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Synthesis of spherical nano-ZSM-5 zeolite with intergranular mesoporous for alkylation of ethylbenzene with ethanol to produce m-diethylbenzene

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Chinese Journal of Chemical Engineering 2024年第3期67卷 298-309页

作者： Siyue Wang Jinhong Li Qingxin Xu Shengjie Song Yu'ni Jiang lidong chen Xin Shi Weiguo cheng Faculty of Chemistry and Chemical Engineering Liaoning Normal UniversityDalian 110629China Beijing Key Laboratory of Ionic Liquids Clean Process Key Laboratory of Green Process and EngineeringInstitute of Process EngineeringChinese Academy of SciencesBeijing 100190China

Catalytic synthesis of m-diethylbenzene(m-DEB)through alkylation of ethylbenzene(EB)may be a promising alternative route in comparison with traditional rectification of mixed DEB,for which the top priority is to develop efficient and stable heterogeneous catalysts.Here,the spherical nano-ZSM-5 zeolite with abundant intergranular mesoporous is synthesized by the seed-mediated growth method for alkylation of EB with ethanol to produce m-DEB.The results show that the spherical nano-ZSM-5 zeolite exhibits better stability and higher alkylation activity at a lower temperature than those of commercial micropore ZSM-5.And then,the spherical nano-ZSM-5 is further modified by La_(2)O_(3) through acid treatment followed by immersion method.The acid treatment causes nano-ZSM-5 to exhibit the increased pore size but decreased the acid sites,and subsequent La_(2)O_(3) loading reintroduces the weak acid sites.As a result,the HNO_(3)-La_(2)O_(3)-modified catalyst exhibits a slight increase in EB conversion and DEB yield in comparison with unmodified one,and meanwhile,it still maintains high m-DEB selectivity.The catalyst after acid treatment achieves higher catalytic stability besides maintaining the high alkylation activity of EB with ethanol.The present study on the spherical nano-HZSM-5 zeolite and its modification catalyst with excellent alkylation ability provides new insights into the production of mDEB.

关键词： Zeolite Modification Alkylation reaction m-diethylbenzene Catalyst Fixed-bed

Doping-induced charge transfer in conductive polymers

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Chinese Chemical Letters 2024年第1期35卷 45-51页

作者： Siyi Luo Zhen Xu Fei Zhong Hui Li lidong chen State Key Laboratory of High Performance Ceramics and Superfine Microstructures Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

Molecular doping has become a widely used method to modulate the electric performance of organic semiconductors(OSC).Highly effective charge transfer during molecular doping is desired to achieve ideal electrical conductivity.Two types of charge transfer mechanisms are widely accepted in molecular doping process:integer charge transfer(ICT)and charge transfer complex(CTC).In this review,fundamental principles of two mechanisms are revisited and the characterization methods are depicted.The key points for the formation of two mechanisms are highlighted from aspects of molecular structure and process engineering.Then,the strategies to improve the proportion of ICT are discussed.Finally,the challenges and perspectives for future developments in the molecular doping of polymer semiconductors are provided.

关键词： Molecular doping Charge transfer Integer charge transfer Charge transfer complex Conjugated polymer

Energy-Efficient Traffic Offloading for RSMA-Based Hybrid Satellite Terrestrial Networks with Deep Reinforcement Learning

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China Communications 2024年第2期21卷 49-58页

作者： Qingmiao Zhang lidong Zhu Yanyan chen Shan Jiang National Key Laboratory of Science and Technology on Communications University of Electronic Science and Technology of ChinaChengdu 611731China The Higher Educational Key Laboratory for Flexible Manufacturing Equipment Integration of Fujian Province Xiamen Institute of TechnologyXiamen 361021China China Mobile(Jiangxi)Communications Group Co. LtdYichun 336000China

As the demands of massive connections and vast coverage rapidly grow in the next wireless communication networks, rate splitting multiple access(RSMA) is considered to be the new promising access scheme since it can provide higher efficiency with limited spectrum resources. In this paper, combining spectrum splitting with rate splitting, we propose to allocate resources with traffic offloading in hybrid satellite terrestrial networks. A novel deep reinforcement learning method is adopted to solve this challenging non-convex problem. However, the neverending learning process could prohibit its practical implementation. Therefore, we introduce the switch mechanism to avoid unnecessary learning. Additionally, the QoS constraint in the scheme can rule out unsuccessful transmission. The simulation results validates the energy efficiency performance and the convergence speed of the proposed algorithm.

