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智能制造 2

3D支架平台 1

Al₂O₃-M_xO_y 1

NPY 1

Scheil原则 1

事件触发控制；分段仿射系统；线性矩阵不等式；执行器饱和；H∞性能 1

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可重构天线 1

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Phosphorous removal from wastewater by lanthanum modified Y zeolites

Weikang ZHANG, Ye TIAN

《化学科学与工程前沿（英文）》 2015年第9卷第2期页码 209-215 doi: 10.1007/s11705-014-1448-4

摘要： The adsorption capacities of Y zeolite and La (III)-modified Y zeolite were studied. A series of La(III)-modified Y zeolites with different La/Y zeolite mass ratios were characterized by X-ray diffraction, X-ray fluorescence and Brunauer-Emmett-Teller surface area analysis. Batch experiments were conducted to evaluate the effects of various experimental parameters, such as pH, ionic strength, coexisting anions ( , Cl , and ) and temperature, on the phosphate adsorption. The capacity of the La (III)-modified Y zeolite to remove phosphate increased as the La/Y zeolite mass ratio increased and after 4 h, a phosphate removal efficiency of 95% was achieved for a La/Y zeolite mass ratio of 0.10. The equilibrium adsorption isotherm data correlated better to the Langmuir model than the Freundlich model and the data followed a pseudo-second-order kinetic equation.

关键词： phosphate removal wastewater lanthanum impregnation Y zeolites

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Confinement effects in methanol to olefins catalysed by zeolites: A computational review

German Sastre

《化学科学与工程前沿（英文）》 2016年第10卷第1期页码 76-89 doi: 10.1007/s11705-016-1557-3

摘要： Small pore zeolites, containing 8-rings as the largest, are widely employed as catalysts in the process of methanol-to-olefins (MTO). Reactants and products diffuse with constraints through 8-rings and this is one of the reaction bottlenecks related to zeolite micropore topology. Small pore zeolites and silicon-aluminophosphates(SAPOs) containing cavities, where olefins are mainly formed through the hydrocarbon pool (HP) mechanism, are frequently tested for MTO. Shape selectivity of transition states within the side-chain methylation will be reviewed as this is one of the controlling steps of the MTO process, with particular attention to the role of hexamethylbenzene (HMB) and heptamethylbenzenium cation (HeptaMB ), which are the most tipically detected reaction intermediates, common to the paring and side-chain routes within the HP mechanism. The relative stability of these and other species will be reviewed in terms of confinement effects in different cage-based zeolites. The role of the different alkylating agents, methanol, dimethyl ether (DME), and surface methoxy species (SMS) will also be reviewed from the computational viewpoint.

关键词： small pore zeolites SAPOs methanol-to-olefins hydrocarbon pool mechanism alkylation of polymethylbenzenes

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Solid-state NMR for metal-containing zeolites: From active sites to reaction mechanism

Xingling Zhao, Jun Xu, Feng Deng

《化学科学与工程前沿（英文）》 2020年第14卷第2期页码 159-187 doi: 10.1007/s11705-019-1885-1

摘要： Metal-containing zeolite catalysts have found a wide range of applications in heterogeneous catalysis. To understand the nature of metal active sites and the reaction mechanism over such catalysts is of great importance for the establishment of structure-activity relationship. The advanced solid-state NMR (SSNMR) spectroscopy is robust in the study of zeolites and zeolite-catalyzed reactions. In this review, we summarize recent developments and applications of SSNMR for exploring the structure and property of active sites in metal-containing zeolites. Moreover, detailed information on host-guest interactions in the relevant zeolite catalysis obtained by SSNMR is also discussed. Finally, we highlight the mechanistic understanding of catalytic reactions on metal-containing zeolites based on the observation of key surface species and active intermediates.

关键词： metal-containing zeolites solid-state NMR active site host-guest interaction reaction mechanism

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Multifunctional heteroatom zeolites: construction and applications

《化学科学与工程前沿（英文）》 2021年第15卷第6期页码 1462-1486 doi: 10.1007/s11705-021-2099-x

摘要： Multifunctional heteroatom zeolites have drawn broad attentions due to the possible synergistic effects in the catalytic reactions. Remarkable achievements have been made on the synthesis, characterization and catalytic applications of multifunctional heteroatom zeolite, while a review on this important topic is still missing. Herein, current research status of multifunctional heteroatom zeolites is briefly summarized, aiming to boost further researches. First, the synthesis strategies toward heteroatom zeolites are introduced, including the direct synthesis and postsynthesis routes; then, the spectroscopic techniques to identify the existing states of heteroatom sites and the corresponding physiochemical properties are shown and compared; finally, the catalytic applications of multifunctional heteroatom zeolites in various chemical reactions, especially in one-step tandem reactions, are discussed.

