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Deactivation Effect Caused by Catalyst-Cocatalyst Pre-contact in Propylene Polymerization with MgCl2-supported Ziegler-Natta Catalyst

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Chinese Journal of Polymer Science 2019年第10期37卷 1023-1030,I0005页

作者： Zhen Zhang Bai-Yu Jiang Biao Zhang Zhi-Sheng Fu Zhi-Qiang Fan Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University

Propylene slurry polymerization with a MgCl2-supported Ziegler-Natta catalyst containing internal electron donor was conducted after different durations of pre-contact of the catalyst with triethylaluminum cocatalyst. The number of active centers([C*]/[Ti])was determined by quenching the polymerization with 2-thiophenecarbonyl chloride and measuring sulfur content in the polymer. The pre-contact treatment caused selective deactivation of a part of active centers with low stereoselectivity and much lower activity in the initial stage of polymerization as compared with the polymerization run without the pre-contact stage. The active center concentration and polymerization activity decreased with prolonging of the pre-contact stage. The proportion of stereoselective active centers was increased by prolonging the pre-contact stage, so the isotacticity of produced polypropylene was enhanced. Release of active centers through catalyst particle fragmentation was significantly retarded, and the polymerization rate curve changed from decay type to induction type by the precontact treatment. In the induction period both non-stereoselective and stereoselective active centers were released and activated, resulting in gradual reduction of the polymer’s isotacticity in the first 5-10 min of polymerization. Selective deactivation of non-stereoselective active centers also took place in propylene polymerization using the catalyst without pre-contacting with the cocatalyst. In this case, the polymerization rate decayed with time after a short induction period of 2-5 min. Over reduction of the active center precursors with low stereoselectivity by triethylaluminum was considered as the reason for their deactivation during the pre-contact or the polymerization processes.

关键词： Propylene Polymerization supported Ziegler-Natta catalyst Cocatalyst Pre-contact

Electrochemical property of multi-layer anode supported solid oxide fuel cell fabricated through sequential tape-casting and co-firing

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Journal of Materials Science & Technology 2019年第4期35卷 695-701页

作者： Xiaoyang Chen Weijie Ni Xiaojia Du Zaihong Sun Tenglong Zhu Qin Zhong Minfang Han School of Chemical Engineering Nanjing University of Science and Technology Suzhou Huatsing Jingkun New Energy Technology Co. Ltd. State Key Laboratory of Power Systems Department of Energy and Power EngineeringTsinghua University

In this work, a multi-layer anode supported solid oxide fuel cell(SOFC) is designed and successfully prepared through sequential tape casting and co-firing. The single cell is consisted of NiO-3 YSZ(3 YSZ: 3 mol.% yttria doped zirconia) anode support, NiO-8 YSZ(8 YSZ: 8 mol.% yttria stabilized zirconia) anode functional layer, dense 8 YSZ electrolyte layer, and porous 3 YSZ cathode scaffold layer with infiltrated La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) cathode. The clear interfaces and good contacts between each layer, without element inter-diffusion being observed, suggest that this sequential tape casting and co-firing is a feasible and successful route for anode supported single cell fabrication. This cell exhibits remarkable high open circuit voltage of 1.097 V at 800?C under room temperature humidified hydrogen, with highly dense and gastight electrolyte layer. It provides a power density of 360 mW/cm^2 under operation voltage of0.75 V at 800?C and a stable operation of ～110 h at 750?C under current density of-300 mA/cm^2. Furthermore, this cell also presents encouraging electrochemical responses under various anode hydrogen partial pressures and maintains high power output at low fuel concentrations.

