煤直接液化残渣热解过程气体产物的析出

采用热重-红外联用(TG-FTIR)技术研究了煤直接液化残渣(DCLR)的热解特性,重点对其热解过程气体的析出规律进行了分析讨论。研究表明,液化残渣热失重分为三个阶段,在405.10 ℃以前为残渣热解第一阶段;405.10～523.83 ℃主要为高沸点油和沥青质等的大量热分解阶段,当温度达到478.45 ℃时,失重速率达到最大值,此时失重量约占总失重的40.27%;523.83 ℃以后残渣的失重曲线较为平缓,失重量约占总失重的50.55%,主要由产物的二次分解和矿物质的热分解所造成。热解过程气体产物的析出也分为三个阶段,第一阶段主要释放的是H₂O和CO₂,第二阶段中析出的主要为CO₂,CH₄,CO、H₂O和少量SO₂,同时在458.4～791.9 ℃范围内伴随着焦油的大量析出,第三阶段主要是CO₂,CO和H₂O的析出。CO₂的释放主要归功于含氧杂环或OCO等含氧基团的断裂,而CO的释放主要由醚键以及含氧杂环热分解造成,脂肪烃的热分解是CH₄释放的主要原因。     

基于TG-FTIR的落叶松木材热失重与热解气相演变规律研究

采用热重红外光谱联用分析法考察了落叶松木材在不同升温速率下的热失重特性及气相演变规律,并与其组分模混物的热解特性进行了对比分析。结果表明,落叶松的主要失重区域相对于模混物较宽,落叶松残炭率(18.97%)相对于模混物(29.83%)较低;在低温段,模混物的活化能高于落叶松木材,而在高温段二者差别不大;落叶松木材热解过程经历了水分析出、主成分热分解、后期炭化等阶段,气体析出主要集中在375℃左右;落叶松在热解反应过程中,主要气体产物生成量顺序为CO2>H2O>CH4>CO,随着升温速率的增加,上述气体产物的生成量明显增多;模混物与落叶松木材热解生成气体规律基本相似,但模混物中各气体析出强度均相对较高。     

麦秆添加大量CaO热解的TG-FTIR实验研究

利用热重-傅里叶变换红外光谱联用方法研究添加CaO对麦秆热解过程和挥发份析出特性的影响.热重和红外光谱分析均表明添加CaO后麦秆热解旱现两个明显的失重和挥发份析出阶段,而纯麦秆热解则只有一个.CaO在第一阶段不但能够吸收CO2,而且能够降低甲苯、苯酚和蚁酸等焦油类物质的产生,使得该阶段失重率和最大失重速率随CaO添加量增加而减小.CaCO3的煅烧分解是添加CaO麦秆热解第二阶段产生的原因,该阶段失重率和最大失重速率随CaO添加量增加而增大.研究结果表明,在采用生物质为原料的零排放系统中添加CaO有利于捕获CO2和减少焦油物质的产生,系统的气化温度应适当降低以防止CaCO3的煅烧分解.     

TG-FTIR法研究低变质煤共热解过程气体的析出规律

采用热重-红外联用技术（TG-FTIR）对比研究了陕北低变质粉煤（SJC）与重油（HS）、焦煤（JM）、液化残渣（DCLR）共热解过程中气相产物的析出特性。研究表明,随热解温度升高,SJC与HS,JM,DCLR的共热解过程均可分为三个阶段。第一阶段表现为原料表面吸附物的释放,第二阶段发生解聚和分解反应,随温度继续升高,第三阶段形成更为稳定的半焦。在热解第二阶段中均存在煤与添加剂之间的协同效应,SJC作为主要的供氢体,热解产生的氢自由基与HS,JM,DCLR热解产生的小分子自由基碎片之间发生相互作用生成焦油和煤气。SJC和SJC+DCLR在450 ℃附近的温度区间内热解反应进行的更加充分,大部分N元素转移到了焦油组分中。热解过程气相产物中H₂O和酚类物质、含N杂环物质及CO的析出伴随着热解的整个温度区间,SJC+JM和SJC+HS热解过程含N物质的转移主要集中在400~650 ℃区间,CH₄和脂肪烃类物质的析出最高峰出现在450 ℃附近,而SJC+DCLR和SJC则出现在550 ℃。JM,HS及DCLR的添加可促使焦油中芳香族化合物的析出,SJC+JM与SJC+HS热解过程芳香族物质大量析出的温度区间在400~550 ℃。该研究结果为低变质粉煤的清洁转化与提质分级新技术的研究开发提供理论依据,对低变质煤的增值利用具有重要的意义。     

