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Fabrication of N-doped carbon nanobelts from a polypyrrole tube by confined pyrolysis for supercapacitors

Wei Wang, Haijun Lv, Juan Du, Aibing Chen

《化学科学与工程前沿（英文）》 2021年 第15卷 第5期   页码 1312-1321 doi: 10.1007/s11705-020-2033-7

摘要： In this present work, N-doped carbon nanobelts (N-CNBs) were prepared by a confined-pyrolysis approach and the N-CNBs were derived from a polypyrrole (Ppy) tube coated with a compact silica layer. The silica layer provided a confined space for the Ppy pyrolysis, thereby hindering the rapid overflow of pyrolysis gas, which is the activator for the formation of carbonaceous materials. At the same time, the confined environment can activate the carbon shell to create a thin wall and strip the carbon tube into belt morphology. This process of confined pyrolysis realizes self-activation during the pyrolysis of Ppy to obtain the carbon nanobelts without adding any additional activator, which reduces pollution and preparation cost. In addition, this approach is simple to operate and avoids the disadvantages of other methods that consume time and materials. The as-prepared N-CNB shows cross-linked nanobelt morphology and a rich porous structure with a large specific surface area. As supercapacitor electrode materials, the N-CNB can present abundant active sites, and exhibits a specific capacitance of 246 F·g , and excellent ability with 95.44% retention after 10000 cycles. This indicates that the N-CNB is an ideal candidate as a supercapacitor electrode material.

关键词： carbon nanobelts     polypyrrole     N-doped     confined pyrolysis     supercapacitor    

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Ultrafine Fe-modulated Ni nanoparticles embedded within nitrogen-doped carbon from Zr-MOFs-confined conversion

《化学科学与工程前沿（英文）》 2022年 第16卷 第7期   页码 1114-1124 doi: 10.1007/s11705-021-2087-1

摘要： Improvement of the low-cost transition metal electrocatalyst used in sluggish oxygen evolution reaction is a significant but challenging problem. In this study, ultrafine Fe-modulated Ni nanoparticles embedded in a porous Ni-doped carbon matrix were produced by the pyrolysis of zirconium metal-organic-frameworks, in which 2,2′-bipyridine-5,5′-dicarboxylate operating as a ligand can coordinate with Ni2+ and Fe3+. This strategy allows formation of Fe-modulated Ni nanoparticles with a uniform dimension of about 2 nm which can be ascribed to the spatial blocking effect of ZrO2. This unique catalyst displays an efficient oxygen evolution reaction electrocatalytic activity with a low overpotential of 372 mV at 10 mA·cm–2 and a small Tafel slope of 84.4 mV·dec–1 in alkaline media. More importantly, it shows superior durability and structural stability after 43 h in a chronoamperometry test. Meanwhile, it shows excellent cycling stability during 4000 cyclic voltammetry cycles. This research offers a new insight into the construction of uniform nanoscale transition metals and their alloys as highly efficient and durable electrocatalysts.

关键词： metal-organic framework     pyrolysis     ultrafine     Fe-modulated Ni nanoparticles     oxygen evolution reaction    

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Development of deep neural network model to predict the compressive strength of FRCM confined columns

Khuong LE-NGUYEN; Quyen Cao MINH; Afaq AHMAD; Lanh Si HO

《结构与土木工程前沿（英文）》 2022年 第16卷 第10期   页码 1213-1232 doi: 10.1007/s11709-022-0880-7

摘要： The present study describes a reliability analysis of the strength model for predicting concrete columns confinement influence with Fabric-Reinforced Cementitious Matrix (FRCM). through both physical models and Deep Neural Network model (artificial neural network (ANN) with double and triple hidden layers). The database of 330 samples collected for the training model contains many important parameters, i.e., section type (circle or square), corner radius rc, unconfined concrete strength fco, thickness nt, the elastic modulus of fiber Ef , the elastic modulus of mortar Em. The results revealed that the proposed ANN models well predicted the compressive strength of FRCM with high prediction accuracy. The ANN model with double hidden layers (APDL-1) was shown to be the best to predict the compressive strength of FRCM confined columns compared with the ACI design code and five physical models. Furthermore, the results also reveal that the unconfined compressive strength of concrete, type of fiber mesh for FRCM, type of section, and the corner radius ratio, are the most significant input variables in the efficiency of FRCM confinement prediction. The performance of the proposed ANN models (including double and triple hidden layers) had high precision with R higher than 0.93 and RMSE smaller than 0.13, as compared with other models from the literature available.

