Characterization of Pr-CeO_2 Nano-crystallites Prepared by Low-temperature Combustion&Hydrothermal Synthesis

Pr-CeO2 Nano-crystalline red pigments were prepared by low-temperature combustion with a later hydrothermal treatment using Ce（NO3）3·6H2O and Pr6O11 as raw materials. The phase composition, coloring mechanism and morphology of pigments were analyzed by XRD, SEM, EDS and XPS. Results showed that Pr-CeO2 solid solution with a fluorite structure was obtained by the diffusion of Pr^＋3 into CeO2 crystal lattice during the synthesis process. XPS analysis indicated that Pr^＋3 substitutes Ce^＋4 in CeO2 and is compensated by oxygen vacancies. Compared with low-temperature combustion synthesis, the Pr-CeO2 pigments prepared with a subsequent hydrothermal treatment have an average grain size of about 16.70 nm, and the crystallinity and red tonality are improved.

Screening non-noble metal oxides to boost the low-temperature combustion of polyethylene waste in air

Globally,the efficient utilization of polymer wastes is one of the most important issues for current sustainable development topics.Herein,a green and efficient low-temperature combustion approach is proposed to deal with polymer wastes and recover heat energy,simultaneously alleviating the environment and energy crisis.Non-noble metal oxides(Al_(2)O_(3),Fe_(2)O_(3),NiO_(2),ZrO_(2),La_(2)O_(3)and CeO_(2)) were prepared,characterized and screened to boost the low-temperature combustion of polyethylene waste at 300℃ in air.The mass change,heat release and CO_(x) formation were studied in details and employed to evaluate the combustion rate and efficiency.It was found that CeO_(2)significantly enhanced the combustion rate and efficiency,which was respectively 2 and 7 times that of non-catalytic case.An interesting phenomenon was observed that the catalytic performance of CeO_(2) in polyethylene low-temperature combustion was significantly improved by the 7-day storage in the room environment or water treatment.XPS analysis confirmed the co-existence of Ce^(3+) and Ce^(4+) in CeO_(2),and the 7-day storage and water treatment promoted the amount of Ce^(3+),which facilitated the formation of the oxygen vacancies.That may be the reason why CeO_(2) exhibited excellent catalytic performance in polyethylene low-temperature combustion.

Catalytic performance and kinetics of Au/γ-Al_2O_3 catalysts for low-temperature combustion of light alcohols

Au/γ-Al2O3 catalysts were prepared by deposition-precipitation method for the catalytic combustion of low concentration alcohol streams(methanol,ethanol,iso-propanol and n-propanol).The catalysts were characterized by X-ray photoelectron spectroscopy(XPS),X-ray diffractometry(XRD) and energy dispersive X-ray micro analysis(EDS) techniques.The XPS results showed that there was only Au0 on the surface of catalysts.The XRD patterns showed that Au was presumably highly dispersed over γ-Al2O3.The temperatures for complete conversion of methanol,ethanol,iso-propanol and n-propanol with concentration of 2.0 g/m3 were 60,155,170 and 137 ℃,respectively,but they were completely mineralized into CO2 and H2O at 60,220,260 and 217 ℃ respectively over the optimized catalyst.The activity of the catalyst was stable in 130 h.The kinetics for the catalytic methanol elimination followed quasi-first order reaction expressed as r=0.652 8c0+0.084 2.The value of apparent activation energy is 54.7 kJ/mol in the range of reaction temperature.

Construction of a macromolecular structural model of Chinese lignite and analysis of its low-temperature oxidation behavior

The aim of this paper is to analyze the change in the active structure of lignite during the process of lowtemperature oxidation by constructing a molecular structure model for lignite. Using quantum computation combined with experimental results of proximate analysis, ultimate analysis, Fourier transform infrared spectroscopy(FTIR) and X-ray photoelectron spectroscopy(XPS), a structural model for the large molecular structure was constructed. By analyzing the bond lengths in the model molecule, the evolution law for the active structure of lignite was predicted for the process of low-temperature oxidation. In low-temperature oxidation,alkanes and hydroxyls are the primary active structures observed in lignite, though ether may also react. These active functional groups react with oxygen to release heat, thereby speeding up the reaction between coal and oxygen. Finally, the content of various functional groups in the process of lignite low-temperature oxidation was analyzed by infrared analysis, and the accuracy of the model was verified.

