It is important to understand the effects of demineralization on the reactivity of coal pyrolysis for demineralization coal in OCCSS systems.The molecular dynamics of the pyrolysis of ZD-R and ZD-D was investigated us...It is important to understand the effects of demineralization on the reactivity of coal pyrolysis for demineralization coal in OCCSS systems.The molecular dynamics of the pyrolysis of ZD-R and ZD-D was investigated using the ReaxFF MD method.It is indicated that the pyrolysis reactivity of ZD-D is enhanced.Acid demineralization treatment helps to enhance the cross-linking reaction of light tar C5-14 molecules in the main pyrolysis stage,generating light tar fragments with higher molecular mass.In the polycondensation pyrolysis stage,the acid demineralization treatment promotes the polycondensation reaction at high temperatures.The generation of H2 in ZD-R pyrolysis is primarily attributed to the N-H bond breaking in pyrrole at low temperatures.At high temperatures,it is predominantly associated with the hydrogen abstraction reaction between carboxyl functional groups and the dehydrogenation reaction of hydrogen bond breaking in the aliphatic hydrocarbon structures.H2O is primarily attributed to the reaction of the hydroxyl group on the carboxyl group.CO_(2) is always related to the carboxyl group.CO is mainly related to the reduction reaction of carbonyl group,carboxyl group,and CO_(2).During the initial pyrolysis stage of ZD-D after acid demineralization treatment,the hydrogen abstraction reaction of the carboxyl functional group and the generation of CO molecules by the methoxy group are enhanced.The generation of H2 by the aliphatic structure is enhanced in the main pyrolysis stage.The ring-opening reaction of the phenoxy group to generate CO in the polycondensation pyrolysis stage is also facilitated.展开更多
Roasting bastnaesite concentrates is a crucial process in extracting rare earths.This study explored an efficient suspension roasting technology and investigated the bastnaesite pyrolysis and cerium(Ce)oxidation.Relev...Roasting bastnaesite concentrates is a crucial process in extracting rare earths.This study explored an efficient suspension roasting technology and investigated the bastnaesite pyrolysis and cerium(Ce)oxidation.Relevant analytical tests were applied to evaluate the phase and surface property variations of bastnaesite,and isothermal kinetic analysis of bastnaesite pyrolysis and Ce oxidation was performed.The results revealed that bastnaesite decomposed rapidly and accompanied by Ce oxidation,and the gas-solid products were identified as CO_(2),Ce_(7)O_(12),La_(2)O_(3),CeF_(3) and LaF_(3),with Ce oxidation restricted by bastnaesite pyrolysis.As roasting time prolonged,cracks and pores appeared on bastnaesite surface;the BET specific surface and pore diameter increased.In later roasting period,the pore diameter continued to increase but the specific surface decreased,assigned to particle fusion agglomeration and pore consolidation.Additionally,the surface C content reduced and Ce(Ⅳ)content increased gradually as roasting progressed.The reaction kinetics all followed Avrami-Erofeev equations,the reaction orders of bastnaesite pyrolysis and Ce oxidation decreased with decreasing reaction temperature.The calculated activation energies at lower temperatures were higher than those calculated at higher temperatures.This study analyzed the bastnaesite reaction mechanism to supply a reference for the application of suspension roasting technology in bastnaesite smelting.展开更多
A novel design of micro-aluminum(μAl)powder coated with bi-/tri-component alloy layer,such as:Ni-P and Ni-P-Cu(namely,Al@Ni-P,Al@Ni-P-Cu,respectively),as combustion catalysts,were introduced to release its huge energ...A novel design of micro-aluminum(μAl)powder coated with bi-/tri-component alloy layer,such as:Ni-P and Ni-P-Cu(namely,Al@Ni-P,Al@Ni-P-Cu,respectively),as combustion catalysts,were introduced to release its huge energy inside Al-core and promote rapid pyrolysis of ammonium perchlorate(AP)at a lower temperature in aluminized propellants.The microstructure of Al@Ni-P-Cu demonstrates that a three-layer Ni-P-Cu shell,with the thickness of~100 nm,is uniformly supported byμAl carrier(fuel unit),which has an amorphous surface with a thickness of~2.3 nm(catalytic unit).The peak temperature of AP with the addition of Al@Ni-P-Cu(3.5%)could significantly drop to 316.2℃ at high-temperature thermal decomposition,reduced by 124.3℃,in comparison to that of pure AP with 440.5℃.It illustrated that the introduction of Al@Ni-P-Cu could weaken or even eliminate the obstacle of AP pyrolysis due to its reduction of activation energy with 118.28 kJ/mol.The laser ignition results showed that the ignition delay time of Al@Ni-P-Cu/AP mixture with 78 ms in air is shorter than that of Al@Ni-P/AP(118 ms),decreased by 33.90%.Those astonishing breakthroughs were attributed to the synergistic effects of adequate active sites on amorphous surface and oxidation exothermic reactions(7597.7 J/g)of Al@Ni-P-Cu,resulting in accelerated mass and/or heat transfer rate to catalyze AP pyrolysis and combustion.Moreover,it is believed to provide an alternative Al-based combustion catalyst for propellant designer,to promote the development the propellants toward a higher energy.展开更多
Coal pyrolysis integrated with dry reforming of low-carbon alkane(CP-DRA)is an effective way to improve tar yield.Ni/La_(2)O_(3)-ZrO_(2) with a La/Zr ratio of 4 was a good catalyst for DRA to inhibit carbon deposition...Coal pyrolysis integrated with dry reforming of low-carbon alkane(CP-DRA)is an effective way to improve tar yield.Ni/La_(2)O_(3)-ZrO_(2) with a La/Zr ratio of 4 was a good catalyst for DRA to inhibit carbon deposition and obtain high tar yield in CP-DRA.In this study,the fraction distribution and component of tars from CP-DRA and coal pyrolysis in N_(2) atmosphere(CP-N_(2))were characterized by using several methods to understand the effect of DRA on coal pyrolysis.The isotope trace method was also used to discuss the role of low-carbon alkane in CP-DRA.The results showed that the tar from CP-N_(2)is mainly composed of aliphatic compounds with more C_(al),H_(al) and CH+CH_(2),and the tar from CP-DRA contains more Car,Har,and CH_(3),and has lower weight-average molecular weight and more light tar content than CP-N_(2).A small amount of C_(2)H_(6) addition in CP-DRA will raise the ratio of H_(β) and CH+CH_(2).Electron paramagnetic resonance(EPR)analysis shows that the tar from CP-DRA has a higher radical concentration while the corresponding char has a lower radical concentration.The isotope trace experiment showed that alkanes provide·H,·CH_(3),etc.to stabilize the radicals from coal pyrolysis and result in more alkyl aromatic compounds during CP-DRA.展开更多