关键词： FRCM     deep neural networks     confinement effect     strength model     confined concrete    

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Fabrication of bimetallic Cu–Zn adsorbents with high dispersion by using confined space for gas adsorptive

《化学科学与工程前沿（英文）》   页码 1623-1631 doi: 10.1007/s11705-022-2202-y

摘要： The number of active components and their dispersion degree are two key factors affecting the performance of adsorbents. Here, we report a simple but efficient strategy for dispersing active components by using a confined space, which is formed by mesoporous silica walls and templates in the as-prepared SBA-15 (AS). Such a confined space does not exist in the conventional support, calcined SBA-15, which does not contain a template. The Cu and Zn precursors were introduced to the confined space in the AS and were converted to CuO and ZnO during calcination, during which the template was also removed. The results show that up to 5 mmol·g–1 of CuO and ZnO can be well dispersed; however, severe aggregation of both oxides takes place in the sample derived from the calcined SBA-15 with the same loading. Confined space in the AS and the strong interactions caused by the abundant hydroxyl groups are responsible for the dispersion of CuO and ZnO. The bimetallic materials were employed for the adsorptive separation of propene and propane. The samples prepared from the as-prepared SBA-15 showed superior performance to their counterparts from the calcined SBA-15 in terms of both adsorption capacity of propene and selectivity for propene/propane.

关键词： bimetallic adsorbents     confined space     mesoporous silica     propene/propane separation    

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Ductility improvement of GFRP-RC beams using precast confined concrete block in compression zone

《结构与土木工程前沿（英文）》 doi: 10.1007/s11709-023-0968-8

摘要： Fiber-reinforced polymers (FRPs) have received considerable research attention because of their high strength, corrosion resistance, and low weight. However, owing to the lack of ductility in this material and the quasi-brittle behavior of concrete, FRP-reinforced concrete (FRP-RC) beams, even with flexural failure, do not fail in a ductile manner. Because the limited deformation capacity of FRP-RC beams depends on the ductility of their compression zones, the present study proposes using a precast confined concrete block (PCCB) in the compression zone to improve the ductility of the beams. A control beam and four beams with different PCCBs were cast and tested under four-point bending conditions. The control beam failed due to shear, and the PCCBs exhibited different confinements and perforations. The goal was to find an appropriate PCCB for use in the compression zone of the beams, which not only improved the ductility but also changed the failure mode of the beams from shear to flexural. Among the employed blocks, a ductile PCCB with low equivalent compressive strength increased the ductility ratio of the beam to twice that of the control beam. The beam failed in pure flexure with considerable deformation capacity and without significant stiffness reduction.

关键词： ductility     four-point bending test     glass fiber-reinforced polymer     precast confined concrete block    

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Centrifuge model test and field measurement analysis for foundation pit with confined water

Chunlin DING , Xiaohong MENG ,

《结构与土木工程前沿（英文）》 2009年 第3卷 第3期   页码 299-304 doi: 10.1007/s11709-009-0035-0

摘要： The similarity law of centrifuge test was developed for the seepage field and stress field of a foundation pit with confined water by analyzing control equations, and a similarity index and a similarity coefficient of centrifuge test were obtained. Based on the deep foundation pit of the Huangxing Road Station of the Shanghai metro line M8, the deformation stability of the pit was tested. Finally, a comparative study was conducted on the test results of the pit deformation and the field measurement results. Comparison results show that the pit deformation regularity of the test is basically identical with that of the field measurement, and the difference in pit deformation between the test and the field measurement is within 50%. The centrifuge model test can effectively simulate the displacement response of the ground and retaining structure during dewatering and excavation for the pit with confined water, which provides a reliable basis for the design and construction of the pit with confined water.

