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Rathsack P.,German Center for Energy Resources | Rathsack P.,TU Bergakademie Freiberg | Riedewald F.,Composite Recycling Ltd. | Sousa-Gallagher M.,University College Cork
Journal of Analytical and Applied Pyrolysis | Year: 2015

Pyrolysis of scrap tyres is a promising technology to recover valuable materials such as pyrolysis liquids, carbon black and steel. Pyrolysis liquids are complex mixtures of organic compounds and may represent a valuable source for chemicals. And because pyrolysis liquids are complex mixtures, high resolution analytical methods are required to accurately characterize these liquids. In this study comprehensive gas chromatography mass spectrometry (GC× GC-MS) using a reversed column setup (polar × apolar) was used for the analysis of a pyrolysis liquid. The tyre pyrolysis liquid analyzed was obtained from a process which places whole tyres onto molten zinc (460-480 °C) providing direct heat transfer and hence rapid pyrolysis. The results show, that the pyrolysis liquid is a complex mixture of acyclic and cyclic, aliphatic, unsaturated and aromatic hydrocarbons and several heteroatomic compounds. Compared to a normal column setup (apolar × polar), the reversed column setup separates structurally similar acyclic and cyclic hydrocarbon compounds with different degree of unsaturation better. A quantification was performed for a set of 40 compounds. A qualitative and quantitative evaluation of the compounds found, that the composition of the pyrolysis liquid is typical for tyre pyrolysis liquids. Nevertheless, comparably high amounts of limonene of 6.6% (w/w) and low amounts of monocyclic aromatic compounds were found. This is attributed to the very high heating rate of this process due to the direct heat contact of the tyres with molten zinc. © 2015 Elsevier B.V. All rights reserved.

Rathsack P.,German Center for Energy Resources | Otto M.,Institute of Analytical Chemistry
Fuel | Year: 2014

The depletion of fossil fuels like crude oil or natural gas in foreseeable future urges the search for alternative fuels. Alternative resources for the production of fuels are biomass or coal, which have already been the feedstock for the chemical industry decades ago. One way for the production of fuels from theses feedstocks is pyrolysis and current research focuses on the influence of process parameters on composition of liquids from pyrolysis and the optimization of the properties necessary for the proposed utilization. To unravel the chemical composition of these oils, high performance instrumental analytical methods like comprehensive gas-chromatography mass-spectrometry (GC×GC-MS) are highly beneficial. Unfortunately obtained data sets are very complex and dedicated interpretation methods are needed. In this study, the classification of about thousand compounds in a GC×GC-MS chromatogram of a brown coal pyrolysis oil is demonstrated by means of linear discriminant analysis. Based on a reference compound training set, the compound classes alkanes, alkenes, thiophenes, and benzothiophenes could be assigned with low classification error. This will help in the understanding of the influence of process parameters and feedstocks on the composition of pyrolysis oils. © 2013 Elsevier Ltd. All rights reserved.

Rathsack P.,German Center for Energy Resources | Rathsack P.,TU Bergakademie Freiberg | Rieger A.,TU Bergakademie Freiberg | Haseneder R.,TU Bergakademie Freiberg | And 3 more authors.
Journal of Analytical and Applied Pyrolysis | Year: 2014

During the pyrolysis of scrap tires a complex mixtures of organic compounds is liberated and can be condensed as liquid product. In this study comprehensive gas chromatography-mass spectrometry (GC×GC-MS) and headspace gas chromatography (HS-GC) are used to unravel the complex nature of pyrolysis liquids from scrap tires produced by means of an inductively heated batch reactor. Two strategies were employed. On the one hand a set of reference compounds was used for quantification, on the other hand unsupervised learning (c-means clustering) was used to deduce compound classes and assignment of compound class structural features from MS data. The clustering finally allowed the evaluation of the influence of time and heating rate on observable peak areas. It could be shown, that peak area of saturated and partially unsaturated (hydroaromatic) compounds decreased during the time course of experiments and with increasing heating rate, whereas aromatic compounds increased during the course and were favorably liberated at high heating rates. © 2014 Elsevier B.V.

Reichel D.,TU Bergakademie Freiberg | Reichel D.,German Center for Energy Resources | Siegl S.,TU Bergakademie Freiberg | Siegl S.,German Center for Energy Resources | And 2 more authors.
Fuel | Year: 2015

Pyrolysis of a pulverized German brown coal was investigated using a new high pressurized drop tube reactor. Influence of temperature (600, 700, 800°C), pressure (25, 60bar (g)) as well as residence time (variation of heated reactor length: 500, 1500, 2500mm) on pyrolysis product yields as well as char and gas composition were evaluated. Particle heating and residence times of gas and particle in the heated reactor section were calculated based on the obtained data. To trace the pyrolysis progress during particle drop in the reactor tube gas sampling over reactor height was done. A good reactor performance and reliable results for the pyrolysis experiments could be obtained for the new reactor equipment. Only a slight pressure influence on product yields, char composition, and gas composition was found, which was contrary at the different temperatures. This indicates competing reactions taking place at the given conditions. Gas species evolution over the reactor height is mainly promoted by rising temperatures. The long gas residence times in the reactor and the obtained CH4, H2, and C2 and C3 hydrocarbon yields are a result of secondary cracking of tar and gaseous hydrocarbons at temperatures above 600°C. Furthermore, it was found, that heterogeneous gasification reactions take place at higher temperatures as well. Comparison between thermogravimetric experiments in "drop-in" mode and the DTR results show significant differences attributed to heat transfer limitations in the particle bulk (TGA) and to the long gas residence times (78-368s) in the drop tube reactor. © 2015 Elsevier Ltd.

Rathsack P.,German Center for Energy Resources | Rathsack P.,TU Bergakademie Freiberg | Kroll M.M.,TU Bergakademie Freiberg | Otto M.,TU Bergakademie Freiberg
Fuel | Year: 2014

Pyrolysis liquids from the slow pyrolysis of a german brown coal obtained at different pyrolysis temperatures were analyzed by electrospray ionization fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) in negative ion mode. Singly charged ions in the range from m/z = 200 to 700 were observed. Assignment of molecular formulas revealed mainly oxygen containing species, which are most probably acidic compounds ionized during ESI in negative ion mode. Compounds detected were of type Oo, OoS 1, OoS2 and OoN1 with oxygen numbers o = 1. 12 depending on the specific class. The formation or decomposition of certain compound classes upon temperature changes was investigated. It could be shown that summation of observed compound class frequencies in terms of number or intensities is not suitable to identify trends. Identification of temperature dependent behavior of certain compound classes can only be revealed by looking at individual ions, which is exemplified for carboxylic acids. © 2013 Elsevier Ltd. All rights reserved.

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