生物质和污泥轻度热解的两步反应动力模型

本文对比研究了典型木质纤维生物质和非木质纤维索类生物质的轻度热解特性,并基于多步反应动力学原理,建立了生物质轻度热解的两步反应动力学模型。结果表明:在同样的停留时间下,木质纤维类生物质的失重明显大于非木质纤维类生物质的;两步反应模型能够很好地预测两类生物质的轻度热解过程,并能预测得到平衡失重百分比。     

基于TG-FTIR的圆柏心、边材热解研究

生物质热解是实现生物质废弃物有效处理及生物质材料高效利用的重要途径之一,因此对生物质热解过程及其机理进行研究具有极大的现实意义。木材作为一种来源广泛的可再生材料也是众多生物质热解原料中的一种,由于组成成分等多方面的差别,不同树种的热解特性具有明显差异。然而,同一种木材的心材与边材由于在组织构造、化学组成及其含量等方面有着明显不同,因此在热解特性和产物方面也存在一定的差异,该工作即对此进行深入研究。试验以心、边材区分明显的常见园林绿化物圆柏为试验材料,通过TG-FTIR联用技术分别得到其心、边材热解过程中的热重曲线和挥发分的红外光谱谱图并对其进行分析。结果表明,纤维素、半纤维素、木质素和抽提物含量对心、边材热解特性影响显著。由于圆柏心材半纤维素、木质素含量较高,在热解前期和热解后期具有比边材更大的失重率,而较高的抽提物含量则在一定程度上增加了其在反应中期的失重率,减小了该范围内心、边材失重率的差异;边材纤维素含量较高,因此其在300~380 ℃,失重明显,在DTG曲线中的最大失重速率也较高。在红外图谱中,心、边材热解所产生的挥发分种类几乎相同,但在数量上有差异,当热解达到最大失重速率时,所产生的挥发分明显增加,且整个过程中边材产生的有机酸类化合物更多,而心材相对产生更多的水和CO₂。     

基于TGA-FTIR研究生物质热解过程中氮化物的生成

基于TGA-FTIR联用技术,考察了升温速率对生物质中氮热解转化成NH3和HCN的影响.结果表明,热解的升温速率影响生物质中氮转化的速率和转化的量,升温速率提高,NH3和HCN的生成量减小,NH3和HCN的起始释放温度及达到最大析出值的温度提高.慢速升温热解,HCN的析出与NH3的析出规律相似,但HCN的析出量明显小于NH3的析出量,生物质中氮主要以NH3的形式析出.     

秸秆/城市生活垃圾混合热解过程中硫及氯的析出特性

基于TGA-FTIR联用技术,研究一种高灰分、低热值城市生活垃圾与秸秆(棉秆及玉米秆)在不同质量配比下混合热解过程中气态硫和氯的析出特性.结果表明,城市生活垃圾掺加秸秆后,促进垃圾的热解,CH4及有机物析出增加;随着秸秆掺加比例提高,H2S及SO2的析出量增加,HC1起始析出温度有所降低,但析出量减小.试验结果为城市生活垃圾及秸秆的综合利用提供理论依据.     

