Design and control of a p-xylene oxidation process

The p-xylene(PX) oxidation process is of great industrial importance because of the strong demand of the global polyester fiber.A steady-state model of the PX oxidation has been studied by many researchers.In our previous work,a novel industrial p-xylene oxidation reactor model using the free radical mechanism based kinetics has been developed.However,the disturbances such as production rate change,feed composition variability and reactor temperature changes widely exist in the industry process.In this paper,dynamic simulation of the PX oxidation reactor was designed by Aspen Dynamics and used to develop an effective plantwide control structure,which was capable of effectively handling the disturbances in the load and the temperature of the reactor.Step responses of the control structure to the disturbances were shown and served as the foundation of the smooth operation and advanced control strategy of this process in our future work.

Preparation of Ordered Mesoporous Nanocrystalline Ceria and Ceria-zirconia for Soot Oxidation

Ordered mesoporous ceria and ceria-zirconia with high specific surface area were prepared by nanocasting of a mesoporous silica KIT-6 template and used for soot oxidation.The as-synthesized ordered mesoporous ceria and ceria-zirconia were characterized by XRD,TEM,Nitrogen adsorption-desorption,Raman spectroscopy,and XRF.The results indicate that mesoporous ceria and ceria-zirconia possess highly ordered mesoporous structure,and exhibited excellent catalytic performance in soot oxidation.T_（50） of mesoporous ceria and ceria-zirconia are 475 and 470 ℃,respectively.The high catalytic activity of mesoporous materials can be attributed to the mesoporous structure and small crystallite size.Moreover,aged mesoporous materials exhibit high catalytic activity.

Efectiveness of national air pollution control policies on the air quality in metropolitan areas of China

Understanding the effectiveness of national air pollution controls is important for control policy design to improve the future air quality in China. This study evaluated the effectiveness of major national control policies implemented recently in China through a modeling analysis. The sulfur dioxide （SO2） control policy during the llth Five Year Plan period （2006-2010） had succeeded in reducing the national SO2 emission in 2010 by 14% from its 2005 level, which correspondingly reduced ambient SO2 and sulfate （SO42-） concentrations by 13%-15% and 8%-10% respectively over east China. The nitrogen oxides （NOx） control policy during the 12th Five Year Plan period （2011-2015） targets the reduction of the national NOx emission in 2015 by 10% on the basis of 2010. The simulation results suggest that such a reduction in NOx emission will reduce the ambient nitrogen dioxide （NO2）, nitrate （NO3-）, 1-hr maxima ozone （03） concentrations and total nitrogen deposition by 8%, 3%-14%, 2% and 2%--4%, respectively over east China. The application of new emission standards for power plants will further reduce the NO2, NO3-, 1-hr maxima 03 concentrations and total nitrogen deposition by 2%-4%, 1%-%, 0-2% and 1%-2%, respectively. Sensitivity analysis was conducted to evaluate the inter-provincial impacts of emission reduction in Beijing-Tianjin-Hebei and the Yangtze River Delta, which indicated the need to implement joint regional air pollution control.

Ion sieving in graphene oxide membranes via cationic control of interlayer spacing

With the support by the National Natural Science Foundation of China,a collaborative study by the research groups led by Prof.Fang Haiping(方海平)from Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Prof.Wu Minghong(吴明红)from Shanghai Applied Radiation Institute。

Triple faced oxide:Electric-field controlled dual-ion switch

Subject Code:A04With the financial support from the National Natural Science Foundation of China,a research team led by Associate Professor Yu Pu(于浦)at the Department of Physics,Tsinghua University recently published their seminal work in Nature(2017,546:124—128).The work,titled“Electric-field control

Triple faced oxide:Electric-field controlled dual-ion switch

With financial support from the National Natural Science Foundation of China,a research team led by Associate Professor Yu Pu(于浦)at the Department of Physics in Tsinghua University published their seminal work recently in the prestigious journal Nature(2017,546:124-128).The work。

One-dimensional Cu-based catalysts with layered Cu-Cu20-CuO walls for the Rochow reaction

A series of copper catalysts with a core-shell or tubular structure containing various contents of Cu, Cu2O, and CuO were prepared via controlled oxidation of Cu nanowires （NWs） and used in the synthesis of dimethyldichlorosilane （M2） via the Rochow reaction. The Cu NWs were prepared from copper （Ⅱ） nitrate using a solution-based reduction method. The samples were characterized by X-ray diffraction, thermogravimetric analysis, temperature-programmed reduction, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy. It was found that the morphology and composition of the catalysts could be tailored by varying the oxidation temperature and time. During the gradual oxidation of Cu NWs, the oxidation reaction inflated on the outer surface and gradually developed into the bulk of the NWs, leading to the formation of catalysts with various structures and layered compositions, e.g., Cu NWs with surface Cu2O, ternary Cu-Cu2O-CuO core-shell NWs, binary Cu2O-CuO nanotubes （NTs）, and single CuO NTs. Among these catalysts, ternary Cu-Cu2O-CuO core-shell NWs exhibited superior M2 selectivity and Si conversion in the Rochow reaction. The enhanced catalytic performance was mainly attributed to improved mass and heat transfer resulting from the peculiar heterostructure and the synergistic effect among layered components. Our work indicated that the catalytic property of Cu-based nanoparticles can be improved by carefully controlling their structures and compositions.