Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Pyrolysis”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
PubMed2004

[Analysis of composition and structure of sulfur compounds in residual oils by pyrolysis-gas chromatography].

Flash pyrolysis-gas chromatography has been used to investigate macromolecular sulphur in heavy oil. The influences of pyrolysis time and pyrolysis temperature have been studied and the analytical methods of pyrolysis were set up. Sulfur-containing products were identified by comparing with reference data and semi-quantified by a pulsed flame photometric detector (PFPD). The investigation conducted on Dagang, Gudao, Qianguo, Russia and mixed Russia-Daqing residual oils using pyrolysis-gas chromatography showed that the contents and composition of sulphur compounds demonstrated various characters in different pyrolysates of residual oils.

Chromatography, Gas↗
PubMed2006

[Study on the pyrolysis behavior of geranyl-beta-D-glucopyranoside by gas chromatography-mass spectrometry].

In order to investigate the pyrolysis behavior of the flavor precursor of geranyl-beta-D-glucopyranoside, the glycoside was pyrolyzed at 200, 300, 400 degrees C in an on-line pyrolyzer under anaerobic conditions and in an off-line mode separately. Gas chromatography-mass spectrometry (GC/MS) was used for the qualitative and quantitative analysis of the pyrolysis products. the results. Little geranyl-beta-D-glucopyranoside was pyrolyzed at 200 degrees C and there were a large amount of geraniol and little by-products produced at 300 degrees C. With the increasing temperature to 400 degrees C, both the pyrolytic products and by-products were significantly increased. Therefore, it indicated that the optimized temperature of pyrolysis was 300 degrees C. The main pyrolysis product of the glycoside was geraniol. It showed the primary decomposition reaction took place with the breaking of glycosidic linkage, the cleavage of O-glycosidic bond as expected. The on-line mode experiment was a rapid and good qualitative method for the pyrolysis, and the off-line mode can be used as a quantitative method based on the qualitative analysis.

Acyclic Monoterpenes↗
PubMed1997

Assessment of bog-body tissue preservation by pyrolysis-gas chromatography/mass spectrometry.

Flash pyrolysis-gas chromatography/mass spectrometry (py-GC/MS) was used to assess the quality and mechanism of protein preservation in the tissue of Iron Age bog bodies from Lindow, UK, and south-eastern Drenthe, The Netherlands. Abundant pyrolysis products of the fresh skin tissue, including 2,5-diketopiperazines of Pro-Gly, Pro-Ala, Pro-Val, Pro-Pro and Hyp, were readily assigned to specific amino acid or dipeptide moieties. Comparison of the pyrolysates of the bog-body tissues with that of modern samples revealed qualitative similarities suggesting good preservation of the collagen and non-collagenous proteins in the ancient tissues. Examination of the pyrolysates of samples of fresh calf skin, which had been treated with various vegetable tanning agents, clearly revealed markers of non-hydrolysable tannins including 1,2-benzenediol, 1,3-benzenediol and 1,2,3-benzenetriol, although chromatographic quality inevitably diminished with increasing functionalization of the compounds. Such markers were not detected in the pyrolysates of the bog-body tissues. Instead 4-isopropenylphenol, a characteristic pyrolysis product of Sphagnum moss, was detected in both solvent-extracted and base-treated samples of tissue. The presence of 4-isopropenylphenol in the pyrolysates of the bog-body tissues provides evidence that their preservation involves reactions of amino acids with sphagnum acid, and possibly other agents derived from the peat. The study constitutes the first chemical characterization of the pyrolysis products of modern and ancient collagen.

Aged↗
PubMed2002

Carbon isotope ratio analysis of organic moieties from fossil mummified wood: establishing optimum conditions for off-line pyrolysis extraction using gas chromatography/mass spectrometry.

