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A comparative single-pulse shock tube experiment and kinetic modeling study on pyrolysis of cyclohexane,methylcyclohexane and ethylcyclohexane

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Defence Technology（防务技术） 2023年第2期20卷 137-148页

作者： Jin-hu Liang Shu-tong Cao Fei Li Xiao-liang Li Rui-ning He Xin Bai Quan-De Wang Yang Li School of Environmental and Safety Engineering North University of ChinaTaiyuan030051People's Republic of China Science and Technology on Combustion Internal Flow and Thermostructure LaboratorySchool of AstronauticsNorthwestern Polytechnical UniversityXi'an 710072People's Republic of China Low Carbon Energy Institute and School of Chemical Engineering China University of Mining and TechnologyXuzhou 221008People's Republic of China

The pyrolysis of cyclohexane,methylcyclohexane,and ethylcyclohexane have been studied behind reflected shock waves at pressures of 5 and10 bar and at temperatures of 930-1550 K for 0.05%fuel diluted by Argon.A single-pulse shock tube(SPST)is used to perform the pyrolysis experiments at reaction times varying from 1.65 to 1.74 ms.Major products are obtained and quantified using gas chromatography analysis.A flame ionization detector and a thermal conductivity detector are used for species identification and quantification.Kinetic modeling has been performed using several detailed and lumped chemical kinetic mechanisms.Differences in modeling results among the kinetic models are described.Reaction path analysis and sensitivity analysis are performed to determine the important reactions controlling fuel pyrolysis and their influence on the predicted concentrations of reactant and product species profiles.The present work provides new fundamental knowledge in understating pyrolysis characteristics of cyclohexane compounds and additional data set for detailed kinetic mechanism development.

关键词： Cyclohexane Alkylated cyclohexane Single-pulse shock tube pyrolysis Kinetic modeling

Hole-growth phenomenon during pyrolysis of a cation-exchange resin particle

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2022年第12期23卷 974-987页

作者： Zheng-liang HUANG Yun-bo YU Qi SONG Yao YANG Jing-yuan SUN Jing-dai WANG Yong-rong YANG Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture Technology College of Chemical and Biological EngineeringZhejiangUniversityHangzhou 310027China State Key Laboratory of Chemical Engineering College of Chemical and Biological EngineeringZhejiang UniversityHangzhou 310027China

A novel central hole-expansion phenomenon is identified, in which the cation-exchange resin is pyrolyzed in a mixed atmosphere of nitrogen and oxygen at 400–500 ℃. In this reaction, the reaction path is predictable and always starts from the center of the resin particle to form a central hole, then continues and expands around the hole, finally forming a uniformly distributed hole group;the particle surface remains intact. Analysis shows that this formation mode is due to the different reaction paths of sulfonic groups between the surface and interior of the particle, caused by the temperature difference. On the surface, transformation reactions happen at high temperatures(410–500 ℃) to form stable organic sulfur structures, while decomposition occurs inside the particle at a relatively low temperature(pyrolysis of the copolymer matrix to form holes.

关键词： Non-catalytic gas-solid reaction Cation-exchange resin pyrolysis Central-hole expansion Temperature difference Transformation

Synergetic process between wind power and sewage sludge pyrolysis in a novel renewable-energy microgrid system

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Clean Energy 2023年第3期7卷 493-508页

作者： Chang Liu Jiankun Zhuo Yanfeng He Shuiqing Li Qiang Yao Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Tsinghua UniversityBeijing 100084China Beijing Engineering Research Center for Ecological Restoration and Carbon Fixation of Saline-alkaline and Desert Land Tsinghua UniversityBeijing 100084China

To relieve the stress of sewage sludge(SS)disposal and effectively increase the use of renewable energy,a novel renewable-energy microgrid system(REMS)was developed,specifically designed to integrate a wind power plant(WPP)with energy storage and the SS pyrolysis process for heat and power generation.Based on a lab-scale pyrolysis experiment and 7-day numerical analysis,we studied the energy-recycling potential of SS and simulated the operational behaviours of REMS.According to the results,the calorific values of the pyrolytic gaseous and liquid products were better than those of the raw material,at 16.19 and 33.53 MJ/kg,respectively.The proposed REMS performed well in power supply and energy utilization with a design performance index of 99.23 when the WPP capacity was 200 MWe and the initial wind-energy curtailment rate was 30%.It indicates that by converting SS into flammable gas,condensable liquid and carbon-rich solid residue,curtailed wind energy could be saved and the synergy between wind power and the SS pyrolysis process enabled the proposed microgrid system to effectively utilize renewable energy and provide reliable on-demand power service.The REMS installed with a 155-MWe WPP achieved the optimal design in system performance,environmental benefit and construction cost under the initial wind-curtailment rate of 34.12%.The design scheme makes REMS capable of satisfying the 15.10-GWh power demand of end users and the 1700-t/day SS disposal need,and the curtailed wind energy could be reduced to zero.