Four sewage sludge(SS)feedstocks with distinct properties were converted into biochars by pyrolysis at 300−700℃,in order to clarify the effects of the composition difference of SS feedstocks.The yields of biochars pr...Four sewage sludge(SS)feedstocks with distinct properties were converted into biochars by pyrolysis at 300−700℃,in order to clarify the effects of the composition difference of SS feedstocks.The yields of biochars present a positive correlation with the contents of ash in SS.Notedly,the contents of organic matter(OM)in SS largely determine the quality of biochars.SS feedstocks with high content of OM are more likely to form stable biochars with higher aromaticity/carbonization degree,and the formed biochars possess higher calorific values.The contents of residual OM in biochars derived from SS feedstocks with low content of OM likely fail to meet the needs of soil improvement(10 wt.%).Most of heavy metals(HMs)existing in raw SS are remained in biochars after pyrolysis.The biochar produced from SS feedstocks with high content of HMs usually contains higher contents of HMs.Surprisingly,the leachability of HMs in biochars is all weakened to some extent compared to raw SS.In addition,the biochars show higher thermal stability and pH values,and P/K nutrients are enriched in biochars.The biochars prepared from four SS feedstocks exhibit different adsorption ability of methylene blue,especially at low dosage of biochar.展开更多
Thermal decomposition of waste epoxy PCBs was performed in different atmospheres （nitrogen, argon, air and vacuum） at a heating rate of 10 ℃/rain by DSC-TGA, and the pyrolysis characteristic was analyzed. The gases...Thermal decomposition of waste epoxy PCBs was performed in different atmospheres （nitrogen, argon, air and vacuum） at a heating rate of 10 ℃/rain by DSC-TGA, and the pyrolysis characteristic was analyzed. The gases volatilized from the experiment were qualitatively analyzed by TG-FTIR. Kinetics study shows that pyrolysis reaction takes place between 300 and 400℃, and the activation energies are 256, 212 and 186.2 kJ/mol in nitrogen, argon and vacuum, respectively. There are two mass-loss processes in the decomposition under air atmosphere. In the first mass-loss process, the decomposition is the main reaction, and in the second process, the oxidation is the main reaction. The activation energy of the second mass-loss process is 99.6 kJ/mol by isothermal heat-treatments. TG-FTIR analysis shows carbon dioxide, carbon monoxide, hydrogen bromide, phenol and substituent phenol are given off during the pyrolysis of waste epoxy PCBs.展开更多
Thermogravimetric study of rubber compositions （operating glove and catheter） in medical waste was carried out using the thermogravimetric analyser （TGA）,at the heating rate of 20 ℃/min in a stream of N2.The resu...Thermogravimetric study of rubber compositions （operating glove and catheter） in medical waste was carried out using the thermogravimetric analyser （TGA）,at the heating rate of 20 ℃/min in a stream of N2.The results indicate that the decomposition process of operating glove appears an obvious mass loss stage at 250-485 ℃,while catheter has two obvious stages at 240-510 ℃ and 655-800 ℃,respectively; both samples present endothermic pyrolysis reaction; the decomposition of operating glove and the first mass loss stage of catheter are in agreement with natural rubber pyrolysis; the second mass loss stage of catheter corresponds to CaCO3 decomposition.Based on the experimental results,a novel two-step four-reaction model was established to simulate the whole continuous processes,which could more satisfactorily describe and predict the pyrolysis processes of rubber compositions,being more mechanistic and conveniently serving for the engineering.展开更多
Two-dimensional plain-weave silicon carbide fiber fabric reinforced silicon carbide(2D-SiC/SiC)composites were molded by stacking method and densified through precursor infiltration and pyrolysis(PIP)process.SiC coati...Two-dimensional plain-weave silicon carbide fiber fabric reinforced silicon carbide(2D-SiC/SiC)composites were molded by stacking method and densified through precursor infiltration and pyrolysis(PIP)process.SiC coating was deposited as the fiber/matrix interphase layer by chemical vapor deposition(CVD)technique.Fiber/matrix debonding and relatively long fiber pullouts were observed on the fracture surfaces.Additionally,the flexural strength and elastic modulus of the composites with and without fiber/matrix interphase layer were investigated using three-point bending test and single-edge notched beam test.The results show that the fiber fraction and the porosity of 2D-SiC/SiC composites with and without coating are 27.2%(volume fraction)and 11.1%,and 40.7%(volume fraction)and 7.5%,respectively.And the flexural strength and elastic modulus of 2D-SiC/SiC composites with and without coating are 363.3 MPa and 127.8 GPa,and 180.2 MPa and 97.2 GPa,respectively.With a proper thickness,the coating can effectively adjust the fiber/matrix interface,thus causing a dramatic increase in the mechanical properties of the composites.展开更多
