Curie point pyrolysis gas chromatography using ferromagnetic tubes as sample supports

Summary In pulse-mode pyrolysis gas chromatography, where a solid sample is pyrolysed by contact with a heated filament, there is usually no thermal equilibrium between sample and support. Such an equilibrium is approached by pyrolysing solid samples within ferromagnetic tubes. Tubes 1.5 mm outside diameter (10 % wall) may be heated and stabilized to the Curie Point (iron: 760 °C) in 60 msec. This type of Curie Point pyrolysis will help to increase reproducibility in pyrolysis gas chromatography.In part presented at the Seventh International Symposium on Advances in Chromatography, Las Vegas, Nevada, November 29 / December 3, 1971 and the Second International Symposium on Pyrolysis Gas Chromatography, Paris, September 28/29, 1972     

Analysis of polycyclic aromatic hydrocarbons in contaminated soil by Curie point pyrolysis coupled to gas chromatography-mass spectrometry, an alternative to conventional methods

Curie point pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) has been compared with classical extraction procedures (Soxhlet, sonication, KOH digestion, microwave-assisted) followed by GC-MS analysis for the determination of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil. In each case, the efficiency of the technique was examined for 16 PAHs included in the US Environmental Protection Agency Priority Pollutant List. The results indicate that the recovery of PAHs is dependent on the extraction technique. The highest recoveries of PAHs were obtained with Curie point pyrolysis and KOH digestion. Py-GC-MS appeared to be interesting alternative method for the determination of PAHs in contaminated soil. The results were validated by certified soil (CRM 104) analysis.     

Pyrolysis-gas chromatography/fourier-transform infrared spectrometry of poly(ester urethane) elastomers

Three types of industrial poly (ester urethane) elastomers were studied by Curie–point pyrolysis–gas chromatography/Fourier–Transform infrared spectrometry (Py–GC/FTIR) with a maximum pyrolysis temperature of 973 K. The samples chosen were the Urepans 600 and 641 from Bayer and Elastollan C 78 A from BASF/Elastogran. The poly(ester urethane) elastomers are composed of three units: a polyesterdiol, a short chain diol and a diisocyanate. Py–GC/FTIR allows a rapid and unambiguous identification of the polymer chains by key fragments.     

A novel technique for the sampling and gas chromatographic analysis of vapours

Summary A conventional pyrolysis gas chromatography system has been adapted to the analysis of vapours. A Curie point pyrolysis wire is used as a holder for granular active carbon on which the sample can be adsorbed. Desorption is achieved in the pyrolysis unit, but no pyrolysis occurs. The present study reports on the completeness of adsorption by the sampler and on the degree of release of adsorbate from it.     

Thermal degradation mechanism of methacrylonitrile-styrene copolymers on flash pyrolysis

The thermal degradation mechanisms of random copolymers of methacrylonitrile (MAN) and styrene (St) have been investigated by pyrolysis gas chromatography in the temperature range of 358 to 920?C using a Curie point pyrolyzer (JHP-2) and comparing results with the results from TG/DTA-FTIR apparatus (SII-6200, JASCO-320). The amount of St monomer from decomposition of the copolymer is higher than that from P(St) alone; whilst that of MAN monomer from copolymer is lower than that from P(MAN). This phenomenon reflects the boundary effect in the pyrolysis of copolymer. The thermal degradation mechanisms of copolymers are discussed in terms of the competition between the depolymerization and the back biting reaction on the basis of bond dissociation energies of C-C and C-H bonds in the copolymer chain.     

A new method for solvent-free application of polymers and inorganic materials to ferromagnetic wires used for pyrolysis-capillary gas chromatographic studies

A method is described that enables soluble and insoluble samples to be applied to ferromagnetic wires. The principle of the method consists in pressing the sample on to a flattened Curie-point wire at a pressure of 15 tonnes. It is shown that this method is suitable for a wide variety of polymers and for inorganic materials. As the pyrolysis—gas chromatographic results obtained are not only influenced by the pyrolysis itself but also to a large extent by the gas chromatographic process, a number of considerations are given with respect to the use of capillary gas chromatography in combination with a Curie-point pyrolyser. The sample application technique described has also been used to check the inertness of the chromatographic system by the preparation of Curie wires loaded with Tenax. These wires have been used for the “injection” of volatile compounds, such as a Grob mixture, with the pyrolyser system.     

