在线裂解气相色谱-质谱法研究单琥珀酸薄荷酯的裂解行为

采用在线裂解气相色谱-质谱联用技术对单琥珀酸薄荷酯的裂解行为进行了研究。在氦气氛围中,分别在300、400、500、600、700、800和900℃下对单琥珀酸薄荷酯进行热裂解,并通过毛细管气相色谱-质谱对裂解产物进行了定性和半定量分析。共鉴定出薄荷醇、p-薄荷-3-烯和琥珀酸等75种裂解产物。结果表明,单琥珀酸薄荷酯在700℃以下裂解出薄荷醇、p-薄荷-3-烯和3-甲基-6-异丙基环己烯等具有致香和清凉作用的物质;而700℃以上没有释放出致香物质。随着裂解温度的升高,裂解产物越来越复杂,有害物质如苯、甲苯、蒽和荧蒽等的含量也逐渐增加。此方法可直接进样,重现性好(相对标准偏差≤2.01%)。根据裂解产物的种类及相对含量变化规律,探讨了裂解成分的形成机理。     

麻浆卷烟纸热裂解产物的气相色谱/质谱分析

采用热失重(TG)和裂解气相色谱/质谱法(PyGC/MS)研究了麻浆卷烟纸的热裂解行为.在He气气氛围中,将麻浆卷烟纸分别在400、500、600、700、800和900℃下进行热裂解,并以GC/MS对其裂解产物进行定性和半定量分析.结果表明,不同的裂解温度直接影响生成产物的类型和相对含量.麻浆卷烟纸可裂解出1-甲基-1,3-环戊二烯、2-甲基呋喃、2,3-二氢香豆酮、苯和甲苯等156种产物.低温下,裂解产物主要为烯类、呋喃类和酮类化合物;随着裂解温度的增加,烯、酮类的含量下降,苯及其衍生物和稠环芳烃的含量逐渐增加.可通过降低卷烟燃烧温度来降低卷烟纸裂解产生的有害成分含量.如果单纯考虑麻浆卷烟纸的影响,卷烟的最佳燃烧温度应控制在500℃左右.     

不同氛围下烟草的热裂解行为研究

烟丝分别在He和空气环境中于600、700、800、900、1 000 ℃下进行热裂解,裂解产物用GC-MS进行在线检测,研究了烟丝样品分别在惰性和有氧氛围中不同温度下的热裂解行为.数据表明,烟丝在He气和空气中热裂解时的产物有较大差异,He气下的裂解产物以烯烃、苯和苯系物为主;在空气下裂解的主要产物为酮、醛、醇、酸和酯等羰基化合物.有氧氛围有益于异戊二烯和1,3-丁二烯的生成,但在一定程度上抑制了酚类物质的产生.在惰性和有氧氛围下,随着温度的升高,多环芳烃化合物的产生量均进一步增加.He氛围下得到的裂解产物类型接近卷烟燃烧时的热解区,而空气氛围下得到的裂解产物类型接近燃烧区.     

裂解气相色谱-质谱法研究壬酸香草酰胺的热裂解

采用在线热裂解/气相色谱-质谱联用技术(Py/GC-MS)对壬酸香草酰胺(PAVA)的热裂解行为进行了研究,在氦气氛围中考察了不同裂解温度和裂解时间对PAVA裂解的影响,通过GC-MS对裂解产物进行定性和半定量分析。结果表明,随着裂解温度的升高,PAVA裂解率快速提高,裂解产物也进一步增多,当裂解温度达到700℃以上时,可裂解出壬酰胺、2-甲氧基-4-甲基苯酚、1-己烯、壬基腈、壬醛等14种产物。同一温度下随着裂解时间的延长,PAVA的裂解率逐步升高,裂解产物发生了进一步的裂解。根据热裂解产物及主要裂解产物的含量变化,初步推断了PAVA的裂解规律。     

热裂解-气相色谱-质谱法分析烟用咖啡颗粒热裂解特性

利用热裂解-气相色谱-质谱联用分析烟用咖啡颗粒的热裂解特性。分别于150、200、250、300、350℃对烟用咖啡颗粒进行热裂解分析，同时针对不同水分含量和粒径的咖啡颗粒在同一温度下进行热裂解成分分析。结果显示，随着温度的升高，热裂解产物逐渐增多，释放物质的种类逐渐也逐渐增多，在250℃时咖啡颗粒生成关键致香成分占比较高。不同水分含量和粒径的咖啡颗粒在250℃裂解时，水分越高，裂解产物中烟碱含量占比越高，烟气越充足；粒径越小，裂解产物中咖啡因和烟碱的总量越大，香气质量也越高。该试验为咖啡颗粒在卷烟中应用时的温度设计和香气品质改善提供理论依据。     

