【作者】 葛少林；

【导师】 盛六四；

【作者基本信息】 中国科学技术大学 ， 同步辐射及应用， 2014， 博士

【摘要】 为改善造纸法再造烟叶刺激性大、杂气重以及CO释放量高等质量缺陷,本文在系统分析造纸法再造烟叶理化特性的基础上,较为深入的研究了造纸法再造烟叶及其主要组成部分(纸基)的热解行为,并从纸基的化学成分调节和外源性磷氮化合物的添加两个方面进行再造烟叶热解过程的调控,进而调节再造烟叶烟气组分,提升卷烟烟气品质。主要研究工作如下：1.造纸法再造烟叶理化特性为充分了解造纸法再造烟叶质量属性,系统分析了烟草化学指标、无机离子化合物以及纤维形态等与热解行为相关理化指标,并比较研究了造纸法再造烟叶与膨胀梗丝、膨胀烟丝在燃烧速率、焦油以及CO释放特性等方面的差异,发现造纸法再造烟叶的燃烧速率高、焦油量低,但CO释放量明显偏高,尤其是单口CO释放量。为揭示其高CO释放量的原因,比较研究了造纸法再造烟叶与纸基的主流烟气成分差异,明确了纸基在造纸法再造烟叶质量调控中的重要作用,并初步得出纸基是造纸法再造烟叶CO释放量偏高的主要原因之一。2.造纸法再造烟叶与纸基的热降解行为为了深入了解造纸法再造烟叶与纸基的热解行为,通过TG/DSC-FTIR实验系统分析不同升温速率条件下造纸法再造烟叶和纸基的热解行为及热解气相产物形成过程。发现两者CO形成过程类似,均发生在两个温度范围内,但纸基CO释放量明显高于造纸法再造烟叶,并且随着升温速率的提高,两者CO释放量均显著增加,进一步证实了纸基CO释放量高是造纸法再造烟叶CO释放量偏高的主要原因。3.果胶与蛋白质的酶降解对纸基热解过程及产物的影响鉴于蛋白质和果胶对卷烟感官品质的不良影响,采用生物酶选择性降解纸基中果胶和蛋白质,并分别考察了蛋白质和果胶的酶降解对纸基热解行为的影响。发现果胶和蛋白质含量降低均能显著改变纸基的热解过程和热解产物(如CO、CO2、NH3、羰基化合物等)的释放特性,说明了果胶和蛋白质对热解气相产物的形成具有一定调节作用。为更清晰地揭示果胶的热解机理,首次利用SVUV-PIMS研究了果胶的热解行为,发现果胶热解主要有两种反应路径：果胶高分子链端半乳糖醛酸单元的低温分子内热裂解反应；以α-(1→4)糖苷键断裂为标志的高温热解反应。在热解产物分析的基础上,理论推导了果胶热解主要产物形成机理,并对相关实验现象进行了理论解释,为果胶热解产物的控制奠定了基础。4.外源氮磷类添加剂调节再造烟叶的热降解过程与烟气组分利用磷酸氢二胺(DAP)、聚磷酸铵(APP)以及磷酸尿素(UP)等含磷氮化合物进行造纸法再造烟叶热解过程的外源性调控研究,并阐述其作用机制。发现含磷氮无机物均可提高残炭的热氧稳定性,并显著降低热解气相产物总量。其中APP和UP还可有效降低成品烟支主流烟气中CO含量。为揭示UP和APP降低CO释放的机制,利用慢速和闪速热解对比实验分别研究了二者对CO释放特性的影响,发现UP和APP主要影响残碳氧化阶段CO的形成。更多还原

【Abstract】 In order to overcomethe quality defects of paper-making reconstituted tobacco (PRT) on the high level of CO and some sensory attributes like irritation and off-tastein mainstream smoke, the thermal degradation behaviors of PRT and paper-base (the principalconstituent of PRT) were first studied deeply on the basement of systematical analysis on its physicochemical properties. Then the thermal degradation process of PRT was regulated via the change of the chemical components of paper-base and the addition of phosphorus-and nitrogen-bearing compounds, respectively, thus adjusting the smoke components of PRT and finally improving smoke quality of cigarette. This dissertation consists of the following parts:(1) In order to get an complete insight into the quality attributes of PRT, its physicochemical performances connected with the thermal decomposition behavior such as chemical components, inorganic ions and fiber morphologies were systematically investigated, and the difference of PRT, expanded cut tobacco (ECT) and expanded cut stem (ECS) in some key parameters, including tar, CO and static burning rate was compared too. It was found that CO delivery of PRT was much higher than that of ECT and ECS, especially CO level per puff, in spite of its higher static burning rate and lower tar delivery than that of ECT and ECS. To figure out the reason of higher CO delivery of PRT, the difference of PRT and paper-base in their respective mainstream components was further compared and the preliminary conclusion obtained is that base-paper is one of the principal reasons causing the higher CO delivery of PRT.(2) To deeply understand the thermal degradation behavior of PRT and paper-base, their respective thermal decomposition process, heat release properties and gas products evolution in the changing heat rates were systematically analyzed by TG/DSC-FTIR. It was shown that paper-base has a much higher CO delivery than PRT although they both present a similar two-stage CO delivery. Furthermore, the CO delivery of both significantly increases with elevating heat rate. These resultsfurther prove that paper-base is one of one of the principal reasons causing the higher CO delivery of PRT.(3) To reduce the bad effect of pectin and protein on the sensory quality of cigarette, pectinase and proteinase were selected to selectively degrade pectin and protein in the paper-base, respectively. The study of thermal degradation behavior of enzyme-treating paper-base displayed that the decrease of pectin and protein in paper-base can obviously change its thermal degradation process and the delivery of gas products like CO, CO2, NH3, carbonyl compounds and so on, implying the presence of regulation of pectin and protein on the formation of volatilized products during the pyrolysis of paper-base. In order to reveal the mechanism of thermal degradation of pectin more clearly, its thermal decomposition was first studied with tunable synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS).The results demonstrated a two-step pyrolysis process: intramolecular pyrolysis of galacturonic acid subunit at the chain ends of polymers in the lowtemperature range and the rupture of α-(→4) glycosidic bond between galacturonic acid subunit in the high temperature range. The deduced mechanism of reaction pathways in pectin pyrolysis should provide insight into the pyrolysis behavior of pectin, laying the foundation for the control of degraded products of prectin.(4) The influence of phosphorus-and nitrogen-containing additives (PNA) like diammonium phosphate (DAP), urea phosphate (UP) and ammonium polyphosphate (APP) on the thermal degradation behavior of PRT was investigated. It was exhibited that PNA can enhance the thermal-oxidative stability of the char residue of PRT and reduce its total amount of volatized species remarkably. And the decrease of CO delivery in the mainstream smoke of cigarette can be achieved by APP and UP. To clarify the mechanism of the reduction of CO delivery caused by APP and UP, a comparative analysis of CO evolution patterns in the flash and slow pyrolysis was carried out and the results showed that UP and APP mainly influenced the CO formation at the stage of thermal-oxidative decomposition of the char residue.更多还原