关键词： sewage sludge pyrolysis wind power microgrid flexible operation

Empirical modeling of normal/cyclo-alkanes pyrolysis to produce light olefins

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Chinese Journal of Chemical Engineering 2022年第2期35卷 389-398页

作者： Xu Hou Bochong Chen Zhenzhou Ma Jintao Zhang Yuanhang Ning Donghe Zhang Liu Zhao Enxian Yuan Tingting Cui School of Chemical Engineering Changchun University of TechnologyChangchun 130012China Advanced Institute of Materials Science Changchun University of TechnologyChangchun 130012China School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225009China Department of Chemistry Tsinghua UniversityBeijing 100084China

Due to the complexity of feedstock,it is challenging to build a general model for light olefins production.This work was intended to simulate the formation of ethylene,propene and 1,3-butadiene in alkanes pyrolysis by referring the effects of normal/cyclo-structures.First,the pyrolysis of n-pentane,n-hexane,n-heptane,n-octane,n-nonane,n-decane,cyclohexane,methylcyclohexane,n-hexane and cyclohexane mixtures,and n-heptane and methylcyclohexane mixtures were carried out at 650–800℃,and a particular attention was paid to the measurement of ethylene,propene and 1,3-butadiene.Then,pseudo-first order kinetics was taken to characterize the pyrolysis process,and the effects of feedstock composition were studied.It was found that chain length and cyclo-alkane content can be qualitatively and quantitively represented by carbon atom number and pseudo-cyclohexane content,which made a significant difference on light olefins formation.Furthermore,the inverse proportional/quadratic function,linear function and exponential function were proposed to simulate the effects of chain length,cycloalkane content and reaction temperature on light olefins formation,respectively.Although the obtained empirical model well reproduced feedstock conversion,ethylene yield and propene yield in normal/cycloalkanes pyrolysis,it exhibited limitations in simulating 1,3-butadiene formation.Finally,the accuracy and flexibility of the present model was validated by predicting light olefins formation in the pyrolysis of multiple hydrocarbon mixtures.The prediction data well agreed with the experiment data for feedstock conversion,ethylene yield and propene yield,and overall characterized the changing trend of 1,3-butadiene yield along with reaction temperature,indicating that the present model could basically reflect light olefins production in the pyrolysis process even for complex feedstock.

关键词： Empirical model Normal-alkane Cyclo-alkane pyrolysis Light olefins

A new perspective on polyethylene-promoted lignin pyrolysis with mass transfer and radical explanation

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Green Energy & Environment 2022年第6期7卷 1318-1326页

作者： Yuyang Fan Chao Liu Xiangchen Kong Yue Han Ming Lei Rui Xiao Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjing210096China

Co-pyrolysis of lignin and waste plastics,for example polyethylene(PE),has been studied,but related reports are basically on condition optimizations.This study revealed a new perspective on PE-promoted lignin pyrolysis to phenolic monomers with mass transfer and radical explanation.Lignin and PE were first pyrolyzed individually to identify pyrolysis characteristics,pyrolytic products,as well as the suitable copyrolysis temperature.Then,co-pyrolysis of blended lignin/PE with various ratios was investigated.Yields of lignin products reached the maximum under lignin/PE ratio of 1:1,but blended approach always inhibited the production of lignin phenols.This resulted from the poor mass transfer and interactions between lignin and PE,in which PE pyrolysates could easily escape from the particle gaps.While in layered approach,PE pyrolysates had to pass through the lignin layer which contributed to the good interactions with lignin pyrolysis intermediates,thus the yields of lignin-derived products were significantly improved.Interactions between lignin and PE(or their pyrolysates)were mainly radical quenching reactions,and X-ray photoelectron spectrum(XPS)and electron paramagnetic resonance(EPR)of pyrolytic chars were conducted to verify these interactions controlled by mass transfer.The percentage of C]C(sp^(2))and concentration of organic stable radicals in layered lignin/PE char were both the lowest compared with those in blended lignin/PE and lignin char,indicating the stabilization of lignin-derived radicals by PE pyrolysates.Moreover,the spin concentration of radicals in the char from layered char/PE was lower than that in lignin char,which further affirmed the quenching of radicals by PE in the layered co-pyrolysis mode.

关键词： Lignin Polyethylene pyrolysis Radical Mechanism

Alkaline earth metal-based minerals/wastes-catalyzed pyrolysis of poly(ethylene terephthalate)/poly(butylene terephthalate)for benzenes-enriched oil production

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Waste Disposal and Sustainable Energy 2023年第3期5卷 269-282页

作者： Kai Sun Zhenyu Lin Qunxing Huang College of Chemical and Biological Engineering Zhejiang UniversityHangzhou310058China Xizi Clean Energy Equipment Manufacturing Co. Ltd.Hangzhou310021China State Key Laboratory of Clean Energy Utilization Zhejiang UniversityHangzhou310027China

