检索结果-南通市图书馆

Determination of particle size distribution by multi-scale analysis of acoustic emission signals in gas-solid fluidized bed

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第4期12卷 260-267页

作者： Cong-jing REN jing-dai wang Di SONG Bin-bo JIANG Zu-wei LIAO Yong-rong YANG State Key Laboratory of Chemical Engineering Department of Chemical and Biochemical Engineering Zhejiang University Hangzhou 310027 China

Particle size distribution(PSD) is an important parameter in the process of fluidization,and it always plays a crucial role in a gas-solid fluidized system.A PSD model for on-line PSD determination based on acoustic emission(AE) measurement was developed according to the mechanism of particle collision with the inner wall of the cylinder and multi-scale wavelet decomposition *** PSD model illuminates the quantitative relationship between the energy percentage of AE signals for different scales and the PSD,which indicates the feasibility of the application of the PSD *** were undertaken both in lab and plant gas-solid fluidized setup with polyethylene particles,and the parameters of the PSD model were calibrated and *** experimental conditions and results proved that the PSD model was suitable for on-line measurement and was sufficiently sensible and *** agglomeration,the PSD model also showed exact serviceability on detecting the onset of agglomeration by abnormal PSD,and the result agreed with that from the radiation ***,AE measurement was found to be a reliable and credible means for understanding the PSD information that affects the behavior of a system,which can provide valuable guidance for practical applications.

关键词： Particle size distribution(PSD) Acoustic emission(AE) Fluidized bed Multi-scale Agglomeration

Characteristics of Titanocene Catalyst Supported on Palygorskite for Ethylene Polymerization

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2006年第5期17卷 653-656页

作者： Xiao Wei YAN jing dai wang Yi Bing SHAN Yong Rong YANG Department of Chemical Engineering Zhejiang University Hangzhou 310027

A series of heterogeneous catalysts with Cp2TiCl2 supported on palygorskite were prepared and evaluated by ethylene slurry polymerizations. The so-called direct supported catalyst, for which the pretreatment of palygorskite with MAO or Al（i-Bu）3 was not necessary, gave the highest activity among these supported catalysts and could be more robust than homogeneous Cp2TiCl2. With the direct supported catalyst, no significant activity loss was observed under low Al/Ti molar ratios （Al/Ti=300） and the decay of polymerization rate was slower when compared to the other supported catalysts. It was found that the surface Lewis acidity of palygorskite after thermal treatment played an important role in activation of metallocene compound and resulted in high catalyst activity.

关键词： Playgorskite supported catalyst ethylene polymerization Lewis acidity.

Self-diffusion coefficients of organic solvents in linear and branched high density polyethylene particles measured by PFG NMR

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2008年第1期19卷 110-114页

作者： Xiao Wei Yan Xiao Hong Ren Siegfried Stap jing dai wang Yong Rong Yang Department of Chemical Engineering Zhejiang University Hangzhou 310027 China FG Technische Physik ll/Polymerphysik Fakultat fiir Mathematik und Naturwissenschaften Technische Universitiit Ilmenau Postfach 100565 D-98684 Ilmenau Germany Institut fiir Technische Chemie und Makromolekulare Chemie RWTH Aachen University Worringerweg 1 D-52056 Aachen Germany

Pulsed field gradient nuclear magnetic resonance （PFG NMR） has been performed to study the diffusion of organic solvents into semicrystalline polyethylene particles. Self-diffusion coefficients in different domains of the sample can be extracted through a bi- exponential fit to the echo intensity attenuation, which allows the precise determination of the tortuosity of the polyethylene particles. Further exploration comes from the measurements with branched polyethylene particles and it was found that the diffusion in polymer phase contributed significantly to the slow component of the exponential decay curve. 2007 jing dai wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

关键词： Self-diffusion coefficients Pulsed field gradient NMR Tortuosity Polyethylene particle

Preparation of Aryloxy-aluminoxanes and Their Use as Activators in the Bis(imino)pyridyl Iron-catalyzed Oligomerization of Ethylene

