANM formation mechanism is also discussed.The synthesis route consists of physical mixing of the raw materials,water-assisted grinding and heating.The formation mechanism involves replacement of a Mo atom by a Ni atom,generating the metastable intermediate（NH4）4（NiH6Mo6O（24））·5H2O.Heating of this intermediate at 120 ℃ removes the added water and produces ANM.Catalysts prepared by this method exhibit almost the same physicochemical properties and catalytic performance during the HDS of dibenzothiophene as materials made from ANM synthesized by a chemical precipitation procedure.Compared with traditional hydrothermal or chemical precipitation methods,this water-assisted,solid-state synthesis provides several significant advantages,including simplifying the synthetic procedure,reducing waste and energy costs and increasing product yields.These features will be highly important with regard to allowing the application of ANM in industrial-scale processes involving HDS reactions.This water-assisted,solid-state strategy can also be extended to the synthesis of isomorphous compounds such as ammonium cobalt（zinc and copper） molybdate.
A simple method for preparation of presulfided eggshell CoMoS/γ-Al2O3 catalysts with sharp boundary is developed, through which the eggshell thicknesses of Co and Mo could be easily regulated by controlling the impregnation time. According to the results characterized by EDS, XRD, HRTEM and FT-IR of adsorbed CO, the active component structures, the nature and/or the amount of active sites on the eggshell catalyst are similar to these on the uniform catalyst. The evaluation results of the catalytic performance in selective hydrodesulfurization （HDS） of FCC gasoline show the presence of significant internal diffusion inhibition effect on HDS of S-compounds especially in the uniform catalyst. Compared with uniform catalyst, the eggshell catalyst could remarkably reduce such an internal diffusion inhibition effect due to a shortened diffusion path of the reactants, thus showing higher HDS activity and selectivity.
Bin LiuYongming ChaiYajing WangYunqi LiuChenguang Liu
The careful design of nano-architectures and smart hybridization of expected active materials can lead to more advanced properties. Here we have engineered a novel hierarchical branching Cu/Cu2O/CuO heteronanostructure by combining a facile hydrothermal method and subsequent controlled oxidation process. The fine structure and epitaxial relationship between the branches and backbone are investigated by high-resolution transmission electron microscopy. Moreover, the evolution of the branch growth has also been observed during the gradual oxidation of the Cu nanowire surface. The experimental results suggest that the surface oxidation needs to be performed via a two-step exposure process to varying humidity in order to achieve optimized formation of a core-shell structured branching architecture. Finally, a proof-of-concept of the function of such a hierarchical framework as the anode material in lithium-ion batteries is demonstrated. The branching core-shell heterostructure improves battery performance by several means： （i） The epitaxially grown branches provide a high surface area for enhanced electrolyte accessibility and high resistance to volume change induced by Li^＋ intercalation/extraction; （ii） the core-shell structure with its well-defined heterojunction increases the contact area which facilitates effective charge transport during lithiation; （iii） the copper core acts as a current collector as well as providing structural reinforcement.
Yuxin ZhaoYing ZhangHu ZhaoXuejin LiYanpeng LiLing wenZifeng YanZiyang Huo