In this study,Tungsten Oxide(WO_3)thin films were prepared by Chemical Spray Pyrolysis(CSP)and Spin Coating(SC)techniques and it was investigated effects of technique and parameter on the films.WO_3 thin films were de...In this study,Tungsten Oxide(WO_3)thin films were prepared by Chemical Spray Pyrolysis(CSP)and Spin Coating(SC)techniques and it was investigated effects of technique and parameter on the films.WO_3 thin films were deposited on ITO(Indium Tin Oxide)coated glasses.The structural,optical and electrochromic properties of the WO_3 thin films were characterized by XRD,SEM,UV,and CV measurements.The sharpest(200)peak was observed in the XRD spectra and optical band gaps were calculated around 2.6～3.1 eVvia UV-Vis spectra for all of the samples.Micro fibrous reticulated surface(filamentous like)morphology for the films deposited by CSP technique and smooth surface morphology with high optical transmittance for the film deposited by SC Technique were obtained from SEM images.In addition to these results,it was revealed that all the samples exhibit good electrochromic performance.展开更多
Biomass is a kind of renewable energy which is used increasingly in different types of combustion systems or in the production of fuels like bio-oil. Lycopodium is a cellulosic particle, with good combustion propertie...Biomass is a kind of renewable energy which is used increasingly in different types of combustion systems or in the production of fuels like bio-oil. Lycopodium is a cellulosic particle, with good combustion properties, of which microscopic images show that these particles have spherical shapes with identical diameters of 31 μm. The measured density of these particles is 1.0779 g/cm2. Lycopodium particles contain 64.06% carbon, 25.56% oxygen, 8.55% hydrogen and 1.83% nitrogen, and no sulfur. Thermogravimetric analysis in the nitrogen environment indicates that the maximum of particle mass reduction occurs in the temperature range of 250-550 ℃ where the maximum mass reduction in the DTG diagrams also occurs in. In the oxygen environment, an additional peak can also be observed in the temperature range of 500-600 ℃, which points to solid phase combustion and ignition temperature of lycopodium particles. The kinetics of reactions is determined by curve fitting and minimization of error.展开更多
The pyrolysis dechlorination of PVC (polyvinyl chloride) has been carried out by batch operation under atmospheric pressure. The kinetics involved in the PVC thermal decomposition was studied by using thermogravimetri...The pyrolysis dechlorination of PVC (polyvinyl chloride) has been carried out by batch operation under atmospheric pressure. The kinetics involved in the PVC thermal decomposition was studied by using thermogravimetric technique. Several tests were carried out at the heating rate of 5-10℃/min, the yields of products and the distribution of chlorine were also studied. The kinetic parameters such as activation energies, reaction orders and preexponential factors under nitrogen atmosphere were calculated by applying Friedman’s method. The results showed that the PVC thermal degradation is substantially a two-step process. The first step mainly involves dechlorination of the polymers. HCI is the main volatile product and this reaction can be seen as a first-order reaction. A kinetic model for the thermal dechlorination of PVC has been developed.展开更多
Decreasing in emissions of greenhouse gases to confront the global warming needs to replace fossil fuels as the main doer of the world climate changes by renewable and clean fuels produced from biomass like wood waste...Decreasing in emissions of greenhouse gases to confront the global warming needs to replace fossil fuels as the main doer of the world climate changes by renewable and clean fuels produced from biomass like wood waste which is neutral on the amount of CO2. An analytical and engineering model for pyrolysis process of a single biomass particle has been presented. Using a two-stage semi global kinetic model which includes both primary and secondary reactions, the effects of parameters like shape and size of particle as well as porosity on the particle temperature profile and product yields have been investigated. Comparison of the obtained results with experimental data shows that our results are in a reasonable agreement with previous researchers' works. Finally, a sensitivity analysis is done to determine the importance of each parameter on pyrolysis of a single biomass particle which is affected by many constant parameters.展开更多
Hydrogen rich gas was produced using rice husk as biomass material on the continuous biomass pyrolysis apparatus which consisted of continuous pyrolysis reactor and secondary catalytic cracking reactor. Ni based catal...Hydrogen rich gas was produced using rice husk as biomass material on the continuous biomass pyrolysis apparatus which consisted of continuous pyrolysis reactor and secondary catalytic cracking reactor. Ni based catalysts of different Ni/Al mass ratio and calcined temperature were prepared by impregnating method. The catalysts were characterized by X-ray diffraction （XRD）, scan electron microscope （SEM） and FT-IR Spectrometer （FT-IR）. Ni based catalyst showed good selectivity for H2 production from biomass. Catalysts prepared under different conditions had little influence on the yields of three states products when used at the same cracking temperature. Ni/Al mass ratio played an important role in products selectivity. However, the content of NiO increased further when Ni/Al mass ratio values reached 0.7 ： 10, and the yield of H2 slightly increased. Hydrogen yield was greatly impacted by calcined temperature. Catalyst calcined at 550℃performed best. When the catalyst was calcined at high temperature, NiO in the catalyst transformed into NiAl2O4, and the acid site also changed, which caused the deactivation of the catalyst. The hydrogen yield increased with the cracking temperature. The highest stable yield of hydrogen was about 30% without increasing with the cracking temperature.展开更多