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2018年第11期36卷 1207-1207,1208-1216页

作者： Wei Zhang Bin-Bo Jiang Jian Ye Zu-Wei Liao Zheng-Liang Huang jing-dai wang Yong-Rong Yang Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture Technology State Key Laboratory of Chemical Engineering College of Chemical and Biological Engineering Zhejiang University

In this study, a series of aryloxy-aluminoxanes originated directly from the hydrolysis of reaction products of A1Me3 and phenols were synthesized, which could serve as effective polymer-retarding activators for the iron-catalyzed ethylene oligomerization. The molar ratios of [PhOH]/[AlMe3] and [H2O]/[Al] during the preparation were explored and their impacts on the oligomerization activity and product distribution were discussed. To obtain the effective activators with good polymer-retarding effect and relatively high activity, the optimized conditions were proposed to be [PhOH]/[AlMe3] = 0.5 and [H2O]/[Al] = 0.7. Various aluminoxanes with different [-OH] sources confirmed the importance of using phenols in preparing the effective polymer-retarding activators. By utilizing these aryloxy-aluminoxanes, the mass fraction of polymers in the total products could be reduced to lower than 1.0 wt%, which is much lower than that of the MAO-activated systems （〉 30 wt%）. This is a potential benefit for the industrial application of the iron-catalyzed oligomerization process.

关键词： Ethylene oligomerization Bis(imino)pyridyl iron catalysts Aryloxy-aluminoxanes Phenols Trimethylaluminum hydrolysis

Crosslinked solubilizer enables nitrate-enriched carbonate polymer electrolytes for stable,high-voltage lithium metal batteries

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2024年第2期69卷 209-217页

作者： Chuyang jing Kuan dai Dong Liu Wenran wang Libao Chen Chunxiao Zhang Weifeng Wei State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China College of Materials and Chemical Engineering Hunan Institute of EngineeringXiangtan 411104China

High-voltage lithium metal batteries(LMBs)have been considered promising next-generation highenergy-density ***,commercial carbonate electrolytes can scarcely be employed in LMBs owing to their poor compatibility with metallic lithium.N,N-dimethylacrylamide(DMAA)-a crosslinkable solubilizer with a high Gutmann donor number-is employed to facilitate the dissolution of insoluble lithium nitrate(LiNO3)in carbonate-based electrolytes and to form gel polymer electrolytes(GPEs)through in situ *** Lit solvation structure of the GPEs is regulated using LiNO3 and DMAA,which suppresses the decomposition of LiPFe and facilitates the formation of an inorganic-rich solid electrolyte ***,the Coulombic efficiency(CE)of the LillCu cell assembled with a GPE increases to 98.5%at room temperature,and the high-voltage LillNCM622 cell achieves a capacity retention of 80.1%with a high CE of 99.5%after 400 *** bifunctional polymer electrolytes are anticipated to pave the way for next-generation high-voltage LMBs.

关键词： Crosslinked solubilizer Lithium nitrate Carbonate electrolytes Gel polymer electrolytes Lithium metal batteries

Lamellar quasi-solid electrolyte with nanoconfined deep eutectic solvent for high-performance lithium battery

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2024年第7期17卷 6176-6183页

作者： Shiwei Liu jing wang Keqi Wu Zhirong Yang Yan dai Junmei Zhang Wenjia Wu jingtao wang School of Chemical Engineering Zhengzhou UniversityZhengzhou 450001China