关键词： deep reinforcement learning energy efficiency hybrid satellite terrestrial networks rate splitting multiple access traffic offloading

High-temperature oxidation mechanism of ZrCoSb-based half-Heusler thermoelectric compounds

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Journal of Materials Science & Technology 2023年第17期148卷 242-249页

作者： Jinyu Gu Lei Wang Qingfeng Song Chao Wang Xugui Xia Jincheng Liao Yi-Yang Sun lidong chen Shengqiang Bai State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

ZrCoSb-based half-Heusler(HH)compounds are among the most promising thermoelectric(TE)materials for high-temperature power generation.Oxidation resistance is one of the key issues for realizing the practical application of TE materials for long-term service in the ambient working environment.In this work,the oxidation behavior of Zr_(0.5)Hf_(0.5)CoSb_(0.8)Sn_(0.2)(ZHCSS)half-Heusler is systematically studied in the service temperature range from 873 to 1073 K.It is revealed that three typical layers of oxidation products tend to form on the surface of HH sample,namely,the dense oxide layer(DOL)composed of(Zr,Hf)O_(2) and CoSb,the alternate oxide layer(AOL)composed of repeated(Zr,Hf)O_(2) and CoSb_(2)O_(6)/Co_(3)O_(4),and the CoSb layer between the DOL and AOL.The mass gain during oxidation is mainly caused by the rapid growth of AOL,which is controlled by the outward diffusion of Zr/Hf and the inward diffusion of oxygen.The formation of a continuous CoSb layer and DOL is found beneficial to block the outward diffusion of Zr/Hf.Based on the analysis of the dominant factors on the outward and inward diffusions as well as the reaction activation energy,a simple approach is proposed to improve the oxidation resistance of Zr_(0.5)Hf_(0.5)CoSb_(0.8)Sn_(0.2)by pre-oxidizing the sample in low oxygen pressure to form the dense(Zr,Hf)O_(2) and CoSb layers as oxidation protecting and/or diffusion blocking layers.The oxidation test shows the effectiveness of such pre-oxidation on the formation and growth of the AOL and therefore on improving the service stability of Zr_(0.5)Hf_(0.5)CoSb_(0.8)Sn_(0.2)at high temperatures in the air.

关键词： Thermoelectric Half-Heusler compounds Oxidation mechanism

Phase-modulated mechanical and thermoelectric properties of Ag_(2)S_(1-x)Te_(x)ductile semiconductors

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Journal of Materiomics 2022年第3期8卷 656-661页

作者： Liming Peng Shiqi Yang Tian-Ran Wei Pengfei Qiu Jiong Yang Zhen Zhang Xun Shi lidong chen State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai200050China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing100049China State Key Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai200240China School of Chemistry and Materials Science Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou310024China Materials Genome Institute Shanghai UniversityShanghai200444China Division of Solid-State Electronics Department of Electrical EngineeringUppsala University75237UppsalaSweden

By virtue of the excellent plasticity and tunable transport properties,Ag_(2)S-based materials demonstrate an intriguing prospect for flexible or hetero-shaped thermoelectric applications.Among them,Ag_(2)S_(1-x)Te_(x)exhibits rich and interesting variations in crystal structure,mechanical and thermoelectric transport properties.However,Te alloying obviously introduces extremely large order-disorder distributions of cations and anions,leading to quite complicated crystal structures and thermoelectric properties.Detailed composition-structure-performance correlation of Ag_(2)S_(1-x)Te_(x)still remains to be established.In this work,we designed and prepared a series of Ag_(2)S_(1-x)Te_(x)(x=0-0.3)materials with low Te content.We discovered that the monoclinic-to-cubic phase transition occurs around x=0.16 at room temperature.Te alloying plays a similar role as heating in facilitating this monoclinic-to-cubic phase transition,which is analyzed based on the thermodynamic principles.Compared with the monoclinic counterparts,the cubic-structured phases are more ductile and softer in mechanical properties.In addition,the cubic phases show a degenerately semiconducting behavior with higher thermoelectric performance.A maximum zT=0.8 at 600 K and bending strain larger than 20% at room temperature were obtained in Ag_(2)S_(0.7)Te_(0.3).This work provides a useful guidance for designing Ag_(2)S-based alloys with enhanced plasticity and high thermoelectric performance.

