【作者】 舒俊生；

【导师】 夏文水；

【作者基本信息】 江南大学 ， 食品科学， 2010， 博士

【摘要】 吸烟有害健康,挥发性羰基化合物和氮氧化物是卷烟烟气中两大类有害成分,降低这两类化合物对提高卷烟安全性有着重要价值。本论文研究卷烟烟气中羰基化合物的形成机理和影响因素以及利用天然可再生资源和过渡金属等低成本材料降低卷烟主流烟气中羰基化合物和氮氧化物的技术,研究对于烟草科学和烟草产业发展具有重要的学术意义和现实意义。论文从理论和实验两个方面探讨了卷烟主流烟气中羰基化合物的形成机理。采用密度泛函(DFT)理论,在B3LYP/6-31G基组下,对烟气中丙三醇的各种化学键断裂反应以及过渡态反应的热力学和动力学进行了分析,计算了各个化学键的解离能以及过渡态活化能,通过理论计算找出了主要裂解路径,推导1,2-丙二醇和1,3-丙二醇的裂解路径和主要反应产物;结果表明:丙三醇在高温下裂解主要初级反应是脱水反应,形成甲醛、乙烯醇、2,3-二羟基丙烯、1,3-二羟基丙烯、羟基丙酮、3-羟基丙醛,脱水反应的活化能在53.64kcal/mol～64.98kcal/mol之间。初级反应产物会继续反应,生成丙烯醛、甲醛和乙醛。1,2-丙二醇脱水反应活化能在60-70kcal/mol,裂解主要产物是丙醛、丙酮和乙醛,其中丙醛的含量最高;而1,3-丙二醇脱水反应活化能在50-60kcal/mol,裂解主要产物是甲醛、乙醛和丙烯醛。理论推导与无氧裂解实验具有很高的一致性。采用正交实验L9(33)研究了温度、氧气浓度和氮气流量对烟草中各种碳水化合物、保润剂和不同类型烟草羰基化合物产率的影响。结果表明:氮气流量是影响各种化合物裂解生成甲醛的显著影响因素,而温度则是影响其他挥发性羰基化合物生成的主要因素,氧气浓度对羰基化合物产率的影响不显著。四种碳水化合物(葡萄糖、果糖、蔗糖和淀粉)的甲醛、乙醛、丙酮、丙烯醛和丙醛的产率都很高,各种因素对不同碳水化合物裂解生成羰基化合物的影响规律类似。在卷烟常用的四种保润剂中,丙二醇在高温下丙酮和丙醛的产率远远高于丙三醇、木糖醇和山梨醇,而丙三醇裂解甲醛、丙烯醛和巴豆醛的产率最高,木糖醇在600℃甲乙酮产率最高,山梨醇在氧气浓度低、氮气流量小的情况下,丁醛的产率最高。温度显著影响不同类型烟草各种羰基化合物的产率,香料烟在600℃甲醛的产率远远超出烤烟和白肋烟,各种羰基化合物在800℃的产率都不高。选择可再生生物大分子壳聚糖以及过渡金属等低成本材料,通过络合方法或共沉淀法以及条件优化,制备了壳聚糖络合物和两种纳米金属复合氧化物,确证了制备物的结构,研究了这些材料对卷烟主流烟气中羰基化合物或氮氧化物的选择性降低作用及其结构与功能性质之间的关系。结果表明:在pH4.8,温度25℃,壳聚糖与硫酸铜配比10:4,时间30min,铜离子负载量为6.2%时,可最优制备壳聚糖-铜(Ⅱ)络合物,壳聚糖氨基或者酰胺基发生与铜离子吸附配位;壳聚糖-铜(Ⅱ)络合物对卷烟主流烟气中羰基化合物的吸附能力与羰基化合物的极性和分子量有重要关系,随着碳链的增加和极性的减弱,吸附量迅速下降。对甲醛的吸附率最高可达53%,而对四碳羰基化合物最高吸附率只能达到12%,在相同碳原子醛酮同分异构体中,对酮的吸附强于醛,而对不饱和羰基化合物的吸附更高。壳聚糖-铜(Ⅱ)络合物对卷烟主流烟气中的苯酚和HCN也有一定得吸附效果,对主流烟气中的CO、烟碱和焦油基本没有吸附效果。铜铁复合氧化物催化剂的较佳制备条件为:原料配比(Cu:Fe)1:5,pH值9.0,陈化90min,煅烧温度300℃,煅烧时间5 h。铜钴复合氧化物催化剂的较佳制备条件为:原料配比(Cu:Co)1:5,碱液添加量15 mL,陈化5 h,煅烧温度200℃,煅烧时间3 h。铜铁、铜钴复合氧化物催化剂能够在低温下选择性催化卷烟主流烟气中的NO,生成没有毒性的N2。两种催化剂在卷烟中的添加量超过2%时,都能显著降低主流烟气中的NO,铜钴复合氧化物的催化效果好于铜铁氧化物,在添加量超过5%时,NO可以降低50%。本论文从卷烟烟气中羰基化合物的形成机理入手,探讨了其有害物的形成规律和影响因素,确定了卷烟主流烟气中羰基化合物的主要前体物和主要影响因素,建立了壳聚糖-铜(Ⅱ)络合物和两种纳米金属复合氧化物降低卷烟烟气中有害成分羰基化合物和NO的减害技术。研究结果对于降低卷烟主流烟气中其他有害成分都有重要指导作用。更多还原