关键词： zeolite multifunctional active sites heteroatom characterization catalysis

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Hierarchically porous zeolites synthesized with carbon materials as templates

《化学科学与工程前沿（英文）》 2021年第15卷第6期页码 1444-1461 doi: 10.1007/s11705-021-2090-6

摘要： Hierarchically porous zeolites are promising candidates in catalytic conversion of relatively bulky molecules, and their syntheses have attracted significant attention. From both industrial and scientific perspectives, different carbon materials have been widely employed as hard templates for the preparation of hierarchically porous zeolites during the past two decades. In this review, the progress in synthetic strategies using carbon materials as templates is comprehensively summarized. Depending on the affinity between the carbon templates and zeolite precursors, the substantial strategies for synthesizing hierarchical zeolites are introduced in direct templates and indirect templates. Direct templates methods, by which the carbon materials are directly mixed with precursors gel as hard templates, are first reviewed. Then, we discuss the indirect templates method (crystallization of carbon-silica composites), by which the carbon is produced by in situ pyrolysis of organic-inorganic precursors. In addition, the technique of encapsulating metal species into zeolites crystals with the assistance of carbon templates is also discussed. In the conclusion part, the factors affecting the synthesis of carbon-templated hierarchically porous zeolites are remarked. This review is expected to attract interest in the synthesis strategies of hierarchically porous zeolites, especially cost-effective and large-scale production methodologies, which are essential to the industrial application of hierarchical zeolites.

关键词： hierarchical zeolites carbon materials direct templates indirect templates carbon-silica composites

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High-precision diffusion measurement of ethane and propane over SAPO-34 zeolites for methanol-to-olefin

Dali Cai, Yu Cui, Zhao Jia, Yao Wang, Fei Wei

《化学科学与工程前沿（英文）》 2018年第12卷第1期页码 77-82 doi: 10.1007/s11705-017-1684-5

摘要： The methanol-to-olefin (MTO) process has attracted much attention and many problems including lifetime and selectivity of light olefins have all been connected to the diffusion problems in zeolite crystals. However, a quantitative study of diffusion problems in SAPO-34 zeolites is lacking. In this paper, we performed a high-precision diffusion measurement of the diffusion behavior of ethane and propane, which represent ethylene and propylene respectively, over SAPO-34. The diffusions of ethane and propane over fresh and coked SAPO-34 zeolites with different crystal sizes were carefully studied. Ethane and propane show different diffusion behavior in SAPO-34. The diffusion of ethane is almost not influenced by the crystal size and coke percentage, whereas that of propane is strongly affected. A slower diffusion velocity was observed in bigger crystals, and the diffusion velocity decline significantly with the coke percentage increasing. The diffusion coefficient was calculated with both the internal and surface diffusion models, and the results show that the surface diffusion plays a key role in the diffusion process of both ethane and propane. We believe that this work would be helpful for understanding the diffusion of different molecules in SAPO-34 zeolites, and may lay the foundation of MTO research.

关键词： diffusion measurement methanol-to-olefin process

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Mesoporous zeolites for biofuel upgrading and glycerol conversion

Jian Zhang, Liang Wang, Yanyan Ji, Fang Chen, Feng-Shou Xiao

《化学科学与工程前沿（英文）》 2018年第12卷第1期页码 132-144 doi: 10.1007/s11705-017-1681-8

摘要： With the recent emphasis and development of sustainable chemistry, the conversion of biomass feedstocks into alternative fuels and fine chemicals over various heterogeneous catalysts has received much attention. In particular, owing to their uniform micropores, strong acidity, and stable and rigid frameworks, zeolites as catalysts or co-catalysts have exhibited excellent catalytic performances in many reactions, including hydrodesulfurization, Fischer-Tropsch synthesis, and hydrodeoxygenation. However, the relatively small sizes of the zeolite micropores strongly limit the conversion of bulky biomolecules. To overcome this issue, mesoporous zeolites with pores larger than those of biomolecules have been synthesized. As expected, these mesoporous zeolites have outperformed conventional zeolites with improved activities, better selectivities, and longer catalyst lives for the upgrading of pyrolysis oils, the transformation of lipids into biofuels, and the conversion of glycerol into acrolein and aromatic compounds. This review briefly summarizes recent works on the rational synthesis of mesoporous zeolites and their superior catalytic properties in biomass conversion.