With citric acid as a polymeric agent layered LiNi0.8Co0.2O2 materials were synthesized by a spray pyrolysis method. The LiNi0.sCo0.2O2 particles were characterized by means of XRD, SEM and TEM. The electrochemical pe...With citric acid as a polymeric agent layered LiNi0.8Co0.2O2 materials were synthesized by a spray pyrolysis method. The LiNi0.sCo0.2O2 particles were characterized by means of XRD, SEM and TEM. The electrochemical performances of LiNi0.8Co0.2O2 particles were studied in a voltage window of 3.00-4.35 V and at a current density of 30 mA/g. The results show that in the pilot-scale spray pyrolysis process, the morphology of particles is dependent upon the precursor concentration and flux of carrier gas. The initial discharge capacity of the LiNi0.8Co0.2O2particles at 720 ℃ for 12 h is 187.3 mA.h/g, and the capacity remains 96.8% with excellent cycleability after 30 cycles. The LiNi0.8Co0.2O2 samples synthesized under the optimized conditions by the spray pyrolysis method shows a good electrochemical performance.展开更多
The effects of pyrolysis mode and pyrolysis parameters on Cl content in alumina were investigated, and the alumina products were characterized by XRD, SEM and ASAP. The experimental results indicate that the spray pyr...The effects of pyrolysis mode and pyrolysis parameters on Cl content in alumina were investigated, and the alumina products were characterized by XRD, SEM and ASAP. The experimental results indicate that the spray pyrolysis efficiency is higher than that of static pyrolysis process, and the reaction and evaporation process lead to a multi-plot state of the alumina products by spray pyrolysis. Aluminum phase starts to transform into γ-Al2O3 at spray pyrolysis temperature of 600 °C, which is about 200 °C lower than that of static pyrolysis process. The primary particle size of γ-Al2O3 product is 27.62 nm, and Cl content in alumina products is 0.38% at 800 °C for 20 min.展开更多
This study presents a detailed analysis of the catalytic de-oxygenation of the liquid and gaseous pyrolytic products of two biomasses (beech wood and flax shives) using different catalysts (commercial HZSM-5 and H-Y,a...This study presents a detailed analysis of the catalytic de-oxygenation of the liquid and gaseous pyrolytic products of two biomasses (beech wood and flax shives) using different catalysts (commercial HZSM-5 and H-Y,and lab-synthesised Fe-HZSM-5,Fe-H-Y,Pt/Al2O3 and CoMo/Al2O3). The experiments were all conducted in a semi-batch reactor under the same operating conditions for all feed materials. BET specific surface area,BJH pore size distribution and FT-IR technologies have been used to characterise the catalysts,while gas chromatography-mass spectrometry (GC-MS),flame ionisation detection (GC-FID) and thermal conductivity detection (GC-TCD) were used to examine the liquid and gaseous pyrolytic products. It was firstly seen that at higher catalyst-to-biomass ratios of 4∶1,de-oxygenation efficiency did not experience any further significant improvement. FeHZSM-5 was deemed to be the most efficient of the catalysts utilised as it helped reach the lowest oxygen contents in the bio-oils samples and the second best was HZSM-5. It was also found that HZSM-5 and H-Y tended to privilege the decarbonylation route(production of CO),whilst their iron-modified counterparts favoured the decarboxylation one (production of CO2) for both biomasses studied. It was then seen that the major bio-oil components (carboxylic acids) underwent almost complete conversion under catalytic treatment to produce mostly unoxygenated aromatic compounds,phenols and gases like CO and CO2. Finally,phenols were seen to be the family most significantly formed from the actions of all catalysts.展开更多
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-...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.展开更多
The interlayer clay-organic complex is an important clay-organic association in sedimentary environments. The interlayer region of clay minerals not only provides storage space for organic matter, but also possesses s...The interlayer clay-organic complex is an important clay-organic association in sedimentary environments. The interlayer region of clay minerals not only provides storage space for organic matter, but also possesses solid acid sites; and these acid sites were proposed to be involved with the transformation of organic matter into liquid and gaseous hydrocarbons. However, the effect of the organic matter storage in the interlayer space of clay minerals on the hydrocarbons generation has not been made clear. In this study, the interlayer complex of 12-aminolauric acid (ALA) and Na+-montmorillonite (Na+-Mt), labeled as ALAinter-Mt (Na), was synthesized to investigate the role of the interlayer space of montmorillonite in hydrocarbon generation. Simply mixed ALA-Mt complex [ALA-Mt (Na)] was also prepared for comparison. The pyrolysis of ALA and ALA-Mt complexes was studied using thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) and a high temperature-pressure system (a confined gold capsule-autoclave system).展开更多
Activated carbon fiber/carbon nanotube(ACF/CNT) composites were fabricated by chemical vapor deposition(CVD) process.The effects of pyrolysis temperature on properties of ACF/CNT composites,including BET specific surf...Activated carbon fiber/carbon nanotube(ACF/CNT) composites were fabricated by chemical vapor deposition(CVD) process.The effects of pyrolysis temperature on properties of ACF/CNT composites,including BET specific surface area,mass increment rate and adsorption efficiency for rhodamine B in solution,were investigated by scanning electron microscopy.The results show that the pyrolysis temperature is a key factor affecting the qualities of ACF/CNT composites.The mass increment rate and BET specific surface area sharply decrease with the increase of pyrolysis temperatures from 550 ℃ to 850 ℃ and the minimum diameter of CNTs appears at 750 ℃.The maximum adsorption efficiency of ACF/CNT composites for rhodamine B is obtained at 650 ℃.ACF/CNT composites are expected to be useful in adsorption field.展开更多
