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Influence of CeO2 morphology on the catalytic oxidation of ethanol in air
Guilin Zhou,Baoguo Gui,Hongmei Xie,Fang Yang,Yong Chen,Shengming Chen,Xuxu Zheng 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.1
Nano-CeO2 catalysts of different shapes were synthesized at different hydrothermal crystallizationtemperatures from an alkaline aqueous solution. X-ray diffraction (XRD), transmission electronmicroscope (TEM), and H2 temperature-programmed reduction (H2-TPR) were used to study thesynthesized nano-CeO2 catalyst samples. The catalytic properties of the prepared nano-CeO2 catalystsfor the catalytic oxidation of ethanol in air were also investigated. TEM analysis showed that CeO2nanorod and nanocube catalysts have been synthesized at hydrothermal crystallization temperatures of373 K and 453 K, respectively. XRD results showed that the synthesized nano-CeO2 catalysts have similarcubic fluorite structures. H2-TPR results indicated that CeO2 nanorod and nanocube catalysts exhibitdifferent reduction behaviors for H2 and that the nanorod catalyst has better low-temperature reductionperformance than the nanocube catalyst. Ethanol catalytic oxidation results indicated that oxidation andcondensation products (including acetaldehyde, acetic acid, CO2, and ethyl acetate) have been producedfrom the prepared catalysts. The ethyl acetate and acetic acid can be ignited by ethanol at lowtemperature on the CeO2(R) catalyst to give low catalytic combustion temperature for ethyl acetate andacetic acid molecules. CeO2 nanorods gave ethanol oxidation conversion rates above 99.2% at 443 K andCO2 selectivity exceeding 99.6% at 483 K, while CeO2 nanocubes gave ethanol oxidation conversion ratesof about 95.1% until 508 K and CO2 selectivity of only 93.86% at 543 K. CeO2 nanorod is a potential lowcostand effective catalyst for removing trace amounts of ethanol to purify air.
A Novel Synchronous Switch Method Based on Kalman Filter
Zheng Guilin,Chen Xi 보안공학연구지원센터 2015 International Journal of Future Generation Communi Vol.8 No.2
In order to create the idea of AC switch without electric arc and inrush voltage to the power system, the study of accurately catches AC zero crossing of a mechanical relay is put forward in this paper. It is the key to make the switch act at the right predicted time which realizes switch on or off exactly at the AC zero crossing point. However, the action time of a mechanical switch is affect by many factors such as driving voltage, ambient temperature, age of the mechanic structure. Aim at the discrete measurements of latching relay action time, the Kalman filter mathematic model is introduced in this paper to eliminate the dynamic noise and measurement noise which affects the bias time drift from the zero voltage or zero current point. Simulation result by matlab and group data get from experiments of a realized multichannel switch indicate that Kalman filter algorithm can overcome the discreteness of latching relay action time measurements. Also confirmed by statistical experiments that synchronous switch action precisely and reliably at AC zero point which can ensure the ability of suppress electric arc and high frequency inrush current.
Chunfeng Wang,Jun Yang,Guilin Liu,Hong Gao,Meiling Chen 한양대학교 세라믹연구소 2022 Journal of Ceramic Processing Research Vol.23 No.4
This study aims to reveal the changes in the microstructure of hypoeutectic gray cast iron under the addition of compositesilicon carbide powder of different mass fractions, and to explore how modified silicon carbide (SiC) particles of different sizesand contents improve the mechanical properties of hypoeutectic gray cast iron. The results showed that the modified SiCparticles increased the nucleation, the undercooling and microstructure of hypoeutectic gray cast iron, and the tensile strengthof the iron at room temperature was increased by 18,28%. The present work solves the problem that traditional SiC ceramicparticles are prone to agglomeration in molten metal, analyzes its action mechanism, and can expand the application of SiCceramic particles to strengthening metal properties of casting materials.