关键词： biomass conversion mesoporous zeolite sustainable chemistry

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Crystalline porous materials: from zeolites to metal-organic frameworks (MOFs)

Zaiku Xie, Bao-Lian Su

《化学科学与工程前沿（英文）》 2020年第14卷第2期页码 123-126 doi: 10.1007/s11705-020-1921-1

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Anion-exchange membrane direct ethanol fuel cells: Status and perspective

Zhao, Y.S. Li, S.Y. Shen

《能源前沿（英文）》 2010年第4卷第4期页码 443-458 doi: 10.1007/s11708-010-0127-5

摘要： Direct ethanol fuel cells (DEFCs) are a promising carbon-neutral and sustainable power source for portable, mobile, and stationary applications. However, conventional DEFCs that use acid proton-exchange membranes (typically Nafion type) and platinum-based catalysts exhibit low performance (i.e., the state-of-the-art peak power density is 79.5 mW/cm at 90°C). Anion-exchange membrane (AEM) DEFCs that use low-cost AEM and non-platinum catalysts have recently been demonstrated to yield a much better performance (i.e., the state-of-the-art peak power density is 160 mW/cm at 80°C). This paper provides a comprehensive review of past research on the development of AEM DEFCs, including the aspects of catalysts, AEMs, and single-cell design and performance. Current and future research challenges are identified along with potential strategies to overcome them.

关键词： fuel cell direct ethanol fuel cells anion-exchange membrane ethanol oxidation reaction oxygen reduction reaction cell performance

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Mesoporous zeolites as efficient catalysts for oil refining and natural gas conversion

Jie ZHU, Xiangju MENG, Fengshou XIAO

《化学科学与工程前沿（英文）》 2013年第7卷第2期页码 233-248 doi: 10.1007/s11705-013-1329-2

摘要： Zeolites have been regarded as one of the most important catalysts in petrochemical industry due to their excellent catalytic performance. However, the sole micropores in zeolites severely limit their applications in oil refining and natural gas conversion. To solve the problem, mesoporous zeolites have been prepared by introducing mesopores into the zeolite crystals in recent years, and thus have the advantages of both mesostructured materials (fast diffusion and accessible for bulky molecules) and microporous zeolite crystals (strong acidity and high hydrothermal stability). In this review, after giving a brief introduction to preparation, structure, and characterization of mesoporous zeolites, we systematically summarize catalytic applications of these mesoporous zeolites as efficient catalysts in oil refining and natural gas conversion including catalytic cracking of heavy oil, alkylation, isomerization, hydrogenation, hydrodesulfurization, methane dehydroaromatization, methanol dehydration to dimethyl ether, methanol to olefins, and methanol to hydrocarbons.

关键词： mesoporous zeolite catalysis oil refining natural gas conversion

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Fabrication of titanosilicate pillared MFI zeolites with tailored catalytic activity

Baoyu Liu, Qiaowen Mu, Jiajin Huang, Wei Tan, Jing Xiao

《化学科学与工程前沿（英文）》 2020年第14卷第5期页码 772-782 doi: 10.1007/s11705-019-1859-3

摘要： Titanosilicate pillared MFI zeolite nanosheets were successfully synthesized by infiltrating the mixed tetraethyl orthosilicate (TEOS)/tetrabutyl orthotitanate (TBOT) solvent into the gallery space between adjacent MFI zeolite layers. The obtained zeolite catalysts were characterized using powder X-ray diffraction, N adsorption/desorption isotherms, scanning electron microscopy, transmission electron microscopy, ultraviolet–visible spectroscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy techniques. The H O oxidation of dibenzothiophene (DBT) was used to evaluate the catalytic performance of the obtained titanosilicate pillared MFI zeolites. The conversion of DBT and selectivity of dibenzothiophene sulfone (DBTS) were most affected by the textural properties of the zeolites. This was attributed to the DBT and DBTS molecules being larger than micropores of the MFI zeolites. The conversion of DBT and yield of DBTS could be systematically tailored by tuning the molar ratio of the TEOS/TBOT solvent. These results implied that a balance between the meso- and microporosity of zeolites and tetrahedrally coordinated Ti(IV) active sites of titanosilicate pillars can be achieved for the preparation of desired catalysts during the oxidation of bulk S compounds.