关键词： foundation pit with confined water     centrifuge model test     seepage-stress coupling field     similarity relation     field measurement     deformation    

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Confined masonry as practical seismic construction alternative–the experience from the 2014 Cephalonia

Fillitsa KARANTONI, Stavroula PANTAZOPOULOU, Athanasios GANAS

《结构与土木工程前沿（英文）》 2018年 第12卷 第3期   页码 270-290 doi: 10.1007/s11709-017-0390-1

摘要：

During August 1953 three strong earthquakes of magnitude ranging from 6.3 to 7.2 shook the Ionian Island of Cephalonia (Kefalonia), Greece, and destroyed almost the entire building stock of the Island which consisted primarily of traditional unreinforced masonry (URM) houses. The authorities went on to restructuring of the building stock, using a structural system that is most like what is known today as confined masonry. They designed about 14 types of one- to two-storey buildings providing the engineers with detailed construction plans. These buildings are known as “Arogi” buildings (Arogi in Greek meaning Aid). On the 24th of January and 3rd of February 2014, two earthquakes of magnitude 6.1 and 6.0 struck the island, causing significant soil damages, developing excessively high ground accelerations. Surprisingly, no damage was reported in the “Arogi” buildings. The seismic behavior of the buildings is examined by FEM linear analysis and it is compared to that of URM structures. Computed results illustrate that the displacements of identical URM buildings would be about twice the magnitudes observed in the corresponding “Arogi” ones, with the implication that the earthquake sequence of 2014 would have caused critical damage should the type of structure be of the URM type. Furthermore, it is illustrated that this low cost alternative method of construction is a very effective means of producing earthquake resilient structures, whereas further reduction of seismic displacement may be achieved in the order of 50% with commensurate effects on damage potential, when reinforced slabs are used to replace the timber roofs.

关键词： Cephalonia     confined masonry     comparative FEM analysis     unreinforced masonry     seismic damage    

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Thermodynamic analysis of reaction pathways and equilibrium yields for catalytic pyrolysis of naphtha

《化学科学与工程前沿（英文）》 2022年 第16卷 第12期   页码 1700-1712 doi: 10.1007/s11705-022-2207-6

摘要： The chain length and hydrocarbon type significantly affect the production of light olefins during the catalytic pyrolysis of naphtha. Herein, for a better catalyst design and operation parameters optimization, the reaction pathways and equilibrium yields for the catalytic pyrolysis of C5–8 n/iso/cyclo-paraffins were analyzed thermodynamically. The results revealed that the thermodynamically favorable reaction pathways for n/iso-paraffins and cyclo-paraffins were the protolytic and hydrogen transfer cracking pathways, respectively. However, the formation of light paraffin severely limits the maximum selectivity toward light olefins. The dehydrogenation cracking pathway of n/iso-paraffins and the protolytic cracking pathway of cyclo-paraffins demonstrated significantly improved selectivity for light olefins. The results are thus useful as a direction for future catalyst improvements, facilitating superior reaction pathways to enhance light olefins. In addition, the equilibrium yield of light olefins increased with increasing the chain length, and the introduction of cyclo-paraffin inhibits the formation of light olefins. High temperatures and low pressures favor the formation of ethylene, and moderate temperatures and low pressures favor the formation of propylene. n-Hexane and cyclohexane mixtures gave maximum ethylene and propylene yield of approximately 49.90% and 55.77%, respectively. This work provides theoretical guidance for the development of superior catalysts and the selection of proper operation parameters for the catalytic pyrolysis of C5–8 n/iso/cyclo-paraffins from a thermodynamic point of view.

关键词： naphtha     catalytic pyrolysis     reaction pathway     equilibrium yield    

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Nano-confined ammonia borane for chemical hydrogen storage

M. A. WAHAB, Huijun ZHAO, X. D. YAO

《化学科学与工程前沿（英文）》 2012年 第6卷 第1期   页码 27-33 doi: 10.1007/s11705-011-1171-3

摘要： There is a great demand for a sufficient and sustainable energy supply. Hence, the search for applicable hydrogen storage materials is extremely important owing to the diversified merits of hydrogen energy. In this regard, ammonia borane (NH BH , AB) containing 19.6 wt-% hydrogen has been considered as a promising material for hydrogen storage applications to realize the “hydrogen economy”, but with limits from slow kinetics of hydrogen release and by-product of trace gases such as ammonia and borazine. In this review, we introduce the recent research on AB, regarding to the nanoconfinement effect on improving the kinetics at a relatively low temperature and the prevention/reduction of undesirable gas formation.