Detecting small lung tumors in mouse models by refractive-index microradiology
Chien, Chia-Chi,Zhang, Guilin,Hwu, Y.,Liu, Ping,Yue, Weisheng,Sun, Jianqi,Li, Yan,Xue, Hongjie,Xu, Lisa X.,Wang, Chang Hai,Chen, Nanyow,Lu, Chien Hung,Lee, Ting-Kuo,Yang, Yuh-Cheng,Lu, Yen-Ta,Ching, Y Springer-Verlag 2011 ANALYTICAL AND BIOANALYTICAL CHEMISTRY Vol.401 No.3
Catalytic combustion of volatile aromatic compounds over CuO-CeO2 catalyst
Hongmei Xie,Qinxiang Du,Hui Li,Guilin Zhou,Shengming Chen,Zhaojie Jiao,Jianmin Ren 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.7
Ce1−xCuxO2 oxide solid solution catalysts with different Ce/Cu mole ratios were synthesized by the one-pot complex method. The prepared Ce1−xCuxO2 catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and H2 temperature-programmed reduction (H2-TPR). Their catalytic properties were also investigated by catalytic combustion of phenyl volatile organic compounds (PVOCs: benzene, toluene, xylene, and ethylbenzene) in air. XRD analysis confirmed that the CuO species can fully dissolve into the CeO2 lattice to form CeCu oxide solid solutions. XPS and H2-TPR results indicated that the prepared Ce1−xCuxO2 catalysts contain abundant reactive oxygen species and superior reducibility. Furthermore, the physicochemical properties of the prepared Ce1−xCuxO2 catalysts are affected by the Ce/Cu mole ratio. The CeCu3 catalyst with Ce/Cu mole ratio of 3.0 contains abundant reactive oxygen species and exhibits superior catalytic combustion activity of PVOCs. Moreover, the ignitability of PVOCs is also affected by the respective physicochemical properties. The catalytic combustion conversions of ethylbenzene, xylene, toluene, and benzene are 99%, 98.9%, 94.3%, and 62.8% at 205, 220, 225, and 225 oC, respectively.
Research on High-Frequency Isolation Type of Dual-PWM Variable Frequency Speed Regulation
Liu Jiangong,Liu Wenzhuang,Wang Yiying,Zhang Guilin,Chen Longfei 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.4
Frequency converters are widely used in power grids, motor speed regulation, and other fields. When the voltage level is above low voltage and the workspace is limited, traditional frequency converters mostly adopt the power frequency transformer to connect to the power grid. But the structure has the problems of bigger volume and complexity. To solve these problems, this paper proposes a three-stage topology structure of high-frequency isolation type of dual-PWM variable frequency speed regulation based on three-phase rectification, single active isolated DC/DC converter, and three-phase inverter, and analyzes its power transmission characteristics in detail. And a new method that combines high-frequency electrical isolation and frequency conversion is discussed. Then, the control strategies of the new method are also described. Lastly, simulation and experiment are constructed to verify the new design method is correct and feasible, and that the steady and dynamic characteristics of the three-stage high-frequency isolated frequency converter are better.
Reduction of CO2 to CO via reverse water-gas shift reaction over CeO2 catalyst
Bican Dai,Shiquan Cao,Hongmei Xie,Guilin Zhou,Shengming Chen 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.2
CeO2 catalysts with different structure were prepared by hard-template (Ce-HT), complex (Ce-CA), and precipitation methods (Ce-PC), and their performance in CO2 reverse water gas shift (RWGS) reaction was investigated. The catalysts were characterized using XRD, TEM, BET, H2-TPR, and in-situ XPS. The results indicated that the structure of CeO2 catalysts was significantly affected by the preparation method. The porous structure and large specific surface area enhanced the catalytic activity of the studied CeO2 catalysts. Oxygen vacancies as active sites were formed in the CeO2 catalysts by H2 reduction at 400 oC. The Ce-HT, Ce-CA, and Ce-PC catalysts have a 100% CO selectivity and CO2 conversion at 580 oC was 15.9%, 9.3%, and 12.7%, respectively. The highest CO2 RWGS reaction catalytic activity for the Ce-HT catalyst was related to the porous structure, large specific surface area (144.9m2∙g−1) and formed abundant oxygen vacancies.