Electrolytes with high-efficiency lithium-ion transfer and reliable safety are of great importance for lithium *** having superior ionic conductivity(10^(−3)–10^(−2) S·cm^(−1)),traditional liquid-state electrolytes always suffer from low lithium-ion transference number(tLi+<0.4)and thus undesirable battery ***,the deep eutectic solvent(DES)is vacuum-filtered into the~1 nm interlayer channel of vermiculite(Vr)lamellar framework to fabricate a quasi-solid electrolyte(Vr-DES QSE).We demonstrate that the nanoconfinement effect of interlayer channel could facilitate the opening of solvation shell around ***,the interaction from channel wall could inhibit the movement of *** enable high-efficiency lithium-ion transfer:2.61×10^(−4)S·cm^(−1)at 25℃.Importantly,the tLi+value reaches 0.63,which is 4.5 times of that of bulk DES,and much higher than most present liquid/quasi-solid *** addition,Vr-DES QSE shows significantly improved interfacial stability with Li anode as compared with *** assembled Li symmetric cell can operate stably for 1000 h at 0.1 mA·cm^(−2).The lithium iron phosphate(LFP)|Vr-DES QSE|Li cell exhibits high capacity of 142.1 mAh·g^(−1)after 200 cycles at 25℃ and 0.5 C,with a capacity retention of 94.5%.The strategy of open solvation shell through nanoconfinement effect of lamellar framework may shed light on the development of advanced electrolytes.

关键词： quasi-solid electrolyte deep eutectic solvent lamellar structure lithium-ion transference number solvation shell

Bimetallic CoNi single atoms supported on three-dimensionally ordered mesoporous chromia:highly active catalysts for n-hexane combustion

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Green Energy & Environment 2024年第7期9卷 1122-1137页

作者： Xiuqing Hao Yuxi Liu Jiguang Deng Lin jing Jia wang Wenbo Pei Hongxing dai Beijing Key Laboratory for Green Catalysis and Separation Key Laboratory of Beijing on Regional Air Pollution ControlKey Laboratory of Advanced Functional MaterialsEducation Ministry of ChinaLaboratory of Catalysis Chemistry and NanoscienceDepartment of Chemical EngineeringFaculty of Environment and LifeBeijing University of TechnologyBeijing100124China

Developing the alternative supported noble metal catalysts with low cost,high catalytic efficiency,and good resistance toward carbon dioxide and water vapor is critically demanded for the oxidative removal of volatile organic compounds(VOCs).In this work,we prepared the mesoporous chromia-supported bimetallic Co and Ni single-atom(Co_(1)Ni_(1)/meso-Cr_(2)O_(3))and bimetallic Co and Ni nanoparticle(Co_(NP)Ni_(NP)/mesoCr_(2)O_(3))catalysts adopting the one-pot polyvinyl pyrrolidone(PVP)-and polyvinyl alcohol(PVA)-protecting approaches,*** results indicate that the Co_(1)Ni_(1)/meso-Cr_(2)O_(3)catalyst exhibited the best catalytic activity for n-hexane(C_(6)H_(14))combustion(T_(50%)and T_(90%)were 239 and 263℃ at a space velocity of 40,000 mL g^(-1)h^(-1);apparent activation energy and specific reaction rate at 260℃ were 54.7 kJ mol^(-1)and 4.3×10^(-7)mol g^(-1)_(cat)s^(-1),respectively),which was associated with its higher(Cr^(5+)+Cr^(6+))amount,large n-hexane adsorption capacity,and good lattice oxygen mobility that could enhance the deep oxidation of n-hexane,in which Ni_(1) was beneficial for the enhancements in surface lattice oxygen mobility and low-temperature reducibility,while Co_(1) preferred to generate higher contents of the high-valence states of chromium and surface oxygen species as well as adsorption and activation of n-hexane.n-Hexane combustion takes place via the Mars van Krevelen(MvK)mechanism,and its reaction pathways are as follows:n-hexane→olefins or 3-hexyl hydroperoxide→3-hexanone,2-hexanone or 2,5-dimethyltetrahydrofuran→2-methyloxirane or 2-ethyl-oxetane→acrylic acid→CO_x→CO_(2)and H_(2)O.