关键词： Anode supported SOFC Sequential tape casting Co-firing Cathode infiltration

Vibration Analysis of a Simply supported Beam Traversed by Uniform Distributed Moving Load

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上海交通大学学报 2004年第z2期38卷 155-160页

作者： Yu YANG Nian-guan TENG Yian-feng TENG School of Civil Engineering and Mechanics Shanghai Jiaotong Univ. Shanghai200030 China School of Civil Engineering and Mechanics Shanghai Jiaotong Univ. Shanghai200030 China School of Civil Engineering and Mechanics Shanghai Jiaotong Univ. Shanghai200030 China

Considering the engineering background of some transportation system like maglev, vertical vibration of the simply supported beam is investigated. The length of the vehicle is assumed to be longer than the beam span. The model of moving distributed load with constant speed is established .The beam can be taken as Euler-Bernoulli beam model and the right side of the control equation is simplified by using a moving status function. Duhamel integral and mode superposition method is used to solve the dynamic behavior of the beam. In this aspect deflection and acceleration are included. The results of different parameters such as the span of beam, velocity of load and ratio vehicle-Beam masses are compared. All results show that the dynamic response of the beam is tied up with these factors: the frequency of the beam, the moving frequency of the load and the ratio of vehicle-beam mass.

关键词： simply supported seam vertical vibration moving load

AgBF_4/[emim][BF_4] supported ionic liquid membrane for carbon monoxide/nitrogen separation

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Journal of Energy Chemistry 2019年第2期28卷 31-39页

作者： Shichao Feng Yuanyuan Wu Jianquan Luo Yinhua Wan State Key Laboratory of Biochemical Engineering Institute of Process EngineeringChinese Academy of Sciences

In this paper,AgBF_4/[emim][BF_4] supported ionic liquid membranes(SILMs) were prepared successfully for CO/N_2 separation using nitrogen pressure immobilization *** incorporation of AgBF_4 could decrease membrane weight loss,improve the pressure-resistant ability,and keep the critical pressure(0.45 MPa) of the *** high viscosity and undissolved Ag BF_4 solids in membrane liquid would disturb gas molecular transport through membrane and give rise to the gas transport ***,the gas permeability decreased remarkably with increasing AgBF_4 carrier content in the *** the molar ratio of AgBF_4 to [emim][BF_4] increased from 0:1 to 0.3:1,the CO/N_2 selectivity of the SILMs showed a great increase from ～1 to ～9 at 20 °C and 0.4 MPa,suggesting that AgBF_4 was an effective carrier for CO facilitated *** permeabilities of N_2 and CO increased at higher transmembrane pressure,indicating that molecular transport would dominate the transport process at high *** temperature-dependent gas permeability followed the Arrhenius ***,the differences between the activation energies of CO and N_2 became larger after introducing AgBF_4,resulting in more obvious decrease in the CO/N_2 selectivity at higher operating temperature.

关键词： supported ionic liquid membranes [emim][BF4] AgBF4 Carbon monoxide separation

Preparation of porous semi-IPN temperature-sensitive hydrogel-supported nZVI and its application in the reduction of nitrophenol

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Journal of Environmental Sciences 2019年第8期31卷 93-102页

作者： Lixia Li Ruiwei Wang Xiaodong Xing Wenqiang Qu Shutong Chen Yunlong Zhang School of Environment and safety engineering Jiangsu University School of Chemical Engineering Nanjing University of Science and Technology