关键词： ammonia borane     hydrogen storage    

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Self-catalytic pyrolysis thermodynamics of waste printed circuit boards with co-existing metals

《环境科学与工程前沿（英文）》 2022年 第16卷 第11期 doi: 10.1007/s11783-022-1581-0

摘要：

● The co-existing metals in WPCBs has positive catalytic influence in pyrolysis.

关键词： Waste printed circuit board     Catalyst     Pyrolysis     Kinetics    

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Co-pyrolysis of sludge and kaolin/zeolite in a rotary kiln: Analysis of stabilizing heavy metals

《环境科学与工程前沿（英文）》 2022年 第16卷 第7期 doi: 10.1007/s11783-021-1488-1

摘要：

• Adding kaolin/zeolite promotes the formation of stable heavy metals.

关键词： Co-pyrolysis     Sewage sludge     Heavy metals     Rotary kiln     Immobilization mechanism    

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Theoretical study on the mechanism of sulfur migration to gas in the pyrolysis of benzothiophene

《化学科学与工程前沿（英文）》 2023年 第17卷 第3期   页码 334-346 doi: 10.1007/s11705-022-2209-4

摘要： The release and control of sulfur species in the pyrolysis of fossil fuels and solid wastes have attracted attention worldwide. Particularly, thiophene derivatives are important intermediates for the sulfur gas release from organic sulfur, but the underlying migration mechanisms remain unclear. Herein, the mechanism of sulfur migration during the release of sulfur-containing radicals in benzothiophene pyrolysis was explored through quantum chemistry modeling. The C1-to-C2 H-transfer has the lowest energy barrier of 269.9 kJ·mol–1 and the highest rate constant at low temperatures, while the elevated temperature is beneficial for C−S bond homolysis. 2-Ethynylbenzenethiol is the key intermediate for the formation of S and SH radicals with the overall energy barriers of 408.0 and 498.7 kJ·mol–1 in favorable pathways. The generation of CS radicals is relatively difficult because of the high energy barrier (551.8 kJ·mol–1). However, it can be significantly promoted by high temperatures, where the rate constant exceeds that for S radical generation above 930 °C. Consequently, the strong competitiveness of S and SH radicals results in abundant H2S during benzothiophene pyrolysis, and the high temperature is more beneficial for CS2 generation from CS radicals. This study lays a foundation for elucidating sulfur migration mechanisms and furthering the development of pyrolysis techniques.

关键词： benzothiophene     sulfur migration     pyrolysis     density functional theory    

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Effect of / molecular structures on pyrolysis performance and heat sink of decalin isomers

《化学科学与工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11705-023-2375-z

摘要： Decalin is considered as an important compound of high-energy-density endothermic fuel, which is an ideal on-board coolant for thermal management of advanced aircraft. However, decalin contains two isomers with a tunable composition, and their effects on the pyrolysis performance, such as the heat sink and coking tendency have not been demonstrated. Herein, we investigated the pyrolysis of decalin isomers, i.e., cis-decalin, trans-decalin and their mixtures (denoted as mix-decalin), in order to clarify the effects of the cis-/trans-structures on the pyrolysis performance of decalin fuels. The pyrolysis results confirmed that conversion of the tested fuels (600–725 °C, 4 MPa) decreased in the order cis-decalin > mix-decalin > trans-decalin. Detailed analyses of the pyrolysis products were used to compare the product distributions from cis-decalin, mix-decalin and trans-decalin, and the yields of some typical components (such as cyclohexene, 1-methylcyclohexene, benzene and toluene) showed significant differences, which could be ascribed to deeper cracking of cis-decalin. Additionally, the heat sinks and coking tendencies of the decalins decreased in the order cis-decalin > mix-decalin > trans-decalin. This work demonstrates the relationship between the cis/trans structures and the pyrolysis performance of decalin, which provides a better understanding of the structure-activity relationships of endothermic hydrocarbon fuels.