【Abstract】 Smoking is harmful to health. Volatile carbonyl compounds and nitrogen oxides are two major types of harmful components in cigarette mainstream smoke. Reducing such harmful components has significant value to enhance safety of cigarette. This paper studied the mechanism of the formation of carbonyl compounds, and discussed the formation rule and influencing factors. We have used some low-cost materials such as the natural renewable resources and the transition metals to reduce carbonyl compounds and nitrogen oxides in cigarette mainstream smoke. The research has important academic and practical significance in the development of tobacco science and tobacco industry.The formation mechanism of the carbonyl compounds in cigarette is researched through theory and experiments.The thermodynamic and kinetic properties of bond dissociation reaction and transiton state reaction was studied using DFT theory in B3LYP/6-31G. Bond dissociation energe and activate energe of transtite state were calculated.Major pyrolysis routes were determined by the theoretical calculation.The mechanism can be used to predict pyrolysis route and major products of 1,2-propylene glycol and 1,3-propylene glycol.The results indicated that the active energy of the dehydration reaction is between 53.64kcal/mol and 64.98kcal/mol.The primary products will formate acrolein,formaldehyde and acetaldehyde.The activation energy of 1,2-propylene glycol dehydration reaction is between 60 kcal/mol and 70 kcal/mol, The main pyrolysis products of 1,2-propylene glycol are propionaldehyde, acetone and acetaldehyde, the yield of propionaldehyde is far higher than others.The active energe of 1,3-propylene glycol is between 50 kcal/mol and 60 kcal/mol. The major procucts of 1,3-propylene glycol are formaldehyde, acetaldehyde and acrolein. The experiment datas showed highly agreement with theoretical derivation.The effects of temperature,oxygen concertration and nitrogen flow on the yield of volatile carbonyl compounds from carbohydrate, humectants and different tobacco type were researched by orthogonal experiments L9(33). The results as followed: Nitrogen flow remarkably affected the yield of formaldehyde; Temperature is the main factor of formatting other volatile carbonyl compounds, while oxygen concentration showed a little effects on the yield of the carbonyl compounds.Formaldehyde, acetaldehyde, acetone and acrolein are produced in high yield during the pyrolysis of glucose, fructose, sucrose and starch, which have the similar low of producing carbonyl compounds through pyrolysis. In the four kinds of humectants, propylene glycol is like to produce much more acetone and propionaldehyde than glecerol, xylitol and sorbitol. Yield of formaldehyde, acrolein and crotonaldehyde, produced by glycerol pyrolysis, are the highest. When pyrolyzed at 600℃, xylitol generated the most methyl ethyl ketone. While sorbitol can produce the most butyraldehyde in the case of low oxygen concentration and nitrogen flow rate.Temperature significantly affected the generation of carbonyl compounds of the three kinds of tobacco. The yield of formaldehyde produced by oriental tobacco was far higher than others when pyrolyzed at 600℃.Furthermore, all kinds of tobacco that were pyrolyzed at 800℃produced little carbonyl compounds.Renewable biomacromolecular resources-chitosan and the transition metals were selected to prepare complex and nano-metal complex oxide through complex and co-precipation method.The preparation structure were charactered.The effect of preparation on carbonyl compounds and nitrogen oxide in mainstream smoke and the structure-activity relationship were studied.The results indicated that the optimized preparation condition of copper-chitosan complex is as followed: pH 4.8, temperature 25℃, molar ratio of chitosan to copper sulfate 10:4, time 30min. In this case,amino or amide groups in chitosan complexed copper ion. There is an important relationship between the adsorption properties of carbonyl compounds on chitosan-copper(Ⅱ) complex and the polarity and molecular weight of carbonyl compounds. The adsorption capacity decreased rapidly with the carbon chain increasing and polarity reducing. The adsorption rate of formaldehyde is up to 53%, nevertheless, only 12% for four carbon carbonyl compounds. Compared aldehydes with its isomer ketones, the result indicated the adsorption of the complex to ketones was stronger than aldehydes, In addition, the complex showed the strongest adsorption capacity to the unsaturated carbonyl compounds. Besides carbonyl compounds, the copper-chitosan complex can adsorb phenol and HCN to certain extent, but has no effect on removing the CO, nicotine and tar in the mainstream smoke.The optimum preparation condition of Copper iron composite oxides can be fixed as follows: molar ratio of copper to iron 1:5,pH 9.0,ageing time 90min,calcination temperature 300℃and calcinations time 5h;the optimal preparation condition condition of CuO/Co3O4 catalysts are as followed: molar ratios of copper to cobalt 1:5,volume of NaOH 15ml,ageing time 5h,calcinated at 200℃for 3h.Copper iron and copper cobalt complex oxides can catalysis NO in cigarette mainstream smoke to formate non-harmful N2 at low temperature.When added in the cigarette, NO in the mainstream smoke can be significantly removed in the additive amount of 2%.Comparison with CuO/Fe2O3 complex,CuO/Co3O4 showed higher catalytic activity. When addition amount to 5%,NO can be converted by 50%。This article explored the mechanism of carbonyl compounds forming in cigarette smoke, the forming pattern and influence factors. We have determined the main precursors of carbonyl compounds in the mainstream smoke, as well as major influence factors. We also established the technique to utilize chitosan-Cu(II) complex and two nano-metal complex oxides to reduce harmful carbonyl compounds and NO in the cigarette smoke. This research is creative and important in reducing other harmful ingredients in mainstream smoke.更多还原