Nanoscale zero-valent iron(n ZVI) particles supported on a porous, semi-interpenetrating(semi-IPN), temperature-sensitive composite hydrogel(PNIPAm-PHEMA). n ZVI@PNIPAmPHEMA, was successfully synthesized and characterized by FT-IR, SEM, EDS, XRD and the weighing method. The loading of nZVI was 0.1548 ± 0.0015 g/g and the particle size was30–100 nm. NZVI was uniformly dispersed on the pore walls inside the *** of the well-dispersed n ZVI, the highly porous structure, and the synergistic effect of PNIPAm-PHEMA, nZVI@PNIPAm-PHEMA showed excellent reductive activity and wide p H applicability. 95% of 4-NP in 100 m L of 400 mg/L 4-NP solution with initial p H 3.0–9.0 could be completely reduced into 4-AP by about 0.0548 g of fresh supported n ZVI at 18–25 °C under stirring(110 r/min) within 45 min reaction time. A greater than 99% 4-NP degradation ratio was obtained when the initial p H was 5.0–9.0. The reduction of 4-NP by nZVI@PNIPAm-PHEMA was in agreement with the pseudo-first-order kinetics model with Kobsvalues of 0.0885–0.101 ***@PNIPAm-PHEMA was able to be recycled, and about 85% degradation ratio of 4-NP was obtained after its sixth reuse cycle. According to the temperature sensitivity of PNIPAmPHEMA, n ZVI@PNIPAm-PHEMA exhibited very good storage stability, and about 88.9%degradation ratio of 4-NP was obtained after its storage for 30 days. The hybrid reducer was highly efficient for the reduction of 2-NP, 3-NP, 2-chloro-4-nitrophenol and 2-chloro-4-nitrophenol. Our results suggest that PNIPAm-PHEMA could be a good potential carrier, with n ZVI@PNIPAm-PHEMA having potential value in the application of reductive degradation of nitrophenol pollutants.

关键词： Porous semi-IPN temperature sensitive hydrogel supported nanoscale zero-valent iron Reductive degradation Nitrophenol Storage stability

Platinum in-situ catalytic oleylamine combustion removal process for carbon supported platinum nanoparticles

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Journal of Energy Chemistry 2020年第2期29卷 120-125页

作者： Qingying Zhao Huanqiao Li Xiaoming Zhang Shansheng Yu Suli Wang Gongquan Sun Division of Fuel Cells and Battery Dalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina2 University of Chinese Academy of Sciences Beijing 100049China Department of Materials Science Jilin UniversityChangchun 130012JilinChina

Colloidal synthesis method such as oleylamine(OAm)-stabilized process is of great interest for obtaining uniform and highly dispersed platinum nanoparticle catalysts, yet the ligand may unavoidably inhibit their electro-catalytic performance. Thus, fully removing these ligands is critical to activate catalyst surface. Previous research of OAm removal process pointed that thermal annealing was the most effective way in comparison with other methods such as chemical washing, UV–Ozone irradiation and cyclic voltammetry sweeping, but generally resulting in undesired growth of platinum nanoparticle. Few studies concerning a more efficient ligand removal process have been published yet. In this work we proposed a platinum in-situ catalytic OAm combustion strategy to elucidate the removal mechanism of OAm ligands in thermal process and the key experimental parameters were also optimized. In addition, heat flow signal based on differential scanning calorimetry(DSC) measurement as a sensitive indicator, is suggested to reveal the ligand removal efficiency, which is much more reliable than the traditional *** comparison with commercial Pt/C sample, such a surface clean Pt/C electrocatalyst has shown an enhanced specific activity for oxygen reduction reaction. Our removal strategy and the evaluation method are highly instructive to efficient removal of different organic ligands.

关键词： Ligand removal Platinum in-situ catalytic OAm combustion Carbon supported platinum electro-catalyst ORR

Numerical analysis of pile lateral behavior of pile supported embankment

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Journal of Central South University 2008年第S2期15卷 87-92页

作者：荆志东刘力郑刚姜岩 School of Civil Engineering Southwest Jiaotong University The 3rd Railway Survey & Design Institute Group Corporation Department of Civil Engineering Tianjin University

A finite difference numerical method was adopted to evaluate the pile lateral behavior of pile supported embankment. A published case history was used to verify the proposed methodology. By simulating the case history, the determination of parameters needed were verified. Then three embankments constructed on different ground conditions with different soil-pile relative stiffnesses were analyzed to study pile lateral behaviors including pile deflection and bending moment. The results show that pile deflections and bending moments induced by soil lateral deformation and embankment vertical load are different for piles at different positions under the same embankment. The relative stiffness between pile and soil affected by the properties of different reinforcing piles such as concrete pile and deep mixing method pile exert important effects on the pile lateral behavior and the pile's failure modes. Consequently, it is necessary to consider the different piles lateral behaviors and possible failure modes at different positions and the different piles proprieties with different reinforcing methods in the embankment stability analysis.

