木质素对再造烟叶烟气中苯酚的影响

通过对木质素以及添加一定比例木质素的再造烟叶进行热裂解分析,探讨木质素对再造烟叶苯酚释放量的影响。结果表明,木质素热裂解产物中酚类物质含量较高;再造烟叶热裂解产生的苯酚及其他酚类物质含量随木质素含量的增加而升高。结果对降低再造烟叶及卷烟苯酚释放量的技术开发具有重要意义。     

全梗全叶再造烟叶热裂解产物与感官质量关系研究

通过对全梗、全叶单体原料制备的再造烟叶热裂解产物GC-MS鉴定分析,探讨热解产物的差异性对感官质量的影响。结果表明,梗、叶单体原料制备的再造烟叶热裂解产物主要包括醛、酮、酚、芳烃、杂环类物质,其中全梗再造烟叶检出49种物质,全叶再造烟叶检出60种物质。全叶再造烟叶热裂解产物中的主要烟草中重要的致香物质醛、酮、酚类物质的数量和所占比例明显高于梗再造烟叶;芳烃和杂环类物质的数量和所占比例较接近;全叶再造烟叶在香气质、杂气、刺激性方面明显优于全梗再造烟叶,这与全叶再造烟叶热裂解产物中的烟草主要致香成分释放量明显高于全梗再造烟叶有直接关系。     

影响热释放速率测量因素的实验研究

热释放速率是描述火灾过程的重要参数之一,体现了火灾中能量释放的大小,是决定火灾发展变化和火灾危险程度的基本参数.本文分析了测量过程中环境湿度、烟气中CO、CO2摩尔分数对热释放速率的影响,并比较它们对热释放速率的影响程度.     

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.     

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.     

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。     

涂布率对再造烟叶综合品质的影响

为了对再造烟叶产品的设计开发与生产控制提供指导,研究涂布率对再造烟叶品质的影响,通过对不同涂布率的样品进行理化指标、感官质量评价,确定再造烟叶涂布率的适宜范围和最佳范围。结果表明,再造烟叶涂布率的适宜范围在45%—75%之间,最佳范围在55%—65%之间。     

烟叶中游离态氨基酸与卷烟主流烟气中氢氰酸的相关关系

分别用氨基酸分析仪法和离子色谱-脉冲安培检测法测定了60种单料烤烟烟叶中游离态氨基酸的含量和烟叶主流烟气中氢氰酸的释放量,通过相关性分析确定了对氢氰酸释放量具有主要影响的氨基酸,建立了氢氰酸释放量的预测模型.结果表明:所有碱性氨基酸和杂环氨基酸都与氢氰酸呈显著正相关,所有酸性氨基酸与氢氰酸都没有呈现显著相关性.根据相关性系数判断对烟草主流烟气中氢氰酸释放量起主要作用的氨基酸依次是:苯丙氨酸、色氨酸、组氨酸、丙氨酸、脯氨酸和丝氨酸.研究结果为吸烟与健康研究提供科学依据.     

城市固体废物(MSW)热解特性及其动力学研究

利用热重-差热分析仪对城市固体废物（MSW）中厨余物、废纸、废塑料、废木料和废织物等典型有机组份进行了热分析研究。试验载气为高纯氮气．加热速率为10K／min．终温为773K。通过对热重（TG）、差热（DTA）和微分热重（DTG）曲线的深入分析,得出了MSW中几种典型有机组份的热解反应动力学参数,并提出了相应的热解机理。     

Role of an additive in retarding coal oxidation at moderate temperatures

The impact of an additive on coal oxidation process is studied from the mechanistic perspective, aiming at development of a guideline in search of effective inhibitors for controlling the coal self-heating phenomena. The salt Na₃PO₄ was chosen as an additive. Behaviors of samples with/without the additive were examined at temperatures up to 400 °C both in oxidative and inert atmosphere using a TGA instrument, and the compounds on coal surface during oxidation and pyrolysis were monitored by FT-IR technique. The TGA data show that the impact of the additive on coal oxidation process can be directly evaluated using a parameter defined as the percentage of mass increase at ∼265 °C, and the addition of Na₃PO₄ slows down the rates of oxygen uptake and decomposition reactions. FT-IR results also indicate that the additive suppresses both the coal oxidation and pyrolysis processes essentially by accelerating the formation of saturated ether linkages. Further analysis suggests that Na₃PO₄ plays a role in modifying the routes for decomposition of hydroxyl, and subsequently improving the coal thermal stability.     

