Zhang Liangmiao

Controlled Synthesis of Mesoporous MnO 2 Nanospindles

We synthesized mesoporous MnO2 nanospindles by a one-step hydrothermal process in an aqueous solution of KMnO4 and glucose. The structure, morphology, purity, and size of the products were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and nitrogen adsorption/desorption (BET) measurements. The reaction time and concentrations of glucose influenced the final structures and shapes of the MnO2nanospindles. The length to diameter ratio of the MnCO3 precursor nanospindles can be easily tuned from 1.35:1 to 2.89:1. A possible formation mechanism for the mesoporous MnO2 nanospindles is proposed and discussed.

Fabrication of Mesoporous NiAl 2 O 4 Nanorods and Their Catalytic Properties for Toluene Hydrocracking

Mesoporous single-crystalline NiAI_2O_4 nanorods were successfully synthesized by a one-step hydrothermal method using a pore-forming agent(NH_4HCO_3).A series of controlled experiments were also carried out to better understand the formation mechanism of NiAI_2O_4 nanorods.The experimental results indicate that the reaction time,reactant concentration and the amount of NH_4HCO_3 play an important role in determining the morphology.The morphology,structure and composition of the nanorods were investigated using transmission electron microscopy,high resolution transmission electron microscopy,scanning electron microscopy and X-ray diffraction.The specific surface area and pore-size distribution of the obtained product was determined by nitrogen adsorption-desorption measurements.NiAI_2O_4 nanorods have a high Brunauer-Emmett-Teller surface area and good porosity properties.The catalytic performance of the NiAI_2O_4 nanorods during toluene hydrocracking was investigated using a fixed bed reactor.After the toluene catalytic reactions over 400 min at a water stream/carbon molar ratio(H_2O/C) of 1.0 with a reaction temperature of 700℃the average conversion efficiency of toluene was about 86.5%.Compared to the NiAI_2O_4 nanoparticles prepared by alkaline precipitation,the mesoporous NiAI_2O_4 nanorods exhibited higher catalytic activity and stability during toluene hydrocracking.A possible formation mechanism for the mesoporous NiAI_2O_4 nanorods is proposed and discussed.

Morphological characterization of A12O3 membrane fabricated by sol-gel dip-coating method

Alumina membranes without pinholes and cracks were prepared by the sol-gel process using ammonium aluminium sulphate as the starting material. The effects of different preparing conditions on morphology characteristics of the membrane were investigated by scanning electron microscopy and 3D rotational microscopy. The preparing conditions include the amounts of drying control chemical additives (DCCA), sintering procedure and sol-gel concentration. The results showed that PVA is a good crack-preventing reagent and the morphology of supported membranes was affected by many factors, including Al2O3 concentration, PVA/Al2O3 ratio, heating rate, membrane thickness and intrinsic defects of the substrate surface.