Catalytic pyrolysis of polypropylene to synthesize carbon nanotubes and hydrogen through a two-stage process

A two-stage reaction process was used to convert polypropylene (PP) into multi-walled carbon nanotubes (MWCNTs) and hydrogen-rich gas. The proposed process consisted of two stages: catalytic pyrolysis of PP over HZSM-5 zeolite in a screw kiln reactor and the subsequent catalytic decomposition of pyrolysis gases over a nickel catalysts in a moving-bed reactor for producing MWCNTs and hydrogen. The resultant gas mainly consisted of hydrogen and methane. SEM and TEM images revealed that carbon products in the moving-bed reactor were in the form of MWCNTs. XRD and TGA characterization indicated that high decomposition temperature resulted in the formation of more highly crystalline nanotubes. The influence of pyrolysis temperature (550-750 °C) and decomposition temperature (500-800 °C) on the performances of the two-stage reaction system were investigated. The MWCNT yield and hydrogen concentration increased with an increase in the decomposition temperature and reached a maximum at 700 °C. With increasing pyrolysis temperature the yield of pyrolysis gas increased while the liquid yield decreased. The yield of MWCNTs in the moving-bed reactor was determined by both the quantity and quality of the pyrolysis gas.     

同时裂解甲基化气相色谱法鉴别合成胶粘剂

 应用同时裂解甲基化气相色谱法 (Py Me GC)对合成胶粘剂进行了鉴别。采用热丝型裂解器、氢火焰离子化气相色谱仪、FFAP毛细管柱、程序升温方式及季铵盐甲基化试剂 ,对刑事案件中常见的丙烯酸酯类及其改性体、醋酸乙烯酯、聚乙烯醇等合成胶粘剂进行了测定 ,并对样品裂解各主要组分峰进行了GC/MS定性分析 ,同时比较了相同样本用常规裂解气相色谱法 (Py GC)测定的结果。结果表明 :Py Me GC法比Py GC法可获得更多的物质组分信息 ,是一种适用于法庭科学鉴定的方法。     

裂解气相色谱—裂解毛细柱气相色谱联用仪

设计了一种裂解气相色谱--裂解毛细柱气相色谱联用仪。在第一级裂解气相色谱仪把聚合物裂解并分离裂解产物,分离了的产物用六通气体进样阀选取并逐个在第二级裂解气相色谱仪裂解,得到聚合物裂解产物的裂解气相色谱图。与低分子化合物的标准指纹图比较,这些裂解产物就得到确认,这样,就可以充分肯定地推断复杂聚合物的组成。     

加拿大合成原油瓦斯油裂解反应规律与产物生成机理

利用小型固定流化床实验装置研究了加拿大合成原油重瓦斯油(HGO)和轻瓦斯油(LGO)的催化裂解性能和热裂解性能。HGO和LGO催化裂解总低碳烯烃(乙烯+丙烯+丁烯)产率在660℃附近达到最大值,分别为33.8%和35.6%。HGO和LGO热裂解反应程度很大,700℃的转化率分别为66.7%和76.3%。HGO热裂解总低碳烯烃的产率在680℃达到最大值27.9%。通过对比分析催化裂解与热裂解气体产物产率的比值发现,催化剂的加入促进了乙烯和液化气的生成,同时抑制了甲烷和乙烷的生成。研究结果揭示了小分子烃类的生成机理,甲烷和乙烷主要是自由基反应的产物,乙烯和液化气是自由基反应和正碳离子反应的共同产物。     

硫酸盐法制浆黑液中主要有机组分的热解特性研究

采用管式炉对硫酸盐法竹子、阔叶木混合制浆黑液固形物(BLS)及其三种主要组分碱木素(AL)、多糖(PLS)和木素-碳水化合物复合体(LCC),在400~800℃进行热解,全面分析了各相热解产物组成与分布规律。结果表明,BLS及其三种主要组分的热解产物组成与分布规律存在明显差异。AL、PLS和LCC对BLS热解产生H₂和CO的产率影响不大,PLS热解生成CO₂的能力明显高于BLS、AL和LCC。BLS热解液相产物中的酚类和醚类主要是来自AL和LCC;酮类和酸类是由AL、PLS和LCC共同贡献的。BLS、AL、PLS和LCC热解半焦表面形貌存在明显差异。在BLS热解过程中,AL、PLS和LCC会相互影响、相互制约,共同决定着BLS的热解特性。     

Comparison between the “one-step” and “two-step” catalytic pyrolysis of pine bark

In this study, one-step and two-step pyrolysis systems were compared in the pyrolysis of pine bark. One-step pyrolysis was performed in a fixed bed reactor with and without catalyst. Two-step pyrolysis was carried out in a dual reactor system over catalyst; the first reactor containing no catalyst whereas the second reactor containing catalyst to upgrade the thermally cracked products. The catalysts used in the pyrolysis systems were ReUS-Y, red mud and ZSM-5. In thermal pyrolysis, the pyrolysis system mainly affected the relative amount of bio-oil. The bio-oil yields obtained from two-step thermal pyrolysis were higher than the yields from one-step thermal pyrolysis. In the catalytic runs, ReUS-Y catalyst slightly decreased the char formation with a consequent increase in aqueous phase yield in the case of one-step pyrolysis. However, the catalysts decreased the bio-oil yield with a consequent increase in the gas yield in the case of two-step pyrolysis. The general compositions of bio-oils obtained from both two pyrolysis systems were affected by using catalysts. In the case of one-step pyrolysis, the formation of water and water soluble compounds were reduced by using ReUS-Y catalyst. In the case of two-step pyrolysis, both ZSM-5 and red mud increased the formation of water soluble compounds while they decreased water formation. In contrast, ReUS-Y decreased the formation of water soluble compounds and increased the amount of pyrolytic lignin compounds in bio-oil. Fuel characteristics of pyrolysis products (gas, bio-oil and char) for both two pyrolysis systems were also investigated comparatively.     