关键词： Thermoelectric materials Ag_(2)S-Ag_(2)Te ductile semiconductors Phase transition Mechanical properties Transport properties

High-performance and stable AgSbTe_(2)-based thermoelectric materials for near room temperature applications

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Journal of Materiomics 2022年第6期8卷 1095-1103页

作者： Yi Wu Pengfei Qiu Yuan Yu Yifei Xiong Tingting Deng Oana Cojocaru-Miredin Matthias Wuttig Xun Shi lidong chen State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai200050China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing100049China Institute of Physics(IA) RWTH Aachen UniversityAachen52056Germany School of Chemistry and Materials Science Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou310024China Peter Grünberg InstitutedJARA-Institute Energy-Efficient Information Technology(PGI-10) Forschungszentrum Jülich GmbHJülich52428Germany

AgSbTe_(2)-based ternary chalcogenides show excellent thermoelectric performance at low-and middletemperature ranges,yet their practical applications are greatly limited by their intrinsic poor thermodynamic stability.In this work,we demonstrate that AgSbTe_(2)-based ternary chalcogenides can be stabilized for service below their decomposition threshold.A series of AgxSb_(2-x)Te_(3-x)(x=1.0,0.9,0.8 and 0.7)samples have been prepared by the melt-quenching method.Among them,phase pure Ag0.9Sb1.1Te2.1 is verified by comprehensive structural characterizations from macroscale by X-ray diffraction to microscale by energy-dispersive spectroscopy and then to sub-nanometer scale by atom probe tomography.This composition is further chosen for the stability investigation.The decomposition threshold of Ag_(0.9)Sb_(1.1)Te_(2.1)appears around 473 K.Below this temperature,the chemical compositions and thermoelectric properties are barely changed even after 720 h annealing at 473 K.The figure-of-merit(zT)value of Ag_(0.9)Sb_(1.1)Te_(2.1)below the decomposition threshold is very competitive for real applications even compared with Bi_(2)Te_(3-)based alloys.The average zT of Ag_(0.9)Sb_(1.1)Te_(2.1)at 300e473 K reaches 0.84,which is higher than most other thermoelectric materials in a similar temperature range,promising applications in miniaturized refrigeration and power generation near room temperature.

关键词： stability performance ternary

Rationalizing phonon dispersion for lattice thermal conductivity of solids

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National Science Review 2018年第6期5卷 888-894页

作者： Zhiwei chen Xinyue Zhang Siqi Lin lidong chen Yanzhong Pei Interdisciplinary Materials Research Center School of Materials Science and Engineering Tongji University State Key Lab of High Performance Ceramics & Superfine Microstructures Shanghai Institute of Ceramics Chinese Academy of Sciences

Lattice thermal conductivity(κL) is one of the most fundamental properties of solids. The acoustic–elastic-wave assumption, proposed by Debye(Debye P. Ann Phys 1912; 344: 789–839), has led to linear phonon dispersion being the most common approximation for understanding phonon transport over the past century. Such an assumption does not take into account the effect of a periodic boundary condition on the phonon dispersion, originating from the nature of periodicity on atomic arrangements. Driven by modern demands on the thermal functionality of materials, with κLranging from ultra-low to ultra-high,any deviation from the Debye approximation in real materials becomes more and more significant. This work takes into account the periodic boundary condition, and therefore rationalizes the phonon dispersion to be more realistic. This significantly improves the precision for quickly predicting κLwithout any fitting parameters, as demonstrated in hundreds of materials, and offers a theoretical basis rationalizing κLto be lower than the minimum currently accepted based on the Debye dispersion. This work paves the way for designing solids with expected κLand particularly inspires the advancement of low-κLmaterials for thermal energy applications.