Molecular composition of low-temperature oxidation products of the heavy oil

Low-temperature oxidation(LTO)is the main reaction that affects fuel formation in the in-situ combustion process,which has important significance for the subsequent combustion propulsion and the successful extraction of crude oil.In this study,heavy oil was subjected to LTO reactions at different temperatures.Three types of reaction products with varying oxidation depths were characterized in terms of the number of oxygen atoms and the polarity of the molecule to reveal the low-temperature oxidation process of the heavy oil.Ketone compounds and acid polyoxides in the oil phase and deep oxidation products with a higher number of oxygen atoms in the coke were identified with increasing oxidation depth.The experimental results showed that the oxidation reaction of the heavy oil changed from kinetic-controlled to diffusion-controlled in the open oxidation system of the heavy oil as the oxidation depth increased.The oxidation reaction of the oil phase reached a maximum and stable value in oxygen content.The molecular compositions of the ketone compound and acid polyoxide did not change significantly with further increase in reaction temperature.The molecular compositions of the deep oxidation products with a higher number of oxygen atoms in the coke phase changed significantly.The coke precursor molecules with a lower oxygen content and condensation degree participated in the coke formation,and the oxidation reaction pathway and the complexity of the oxidation product component also increased.

The Feasibility of Applying AC Driven Low-Temperature Plasma for Multi-Cycle Detonation Initiation

Ignition is a key system in pulse detonation engines （PDE）. As advanced ignition methods, nanosecond pulse discharge low-temperature plasma ignition is used in some combustion systems, and continuous alternating current （AC） driven low-temperature plasma using dielectric barrier discharge （DBD） is used for the combustion assistant. However, continuous AC driven plasmas cannot be used for ignition in pulse detonation engines. In this paper, experimental and numerical studies of pneumatic valve PDE using an AC driven low-temperature plasma igniter were described. The pneumatic valve was jointly designed with the low-temperature plasma igniter, and the numerical simulation of the cold-state flow field in the pneumatic valve showed that a complex flow in the discharge area, along with low speed, was beneficial for successful ignition. In the experiments ethylene was used as the fuel and air as oxidizing agent, ignition by an AC driven low-temperature plasma achieved multi-cycle intermittent detonation combustion on a PDE, the working frequency of the PDE reached 15 Hz and the peak pressure of the detonation wave was approximately 2.0 MPa. The experimental verifications of the feasibility in PDE ignition expanded the application field of AC driven low-temperature plasma.

Low-Temperature Reforming Products Coupling Spark Plug on Gasoline Compression Ignition and Combustion Characteristics under Low-Load Condition

Gasoline compression combustion engine has the advantages of low emission and high efficiency,which is very promising for research,but it is difficult to apply under low-load conditions.Gasoline has the characteristics of low reactivity;in the case of low thermodynamic state in the cylinder,the fire delay period of the fuel is longer,and the combustion phase is relatively lagging,which will lead to the increase of combustion cycle fluctuations,and even difficult to ignite and other adverse combustion phenomena.In order to improve the combustion stability of Gasoline Compression Ignition(GCI)engine under low-load condition and expand the limit of low-load combustion boundary,gasoline was reformed without catalyst under the boundary condition of reforming temperature of 488 K and reforming equivalent ratio of 8,and the concentration of reformed product was measured by a gas detection device.Subsequently,the coupling of the reformed product and spark plug with GCI engine under low-load condition was investigated to analyze the effect on engine combustion and emission.The results showed that the initial combustion timing of the low-load GCI engine was late,but the addition of reformed products could advance the combustion phase,shorten the combustion duration,reduce single-cycle NOx emission,and improve the small-load operation characteristics of GCI engine.Coupled spark plug ignition on the basis of adding reformed products could further improve the problem of combustion stability under low-load GCI engine.And the optimization effect became more obvious as the ignition position of the spark plug moves down.However,spark plug ignition would cause local high temperature areas,resulting in an increase in NOx,emission.

