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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

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

Thermoelectric Transport Properties of R_yFe_3NiSb_(12)(R=Ba,Nd and Yb)

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Journal of Materials Science & Technology 2014年第11期30卷 1134-1140页

作者： Ruiheng Liu Jung Young Cho Jiong Yang Wenqing Zhang lidong chen CAS Key Laboratory for Energy-conversion Materials Shanghai Institute of CeramicsChinese Academy of Sciences Materials and Processes Laboratory GM R&D CenterWarrenMI 48090USA Department of Materials Science & Engineering University of Washington

To evaluate the influence of Ni substitution on electrical transport properties, the thermoelectric transport properties of the p-type skutterudites RyFe3NiSb12 （R = Ba, Nd and Yb） are systematically investigated from 2.5 K to 800 K. By carefully modifying the filling fractions of the three fillers, Ba, Nd and Yb, the carrier concentration is precisely adjusted, which changes proportionally to the nominal value calculated by valence counting rule. The carrier concentration dependences of mobility and Seebeck coefficient represent two band contribution in the valence band, and the optimized carrier concentration for thermoelectric performance is between （5-9） × 10^20 cm^-3. The lattice thermal conductivity of samples filled with rare-earth elements （Nd and Yb） are significantly lower as compared to Ba-filled, due to the lower resonant frequency and partial filling. Compared with Co substitution, Ni substitution tends to close the band gap, which results in heavier bipolar diffusion at high temperature for RyFe3NiSb12. However, due to state, when the carrier concentrations are similar, RyFe3NiSb12 possess higher thermal power and thus higher power factor than RyFe2Co2Sb12 in the lower temperature range. A ZT value of 0.73 is obtained for Yb0.77Fe3NiSb12 at 660 K.

关键词： Thermoelectric Skutterudites Band structure Bipolar diffusion

Crystalline Structure-Dependent Mechanical and Thermoelectric Performance in Ag_(2)Se_(1‐x)S_(x)System

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Research 2020年第1期2020卷 1089-1098页

作者： Jiasheng Liang Pengfei Qiu Yuan Zhu Hui Huang Zhiqiang Gao Zhen Zhang Xun Shi lidong chen 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 Division of Solid-State Electronics Department of Electrical EngineeringUppsala UniversityUppsalaSweden School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China

Self-powered wearable electronics require thermoelectric materials simultaneously with a high dimensionless figure of merit(zT)and good flexibility to convert the heat discharged by the human body into electricity.Ag_(2)(S,Se)-based semiconducting materials can well satisfy these requirements,and thus,they are attracting great attention in thermoelectric society recently.Ag_(2)(S,Se)crystalizes in an orthorhombic structure or monoclinic structure,depending on the detailed S/Se atomic ratio,but the relationship between its crystalline structure and mechanical/thermoelectric performance is still unclear to date.In this study,a series of Ag_(2)Se_(1-x)S_(x)(x=0,0.1,0.2,0.3,0.4,and 0.45)samples were prepared and their mechanical and thermoelectric performance dependence on the crystalline structure was systematically investigated.x=0:3 in the Ag_(2)Se_(1-x)S_(x)system was found to be the transition boundary between orthorhombic and monoclinic structures.Mechanical property measurement shows that the orthorhombic Ag_(2)Se_(1-x)S_(x)samples are brittle while the monoclinic Ag_(2)Se_(1-x)S_(x)samples are ductile and flexible.In addition,the orthorhombic Ag_(2)Se_(1-x)S_(x)samples show better electrical transport performance and higher zT than the monoclinic samples under a comparable carrier concentration,most likely due to their weaker electron-phonon interactions.This study sheds light on the further development of flexible inorganic TE materials.

关键词： ductile crystalline attracting