Molecular turnover time of soil organic matter in particle‐size fractions of an arable soil

The composition and molecular residence time of soil organic matter (SOM) in four particle‐size fractions (POM >200 µm, POM 63–200 µm, silt and clay) were determined using Curie‐point pyrolysis/gas chromatography coupled on‐line to mass spectrometry. The fractions were isolated from soils, either continuously with a C₃ wheat (soil ¹³C value = ?26.4‰), or transferred to a C₄ maize (soil ¹³C value = ?20.2‰) cropping system 23 years ago. Pyrograms contained up to 45 different pyrolysis peaks; 37 (ca. 85%) were identifiable compounds. Lignins and carbohydrates dominated the POM fractions, proteins were abundant, but lignin was (nearly) absent in the silt and clay fractions. The mean turnover time (MRT) for the pyrolysis products in particulate organic matter (POM) was generally <15 years (fast C pool) and 20–300 years (medium or slow C pools) in silt and clay fractions. Methylcyclopentenone (carbohydrate) in the clay fraction and benzene (mixed source) in the silt fraction exhibited the longest MRTs, 297 and 159 years, respectively. Plant‐derived organic matter was not stored in soils, but was transformed to microbial remains, mainly in the form of carbohydrates and proteins and held in soil by organo‐mineral interactions. Selective preservation of plant‐derived OM (i.e. lignin) based on chemical recalcitrance was not observed in these arable soils. Association/presence of C with silt or clays in soils clearly increased MRT values, but in an as yet unresolved manner (i.e. ‘truly’ stabilized, or potentially still ‘labile’ but just not accessible C). Copyright © 2009 John Wiley & Sons, Ltd.     

碱／碱土金属催化松木屑快速热解机制

研究碱／碱土金属（AAEM）对生物质的热解及其热解产物组成的影响规律,可为生物质热解特性研究和热解产物的高效利用提供重要的理论依据。本文以松木屑为原料,将原样进行酸洗,并对酸洗样分别用K、Ca、Na和Mg氯化盐溶液浸渍,在500℃和Ar气氛下对各样品进行快速热解,考察了4种金属离子对松木屑热解产物组成分布的影响规律;通过热重分析考察了各个样品的热解特性;通过对热解生物油的气相色谱／质谱（GC／MS）分析考察了快速热解的焦油成分。研究结果表明：AAEM对松木屑有明显的催化作用,AAEM的存在能够提高热解气体和固体的产率,降低热解焦油的产率;AAEM能够降低热解温度,使热解更加容易进行;快速热解的焦油成分主要有酚类、酮类、醛类、芳烃、醇类、脱水糖类、呋喃类以及酸类,AAEM显著影响焦油产物组成,特别是呋喃类和芳烃的含量会有所增加。本文为优化生物质的热解条件与提高热解生物油品质具有重要意义。     

Autoinflammation et stabilité thermique de la poly(vinyl-4-pyridine) quaternisée—IV Methode d'étude des mécanismes d'autoinflammation. Application aux cas du bromure de poly(vinyl-4-pyridinium) et du bromure de poly(N(3-propionyl)4-vinylpyridinium)

We have determined the nature of the combustible gas produced from oxidizing pyrolysis of a polymer (the bromide of poly(vinyl-4-pyridinium) and the bromide of poly(N(3-propionyl)4-vinylpyridinium)). The pyrolysis temperature chosen was just below the self ignition temperature and the pyrolysis was performed in air at atmospheric pressure. We analysed the gaseous products by gas chromatography and mass spectrometry. We found a correlation between the change of the self ignition temperature, the change of the composition of the gas phase and the change of the percentage of residue. We assumed that the gas mixture originates the self ignition of the polymer. The composition of the gas mixture depends on the composition of the polymer.     