The pyrolysis of 5-HMF was investigated using density functional theory methods at B3LYP/6-31 G++(d, p) level. Two possible pyrolytic pathways were proposed and full optimization of the energy gradient for the structu...The pyrolysis of 5-HMF was investigated using density functional theory methods at B3LYP/6-31 G++(d, p) level. Two possible pyrolytic pathways were proposed and full optimization of the energy gradient for the structures of reactants, products, intermediates and transition states of various reactions was implemented. The standard kinetic parameters in each reaction pathway were calculated and the formation and evolution mechanism of main pyrolysis products were analyzed. Bond dissociation energies calculation results show that the bond dissociation energy of CH_3—OH of 5-HMF is the lowest and the order of all kinds of bond dissociation energy is CH_3—OH<C—H<CH_3 OH—C_(aromatic)<CHO—C_(aromatic)<C_(aromatic)—H. In pathway(1), the energy barrier of furfural is 322.8 kJ/mol, the energy barrier of 2-furfuryl alcohol is 375.4 kJ/mol; the energy barrier of furan-2,5-dicarbaldehyde is 496.1 kJ/mol; the energy barrier of 5-methyl furfural is 375.8 kJ/mol, and the energy barrier of 2-methyl furan is 375.8 kJ/mol. In pathway(2), the activation energy required for open-loop with H_2O is higher.展开更多
文摘It is important to understand the effects of demineralization on the reactivity of coal pyrolysis for demineralization coal in OCCSS systems.The molecular dynamics of the pyrolysis of ZD-R and ZD-D was investigated using the ReaxFF MD method.It is indicated that the pyrolysis reactivity of ZD-D is enhanced.Acid demineralization treatment helps to enhance the cross-linking reaction of light tar C5-14 molecules in the main pyrolysis stage,generating light tar fragments with higher molecular mass.In the polycondensation pyrolysis stage,the acid demineralization treatment promotes the polycondensation reaction at high temperatures.The generation of H2 in ZD-R pyrolysis is primarily attributed to the N-H bond breaking in pyrrole at low temperatures.At high temperatures,it is predominantly associated with the hydrogen abstraction reaction between carboxyl functional groups and the dehydrogenation reaction of hydrogen bond breaking in the aliphatic hydrocarbon structures.H2O is primarily attributed to the reaction of the hydroxyl group on the carboxyl group.CO_(2) is always related to the carboxyl group.CO is mainly related to the reduction reaction of carbonyl group,carboxyl group,and CO_(2).During the initial pyrolysis stage of ZD-D after acid demineralization treatment,the hydrogen abstraction reaction of the carboxyl functional group and the generation of CO molecules by the methoxy group are enhanced.The generation of H2 by the aliphatic structure is enhanced in the main pyrolysis stage.The ring-opening reaction of the phenoxy group to generate CO in the polycondensation pyrolysis stage is also facilitated.
基金Projects(2022YFC2905800,2021YFC2901000)supported by the National Key R&D Program of ChinaProject(52174242)supported by the National Science and Technology of ChinaProject(52130406)supported by the National Science and Technology Major Project of China。
文摘Roasting bastnaesite concentrates is a crucial process in extracting rare earths.This study explored an efficient suspension roasting technology and investigated the bastnaesite pyrolysis and cerium(Ce)oxidation.Relevant analytical tests were applied to evaluate the phase and surface property variations of bastnaesite,and isothermal kinetic analysis of bastnaesite pyrolysis and Ce oxidation was performed.The results revealed that bastnaesite decomposed rapidly and accompanied by Ce oxidation,and the gas-solid products were identified as CO_(2),Ce_(7)O_(12),La_(2)O_(3),CeF_(3) and LaF_(3),with Ce oxidation restricted by bastnaesite pyrolysis.As roasting time prolonged,cracks and pores appeared on bastnaesite surface;the BET specific surface and pore diameter increased.In later roasting period,the pore diameter continued to increase but the specific surface decreased,assigned to particle fusion agglomeration and pore consolidation.Additionally,the surface C content reduced and Ce(Ⅳ)content increased gradually as roasting progressed.The reaction kinetics all followed Avrami-Erofeev equations,the reaction orders of bastnaesite pyrolysis and Ce oxidation decreased with decreasing reaction temperature.The calculated activation energies at lower temperatures were higher than those calculated at higher temperatures.This study analyzed the bastnaesite reaction mechanism to supply a reference for the application of suspension roasting technology in bastnaesite smelting.
基金supported by the National Natural Science Foundation of China,China(Grant Nos.U20B2018,U21B2086,11972087)。
文摘A novel design of micro-aluminum(μAl)powder coated with bi-/tri-component alloy layer,such as:Ni-P and Ni-P-Cu(namely,Al@Ni-P,Al@Ni-P-Cu,respectively),as combustion catalysts,were introduced to release its huge energy inside Al-core and promote rapid pyrolysis of ammonium perchlorate(AP)at a lower temperature in aluminized propellants.The microstructure of Al@Ni-P-Cu demonstrates that a three-layer Ni-P-Cu shell,with the thickness of~100 nm,is uniformly supported byμAl carrier(fuel unit),which has an amorphous surface with a thickness of~2.3 nm(catalytic unit).The peak temperature of AP with the addition of Al@Ni-P-Cu(3.5%)could significantly drop to 316.2℃ at high-temperature thermal decomposition,reduced by 124.3℃,in comparison to that of pure AP with 440.5℃.It illustrated that the introduction of Al@Ni-P-Cu could weaken or even eliminate the obstacle of AP pyrolysis due to its reduction of activation energy with 118.28 kJ/mol.The laser ignition results showed that the ignition delay time of Al@Ni-P-Cu/AP mixture with 78 ms in air is shorter than that of Al@Ni-P/AP(118 ms),decreased by 33.90%.Those astonishing breakthroughs were attributed to the synergistic effects of adequate active sites on amorphous surface and oxidation exothermic reactions(7597.7 J/g)of Al@Ni-P-Cu,resulting in accelerated mass and/or heat transfer rate to catalyze AP pyrolysis and combustion.Moreover,it is believed to provide an alternative Al-based combustion catalyst for propellant designer,to promote the development the propellants toward a higher energy.