裂解气相色谱-质谱联用法对香叶醇的热裂解产物分析

采用裂解气相色谱-质谱法(Py-GC-MS)研究了香叶醇热裂解性质。以氦气为载气,将香叶醇样品分别在不同温度(300,400,500,600,650,700,800℃)下进行热裂解,将热解产物直接引入气相色谱-质谱仪进行定性和半定量分析。结果表明:在700℃时香叶醇完全裂解,裂解产物可达87种。根据主要的裂解产物和其相对含量的变化对香叶醇裂解机理进行初步探讨,为香叶醇在卷烟中的作用评价提供重要的理论依据。     

应用裂解气相色谱对生物质快速裂解反应条件的研究

采用现代化学分析领域中重要的分析方法 -裂解气相色谱法 ,对生物质的快速裂解进行了探索性研究。以杨木木屑为研究对象 ,在裂解温度 40 0～ 80 0℃ ,升温速率 1 0 0℃ s、2 50℃ s、50 0℃ s,挥发性产物停留时间 0 6～4 0s的裂解条件下 ,考察了杨木木屑快速裂解气、液、固三种产物及气相组分的分布规律。实验结果表明 ,气、液、固三种产物所占比例及其组分含量取决于裂解条件 -裂解温度、挥发份停留时间和升温速率 ,杨木在升温速率50 0℃ s、挥发性产物停留时间 0 6s、裂解温度 50 0℃下快速裂解 ,可获得最大的产液率 80 % (含水 )。物料平衡的结果证明了裂解色谱研究方法的有效性和可行性。     

香料成分的结构与高温裂解产生芳香物质含量的关系研究

应用在线热裂解/气相色谱-质谱(PY/GC-MS)研究了紫苏葶、β-紫罗兰酮、香紫苏内酯、异丁香酚、苯甲醛、2-乙酰基吡嗪、2-乙酰基噻唑、3-乙酰基吡啶、山楂酊、树兰净油在氦气氛围中分别于300、600、800℃下的裂解产物,通过对裂解产物中芳香烃类化合物的分析,讨论了裂解温度和香料组分化学结构对芳香族物质产生量的影响,并以有机结构理论总结了香料成分的结构与高温裂解产生芳烃物质含量的关系。研究结果表明:β-紫罗兰酮、香紫苏内酯、异丁香酚、树兰净油等在800℃时均裂解生成芳香烃类化合物(苯系物、茚系物和萘系物),其中裂解物中芳香烃类物质含量最高者为β-紫罗兰酮,达到16.290%,树兰净油为5.376%;而2-乙酰基吡嗪、2-乙酰基噻唑、3-乙酰基吡啶的裂解产物中未检测到上述芳香烃类物质,香料成分的结构是高温裂解产生芳烃物质的重要因素;随着裂解温度的升高,裂解产物中芳香烃类化合物的含量呈上升趋势;其中2-乙酰基吡嗪、2-乙酰基噻唑和3-乙酰基吡啶适宜用作卷烟香料。     

氰酸酯树脂热分解的高分辨裂解气相色谱-质谱分析

采用高分辨裂解气相色谱-质谱(HRPycC—Ms)研究了在不同裂解温度下氰酸酯树脂裂解产物分布以及主要裂解物的产率与裂解温度的关系,根据热分解产物的组成及其温度依赖性,讨论了氰酸酯树脂的热分解机理。     

四元共聚物的热裂解色谱-质谱分析

报道了2－丁烯、甲基丙烯酸甲酯、丙烯酸丁酯、丙烯酸辛酯四元共聚物在不同裂解温度下的热裂解行为。用热裂解色谱－质谱分析方法，研究了裂解温度对裂解产物的影响，并讨论了四元共聚物的热裂解规律。     