纤维素、木质素含量对生物质热解气化特性影响的实验研究

本文采用化学方法测定了六种生物质中纤维素和木质素的含量,通过热重研究了实际生物质及用纤维素、木质素按一定比例混合模拟生物质的热解和气化特性,并结合电子扫描电镜(SEM)对焦样进行了微观形貌分析.结果表明:在本文所选择的生物质中纤维素的含量高于木质素,两者一般在55%～85%和10%～35%.生物质热解分为纤维素热解和木质素分解两个阶段,应于气化过程中挥发份析出和焦炭气化.在热解过程中,首先纤维素发生热解呈现快速失重过程,接着木质素缓慢热解.实验发现生物质中纤维素含量越高,热解反应速率就越大;反之,木质素含量越高,热解反应速率越小.通过对焦形貌与气化研究,发现气化特性与生物质中纤维素和木质素的含量有着密切联系.因此纤维素、木质素含量是影响生物质热解气化特性的重要因素之一.     

聚氨酯的FTIR光谱与热分析研究

采用原位傅里叶变换红外光谱法,研究了聚酯型聚氨酯和聚醚型聚氨酯在空气气氛中从室温到400 ℃之间的热解反应,实时考察了其在不同温度条件下分解残留物的基团特性。利用热分析技术考察了它们在不同气氛下从室温到700 ℃之间的热解反应。探讨了在有氧条件下的热解反应机理。结果表明聚酯型聚氨酯在空气中存在硬段和软段先后分解的两个阶段,而聚醚型聚氨酯则是硬段与软段同时分解。热分解结果也显示,硬段相同的聚氨酯,聚酯型聚氨酯的起始失重温度高于聚醚型聚氨酯,显示聚酯型的热稳定性强于聚醚型。同时聚氨酯在空气中的起始失重温度比在氮气中提前,说明氧气的存在能促进聚氨酯主链上C—C和C—O键的断裂。     

Effect of Annealing Treatment on Meta-poly(arylene sulfide sulfone amide)

A useful annealing treatment above glass transition temperature of high molecular weight amorphous m-poly(arylene sulfide sulfone amide) (m-PASSA) was employed in this work. No crystalline or cross-link structures were formed according to X-ray diffraction, differential scanning calorimetry, and nuclear magnetic resonance results; nevertheless, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis results showed that the number of terminal carboxyl groups of annealed m-PASSA decreased after the annealing treatment. The volatiles formed in the decomposition of m-PASSA were investigated by combined thermogravimetric analysis and online FTIR. The initial volatile products in the decomposition experiments supported a process that involved the cleavage of an aromatic carboxyl group, followed by the emission of major volatile products—carbon dioxide, sulfur dioxide, and benzenthiol—released from the amide, sulfone, and diphenyl sulphide groups in m-PASSA. Annealed m-PASSA exhibited different thermal properties, as evidenced by thermogravimetric analysis, compared to the untreated polymer. The degradation activation energy increased from 154.4 kJ/mol to 173.6 kJ/mol after annealing treatment, and the lifetime was extended by more than 1000 times.     

Intumescent Flame Retardancy and Thermal Degradation of Epoxy Resin Filled with Ammonium Polyphosphate Using Thermogravimetric Analysis–Fourier Transform Infrared Spectroscopy and Thermogravimetric Analysis–Mass Spectrometry