基金supported by the National Natural Science Foundation of China(21576046)the Innovation Team Support Program in Key Areas of the Dalian Science and Technology Bureau(2019RT10).
文摘Coal pyrolysis integrated with dry reforming of low-carbon alkane(CP-DRA)is an effective way to improve tar yield.Ni/La_(2)O_(3)-ZrO_(2) with a La/Zr ratio of 4 was a good catalyst for DRA to inhibit carbon deposition and obtain high tar yield in CP-DRA.In this study,the fraction distribution and component of tars from CP-DRA and coal pyrolysis in N_(2) atmosphere(CP-N_(2))were characterized by using several methods to understand the effect of DRA on coal pyrolysis.The isotope trace method was also used to discuss the role of low-carbon alkane in CP-DRA.The results showed that the tar from CP-N_(2)is mainly composed of aliphatic compounds with more C_(al),H_(al) and CH+CH_(2),and the tar from CP-DRA contains more Car,Har,and CH_(3),and has lower weight-average molecular weight and more light tar content than CP-N_(2).A small amount of C_(2)H_(6) addition in CP-DRA will raise the ratio of H_(β) and CH+CH_(2).Electron paramagnetic resonance(EPR)analysis shows that the tar from CP-DRA has a higher radical concentration while the corresponding char has a lower radical concentration.The isotope trace experiment showed that alkanes provide·H,·CH_(3),etc.to stabilize the radicals from coal pyrolysis and result in more alkyl aromatic compounds during CP-DRA.
基金Project(21707056)supported by the National Natural Science Foundation of ChinaProject(20192BAB203019)supported by the Natural Science Foundation of Jiangxi Province,China。
文摘Four sewage sludge(SS)feedstocks with distinct properties were converted into biochars by pyrolysis at 300−700℃,in order to clarify the effects of the composition difference of SS feedstocks.The yields of biochars present a positive correlation with the contents of ash in SS.Notedly,the contents of organic matter(OM)in SS largely determine the quality of biochars.SS feedstocks with high content of OM are more likely to form stable biochars with higher aromaticity/carbonization degree,and the formed biochars possess higher calorific values.The contents of residual OM in biochars derived from SS feedstocks with low content of OM likely fail to meet the needs of soil improvement(10 wt.%).Most of heavy metals(HMs)existing in raw SS are remained in biochars after pyrolysis.The biochar produced from SS feedstocks with high content of HMs usually contains higher contents of HMs.Surprisingly,the leachability of HMs in biochars is all weakened to some extent compared to raw SS.In addition,the biochars show higher thermal stability and pH values,and P/K nutrients are enriched in biochars.The biochars prepared from four SS feedstocks exhibit different adsorption ability of methylene blue,especially at low dosage of biochar.
基金Project(2006AA06Z375) supported by the National High-tech Research and Development Program of China
文摘Thermal decomposition of waste epoxy PCBs was performed in different atmospheres （nitrogen, argon, air and vacuum） at a heating rate of 10 ℃/rain by DSC-TGA, and the pyrolysis characteristic was analyzed. The gases volatilized from the experiment were qualitatively analyzed by TG-FTIR. Kinetics study shows that pyrolysis reaction takes place between 300 and 400℃, and the activation energies are 256, 212 and 186.2 kJ/mol in nitrogen, argon and vacuum, respectively. There are two mass-loss processes in the decomposition under air atmosphere. In the first mass-loss process, the decomposition is the main reaction, and in the second process, the oxidation is the main reaction. The activation energy of the second mass-loss process is 99.6 kJ/mol by isothermal heat-treatments. TG-FTIR analysis shows carbon dioxide, carbon monoxide, hydrogen bromide, phenol and substituent phenol are given off during the pyrolysis of waste epoxy PCBs.
基金Project(50378062)supported by the National Natural Science Foundation of ChinaProject(09JCYBJC08100)supported by the Natural Science Foundation of Tianjin Municipality,ChinaProject supported by Key Laboratory Program of the Ministry of Education,China
文摘Thermogravimetric study of rubber compositions （operating glove and catheter） in medical waste was carried out using the thermogravimetric analyser （TGA）,at the heating rate of 20 ℃/min in a stream of N2.The results indicate that the decomposition process of operating glove appears an obvious mass loss stage at 250-485 ℃,while catheter has two obvious stages at 240-510 ℃ and 655-800 ℃,respectively; both samples present endothermic pyrolysis reaction; the decomposition of operating glove and the first mass loss stage of catheter are in agreement with natural rubber pyrolysis; the second mass loss stage of catheter corresponds to CaCO3 decomposition.Based on the experimental results,a novel two-step four-reaction model was established to simulate the whole continuous processes,which could more satisfactorily describe and predict the pyrolysis processes of rubber compositions,being more mechanistic and conveniently serving for the engineering.
基金Project(NCET-07-0228)support by the New Century Excellent Talents in University
文摘Two-dimensional plain-weave silicon carbide fiber fabric reinforced silicon carbide(2D-SiC/SiC)composites were molded by stacking method and densified through precursor infiltration and pyrolysis(PIP)process.SiC coating was deposited as the fiber/matrix interphase layer by chemical vapor deposition(CVD)technique.Fiber/matrix debonding and relatively long fiber pullouts were observed on the fracture surfaces.Additionally,the flexural strength and elastic modulus of the composites with and without fiber/matrix interphase layer were investigated using three-point bending test and single-edge notched beam test.The results show that the fiber fraction and the porosity of 2D-SiC/SiC composites with and without coating are 27.2%(volume fraction)and 11.1%,and 40.7%(volume fraction)and 7.5%,respectively.And the flexural strength and elastic modulus of 2D-SiC/SiC composites with and without coating are 363.3 MPa and 127.8 GPa,and 180.2 MPa and 97.2 GPa,respectively.With a proper thickness,the coating can effectively adjust the fiber/matrix interface,thus causing a dramatic increase in the mechanical properties of the composites.