Mummified fossil wood was studied using off-line pyrolysis-gas chromatography/mass spectrometry to reveal detailed insights into the pyrolysis conditions that are needed to obtain simultaneously sufficient amounts of both cellulose and lignin markers for stable carbon isotope analyses. The off-line pyrolysis was applied at a range of temperatures (200, 250 and 300 degrees C) and times (1 and 2 h) to determine the optimum temperature and time that yielded the highest quantity of true markers for lignin and cellulose. Increasing the time from 1 to 2 h had no effect whereas increasing the temperature led to large differences. The products released during the low-temperature pyrolysis were mostly related to thermally labile moieties. Only at 300 degrees C were sufficient amounts of products released that represent true cellulose and lignin building blocks and which could be studied using gas chromatography/combustion isotope ratio mass spectrometry.

Alcohols↗
PubMed1988

Fast profiling of food by analytical pyrolysis.

The analytical application of direct pyrolysis (Py) field ionization (FI)-mass spectrometry (MS) und Curie-point pyrolysis gas chromatography-mass spectrometry (Py-GC/FIMS) to various whole foodstuffs is described for the first time. The former technique yields highly differentiated information from the sample in typically 15 min, namely the molecular weight distribution of released volatiles and pyrolysis products in a single spectrum which, owing to the good reproducibility and high significance of the resulting data, has previously been shown to be suitable for the application of chemometric methods. Such mass spectral peaks are further characterized and assigned by high resolution mass measurement and/or by electron ionization after Curie-point pyrolysis and gas chromatographic separation of the components. In this first report, typical results are presented for ground roasted coffee, rosehip tea, wheatmeal biscuit, chocolate drink powder and milk chocolate. The FI mass spectrum obtained from the latter sample is compared with those obtained using the complementary soft ionization techniques of chemical ionization (CI) and direct chemical ionization (DCI).

Animals↗
PubMed1995

Confined-pyrolysis as an experimental method for hydrothermal organic synthesis.

A closed pyrolysis system has been developed as a tool for studying the reactions of organic compounds under extreme hydrothermal conditions. Small high pressure stainless steel vessels in which the ratio of sediment or sample to water has been adjusted to eliminate the headspace at peak experimental conditions confines the organic components to the bulk solid matrix and eliminates the partitioning of the organic compounds away from the inorganic components during the experiment. Confined pyrolysis experiments were performed to simulate thermally driven catagenetic changes in sedimentary organic matter using a solids to water ratio of 3.4 to 1. The extent of alteration was measured by monitoring the steroid and triterpenoid biomarkers and polycyclic aromatic hydrocarbon distributions. These pyrolysis experiments duplicated the hydrothermal transformations observed in nature. Molecular probe experiments using alkadienes, alkenes and alkanes in H2O and D2O elucidated the isomerization and hydrogenation reactions of aliphatic compounds and competing oxidative reactions occurring under hydrothermal conditions. This confined pyrolysis technique is being applied to test experiments on organic synthesis of relevance to chemical evolution for the origin of life.

Alkanes↗
PubMed1999

Liquid-Saturated Hydrocarbons Resulting from Pyrolysis of the Marine Coccolithophores Emiliania huxleyi and Gephyrocapsa oceanica.

: Two nanoplanktonic marine coccolithophores, Emiliania huxleyi and Gephyrocapsa oceanica, were grown at 23 degrees C with a 16-hour light and 8-hour darkness regimen. The cells were dried at room temperature and then subjected to pyrolysis at 100 degrees to 500 degrees C under anoxygenic conditions to produce hydrocarbons. Temperature-dependent profiles of the liquid-saturated hydrocarbons (saturates) produced during pyrolysis were very similar for the two strains, although the total amount was higher in E. huxleyi than in G. oceanica. The amount of saturates produced was only 0.05% to 0.15% below 200 degrees C, but about 2.1% to 2.8% at 300 degrees C. Their major components were normal alkanes in a series ranging from nC(11) to nC(35) with the predominant peak at nC(15). At 400 degrees and 500 degrees C most of saturates transformed into gaseous compounds. The major saturates identified in all pyrolysates were normal C(31) monounsaturated and diunsaturated alkenes, a series of normal alkanes, phytenes, C(28) sterenes, and steranes. Profiles of saturates in gas chromatography-mass spectroscopy varied with increasing pyrolysis temperature and also differed between E. huxleyi and G. oceanica. The two coccolithophores are useful candidates for the production of renewable liquid fuel through pyrolysis-especially E. huxleyi, which has higher production. The results also provide information for further studies on the characterization, source, and paleogeographic distribution of marine sediment.