The flammability of epoxy resin (EP) and its composite with ammonium polyphosphate (EPAPP) was investigated with limiting oxygen index (LOI), UL 94, and cone calorimeter tests. A systematic and comparative evaluation of the thermal degradation of EP and EPAPP has been investigated using thermogravimetry coupled with Fourier transform infrared spectroscopy (TG–FTIR) and thermogravimetry coupled with mass spectrometry (TG–MS). The results showed that the flame retardant of ammonium polyphosphate (APP) can constitute an intumescent flame retardant (IFR) system with EP, and APP can effectively improve the LOI of EP; with 6 wt% addition level of APP, EPAPP can pass UL 94 V 0 test. The cone calorimeter test results showed that the flame retardancy and smoke suppression of EP were significantly improved by APP, and toxic gas products such as carbon monoxide and carbon dioxide obviously decreased. Thermogravimetry–Fourier transform infrared spectroscopy and TG–MS results showed that the degradation process of EP produces large amounts of gas products and mainly containing of water, carbon dioxide, methane, benzene and its derivatives, as well as phenol and its derivatives. Compared to EP, the kinds of decomposition products of EPAPP sample were not changed significantly, except that more ammonia gas was generated. For the EPAPP sample, the products of water, benzene, and phenol increased, whereas the carbon dioxide and the flammable hydrocarbon fragments C_xH_y decreased significantly during the decomposition.     

Preparation and Characterization of Para-Aramid Fibers with the Main Chain Containing Heterocyclic Units

Abstract

A para-aramid fiber whose main chain contained heterocyclic units was prepared by low temperature copolycondensation, wet-spinning, and high temperature thermal treatment. The prepared fibers (named F-368) and two commercial aramid fibers, K49 (Kevlar 49, Dupont de Nemours Co., USA) and APMOC (Kamenskvolokno and Tver’khimvolokno, Russia), were characterized and analyzed in detail. Infrared spectroscopy (IR) and wide-angle X-ray diffraction (WAXD) were employed to characterize their chemical and aggregation structures, respectively. The results showed the introduction of heterocyclic units into the wholly para-aromatic polyamide backbone of K49 in the F-368 and APMOC reduced the crystallinity significantly. The tenacity of F-368 and APMOC were 32.2 and 30.5cN/dtex, which were about 68% and 59% higher than that of K49, respectively. Thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) were used to investigate their thermal properties; the results indicated that these aramid fibers showed exceptional thermal properties with glass transition temperatures of 240–260?°C, and decomposition temperatures at 510–560?°C, both in nitrogen and air. The TGA results also showed the decomposition mechanism of K49 and the heterocyclic aramid fibers in nitrogen and air were different. The decomposition temperature of K49 was higher than that of the heterocyclic copolyaramid fibers both in nitrogen and air. On the contrary, the char yields of the heterocyclic copolyaramid fibers at 800?°C were higher than that of K49 in both nitrogen and air.     

钾基CO2吸收剂再生反应特性

通过热重分析试验研究了钾基 CO2 吸收剂的再生反应特性.深入分析了气氛、分解终温和升温速率对再生转化率和分解反应速率的影响.通过热分析方法求取了反应动力学参数.研究发现,其分解终温最佳值为 200℃;CO2 和H2O 在分解终温较低时对反应过程的影响较大;升温速率对反应的影响程度在其高于 10℃/min 后明显减弱;KHCO3分解反应的表观活化能为 90～120 kJ/mol.本文为干法 K2CO3/KHCO3 循环脱除 CO2 的研究提供了一定的基础数据.     

Ammonia modification of activated carbon to enhance carbon dioxide adsorption: Effect of pre-oxidation

A commercial granular activated carbon (GAC) was subjected to thermal treatment with ammonia for obtaining an efficient carbon dioxide (CO₂) adsorbent. In general, CO₂ adsorption capacity of activated carbon can be increased by introduction of basic nitrogen functionalities onto the carbon surface. In this work, the effect of oxygen surface groups before introduction of basic nitrogen functionalities to the carbon surface on CO₂ adsorption capacity was investigated. For this purpose two different approaches of ammonia treatment without preliminary oxidation and amination of oxidized samples were studied. Modified carbons were characterized by elemental analysis and Fourier Transform Infrared spectroscopy (FT-IR) to study the impact of changes in surface chemistry and formation of specific surface groups on adsorption properties. The texture of the samples was characterized by conducting N₂ adsorption/desorption at −196 °C. CO₂ capture performance of the samples was investigated using a thermogravimetric analysis (TGA). It was found that in both modification techniques, the presence of nitrogen functionalities on carbon surface generally increased the CO₂ adsorption capacity. The results indicated that oxidation followed by high temperature ammonia treatment (800 °C) considerably enhanced the CO₂ uptake at higher temperatures.     