基金supported by Erzincan University Scientific Research Project(Project No:09.02.01)and Tübitak-Bideb National Scholarship Program for PhD S tudent
文摘In this study,Tungsten Oxide(WO_3)thin films were prepared by Chemical Spray Pyrolysis(CSP)and Spin Coating(SC)techniques and it was investigated effects of technique and parameter on the films.WO_3 thin films were deposited on ITO(Indium Tin Oxide)coated glasses.The structural,optical and electrochromic properties of the WO_3 thin films were characterized by XRD,SEM,UV,and CV measurements.The sharpest(200)peak was observed in the XRD spectra and optical band gaps were calculated around 2.6～3.1 eVvia UV-Vis spectra for all of the samples.Micro fibrous reticulated surface(filamentous like)morphology for the films deposited by CSP technique and smooth surface morphology with high optical transmittance for the film deposited by SC Technique were obtained from SEM images.In addition to these results,it was revealed that all the samples exhibit good electrochromic performance.
基金supported by the Ministry of Science, Research & Technology of Iran
文摘Biomass is a kind of renewable energy which is used increasingly in different types of combustion systems or in the production of fuels like bio-oil. Lycopodium is a cellulosic particle, with good combustion properties, of which microscopic images show that these particles have spherical shapes with identical diameters of 31 μm. The measured density of these particles is 1.0779 g/cm2. Lycopodium particles contain 64.06% carbon, 25.56% oxygen, 8.55% hydrogen and 1.83% nitrogen, and no sulfur. Thermogravimetric analysis in the nitrogen environment indicates that the maximum of particle mass reduction occurs in the temperature range of 250-550 ℃ where the maximum mass reduction in the DTG diagrams also occurs in. In the oxygen environment, an additional peak can also be observed in the temperature range of 500-600 ℃, which points to solid phase combustion and ignition temperature of lycopodium particles. The kinetics of reactions is determined by curve fitting and minimization of error.
文摘The pyrolysis dechlorination of PVC (polyvinyl chloride) has been carried out by batch operation under atmospheric pressure. The kinetics involved in the PVC thermal decomposition was studied by using thermogravimetric technique. Several tests were carried out at the heating rate of 5-10℃/min, the yields of products and the distribution of chlorine were also studied. The kinetic parameters such as activation energies, reaction orders and preexponential factors under nitrogen atmosphere were calculated by applying Friedman’s method. The results showed that the PVC thermal degradation is substantially a two-step process. The first step mainly involves dechlorination of the polymers. HCI is the main volatile product and this reaction can be seen as a first-order reaction. A kinetic model for the thermal dechlorination of PVC has been developed.
文摘Decreasing in emissions of greenhouse gases to confront the global warming needs to replace fossil fuels as the main doer of the world climate changes by renewable and clean fuels produced from biomass like wood waste which is neutral on the amount of CO2. An analytical and engineering model for pyrolysis process of a single biomass particle has been presented. Using a two-stage semi global kinetic model which includes both primary and secondary reactions, the effects of parameters like shape and size of particle as well as porosity on the particle temperature profile and product yields have been investigated. Comparison of the obtained results with experimental data shows that our results are in a reasonable agreement with previous researchers' works. Finally, a sensitivity analysis is done to determine the importance of each parameter on pyrolysis of a single biomass particle which is affected by many constant parameters.
基金Supported by Key Project of Natural Science in Guangdong Province (06Z004)Science and Technology Projects in Guangdong (2009B050600008)
文摘Hydrogen rich gas was produced using rice husk as biomass material on the continuous biomass pyrolysis apparatus which consisted of continuous pyrolysis reactor and secondary catalytic cracking reactor. Ni based catalysts of different Ni/Al mass ratio and calcined temperature were prepared by impregnating method. The catalysts were characterized by X-ray diffraction （XRD）, scan electron microscope （SEM） and FT-IR Spectrometer （FT-IR）. Ni based catalyst showed good selectivity for H2 production from biomass. Catalysts prepared under different conditions had little influence on the yields of three states products when used at the same cracking temperature. Ni/Al mass ratio played an important role in products selectivity. However, the content of NiO increased further when Ni/Al mass ratio values reached 0.7 ： 10, and the yield of H2 slightly increased. Hydrogen yield was greatly impacted by calcined temperature. Catalyst calcined at 550℃performed best. When the catalyst was calcined at high temperature, NiO in the catalyst transformed into NiAl2O4, and the acid site also changed, which caused the deactivation of the catalyst. The hydrogen yield increased with the cracking temperature. The highest stable yield of hydrogen was about 30% without increasing with the cracking temperature.
基金Project(50604018) supported by the National Natural Science Foundation of China
文摘With citric acid as a polymeric agent layered LiNi0.8Co0.2O2 materials were synthesized by a spray pyrolysis method. The LiNi0.sCo0.2O2 particles were characterized by means of XRD, SEM and TEM. The electrochemical performances of LiNi0.8Co0.2O2 particles were studied in a voltage window of 3.00-4.35 V and at a current density of 30 mA/g. The results show that in the pilot-scale spray pyrolysis process, the morphology of particles is dependent upon the precursor concentration and flux of carrier gas. The initial discharge capacity of the LiNi0.8Co0.2O2particles at 720 ℃ for 12 h is 187.3 mA.h/g, and the capacity remains 96.8% with excellent cycleability after 30 cycles. The LiNi0.8Co0.2O2 samples synthesized under the optimized conditions by the spray pyrolysis method shows a good electrochemical performance.