热解产物逸出行为研究中新型内标释放装置的建立及其应用

实验在流动载气-液滴微萃取(GF-LDME)技术的基础上增加了液滴托附装置,设计并建立了内标物释放和热解产物富集的新型联用装置,使内标物和热解产物在相同条件下完成液滴的萃取和富集,实现了各温度段间目标热解产物相对含量的纵向比较。实验利用热重模拟咖啡生豆的烘焙过程,同时利用联用装置结合气相色谱-质谱研究了咖啡生豆在热重程序升温过程中发生的热解反应及其热解产物的逸出行为。热重条件:初始温度为50℃;以10℃/min升温至500℃;空气为载气。结果表明,在100~400℃范围内共发现13个热解产物,在280~300℃温度段,逸出量达到峰值的热解产物包括羟基丙酮、吡啶、糠醇、γ-丁内酯和正戊醛;在300~320℃温度段,逸出量达到峰值的热解产物包括乙酸、苯酚、2-环戊烯酮和愈创木酚。建立的联用装置在热解产物的逸出行为研究中具有明显优势。     

升温速率对生物质热解的影响

稻壳、稻秆及麦秆是中国主要的农业废弃物,如何综合、有效地利用这些农业废弃物进行资源化研究显得十分必要。热解是热化学转化中最为基本的过程,是气化、液化及燃烧过程的初始和伴生反应,对热解的分析有助于热化学转化过程控制及高效转化工艺的开发。目前,国内外对生物质及其组分的热解已有大量的研究,但对中国主要的农业废弃物稻壳、稻秆及麦秆的研究较少。本研究利用热重和红外联用技术深入研究了升温速率对三种典型生物质热解气体产物的影响,并对生物质的热解动力学及热解气体产物的析出规律进行实时在线分析。     

废弃印刷电路板材料裂解产物的高分辨裂解气相色谱-质谱分析

采用高分辨裂解气相色谱-质谱法(PyGC-MS)分析了FR-4型印刷电路板粉末样品的裂解产物。在氦气氛围中,分别在350,450,550,650和750 ℃下对印刷电路板粉末样品进行热裂解,并通过毛细管气相色谱-质谱对裂解产物进行分析,研究了不同裂解温度下裂解产物分布以及主要裂解产物的产率与裂解温度的关系,根据热分解产物的组成,探讨了热分解反应机理。     

Influence of particle size and kinetic parameters on tire pyrolysis

One of the most important parameters that can significantly affect the cost of the tire pyrolysis process is the time needed for thermal decomposition of the tire material. In this work, the influence of particle size and kinetics of thermal decomposition on the pyrolysis time was studied. The apparent kinetic parameters of tire thermal decomposition were estimated using three different approaches based on thermogravimetry measurements. In separate experiments, tire particles with different sizes were pyrolyzed under isothermal conditions in a laboratory flow reactor at different residence times of the particles in the reactor and the data recorded were employed in the determination of tire conversion during the thermal decomposition. A mathematical model of tire pyrolysis considering heat conduction in the tire particles was developed. All three types of estimated kinetic parameters were used to determine the conversion behavior at isothermal conditions and the results were compared with experimental data obtained. The model was used also to calculate the pyrolysis time in an industrial scale reactor at different temperatures and particle sizes.     

Detoxification of brominated pyrolysis oils

The development of an innovative technology for the pyrolytic conversion of brominated phenols in a reductive medium aimed at product recovery for commercial use is discussed in this paper. Brominated phenols are toxic products, which contaminate pyrolysis oil of wastes from electronic and electrical equipment (WEEE). The pyrolysis experiments were carried out with 2,6-dibromophenol, tetrabromobisphenol A, WEEE pyrolysis oil and polypropylene or polyethylene in encapsulated ampoules under inert atmosphere in quasi-isothermal conditions (300–400 °C) with a different residence time (10–30 min). Optimal conditions were found to be the use of polypropylene at 350 °C with a residence time of 20 min. The main pyrolysis products were identified as HBr and phenol. A radical debromination mechanism for the pyrolytic destruction of brominated phenols is suggested.     

High-temperature pyrolysis of ethanol

A small, heated alumina tube was used as a pyrolysis reactor to study the thermal decomposition of ethanol at residence times of about 5 ms and temperatures from 1050 to 1275 K. The gas mixture leaving the reactor was analysed by molecular beam sampling mass spectroscopy. The products observed were ethene, water, hydrogen, methane and carbon monoxide and acetaldehyde as an intermediate. The ratio of the amounts of ethene and water formed to the other products was ca. 2:1. The experimental results are discussed in terms of a reaction mechanism and compared with other literature data. The disappearance of ethanol can be modelled by a first-order overall reaction.     