关键词： thermoelectric thermal conductivity minimal thermal conductivity phonon dispersion

Fabrication,Microstructure and Mechanical Properties of TiC/Ti_2AlC/TiAl_3 in situ Composite

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Journal of Materials Science & Technology 2011年第3期27卷 239-244页

作者： Lu Shi Jianfeng Zhang Lianjun Wang Wan Jiang lidong chen State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of Ceramics Chinese Academy of Science Shanghai 200050 China State Key Laboratory for Modification of chemical Fibers and Polymer Materials Donghua University Shanghai 201620 China

This paper described a process for synthesizing a new multiphase TiC/Ti2AlC/TiAl3 composite, in which Ti, A14C3 and graphite powders were utilized as raw materials, and in situ spark plasma sintering-reactive sintering （SPS-RS） methods were involved. The intermediate phases of Ti3Al and TiAl were found during the reactive sintering process and the reactions for the phase＇s formation were proposed. The microstructure and mechanical properties of the composites were investigated. The high-resolution transmission electron microscopy （HRTEM） image of the interface showed that no amorphous phases were detected along the grain boundary. The orientation relationships between the Ti2AIC and the TiC were shown to be （0001）Ti2AlC｜｜（111）TiC and [1210]Ti2AlC｜｜[110]Tic. The average hardness, fracture toughness, Young＇s modulus and bending strength of the composite were 15.1±0.8 GPa, 4.9±0.3 MPa.mU2, 261±13 GPa and 776±18 MPa, respectively. The toughening mechanism was also discussed.

关键词： Ceramic Sintering Mechanical properties Microstructure

自制体外膜肺氧合系统救治危重症患者的装机策略和临床观察

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中华危重病急救医学 2024年第4期36卷 410-414页

作者：陈月钱晓亮豆立冬李建朝河南省人民医院(阜外华中心血管病医院)麻醉与围术期医学科郑州450000 河南省人民医院(阜外华中心血管病医院)体外循环科郑州450000

目的总结危重症患者采用自制体外膜肺氧合(ECMO)系统辅助治疗的策略与方法。方法采用观察性研究方法,选择2020年12月至2021年12月在阜外华中心血管病医院进行ECMO辅助支持的56例心血管危重症患者作为研究对象,根据患者临床情况并结合家... 详细信息

目的总结危重症患者采用自制体外膜肺氧合(ECMO)系统辅助治疗的策略与方法。方法采用观察性研究方法,选择2020年12月至2021年12月在阜外华中心血管病医院进行ECMO辅助支持的56例心血管危重症患者作为研究对象,根据患者临床情况并结合家属意愿选择使用常规ECMO套包(常规组)或自制ECMO套包(自制组)。常规组采用一次性使用ECMO套包进行装机、预充排气等操作;自制组采用心脏手术体外循环中常规使用的一次性耗材(包括离心泵头、膜肺、管道、连接头等)自制ECMO系统,针对患者情况进行个体化的管路型号选择和长短控制。记录两组ECMO系统装机准备时间、辅助时间、辅助方式、总体预充量、ECMO运转2 h后游离血红蛋白(FHb)水平和上机费用,以及置入ECMO后48 h内血流动力学、动脉血气分析和血液指标的变化;同时观察两组患者ECMO辅助治疗过程中ECMO系统相关不良事件发生情况。结果56例患者均纳入最终分析,常规组与自制组各28例,均成功完成ECMO辅助治疗。常规组与自制组ECMO系统装机准备时间、辅助时间、辅助方式、ECMO运转2 h后FHb水平差异均无统计学意义〔装机准备时间(min):13±4比15±5,辅助时间(h):287±34比276±42,静脉-动脉ECMO(例):22比24,静脉-静脉ECMO(例):6比4,ECMO运转2 h后FHb(mg/L):226±67比253±78,均P>0.05〕;但自制组总体预充量和上机费用明显少于常规组〔总体预充量(mL):420±25比650±10,上机费用(万元):3.8±0.4比6.7±0.3,均P<0.01〕。两组患者上机后48 h内血流动力学、动脉血气分析和血液指标均处于相对稳定状态,且两组间大部分指标差异无统计学意义;自制组上机后12、24、48 h血红蛋白(Hb)水平明显高于常规组(g/L:12 h为128.5±23.7比117.5±24.3,24 h为121.3±31.3比109.6±33.2,48 h为118.5±20.1比105.2±25.7,均P<0.05)。两组患者在ECMO辅助治疗过程中均未出现膜肺渗漏、接头脱落、大量溶血等ECMO系统相关不良事件。结论临床针对危重症患者实施ECMO时,可以利用心脏手术体外循环中常规使用的一次性耗材自制ECMO系统进行心肺功能辅助支持,从而节省患者的医疗费用,缓解临床上对一次性ECMO套包的依赖。

关键词：体外膜肺氧合体外循环体外膜肺氧合套包