Journal Article↗
PubMed2006

Structural investigations of neuromelanin by pyrolysis-gas chromatography/mass spectrometry.

Pyrolysis combined with gas chromatography and mass spectrometry (Py-GC/MS) was applied for structural investigations of the human substantia nigra neuromelanin. Using synthetic neuromelanins, we have demonstrated that Py-GC/MS is suitable for identification and differentiation of both eumelanin (dopamine-derived) and pheomelanin (cysteinyldopamine-derived) component of the pigment. Structural information on melanin monomers was inferred from their pyrolytic markers. When the human neuromelanin was subjected to pyrolysis, none of the heterocyclic, sulfur-containing markers of pheomelanin component was detected among the thermal degradation products. We have concluded that nigral pigment isolated from normal brain tissue does not contain benzothiazine-type monomers, and that cysteinyldopamine-originated units may be incorporated into the polymer in uncyclized form. The most abundant pyrolysis product was identified as limonene, which indicates that nigral pigment is tightly associated with an isoprenoid-type compound. Pyrolysis in the presence of the methylating reagent allowed identification of high levels of saturated and monounsaturated straight-chain C14-C18 fatty acid species chemically bound to the pigment macromolecule.

Gas Chromatography-Mass Spectrometry↗
PubMed2005

Activated carbon from char obtained from vacuum pyrolysis of teak sawdust: pore structure development and characterization.

The preparation of activated carbon from vacuum pyrolysis char of teak sawdust was studied and the results are presented in this paper. The effects of process variables such as temperature and activation time on the pore structure of activated carbons were studied. The activated carbon prepared from char obtained by vacuum pyrolysis has higher surface area and pore volume than that from atmospheric pyrolysis char. The BET surface area and pore volume of activated carbon prepared from vacuum pyrolysis char were 1150 m2/g and 0.43 cm3/g, respectively.

Carbon↗
PubMed2006

Study on the pyrolysis of polyethylene in the presence of iron and copper chlorides.

Pyrolysis experiments were conducted to elucidate the effects of metal chlorides on the thermal degradation of low-density polyethylene on a continuous pyrolysis temperature range of 600 degrees C to 1100 degrees C. The present work focusses on the ratio of aromatics generated on increasing the pyrolysis temperature in the presence of metal salts, iron(II), iron(III) and copper(II) chlorides. It was observed that beside alpha,omega-dienes, alpha-olefins and n-alkanes which are usually observed during the thermal decomposition of polyethylene, the level of aromatics noticeably increases with the addition of metal salts. At high temperatures, the formation of these aromatics took place in such a way that they become the major products when polyethylene is pyrolyzed in presence of FeCl(3) and CuCl(2). Quantification of the effect of metal salts has been tempted comparing the variation of the ratio of aromatics with pyrolysis temperatures. Mechanisms responsible for the formation of these aromatics in presence of metal salts have been tentatively investigated. They are proposed to result from cyclization/dehydrogenation reactions similar to those observed during the thermal decomposition of polyethylene, but with an increased efficiency due to the metal salts.

Chlorides↗
PubMed2005

Identification and quantification of (polymeric) hindered-amine light stabilizers in polymers using pyrolysis-gas chromatography-mass spectrometry and liquid chromatography-ultraviolet absorbance detection-evaporative light scattering detection.