燃气轮机燃烧室燃烧天然气和燃烧中低热值煤气的比较

本文使用商业软件FLUENT,对某燃气轮机燃烧室燃烧大然气和燃烧中低热值煤气进行了比较。原本燃烧天然气的燃烧室直接改为燃烧中低热值煤气,会产生燃料射流速度太快的问题,使阻燃孔失效,火焰太长,高温燃气直接冲击下简壁出口。仅仅增大燃料喷嘴口径可以在一定程度上改善燃烧室内流动结构,使掺混孔起一定的作用,气膜冷却射流也将高温区抬离了下简壁。

变截面管内燃煤烟气PM2.5声波团聚实验研究

声波团聚PM_（2.5）减排工业应用的瓶颈问题包括缺乏大功率高效强声源和能耗过高等。基于气流声源（高频旋笛）和突变截面驻波管建立了160dB以上燃煤烟气声波团聚实验系统。系统设计中,通过团聚敏感频率与驻波管共振频率相匹配,在相同输入声功率前提下提高了管内声强和团聚效率,并通过复合透声板实现了团聚舱内功率气流与强声场的分离。通过模态分析法和有限元模型研究了舱内声场特性和共振频率的影响因素。实验研究了500Hz至1.5kHz宽频范围内舱内强声信号和共振工况条件,对比了不同频率和声压级条件下烟气中5μm以下粒径的分布变化。结果表明,全频段内声压级获得5dB至15dB的共振增益,700Hz最大基频声压级达到167dB。烟气团聚较优频率为700Hz和1.4kHz,PM2.5减排效率最高99%,达到了PM2.5高效脱除和提高声能利用率的目的。

氮气压力和稀释剂对燃烧合成β-Sialon的影响

以Si、al、Al2O3和Si3N4粉末为原料，采用燃烧合成工艺，在高氮气压力下制备了单相β-Sialon（z≈0．5～2．0）粉末；并详细讨论了氮气压力和稀释剂的量对燃烧产物的相组成和显微结构的影响．

氧化铁成分对合成SHS复合弯管内衬陶瓷的影响

基于重力分离SHS法制备陶瓷内衬复合弯管 ,研究了氧化铁粉末化学组成对SHS复合弯管内衬陶瓷的影响。研究发现 :在加入相同质量分数铝热剂条件下 ,存在于工业原料Fe2 O3粉末中的杂质对燃烧过程的稀释效应比SiO2 添加剂更为强烈 ;在工业原料Fe2 O3+Al体系中加入适量的Fe3O4+Al体系 ,使燃烧温度、蔓延速率及SHS反应转化率均有所提高 ;但加入过量的Fe3O4+Al体系 ,虽可使蔓延速率进一步增大 ,却引起燃烧温度和SHS反应转化率有所下降。实验表明 ,在工业原料Fe2 O3+Al体系中加入 15%的Fe3O4+Al体系 ,可使复合弯管内衬陶瓷性能达到并超过用分析纯Fe2 O3+Al体系所制备的复合弯管内衬陶瓷性能。

燃烧法制备LiFePO_4及其燃烧机制（英文）

许多合成磷酸铁锂（LFP）的传统方法具有反应时间长或者Fe^2＋易氧化的缺点.使用硫酸亚铁、磷酸氢二铵和硝酸锂为主要原料,通过燃烧法制备LFP,由XRD和TG-DSC表征所得样品.结果表明,该燃烧法可以在600℃短时间内合成较纯的LFP,并且不需要通入保护气体.对燃烧机制的研究表明,从120~290℃,干凝胶的燃烧导致有机柠檬酸的自蔓延燃烧反应,同时引入的碳防止Fe^2＋的氧化,并且当φ=n（CA）/n（LFP）=2时,是合成LFP材料柠檬酸的最佳用量.