The pyrolysis of poly(ethylene terephthalate)(PET)/poly(butylene terephthalate)(PBT)catalyzed by five alkaline earth metal-based minerals/wastes,namely calcined dolomite,calcite,magnesite,calcium carbide slag(CCS),and ophicalcitum,was conducted by a pyrolyzer-gas chromatography-mass spectrometer(Py-GC-MS)with the objective of recovering benzenes-enriched oil.Compared with magnesium-based catalysts and pure CaO,the calcium-based catalysts with calcium hydroxide as the main component performed better catalytic effect,which could simultaneously promote the hydrolysis of ester products and the decarboxylation of aromatic acids after hydrolysis.For PET,the addition of solid base catalysts at 600℃promoted the complete degradation of aromatic acids and aryl esters,which accounted for 32.6%and 30.7%of the pyrolysis oil,respectively.The content of benzene in oil increased from 8.8%to 31.7%–78.8%.For PBT,the addition of solid base catalysts at 600℃completely decomposed the aromatic acids,which accounted for 67.1%of the pyrolysis oil,and the content of benzene in oil increased from 12.3%to 34.5%–81.0%.During the deoxygenation of polyester pyrolysis products,increasing temperature was more effective for the decomposition/conversion of acetone and tetrahydrofuran,while increasing the alkalinity of the reaction environment contributed to the rapid decrease in acetaldehyde and aryl ketone contents.

关键词： pyrolysis Benzene Poly(ethylene terephthalate) Poly(butylene terephthalate) Decarboxylation Py-GC-MS

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

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Frontiers of Chemical Science and Engineering 2023年第3期17卷 334-346页

作者： Ji Liu Shuang-Wei Yang Wei Zhao Yu-Long Wu Bin Hu Si-Han Hu Shan-Wei Ma Qiang Lu National Engineering Research Center of New Energy Power Generation North China Electric Power UniversityBeijing 102206China Suzhou Institute of North China Electric Power University Suzhou 215000China Institute of Nuclear and New Energy Technology Tsinghua UniversityBeijing 100084China School of Chemistry and Chemical Engineering Xinjiang UniversityUrumqi City 830046China

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 C_(1)-to-C_(2)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 H2 S 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

Insight into pyrolysis of hydrophobic silica aerogels:Kinetics,reaction mechanism and effect on the aerogels

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Chinese Journal of Chemical Engineering 2023年第6期58卷 266-281页

作者： Xinyu Liu Hongliang Sheng Song He Chunhua Du Yuansheng Ma Chichi Ruan Chunxiang He Huaming Dai Yajun Huang Yuelei Pan School of Safety Science and Emergency Management Wuhan University of TechnologyWuhan 430070China Wuhan Building Material Industry Design&Research Institute Co. LtdWuhan 430200China State Key Laboratory of Fire Science University of Science and Technology of ChinaHefei 230027China

Silica aerogels have promising applications in thermal insulation,but their flammability and reaction mechanisms have rarely been investigated.The pyrolysis kinetics and thermodynamics of hydrophobic silica aerogels under N_(2) environment were studied.The kinetic and thermodynamic parameters were obtained by three model-free methods.Based on the calculated kinetic parameters,the pyrolysis mechanism of silica aerogels was discussed by the master plots method.The results indicate that the reactions of the whole pyrolysis phase can be characterized by a random nuclear model.In addition,FTIR test results show that the volatile products of silica aerogel pyrolysis are mainly hydrocarbons generated by the decomposition of hydrophobic groups(methyl groups)on the surface.Finally,the effects of pyrolysis on the properties of silica aerogels Finally,the effects of pyrolysis on the properties of silica aerogels were investigated based on the analysis results of SEM,specific surface area,pore size distribution,X-ray diffraction,XPS and infrared spectroscopy.

关键词： pyrolysis Thermodynamics Reaction kinetics

Synergistic reaction behavior of pyrolysis and reduction of briquette prepared by weakly caking coal and metallurgical dust

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Journal of Iron and Steel Research(International) 2023年第7期30卷 1367-1380页

作者： Zheng-jian Liu Ming-hui Cao Jian-liang Zhang Run-sheng Xu Yao-zu Wang Ji-yong Yu Yu-chen Zhang School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

Co-carbonization of weakly caking coal and zinc-containing dust to prepare highly reactive ferro-coke and collaboratively recover zinc powder is one of the feasible ways for steel enterprises to recycle zinc-containing dust.The pyrolysis mass loss behavior of adding blast furnace dust with different zinc contents to different ferro-coke materials was systematically studied by thermogravimetry and differential thermogravimetry analysis,and the kinetic mechanism of pyrolysis-reduction reaction of hybrid briquette was explored.The results of thermogravimetric curve analysis show that the addition of zinc oxide to the sample has no significant effect on the mass loss rate of the sample below 580℃,and the pyrolysis mass loss of zinc oxide mainly occurs between 800 and 1000℃.Kinetic analysis results show that the pyrolysis of zinc-containing samples is controlled by chemical reactions below 580℃.The reaction at 580–700℃ is controlled by the nucleation and growth model,and that above 700℃ is mainly controlled by diffusion.The results of X-ray diffraction analysis show that the pyrolysis process can effectively remove zinc oxide from ferro-coke.

关键词： Zinc-containing dust Weakly caking coal Ferro-coke pyrolysis Reduction Thermal reaction analysis Kinetic analysis