六氟丙烷洁净气体灭火剂热分解性能研究

利用气相色谱(GC)、气相色谱-质谱(GC-MS)和傅里叶变换红外光谱(FTIR)研究了六氟丙烷洁净气体灭火剂在管式反应器中500～750 ℃时的热分解性能。经测试发现热分解气体中含有氟化氢,GC-MS分析发现含有五氟丙烯,说明六氟丙烷高温热分解时主要是脱去氟化氢、生成五氟丙烯的过程。GC和FTIR结果表明,反应温度对六氟丙烷的热分解有明显影响,600 ℃时开始发生微弱分解,750 ℃时发生强烈分解。FTIR可作为在线研究含氟气体灭火剂灭火机理的新方法。     

Sensing ammonia with ferrocene-based polymer coated tapered optical fibers

The application of ferrocene-based polymers as variable index materials is discussed. The refractive index of thin film of a particular polymer known as poly(methylphenylsilyeneferrocenylene) is examined during exposure to ammonia, nitrous oxide, nitric oxide, nitrogen, carbon dioxide, carbon monoxide, and argon. A maximum of 9% deviation in the refractive index of the polymer upon exposure to ammonia is observed. The theory of operation and fabrication of polymer-coated tapered optical fiber gas sensors are explained. Experimental data is presented showing qualitative response to ammonia and other gases.     

KOH activated carbon fabrics as supercapacitor material

Carbon fabrics from viscose fibers activated with KOH have been investigated as possible electrode materials for electrochemical capacitors. The fibers were first pyrolysed at 400 or 600 °C, then saturated with KOH at C/KOH ratios from 1:3.5 to 1:5 and treated in the temperature range from 700 to 800 °C. The carbon fibers saturated with KOH were analysed by thermogravimetric and differential thermal analysis in order to get information on the temperature dependence of the KOH reaction with carbon. The electrochemical properties of the activated carbons were determined using three-electrode Swagelok^® type capacitors both in 4 M H₂SO₄ and 7 M KOH aqueous electrolytes. Specific capacities of ca. 340 and 270 F/g were determined in acidic and alkaline medium, respectively. We demonstrate that the electrical capacity for both negative and positive electrodes depends on the treatment method. The capacitance values are discussed taking into account the porous texture, the elemental composition and the surface functionality of the activated carbon fibers.     

Studies on the Decomposition of Carbon Dioxide in a Low-Temperature Plasma

The decomposition of carbon dioxide was studied in an argon plasma jet, generated by a direct-current arc discharge. The decomposition degree of carbon dioxide was up to 0,4 at an effective energy consumption lower than 1 MJ/mole CO. The efficiency of high-temperature decomposition of carbon dioxide to carbon monoxide and oxygen is essentially dependent both on the quenching intensity of the products, which prevents from the reverse oxidation reaction in the system, as well as on the proper conditions of plasma-substrate mixing.     

一种新型希夫碱锌配合物的合成及光谱学性质

合成了一种希夫碱有机金属配合物2-羟基-1-萘甲醛缩邻苯二胺合锌(ZnL)。通过质谱、元素分析、红外光谱、热重分析对其结构进行了表征;利用紫外-可见光吸收光谱、激发和发射光谱研究了该配合物的光物理性能。结果表明:ZnL的热分解温度为433.2℃,具有很好的热稳定性;在DMF溶液体系中,配合物ZnL的紫外吸收带位于250~500 nm,荧光激发带位于343~493 nm,在紫外光的激发下发射峰在626 nm处,为橙红色光,最佳激发波长为470 nm,禁带宽度2.32 eV。