Direct analysis of polymers containing polymeric hindered amine light stabilizers (HALS) by using pyrolysis coupled to GC-MS is applied successfully for fast and straightforward identification of these HALS additives. Each of the HALS additives shows different pyrolysis gas chromatograms containing characteristic pyrolysis products. As a result, HALS additives with very similar chemical structures, e.g. Chimassorb 944 and Chimassorb 2020, can be distinguished. A HPLC method with both ultraviolet (UV) and evaporative light scattering detection (ELSD) is developed to quantify the various HALS additives in extracts of polymers. The critical factor of the HPLC method is the use of a basic amine, like n-hexylamine, as a solvent additive to facilitate the elution of HALS additives. The various HALS additives can be distinguished according to retention time and peak shape and by using different detection methods. The suitability of the developed methods is demonstrated by the analytical performance of the HPLC method and the identification and determination of the actual content of HALS additives in polyolefines using pyrolysis GC-MS and HPLC. The HPLC method can also be used for the determination of the specific migration of HALS additives from food contact materials.

Amines↗
PubMed2006

Characterization of acrylic resins used for restoration of artworks by pyrolysis-silylation-gas chromatography/mass spectrometry with hexamethyldisilazane.

A procedure based on the technique of the pyrolysis-GC/MS has been applied, in this work, in order to determine the composition of synthetic acrylic resins employed in artworks. The method is based on the on line derivatization of these resins using hexamethyldisilazane (HMDS). Results obtained have been compared with those others from direct pyrolysis and in situ thermally assisted hydrolysis and methylation with tetramethylammonium hydroxide (TMAH). Sensitivity using HMDS as derivatising reagent is found similar to that from direct pyrolysis and methylation with TMAH. Better resolution of the most representative peaks has been also obtained. Additionally, this method reduces the formation of free acrylic acid molecules during the pyrolysis process and, in consequence, more simplified and well-resolved chromatograms are obtained. Finally, the reported procedure has been successfully used for characterizing several acrylic-based varnishes and binding media currently used in Fine Arts and real pictorial samples from graffiti performed on a Middle Ages bridge.

Acrylic Resins↗
PubMed2004

Effect of pyrolysis on solvent extractability of toxic metals from chromated copper arsenate (CCA)-treated wood.

Solvent extraction was conducted to investigate the behavior of toxic metals in chromated copper arsenate (CCA)-treated wood and its pyrolysis residue. Four kinds of solvents, along with sulfuric and phosphoric acid as mineral agents, and citric and oxalic acid as complexing agents, were used. The CCA elements from the wood treated without pyrolysis were easily extracted. However, only a small amount of CCA elements were extracted from the pyrolyzed residue, even under very low pH conditions. The toxic elements in the pyrolyzed wood showed high stabilization against the solvent extraction. Pyrolysis strongly immobilized the toxic elements in the residue. Therefore, pyrolysis is not suitable as a pretreatment.

Arsenates↗
PubMed2005

WEEE recycling: Pyrolysis of fire retardant model polymers.

Pyrolysis treatments of model polymers were made with the aim of studying the recycling of wastes from electronic, electric equipment containing brominated flame retardants. Pyrolysis of flame retarded high impact polystyrene and epoxy resins were made both in flow and closed systems. Products of pyrolysis were analysed with FT-IR spectroscopy and GC-MS and the evolution of bromine was followed with a bromine ion specific electrode. The effect of alkali on pyrolysis was also studied demonstrating, as far epoxy resin is concerned, to be effective on decreasing bromine content in oil and volatile products leading to the recovery of bromine from the residue by washing. The alkali treatment was shown to be less effective in styrenic polymers containing brominated flame retardants.

Conservation of Natural Resources↗
PubMed2002

Simple off-line flash pyrolysis procedure with in situ silylation for the analysis of hydroxybenzenes in humic acids and coals.