压力对塔里木原油四组分热解性能的影响

压力对深层油藏原油热化学过程的影响尚存在较大争议,为研究其在油藏原油热解成气过程中的作用机理,我们在450℃、5~40 MPa压力下对塔里木原油四组分(饱和分、芳香分、胶质和沥青质)进行了封闭体系的热解实验,通过气相色谱(GC)和气相色谱/质谱(GC/MS)分别对原油四组分热解反应的气体产物及饱和分热解过程的液态产物进行了分析。结果表明,在450℃、24 h及不同压力下,沥青质热解产气率高于胶质、芳香分和饱和分;四组分的气相热解产物中,C1的产率明显高于C2~C5组分。增大压力抑制沥青质、胶质及芳香分的热解产气过程而促进饱和分的热解产气过程。随压力的增大,饱和分热解的液态产物的主峰组分碳数先减小,再增大。压力低于20 MPa时,饱和分热解过程中以裂解反应为主;高于30 MPa时,增大压力有利于缩合反应。研究结果可为认识深层油藏原油的稳定程度及天然气的成因提供一定的理论参考。     

不同氛围下绿原酸的热解行为及其裂解产物中苯酚含量分布规律研究

采用热重分析法(TGA)及在线裂解气相色谱-质谱联用仪(Py/GC - MS)研究了烟草中绿原酸在不同氛围下的热解行为及其含量分布规律.先用TGA确定了绿原酸在氮气氛围中的主要热失重区间,选取4个典型的温度点,再结合卷烟在高温燃烧区的3个温度点,分别在惰性(氦气)和有氧(含9％氧气的氮氧混合气)氛围中进行热裂解实验,对...     

Determination of branching in polyethylene and poly(vinyl chloride) using pyrolysis gas chromatography

A series of polyethylenes (PE), reduced poly(vinyl chlorides), and precursor poly(vinyl chloride) (PVC) systems were studied by pyrolysis–gas chromatography (PGC) and by pyrolysis–hydrogenation–gas chromatography (PHGC). The branch content of these polymers has been interpreted on the basis of previously established literature information. Low-density PE (LDPE) was found to contain a significant number of ethyl branches. The pyrolysis results on an LAH-reduced PVC series gave significant insight on PVC microstructure. It was determined that the short-chain branches in PVC are mainly one carbon long. Some ethyl side chains and virtually no butyl branches were found in this experimental PVC series. The effect of chain branching on the pyrolysis of PVC is to increase fragmentation. The benzene/toluene ratio, along with relative amounts of benzene and naphthalene formed, may be used to indicate the relative degree of branching in this system. The application of PGC and PHGC have thus been shown to successfully extend analytical work on PE and PVC and to provide microstructural information.     

富氢气氛下煤热解脱硫脱氮的研究

本文对兖州高硫煤在１０ｍｌ固定床反应器中分别与相当条件下的焦炉煤气、合成气、氢气共热解所得半焦及焦油元素进行系统的分析比较。结果表明,在压力为３ＭＰａ,温度为６５０℃,升温速率为１０℃／ｍｉｎ相对温和的热解条件下,兖州高硫煤与焦炉气、合成气、氢气共热解脱氮率分别为３０１％、３５７％、４４０％（ｗ％,ａｄ）,脱硫率基本相当约为８０％（ｗ％,ａｄ）,且在此三种热解气氛下煤中硫在热解固、液、气产物中的分布极为相似,分别约为２０％、１０％、７０％。与相当氢分压下的纯氢加氢热解相比,５ＭＰａ焦炉气气氛下兖州煤热解脱硫率增加约４５％,脱氮率降低约３５％。用焦炉气顶替纯氢气进行煤加氢热解具有较大的脱硫优势,这不失为我国高硫煤洁净利用的新途径     

Comparison of EI and metastable atom bombardment ionization for the identification of polyurethane thermal degradation products

Polyurethanes are widely used in the manufacture of commercial products such as foams and paints. During combustion, these polymers can generate isocyanates, which induce adverse health effects. Polymer pyrolysis (Py) hyphenated with mass spectrometry (MS) allows the investigation of polymer thermal degradation over time/temperature. A diphenylmethanediisocyanate (MDI) polyurethane foam was analyzed with electron ionization (EI) and metastable atom bombardment (MAB) ionization at a pyrolysis temperature of 400 °C. The recently introduced MAB ionization source uses discrete energy stored in metastable atoms of gases to ionize the analytes. This characteristic allows modulation of the ionization energy by simply changing the ionization gas. The extensive fragmentation of molecular ions observed using EI 70 eV is not totally eliminated with EI 10 eV. However, only molecular ions are observed with MAB using N₂ as the ionization gas. Temperature gradients were used to separate the products generated during the thermal degradation of a 1,6-hexamethylenediisocyanate (HDI) polyurethane paint. The analysis of mass spectra was facilitated owing to a selective desorption of pyrolysis products. Furthermore, changing the MAB ionization gas allows elucidation of the structure of the pyrolysis products by controlling the extent of their fragmentation. During these experiments, isocyanic acid, methyleneisocyanate, ethyleneisocyanate, propylisocyanate and butylisocyanate were detected.