关键词： Three-dimensional ordered mesoporous chromium oxide Supported bimetallic single-atom catalyst Cobalt-nickel single atoms n-Hexane combustion Catalytic reaction mechanism

Used car price prediction based on XGBoost and retention rate

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2024年第3期31卷 72-79页

作者： Shen Yutian Chen Jian dai Min Zhang Sirui Xu jing wang Qing College of Mechanical Engineering Yangzhou UniversityYangzhou 225127China College of Economics and Management Southeast University Chengxian CollegeNanjing 210088China Shandong Shuncheng Automobile Trade Co. LtdJinan 250000China

In order to improve the accuracy of used car price prediction,a machine learning prediction model based on the retention rate is proposed in this ***,a random forest algorithm is used to filter the variables in the *** main characteristic variables that affect used car prices,such as new car price,service time,mileage and so on,are filtered ***,the linear regression classification method is introduced to classify the test data into high and low retention rate *** that,the extreme gradient boosting(XGBoost)regression model is built for the two datasets *** prediction results show that the comprehensive evaluation index of the proposed model is 0.548,which is significantly improved compared to 0.488 of the original XGBoost ***,compared with other representative machine learning algorithms,this model shows certain advantages in terms of mean absolute percentage error(MAPE),5%accuracy rate and comprehensive evaluation *** a result,the retention rate-based machine learning model established in this paper has significant advantages in terms of the accuracy of used car price prediction.

关键词： random forest data dimensionality reduction extreme gradient boosting(XGBoost) retention rate price prediction

Pd Pt VO_(x)/CeO_(2)-ZrO_(2):Highly efficient catalysts with good sulfur dioxide-poisoning reversibility for the oxidative removal of ethylbenzene

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2024年第4期138卷 153-166页

作者： Jia wang Yuxi Liu Jiguang Deng Lin jing Xiuqing Hao Xing Zhang Xiaohui Yu Hongxing dai Beijing Key Laboratory for Green Catalysis and Separation Key Laboratory of Beijing on Regional Air Pollution ControlKey Laboratory of Advanced Functional MaterialsEducation Ministry of ChinaLaboratory of Catalysis Chemistry and NanoscienceDepartment of Chemical EngineeringFaculty of Environment and LifeBeijing University of TechnologyBeijing 100124China

The PdPtVO_(x)/CeO_(2)-ZrO_(2)(PdPtVO_(x)/CZO)catalysts were obtained by using different approaches,and their physical and chemical properties were determined by various *** activities of these materials in the presence of H_(2)O or SO_(2)were evaluated for the oxidation of ethylbenzene(EB).The PdPtVO_(x)/CZO sample exhibited high catalytic activity,good hydrothermal stability,and reversible sulfur dioxide-poisoning performance,over which the specific reaction rate at 160℃,turnover frequency at 160℃(TOF_(Pd or Pt)),and apparent activation energy were 72.6 mmol/(g_(Pt)·sec)or 124.2 mmol/(g_(Pd)·sec),14.2 sec^(-1)(TOF_(Pt))or 13.1 sec^(-1)(TOF_(Pd)),and 58 k J/mol,*** large EB adsorption capacity,good reducibility,and strong acidity contributed to the good catalytic performance of PdPtVO_(x)/*** activity of PdPtVO_(x)/CZO decreased when 50 ppm SO_(2)or(1.0 vol.%H_(2)O+50 ppm SO_(2))was added to the feedstock,but was gradually restored to its initial level after the SO_(2)was cut *** good reversible sulfur dioxide-resistant performance of PdPtVO_(x)/CZO was associated with the facts:(i)the introduction of SO_(2)leads to an increase in surface acidity;(ii)V can adsorb and activate SO_(2),thus accelerating formation of the SO_(x)^(2-)(x=3 or 4)species at the V and CZO sites,weakening the adsorption of sulfur species at the PdPt active sites,and hence protecting the PdPt active sites to be not poisoned by SO_(2).EB oxidation over PdPtVO_(x)/CZO might take place via the route of EB→styrene→phenyl methyl ketone→benzaldehyde→benzoic acid→maleic anhydride→CO_(2)and H_(2)O.

关键词： Ceria-zirconia Supported palladium-platinum-vanadium catalyst Volatile organic compound Ethylbenzene oxidation Sulfur dioxide resistance