SrIn_2O_4∶Sm^(3+)红色荧光粉的发光特性

采用燃烧法合成了SrIn2O4:Sm3+红色荧光粉并研究了其发光性质。发射光谱由位于红橙区的3个主要荧光发射峰组成,峰值分别为568,606,660nm,对应Sm3+的4G5/2→6H5/2、4G5/2→6H7/2和4G5/2→6H9/2特征跃迁发射,其中606nm的发射最强。激发光谱包括峰值位于323,413nm的宽带,说明该荧光粉可以被近紫外-紫色发光二极管管芯激发发射红光。研究了Sm3+的掺杂浓度对样品发光强度的影响。实验结果表明SrIn2O4:Sm3+是一种可用于制作白光LED的红色荧光粉。

Preparation of Nano-MnFe2O4 and Its Catalytic Performance of Thermal Decomposition of Ammonium Perchlorate

Nano-MnFe2O4 particles were synthesized by co-precipitation phase inversion method and low-temperature combustion method respectively, using MnCl2, FeCl3, Mn（NO3）2, Fe（NO3）3, NaOH and C6H8O7. X-ray diffraction （XRD）, transmission electron microscope （TEM）, Fourier transform infrared spectroscopy （FT-IR）, thermogravim-etry-differential thermal analysis （TG-DTA） and differential scanning calorimetry （DSC） were used to characterize the structure, morphology, thermal stability of MnFe2O4 and its catalytic performance to ammonium perchlorate. Results showed that single-phased and uniform spinel MnFe2O4 was obtained. The average particle size was about 30 and 20 nm. The infrared absorption peaks appeared at about 420 and 574 cm-1, and the particles were stable below 524 ℃. Using the two prepared catalysts, the higher thermal decomposition temperature of ammonium perchlorate was decreased by 77.3 and 84.9 ℃ respectively, while the apparent decomposition heat was increased by 482.5 and 574.3 J？g？1. The catalytic mechanism could be explained by the favorable electron transfer space provided by outer d orbit of transition metal ions and the high specific surface absorption effect of MnFe2O4 particles.

乌石化二合成氨装置工艺特点及投料试车总结

对乌石化二合成氨生产装置的特点做了较全面的介绍，并对装置从１９９７年３月２２日一段转化炉点火，４月７日化工投料，直至５月２３日出合格氨产品的整个试车过程做了系统的总结。

Quantitative behavior of vibrational excitation in AC plasma assisted dry reforming of methane

Quantitative behavior of non-equilibrium excitation by direct electron impact in low-temperature dry reforming of methane was investigated by integrated studies of experimental validation and kinetic modeling.A plasma chemistry kinetic mechanism incorporating the reactions involving vibrational excitation of CH4,CO2,H2 and CO molecules as well as the low temperature He/CH4/CO2 conversion pathways was developed and validated.The calculation results showed that at lower E/N values(<150 Td)large population of energized electrons generated in a He/CH4/CO2 discharge resulted in an intensification of vibrational excitation.Despite the large generation of vibration,the vibrationally excited molecules in a 0.5/0.25/0.25 of He/CH4/CO2 discharge mixture were easy to relax,due to the strong coupling of the vibration of different molecules in a gas mixture.The results showed that the moderate levels of the vibrational excitation,such as CO2(v10,11,...,18)and CO(v9,10),presented most efficient in the stimulation of species generation including CO,CH2 O,CH3 OH,C2 H4 and C2 H6.Specifically,under conditions of E/N of 108 Td,14.9%of CO formation was estimated from the recombination of CO2(v)with CH3 and H,CO2(v)+CH3→CH3 O+CO,CO2(v)+H→CO+OH.Also,4.8%of C2 H4 formation was from the recombination reaction CH4(v)+CH→C2 H4+H.These results highlight the strong roles of vibrational states in a complex plasma chemistry system.