关键词： endothermic fuel     decalin     pyrolysis     heat sink     molecular structure    

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Fast and catalytic pyrolysis of xylan: Effects of temperature and M/HZSM-5 (M= Fe, Zn) catalysts on pyrolytic

Xifeng ZHU, Qiang LU, Wenzhi LI, Dong ZHANG,

《能源前沿（英文）》 2010年 第4卷 第3期   页码 424-429 doi: 10.1007/s11708-010-0015-z

摘要： Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was employed to achieve fast pyrolysis of xylan and on-line analysis of pyrolysis vapors. Tests were conducted to investigate the effects of temperature on pyrolytic products, and to reveal the effect of HZSM-5 and M/HZSM-5 (M= Fe, Zn) zeolites on pyrolysis vapors. The results showed that the total yield of pyrolytic products first increased and then decreased with the increase of temperature from 350°C to 900°C. The pyrolytic products were complex, and the most abundant products included hydroxyacetaldehyde, acetic acid, 1-hydroxy-2-propanone, 1-hydroxy-2-butanone and furfural. Catalytic cracking of pyrolysis vapors with HZSM-5 and M/HZSM-5 (M= Fe, Zn) catalysts significantly altered the product distribution. Oxygen-containing compounds were reduced considerably, and meanwhile, a lot of hydrocarbons, mainly toluene and xylenes, were formed. M/HZSM-5 catalysts were more effective than HZSM-5 in reducing the oxygen-containing compounds, and therefore, they helped to produce higher contents of hydrocarbons than HZSM-5.

关键词： xylan     fast pyrolysis     catalytic pyrolysis     Py-GC/MS     HZSM-5    

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Mechanism insight into the formation of HS from thiophene pyrolysis: A theoretical study

《环境科学与工程前沿（英文）》 2021年 第15卷 第6期 doi: 10.1007/s11783-021-1404-8

摘要：

• Possible formation pathways of H2S were revealed in thiophene pyrolysis.

关键词： Density functional theory     Waste rubber     Thiophene     H2S     Pyrolysis    

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标题 作者 时间 类型 操作

Fabrication of N-doped carbon nanobelts from a polypyrrole tube by confined pyrolysis for supercapacitors

Wei Wang, Haijun Lv, Juan Du, Aibing Chen

期刊论文

Ultrafine Fe-modulated Ni nanoparticles embedded within nitrogen-doped carbon from Zr-MOFs-confined conversion

期刊论文

Development of deep neural network model to predict the compressive strength of FRCM confined columns

Khuong LE-NGUYEN; Quyen Cao MINH; Afaq AHMAD; Lanh Si HO

期刊论文

Fabrication of bimetallic Cu–Zn adsorbents with high dispersion by using confined space for gas adsorptive

期刊论文

Ductility improvement of GFRP-RC beams using precast confined concrete block in compression zone

期刊论文

Centrifuge model test and field measurement analysis for foundation pit with confined water

Chunlin DING , Xiaohong MENG ,

期刊论文

Confined masonry as practical seismic construction alternative–the experience from the 2014 Cephalonia

Fillitsa KARANTONI, Stavroula PANTAZOPOULOU, Athanasios GANAS

期刊论文

Thermodynamic analysis of reaction pathways and equilibrium yields for catalytic pyrolysis of naphtha

期刊论文

Nano-confined ammonia borane for chemical hydrogen storage

M. A. WAHAB, Huijun ZHAO, X. D. YAO

期刊论文

Self-catalytic pyrolysis thermodynamics of waste printed circuit boards with co-existing metals

期刊论文

Co-pyrolysis of sludge and kaolin/zeolite in a rotary kiln: Analysis of stabilizing heavy metals

期刊论文

Theoretical study on the mechanism of sulfur migration to gas in the pyrolysis of benzothiophene

期刊论文

Effect of / molecular structures on pyrolysis performance and heat sink of decalin isomers

期刊论文

Fast and catalytic pyrolysis of xylan: Effects of temperature and M/HZSM-5 (M= Fe, Zn) catalysts on pyrolytic

Xifeng ZHU, Qiang LU, Wenzhi LI, Dong ZHANG,

期刊论文

Mechanism insight into the formation of HS from thiophene pyrolysis: A theoretical study

期刊论文