Effects of thermo-physical and flow parameters on the static and dynamic burning of a cigarette

Effects of thermo-physical and operating parameters influencing the combustion of a cigarette were systematically studied using a three-dimensional first-principles-based mathematical model. Thermo-physical properties include packing density and thermal conductivity of materials forming the packed bed in the cigarette, and operating parameters include ambient oxygen concentration, air flow rate through the cigarette, and the ambient cross flow. The model was first validated with the existing experimental data which provided a satisfactory result. Increasing the ambient cross flow while increasing the burn rate and temperatures in the cigarette column, decreases the delivery of gaseous products owing to air infiltration through the paper into the column and enhances diffusion of gases out of column. Reducing the oxygen concentration reduces the burn rate to a point at which burning would be extinguished during the smoldering step. Increasing the air flow monotonically increases the burn rate, temperature and delivery of products in a burning cigarette. While thermal conductivity in the range varied here (50% above and 50% below the base case) it did not significantly affect the outcomes of the burning process; decreasing the packing density increases the heat generated and solid and gas temperatures, and decreases the delivery of some gaseous products.     

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。     

原位漫反射红外光谱研究升温速率对HMX炸药热分解过程的影响

原位红外光谱法是一种新兴的动态研究方法。该方法具有原位实时监控和红外光谱精确分析物质化学结构的优点,能够实时跟踪材料在不同温度下的化学变化,测定材料的微观结构与温度的关系。采用原位漫反射红外光谱研究了炸药1,3,5,7-四硝基-1,3,5,7-四氮杂环辛烷(HMX)分别在每min 5, 10, 20和40 ℃四种不同升温速率下的热分解行为。研究结果表明：在5 ℃·min-1升温速率下,断裂的HMX环发生分子内结合,在10, 20和40 ℃·min-1升温速率下,断裂的HMX发生分子间成环,形成稳定的八元环结构。随着温度的升高,C—N键的断裂数率远高于N—N键的断裂速率。随着升温速率的增加,C—N键的起始分解温度增加,表明增加升温速率会引起HMX分解的滞后。检测到HMX的分解所释放出CO₂, N₂O, CO, NO, HCHO, HONO, NO₂和HCN共八种气体,升温速率的变化未改变HMX的分解机理。     

Electron energy loss spectroscopy of the decomposition of formic acid on Ru(001)

Electron energy loss spectroscopy has demonstrated the existence of both a monodentate and a symmetric bidentate bridging formate as stable intermediates in the decomposition of formic acid on the Ru(001) surface. The monodentate formate converts upon heating to the bidentate formate which decomposes via two pathways: CH bond cleavage to yield CO₂ and adsorbed hydrogen; and CO bond cleavage to yield adsorbed hydrogen, oxygen and CO. Thermal desorption spectra demonstrate the evolution of H₂,H₂O, CO and CO₂ as gaseous products of the decomposition reaction. The observation of this product distribution from Ru(100), Ni(100) and Ni(110) had prompted the proposal of a formic anhydride intermediate, the existence of which is rendered questionable by the spectroscopic results reported here.     

The decomposition of formic acid on Ru(101̄0)

The decomposition of formic acid was studied on a clean Ru(101̄0) surface adsorption temperature between 100 and 460 K by means of flash thermal desorption. The decomposition products observed were H₂, CO₂, H₂O and CO. HCOOH itself was also desorbed, although at low exposures no formic acid was observed. The H₂ and CO₂ products were desorbed in identical first order peaks, with a peak temperature of 395 K. The H₂O product desorbed in a second order peak at 813 K, in contrast to H₂O desorption from low coverage H₂O adsorption which occurs in two peaks in the region of 220 and 265 K. The CO product desorbed in a first order peak at 488 K, identical to CO from CO adsorption. The dependence of the product peaks on adsorption temperature of the Ru surface was also studied. These results suggest a model involving the formation and decomposition of a surface intermediate species.     

Thermal decomposition of CO on a stepped Ni surface

The adsorption-desorption behaviour of CO on the stepped Ni(S) [5(111) × (11̄0)] and the smooth Ni(111) plane are compared by using LEED, thermal flash desorption and AES. Above room temperature flash desorption from the Ni(111) face yields a single α peak characteristic of molecularly adsorbed CO whereas from the stepped surface in addition to the a peak α second desorption peak (β2) appears around 550°C which is assigned to associative CO desorption. If carbon and oxygen are separately chemisorbed on Ni(111) associative desorption of CO leads to a desorption peak around 350° C. It is concluded that steps lower the activation energy for CO decomposition but increase the activation energy for associative desorption.