A simple device consisting of a glass pyrolysis chamber fitted for a commercial resistively heated pyrolysis probe and connected to a solvent desorption tube for air monitoring was applied to off-line pyrolysis under silylating conditions of humic acids (soil, lake) and coals. Samples were flash pyrolysed at 700 degrees C in the presence of excess hexamethyldisilazane, and evolved products were swept off by a nitrogen stream and trapped onto a charcoal filter from where they were desorbed with dichloromethane and analysed by gas chromatography (GC)-mass spectrometry. Humic acids afforded trimethylsilyl (TMS) ethers of phenols, 2-methoxyphenols (guaiacols), 2,6-dimethoxyphenols (syringols), and dihydroxy and trihydroxybenzenes as major products. TMSoxy benzenes were the principal products observed from pyrolysis/silylation of coals. In comparison with conventional pyrolysis, the in-situ derivatisation process enhances the levels of phenols with respect to hydrocarbons and improves the GC separation of isomers (e.g. meta- from para-cresol). With respect to tetramethylammonium hydroxide thermochemolysis, pyrolysis/silylation operates under milder conditions and permits discrimination between free and methylated hydroxy groups. The performance of the method for the quantitative determination of evolved product is described. Yields of evolved silylated mono and dihydroxybenzenes occur in the mg/g range with relative standard deviations generally between 16 and 30%.

Coal↗
PubMed2003

Gas chromatographic-mass spectrometric study of the oil fractions produced by microwave-assisted pyrolysis of different sewage sludges.

The pyrolysis of sewage sludge was studied in a microwave oven using graphite as microwave absorber. The pyrolysis temperature ranged from 800 to 1000 degrees C depending on the type of sewage sludge. A conventional electrical furnace was also employed in order to compare the results obtained with both methods. The pyrolysis oils were trapped in a series of condensers and their characteristics such as elemental analysis and calorific value were determined and compared with those of the initial sludge. The oil composition was analyzed by GC-MS. The oils from the microwave oven had n-alkanes and 1-alkenes, aromatic compounds, ranging from benzene derivatives to polycyclic aromatic hydrocarbons (PAHs), nitrogenated compounds, long chain aliphatic carboxylic acids, ketones and esters and also monoterpenes and steroids. The oil from the electric oven was composed basically of PAHs such as naphthalene, acenapthylene, phenanthrene, fluoranthene, benzo[a]anthracene, benzofluoranthenes, benzopyrenes, indenepyrene, benzo[ghi]perylene, and anthanthrene. In contrast, these compounds were not produced in the case of microwave-assisted pyrolysis.

Gas Chromatography-Mass Spectrometry↗
PubMed1999

Pyrolysis of humic acids from digested and composted sewage sludge

Humic acids (HAs) were extracted from four digested sewage sludge samples composted for four months, one, two and four years. HAs were pyrolyzed at three different temperatures applying both conventional and in situ methylation (ISM) pyrolysis. The pyrolysates were analyzed using gas chromatography-mass spectrometry (GC/MS). Derivatization (ISM) and pyrolysis temperature had dramatic effects on the composition and relative amounts of the pyrolysates. Among the derivatized HA fragments aliphatic compounds prevailed under all the pyrolysis conditions tested. Aromatic substances consisting mainly of guaiacyl-type compounds were detected in higher abundances only at elevated temperatures. Without ISM the contribution of aromatic structures to the total pyrogram was considerably greater than that of the aliphatics. Increase of the pyrolysis temperature from 450 degrees C to 600 degrees C had smaller effect on the proportions and composition of the compounds studied than increase from 350 degrees C to 450 degrees C.

Journal Article↗
PubMed2003

Pyrolysis kinetics of electronic packaging material in a nitrogen atmosphere.

The kinetics of pyrolysis of electronic packaging material are investigated under various heating rates (5, 10, 15, 20 K/min) in an inert atmosphere using a thermogravimetric analysis (TGA) technique. The pyrolysis characteristics of samples are examined by SEM, XRD, FTIR, ICP-MS and EA. The effect of heating condition on the surface area and pore structure of samples is discussed. Two reaction stages are involved for the pyrolysis of electronic packaging material when nitrogen is present in the carrier gas. The corresponding kinetic parameters, including activation energy, pre-exponential factor and reaction order are presented. The apparent activation energies can be divided into three groups. The results will be useful in developing pyrolysis or incineration systems for plastic waste from electronic components.

Electronics↗