关键词： MFI zeolite catalysis nanosheets fabrication

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The effect of hierarchical single-crystal ZSM-5 zeolites with different Si/Al ratios on its pore structure

Yuexin Hou, Xiaoyun Li, Minghui Sun, Chaofan Li, Syed ul Hasnain Bakhtiar, Kunhao Lei, Shen Yu, Zhao Wang, Zhiyi Hu, Lihua Chen, Bao-Lian Su

《化学科学与工程前沿（英文）》 2021年第15卷第2期页码 269-278 doi: 10.1007/s11705-020-1948-3

摘要： Hierarchical single-crystal ZSM-5 zeolites with different Si/Al ratios (Hier-ZSM-5- , where = 50, 100, 150 and 200) were synthesized using an ordered mesoporous carbon-silica composite as hard template. Hier-ZSM-5- exhibits improved mass transport properties, excellent mechanical and hydrothermal stability, and higher catalytic activity than commercial bulk zeolites in the benzyl alcohol self-etherification reaction. Results show that a decrease in the Si/Al ratio in hierarchical single-crystal ZSM-5 zeolites leads to a significant increase in the acidity and the density of micropores, which increases the final catalytic conversion. The effect of porous hierarchy on the diffusion of active sites and the final catalytic activity was also studied by comparing the catalytic conversion after selectively designed poisoned acid sites. These poisoned Hier-ZSM-5- shows much higher catalytic conversion than the poisoned commercial ZSM-5 zeolite, which indicates that the numerous intracrystalline mesopores significantly reduce the diffusion path of the reactant, leading to the faster diffusion inside the zeolite to contact with the acid sites in the micropores predominating in ZSM-5 zeolites. This study can be extended to develop a series of hierarchical single-crystal zeolites with expected catalytic performance.

关键词： hierarchical zeolites single crystalline interconnected pores improved diffusion performance benzyl alcohol self-etherification reaction

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A pre-compensation method of the systematic contouring error for repetitive command paths

ZHANG,Y. H. CHEN,Y. P. CHEN

《机械工程前沿（英文）》 2015年第10卷第4期页码 367-372 doi: 10.1007/s11465-015-0367-5

摘要：

For a repetitive command path, pre-compensating the contouring error by modifying the command path is practical. To obtain the pre-compensation value with better accuracy, this paper proposes the use of a back propagation neural network to extract the function of systematic contouring errors. Furthermore, by using the extracted function, the contouring error can be easily pre-compensated. The experiment results verify that the proposed compensation method can effectively reduce contouring errors.

关键词： contouring error pre-compensation motion control system back propagation (BP) neural network

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Layer-like FAU-type zeolites: A comparative view on different preparation routes

Bastian Reiprich, Tobias Weissenberger, Wilhelm Schwieger, Alexandra Inayat

《化学科学与工程前沿（英文）》 2020年第14卷第2期页码 127-142 doi: 10.1007/s11705-019-1883-3

摘要： The creation of intergrown layer-like zeolite crystals is one route to form hierarchical zeolites. Faujasite-type (FAU-type) zeolites are among the industrially most important zeolites and the implementation of hierarchical porosity is a promising way to optimise their catalytic and adsorptive performance. After a short general survey into routes for the preparation of hierarchical pore systems in FAU, we will review the currently existing strategies for the synthesis of FAU with layer-like morphology. Those strategies are mainly based on the presence of morphology modifying agents in the synthesis mixture. However, a very recent approach is the synthesis of layer-like FAU-type zeolite crystals assembled in an intergrown manner in the absence of such additives, just by finely adjusting the crystallization temperature. This additive-free preparation route for layer-like FAU, which appears very attractive from an ecological as well as economic point of view, is highlighted in this review. Concluding, a comparison, including powder X-ray diffraction, scanning and transmission electron microscopy, nitrogen physisorption and elemental analysis, between conventional FAU and three layer-like FAU obtained by different synthesis routes was carried out to show the structural, morphological and textural differences and similarities of these materials.

关键词： FAU hierarchical zeolite layer-like morphology

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Research on the valveless piezoelectric pump with Y-shape pipes

ZHANG Jianhui, LU Jizhuang, XIA Qixiao

《机械工程前沿（英文）》 2007年第2卷第2期页码 144-151 doi: 10.1007/s11465-007-0024-8

摘要： A piezoelectric pump with its Y-shape elements is presented. Two Y-shape pipes are fixed outside the chamber serving as an inlet and outlet, with the chamber and a piezoelectric vibrator being the actor. The pump has the potential to be miniaturized and integrated. Eddies occurring in the Y-shape elements are smaller, which is beneficial for the transport of living cells or long-link macromolecules. In this paper, the structure of the pump is first presented. Then, the equations on the change in volume and the mean pressure in the chamber are established, as well as the relation between the flow rate and the working frequency of the piezoelectric vibrator. Moreover, the relation between the mean pressure in the chamber and the working frequency of the piezoelectric vibrator is established. Finally, experiments are carried out to test the characteristics of the pump and to verify the correction of the theory on this pump.

关键词： chamber serving beneficial working frequency long-link correction