Kinetics of aniline oxidation with chlorine dioxide

For the first time, kinetics of aniline oxidation with chlorine dioxide(ClO 2) were investigated systematically by detecting concentration of aniline with HPLC at regular intervals. Results showed that the reaction was first-order both in ClO 2 and in aniline, and the oxidation reaction could be described as second-order reaction. Stoichiometric factor η was experimentally determined to be 2 44. The second-order-reaction rate constant k was 0 11 L/(mol·s) under condition of pH 6 86 and water temperature(T w) 287K. Reaction activation energy was 72 31 kJ/mol, indicating that the reaction could take place under usual water treatment conditions. The reaction rate constants in acidic and alkali media were greater than that in neutral medium. Chlorite ion could slightly increase reaction rate in acidic medium. p-aminophenol and azobenzene were detected by GC-MS as intermediates.

Catalytic Combustion of Methane over MnO_x/ZrO_2-Al_2O_3 Catalysts

MnO_x/Al_2O_3 and MnO_x/ZrO_2-Al_2O_3 catalysts were prepared by incipientwetness impregnation of Mn(CH_3COO)_2 on the corresponding supports, followed by thecharacterization using X-ray diffraction (XRD), temperature programmed reduction (TPR) and BETsurface area techniques. The result shows the BET surface area of ZrO_2-Al_2O_3 is lower than thatof Al_2O_3 due to the loading of ZrO_2. However the resulted MnO_x/ZrO_2-Al_2O_3 catalyst exhibitshigher activity for methane combustion than MnO_x/Al_2O_3, because the addition of ZrO_2 ontoAl_2O_3 is beneficial for the dispersion of Mn species and the improvement of the lattice oxygenactivity in MnO_x, subsequently the activation of methane during combustion. The optimum loading ofZr in MnO_x/ZrO_2-Al_2O_3 is in the range of 5%-10% correlated with the calcination temperatures ofcatalyst supports.

Catalytic Combustion of Methane over Ti-Pillared Clay Supported Copper Catalysts

A natural montmorillonite, produced from Laiyang of Shandong Province, was pillared by Tipolyeations to form Ti-pillared clay (Ti-PILC), and characterized by BET surface area, infrared spectra and thermal analysis. The characterization results show that Ti-PILC has a larger surface area and more hydroxyl groups than that of the natural clay, thus was used as the catalytic carriers to prepare supported Cu catalysts (Cu/Ti-PILC). The 20%Cu/Ti-PILC with 10mmol/g of Ti/clay shows a high catalytic performance of methane combustion in the temperature range of 400 500℃.

SEM analysis of the changes of carbon layer structure of mesocarbon microbeads heat-treated at different temperatures

Mesocarbon microbeads (MCMB) with narrow size distribution, excellent sphericity and no obvious conglu-tination have been prepared with a coal tar pitch containing quinoline insolubles (QI) as the raw material. Optical mi-croscopy and scanning electron microscopy (SEM) are used to examine the structure of the MCMB. It has been found that SEM technique shows the structural information of MCMB clearly in the form of micrographs even when the structure of MCMB is complex, while the optical technique is useful for analysis of the regular structure of the mesophase spheres but cannot be effectively used to analyze either the complex structure of the green MCMB or the structures of the further heat-treated ones at different temperatures. Ac-cording to the characteristics of the carbon layers, the struc-tures of the as-prepared MCMB in the present experiment could be classified as (1) Parallel Layer type structure and (2) Bent Layer type structure with the carbon layers gathering at one or two points in the MCMB. In the experiments, SEM is also utilized to investigate the structures of MCMB that are heat-treated at different temperatures. It has been found that the MCMB without any further heat-treatment show no layered-carbons, while the ones heat-treated at temperature higher than 1000℃ exhibit obvious layered carbons across their sections. When increasing the heat-treatment tempera-ture, the carbon layers become thinner and flatter.