Effect of Heat-treatment Temperature on HA-coated Titanium Materials

Homogeneous HA coating materials were prepared on porous titanium by the low-temperature combustion synthesis. It was found that the mechanical properties of the specimen depend on the coating process and the heat treatment, and the bending strength would be reduced during the coating process but could be improved by heat treatment. The effects of the temperature during heat- treatment on the phase composition and microstructure of the as-prepared coating, and the bending strength of the specimen were investigated by XRD and SEM. The experimental results show that in the coating process, slight oxidation of the substrate may give rise to a drop in bending strength ; however, it could be increased by the reaction of HA and TiO2 , and the sintering of the coating during heat treatment. The HA particles in the coating, with very fine sized particles. were pretty active and would decompose at 800℃.

Low-temperature Heat Capacity and Standard Molar Enthalpy of Formation of Potassium L-Threonate Hydrate K（C4H7O5）·H2O

The solid potassium L-threonate hydrate, K（C4H7O5）·H2O, was synthesized by the reaction of L-threonic acid with aqueous potassium hydrogen carbonate and characterized by means of chemical and elemental analyses, IR and TG-DTG. Low-temperature heat capacity of K（C4H7O5）·H2O has been precisely measured with a small sample precise automated adiabatic calorimeter over the temperature range from 78 to 395 K. An obvious process of the dehydration occurred in the temperature region of 364-382 K. The peak temperature of the dehydration of the compound has been observed to be （380.524±0.093） K by means of the heat capacity measurements. The molar enthalpy, △dHm, and molar entropy, △dSm, of the dehydration of K（C4H7O5）·H2O were calculated to be （19.655 ± 0.012） kJ/mol and （51.618 ± 0.051） J/（K·mol） by the analysis of the heat-capacity curve. The experimental molar heat capacities of the solid from 78 to 362 K and from 382 to 395 K have been respectively fitted to two polynomial equations of heat capacities against the reduced temperatures by least square method. The constant-volume energy of combustion of the compound, △cUm, has been determined to be （- 1749.71 ±0.91） kJ·mol^-1 by an RBC-Ⅱ precision rotary-bomb combustion calorimeter at 298.15 K. The standard molar enthalpy of formation of the compound, △fHm , has been calculated to be （- 1292.56± 1.06） kJ·mol^-1 from the combination of the standard molar enthalpy of combustion of the compound with other auxiliary thermodynamic quantities.

Low-Temperature Heat Capacities and Standard Molar Enthalpy of Formation of Gramine （C11H14N2）

Low-temperature heat capacities of gramine （C11H14N2） were measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 401 K. A polynomial equation of heat capacities as a function of temperature was fitted by least squares method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at 5 K intervals. The constant-volume energy of combustion of the compound at T=298.15 K was measured by a precision oxygen-bomb combustion calorimeter as △cU=-（35336.7±13.9） j·g^-1. The standard molar enthalpy of combustion of the compound was determined to be △cHm=-（6163.2±2.4） kJ·mol^-1, according to the definition of combustion enthalpy. Finally, the standard molar enthalpy of formation of the compound was calculated to be △cHm=-（166.2±2.8） kJ·mol-1 in accordance with Hess law.

Nanosized Carbon Dots from Organic Matter and Biomass

Carbon nanoparticles（C-dots） were prepared by refluxing the combustion soots of candles and corn stalk in nitric acid.The synthesized C-dots were characterized.The results showed a sharp increase in oxygen content and a sharp decrease in carbon content after oxidation.The C-dots had-OH and-CO2H groups introduced which made them hydrophilic.However,their difference was also obvious.The C-dots from candle soot had a 10-45 nm broad particle size distribution,and those from corn stalk soot had a 6-18 nm relatively small and narrow size distribution.The C-dots were mainly of sp2 and sp3 carbon structure different from the C-dots of diamond-like structure from candle soot.Interestingly,two kinds of C-dots all exhibited unique photoluminescent properties.The obtained C-dots have potential applications in a broad range of areas.