关键词： pile supported embankment stability analysis lateral soil deformation soil-pile interaction three-dimensional analysis

Metal-support interaction controlled migration and coalescence of supported particles

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Science China(Technological Sciences) 2019年第5期62卷 762-772页

作者： HU SuLei LI Wei-Xue Department of Chemical Physics School of Chemistry and Materials ScienceiCHeMCAS Excellence Center for NanoscienceUniversity of Science and Technology of ChinaHefei 230026China Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China

The particle migration and coalescence(PMC) kinetics of a supported metal are the main deactivation mechanisms restricting the successful industrialization of nanoparticles, but the theoretical insights regarding these kinetics are lacking. One key issue is the lack of a physical model to predict the effects of metal-support interaction(MSI) on PMC kinetics. In this paper, we report a theoretical study of PMC kinetics and their dependence on MSI. A new particle diffusion model is proposed based on the surface premelting hypothesis that considers the contact angle of a hemispherical particle on the support. Enhanced MSI suppresses PMC by increasing the radius of curvature and the interfacial adhesion energy, even though the accompanying reduction in the geometry factor partially promotes PMC kinetics. The increased surface energy increases the chemical potential of the atoms in the particle, which is conducive to PMC; an increased surface energy also results in enhanced MSI, which suppresses PMC. The competition between these two contradictory effects leads to a critical contact angle where the surface energy has no influence on the diffusion and resulting PMC kinetics. The proposed diffusion theory mode lincluding the effects of the support and the corresponding kinetic simulations, shed light onto the support-dependence of PMC kinetics and provide a foundation for further optimization and design of supported particles with better stability.

关键词： particle migration and coalescence metal-support interaction supported particles diffusion coefficient Smoluchowski

Non-phosgene synthesis of hexamethylene-1,6-diisocyanate from thermal decomposition of hexamethylene-1,6-dicarbamate over Zn–Co bimetallic supported ZSM-5 catalyst

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Chinese Journal of Chemical Engineering 2019年第3期27卷 549-555页

作者： Yan Cao Yafang Chi Ammar Muhammad Peng He liguo Wang Huiquan Li CAS Key Laboratory of Green Process and Engineering Institute of Process Engineering Chinese Academy of Sciences National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology Institute of Process Engineering Chinese Academy of Sciences University of Chinese Academy of Sciences

A non-phosgene route for the synthesis of hexamethylene-1,6-diisocyanate(HDI) was developed via catalytic decomposition of hexamethylene-1,6-dicarbamate(HDC) over Zn–Co bi-metallic supported ZSM-5 *** catalyst was characterized by FTIR and XRD analyses. Three solvents dioctyl sebacate(DOS), dibutyl sebacate(DBS) and 1-butyl-3-methylimidazolium tetrafluoroborate(BMIMBF_4) were investigated and compared; DOS gave better performance. The catalytic performances for thermal decomposition of HDC to HDI using DOS as solvent were then investigated, and the results showed that, under the optimized reaction conditions, i.e.,10 wt%concentration of HDC in DOS, 250 °C temperature, 60 min reaction time, 83.8% yield of HDI had been achieved over Zn–Co/ZSM-5. Decomposition of the intermediate hexamethylene-1-carbamate-6-isocyanate(HMI) over Zn–Co/ZSM-5 in DOS solvent was further studied and the results indicated that yield of HDI from HMI reached to 69.6%(98.6% HDI selectively) at 270 °C, which further increased the yield of the total HDI(HDI_(tol)) to as high as 95.0%. Recycling of catalyst showed that HDI and HMI yield slightly decreased, and by-product yield increased after the catalyst was reused for 4 times. At last possible reaction mechanism was proposed.

关键词： Non-phosgene Thermal decomposition Hexamethylene-1,6-diisocyanate Hexamethylene-1,6-dicarbamate Bimetallic supported ZSM-5 catalyst