基金Projects(U1202274,51004033,51204040)supported by the National Natural Science Foundation of ChinaProject(2012AA062303)supported by the National High Technology Research and Development Program of China+2 种基金Project(2012BAE01B02)supported by the National Science and Technology Support Program of ChinaProject(L2014096)supported by the Education Department of Liaoning Province,ChinaProject(N130702001)supported by the Fundamental Research Funds for the Central Universities,China
文摘The effects of pyrolysis mode and pyrolysis parameters on Cl content in alumina were investigated, and the alumina products were characterized by XRD, SEM and ASAP. The experimental results indicate that the spray pyrolysis efficiency is higher than that of static pyrolysis process, and the reaction and evaporation process lead to a multi-plot state of the alumina products by spray pyrolysis. Aluminum phase starts to transform into γ-Al2O3 at spray pyrolysis temperature of 600 °C, which is about 200 °C lower than that of static pyrolysis process. The primary particle size of γ-Al2O3 product is 27.62 nm, and Cl content in alumina products is 0.38% at 800 °C for 20 min.
基金supported by the European Union with the European Regional Development Fund(ERDF)the Regional Council of Normandie
文摘This study presents a detailed analysis of the catalytic de-oxygenation of the liquid and gaseous pyrolytic products of two biomasses (beech wood and flax shives) using different catalysts (commercial HZSM-5 and H-Y,and lab-synthesised Fe-HZSM-5,Fe-H-Y,Pt/Al2O3 and CoMo/Al2O3). The experiments were all conducted in a semi-batch reactor under the same operating conditions for all feed materials. BET specific surface area,BJH pore size distribution and FT-IR technologies have been used to characterise the catalysts,while gas chromatography-mass spectrometry (GC-MS),flame ionisation detection (GC-FID) and thermal conductivity detection (GC-TCD) were used to examine the liquid and gaseous pyrolytic products. It was firstly seen that at higher catalyst-to-biomass ratios of 4∶1,de-oxygenation efficiency did not experience any further significant improvement. FeHZSM-5 was deemed to be the most efficient of the catalysts utilised as it helped reach the lowest oxygen contents in the bio-oils samples and the second best was HZSM-5. It was also found that HZSM-5 and H-Y tended to privilege the decarbonylation route(production of CO),whilst their iron-modified counterparts favoured the decarboxylation one (production of CO2) for both biomasses studied. It was then seen that the major bio-oil components (carboxylic acids) underwent almost complete conversion under catalytic treatment to produce mostly unoxygenated aromatic compounds,phenols and gases like CO and CO2. Finally,phenols were seen to be the family most significantly formed from the actions of all catalysts.
文摘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.
文摘The interlayer clay-organic complex is an important clay-organic association in sedimentary environments. The interlayer region of clay minerals not only provides storage space for organic matter, but also possesses solid acid sites; and these acid sites were proposed to be involved with the transformation of organic matter into liquid and gaseous hydrocarbons. However, the effect of the organic matter storage in the interlayer space of clay minerals on the hydrocarbons generation has not been made clear. In this study, the interlayer complex of 12-aminolauric acid (ALA) and Na+-montmorillonite (Na+-Mt), labeled as ALAinter-Mt (Na), was synthesized to investigate the role of the interlayer space of montmorillonite in hydrocarbon generation. Simply mixed ALA-Mt complex [ALA-Mt (Na)] was also prepared for comparison. The pyrolysis of ALA and ALA-Mt complexes was studied using thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) and a high temperature-pressure system (a confined gold capsule-autoclave system).
基金Project(50802115) supported by the National Natural Science Foundation of ChinaProject(2010FJ4075) supported by the Science and Technology Plan of Hunan ProvinceProject(CDJJ-10010205) supported by Changsha University
文摘Activated carbon fiber/carbon nanotube(ACF/CNT) composites were fabricated by chemical vapor deposition(CVD) process.The effects of pyrolysis temperature on properties of ACF/CNT composites,including BET specific surface area,mass increment rate and adsorption efficiency for rhodamine B in solution,were investigated by scanning electron microscopy.The results show that the pyrolysis temperature is a key factor affecting the qualities of ACF/CNT composites.The mass increment rate and BET specific surface area sharply decrease with the increase of pyrolysis temperatures from 550 ℃ to 850 ℃ and the minimum diameter of CNTs appears at 750 ℃.The maximum adsorption efficiency of ACF/CNT composites for rhodamine B is obtained at 650 ℃.ACF/CNT composites are expected to be useful in adsorption field.
基金Project(51276023)supported by the National Natural Science Foundation of China
文摘The pyrolysis of 5-HMF was investigated using density functional theory methods at B3LYP/6-31 G++(d, p) level. Two possible pyrolytic pathways were proposed and full optimization of the energy gradient for the structures of reactants, products, intermediates and transition states of various reactions was implemented. The standard kinetic parameters in each reaction pathway were calculated and the formation and evolution mechanism of main pyrolysis products were analyzed. Bond dissociation energies calculation results show that the bond dissociation energy of CH_3—OH of 5-HMF is the lowest and the order of all kinds of bond dissociation energy is CH_3—OH<C—H<CH_3 OH—C_(aromatic)<CHO—C_(aromatic)<C_(aromatic)—H. In pathway(1), the energy barrier of furfural is 322.8 kJ/mol, the energy barrier of 2-furfuryl alcohol is 375.4 kJ/mol; the energy barrier of furan-2,5-dicarbaldehyde is 496.1 kJ/mol; the energy barrier of 5-methyl furfural is 375.8 kJ/mol, and the energy barrier of 2-methyl furan is 375.8 kJ/mol. In pathway(2), the activation energy required for open-loop with H_2O is higher.