Influence of pyrolysis temperature and time on the cellulose fast pyrolysis products: Analytical Py-GC/MS study

Analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was employed to achieve fast pyrolysis of cellulose and on-line analysis of the pyrolysis vapors. Experiments were performed to reveal the effects of pyrolysis temperature and time on the distribution of the pyrolytic products, especially the formation characteristics of eighteen important products. During the fast pyrolysis process, the cellulose started decomposition to form organic volatile products at the set pyrolysis temperature of 400 °C. The pyrolytic products included various anhydrosugars (dominated by the levoglucosan (LG)), anhydrosugar derivatives (mainly the levoglucosenone (LGO), 1,4:3,6-dianhydro-α-d-glucopyranose (DGP), 1,5-anhydro-4-deoxy-d-glycero-hex-1-en-3-ulose (APP) and 1-hydroxy-3,6-dioxabicyclo[3.2.1]octan-2-one (LAC)), furan compounds (typically the 5-hydroxymethyl-furfural (HMF), furfural (FF) and furan (F)), as well as light linear carbonyls (mainly the hydroxyacetaldehyde (HAA) and 1-hydroxy-2-propanone (HA)). These products were generated with different characteristics. The LG was the most important product, it was thermally stable, and its formation was favored at elevated pyrolysis temperature and time. Most of the other products were also enhanced at elevated pyrolytic conditions. However, some products, such as the LGO, were favorable to be produced at low temperatures. Based on these characteristics, discussion was performed on the possible pyrolytic pathways for the formation of the important products.     

Studies on structure characterization of tryptophan melanin: Comparison between filament and curie-point pyrolysis gas chromatography/mass spectrometry

Structural studies of a synthetic melanin, obtained by means of performic acid oxidation of tryptophan, were carried out by pyrolysis gas chromatography/mass Spectrometry (Py-GC/MS). To identify the best pyrolysis conditions, both Curie-point pyrolysis and filament pyrolysis were employed and the effects of pyrolysis temperatures and times were studied. Using the first approach, various compounds were identified: toluene, ethylbenzene, styrene, indole, methylindole, ethylindole, phenol, cresol and ethylphenol. Using filament pyrolysis some interesting differences could be observed. Whereas toluene, ethylbenzene, phenol, cresol and methylindole were found, neither indole nor ethylindole was detected. Instead, new pyrolysis products were evident, such as methylpyrrole and indolin-2-one. Hence filament pyrolysis seems to activate different thermal decomposition pathways of the melanin under study. It is suggested that tryptophan melanin is a polymer containing indole and hydroxyindole derivatives as subunits.     

全温度段裂解提质对锡盟褐煤成浆特性的影响

通过对锡盟褐煤进行涵盖高、中、低完整温度段的裂解提质,研究了裂解过程对煤质特性、成浆浓度、浆体流变特性以及稳定性的影响。对锡盟褐煤在隔绝空气条件下裂解,测量不同浓度浆体的黏度,并对剪切速率和表观黏度进行拟合得到不同浆体不同浓度的流变特性曲线,根据国标规定方法测量浆体的实际浓度以及浆体稳定性。并从裂解过程中样品表面官能团和孔隙结构变化角度分析裂解对锡盟原煤及半焦成浆特性的作用机理。实验结果表明,裂解过程可以减少样品中的含氧官能团,降低其亲水性,有利于成浆浓度的提高,成浆浓度随裂解温度的升高呈现先增大后减小的变化趋势,但是裂解对浆体的稳定性有负面影响。随裂解温度的提高,含氧官能团的分解导致半焦的孔隙结构发生显著变化,平均孔径先减小后增大,比表面积和孔容积呈先增大后减小趋势。     

Flash pyrolysis of grape residues into biofuel in a bubbling fluid bed

The pyrolysis of two grape residues (grape skins and the mixture of grape skins and seeds) has been carried out in a pilot bubbling fluidized bed pyrolyzer operating under a range of temperature from 300 to 600 °C and three vapor residence time (2.5, 5, and 20 s), with the aim of determining their pyrolysis behavior including products yields and heat requirements. The composition of the product gases was determined, from which their heating value was calculated. The liquid bio-oil was recovered with cyclonic condensers and separated into two phases, an aqueous phase and an organic phase. The chemical composition of these liquid phases was characterized. In addition, the environmental parameters of the distilled fraction (85–115 °C) of the aqueous phase were tested, while the heating value of the organic phase was determined. Furthermore, the thermal sustainability of the pyrolysis process was estimated by considering the energy contribution of the product gases and of the liquid bio-oil in relation to the pyrolysis heat requirements. The optimum pyrolysis temperatures were identified in terms of maximizing the liquid yield, maximizing the energy from the product bio-oil, and maximizing the net energy from the product bio-oil after ensuring a self-sustainable process by utilizing the product gases and bio-oil as heat sources.