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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.


Bauer D.,German Center for Energy Resources | Bauer D.,TU Bergakademie Freiberg | Vogt T.,German Center for Energy Resources | Vogt T.,TU Bergakademie Freiberg | And 4 more authors.
Analytical Chemistry | Year: 2014

A new direct solid sampling method for speciation of sulfur in coals by electrothermal vaporization inductively coupled plasma optical emission spectrometry (ETV-ICP OES) is presented. On the basis of the controlled thermal decomposition of coal in an argon atmosphere, it is possible to determine the different sulfur species in addition to elemental sulfur in coals. For the assignment of the obtained peaks from the sulfur transient emission signal, several analytical techniques (reflected light microscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy and X-ray diffraction) were used. The developed direct solid sampling method enables a good accuracy (relative standard deviation ≤ 6%), precision and was applied to determine the sulfur forms in the Argonne premium coals, varying in rank. The generated method is time- and cost-effective and well suited for the fast characterization of sulfur species in coal. It can be automated to a large extent and is applicable for process-accompanying analyses. © 2014 American Chemical Society.


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.


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 | 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.


Vogt T.,German Center for Energy Resources | Vogt T.,TU Bergakademie Freiberg | Bauer D.,German Center for Energy Resources | Bauer D.,TU Bergakademie Freiberg | And 2 more authors.
Analytical Chemistry | Year: 2015

A new analytical method for direct determination of total oxygen contents in eight coal samples of the Argonne Premium Coal (APC) series and in the NIST SRM 1632d is presented. The development of a suitable calibration procedure, optimization of measurement conditions, and the application of a tailored data processing for handling of plasma effects and high blanks enable the quantification of oxygen simultaneously with other trace, minor, or major elements in whole coal samples by means of electrothermal vaporization inductively coupled plasma optical emission spectrometry (ETV-ICP OES). For comparison, the oxygen contents were determined by a direct oxygen analyzer. The obtained oxygen values of the APC and the reference material NIST SRM 1632d were compared to data in the literature. The precision of the ETV-ICP OES was within ±3.5%, and the recovery better than 92%. With this good accuracy, the developed direct solid sampling method ETV-ICP OES is well suited for the fast determination of oxygen in coals, varying in rank from lignite to semianthracite, in a content range of about 100 ppm up to 27% using 1.5 mg sample weight. This direct analysis method represents an accurate, advantageous alternative to currently used methods for estimation of total oxygen contents in coals. © 2015 American Chemical Society.


Rathsack P.,German Center for Energy Resources | Rathsack P.,TU Bergakademie Freiberg | Wolf B.,German Center for Energy Resources | Wolf B.,TU Bergakademie Freiberg | And 2 more authors.
Analytical Chemistry | Year: 2015

Pyrolysis liquids from coal are complex mixtures of organic compounds with low to high molecular mass and low to high polarity. Compared to low-molecular-weight compounds, little information is available regarding high-molecular-weight compounds in pyrolysis liquids, although their characterization is important for the elucidation of degradation pathways. In this study, laser desorption ionization (LDI) using graphite powder as the support material has been used in conjunction with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) for the analysis of a pyrolysis liquid from brown coal. The acquired data is compared to previous results of the same sample using electrospray ionization (ESI). Using LDI, compounds with masses between 300 and 900 Da were detected by LDI. An evaluation of the spectra was based on the frequency of molecular formulas with a different number of heteroatoms. Hydrocarbon compounds and heteroatomic compounds containing oxygen and sulfur were found. A comparison to ESI results shows that the numbers of observed molecular formulas are virtually the same, but a higher quantity of molecular formulas with a low number of oxygen can be detected by LDI. The observation of molecular formulas without oxygen is a unique feature of the LDI spectra. A more detailed investigation was possible by the utilization of double bond equivalent plots versus carbon number, which revealed a prevalence of LDI for the ionization of compounds with higher DBE. © 2015 American Chemical Society.


Vogt T.,German Center for Energy Resources | Vogt T.,TU Bergakademie Freiberg | Bauer D.,German Center for Energy Resources | Bauer D.,TU Bergakademie Freiberg | And 2 more authors.
Fuel | Year: 2015

A new and highly efficient solid sampling method was developed for fast direct multi-element analysis in coals using electrothermal vaporization as sample introduction system for inductively coupled plasma optical emission spectrometry (ETV-ICP OES). With ETV coupled to ICP OES it is possible to analyze trace and major elements simultaneously in whole coal samples with a minimum effort of sample preparation and short analyzing times. The quantitative determination of Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, S, Si, Ti, V and Zn by ETV-ICP OES in all eight Argonne Premium Coals, covering the rank range from lignite to semi-anthracite, is presented. The results are comparable with the reported element contents in literature. It is shown, that the fast direct solid sampling multi-element spectroscopic method, based on electrothermal vaporization of powdered samples, is proved to be a suitable alternative to labor intensive traditional methods. © 2014 Elsevier Ltd. All rights reserved.


Reichel D.,TU Bergakademie Freiberg | Reichel D.,German Center for Energy Resources | Klinger M.,TU Bergakademie Freiberg | Klinger M.,German Center for Energy Resources | And 2 more authors.
Fuel | Year: 2013

The influence of inorganic constituents on the pyrolysis behavior of different biomass materials and brown coals was studied in a fixed bed reactor within a temperature range of 250-700 °C. The tests were carried out with untreated and demineralized samples. Inorganic elements dominant in the used brown coals are calcium, silicon, iron, magnesium, and for some samples also sodium and aluminum. Biomass inorganic constituents mainly involve potassium, silicon and calcium. Nearly total demineralization was accomplished for brown coals via HCl and HF treatment. To prevent exceeding structural changes for biomass materials only HCl was used to remove elements like potassium, magnesium, calcium, and phosphorus. Yields, product composition and HHV were determined for each pyrolysis temperature to create mass and energy balances. Demineralization causes an increase in total liquid yields, while gas yield and char yield (only slightly) decrease. Biomass materials show a stronger effect and main decomposition stage is shifted to higher temperatures. Gas composition is also affected by acid treatment, whereas differences occur between the various fuels. Furthermore, the pyrolysis process becomes more endothermic for the demineralized samples. © 2013 Elsevier Ltd. All rights reserved.


PubMed | TU Bergakademie Freiberg and German Center for Energy Resources
Type: Journal Article | Journal: Analytical chemistry | Year: 2015

A new analytical method for direct determination of total oxygen contents in eight coal samples of the Argonne Premium Coal (APC) series and in the NIST SRM 1632d is presented. The development of a suitable calibration procedure, optimization of measurement conditions, and the application of a tailored data processing for handling of plasma effects and high blanks enable the quantification of oxygen simultaneously with other trace, minor, or major elements in whole coal samples by means of electrothermal vaporization inductively coupled plasma optical emission spectrometry (ETV-ICP OES). For comparison, the oxygen contents were determined by a direct oxygen analyzer. The obtained oxygen values of the APC and the reference material NIST SRM 1632d were compared to data in the literature. The precision of the ETV-ICP OES was within 3.5%, and the recovery better than 92%. With this good accuracy, the developed direct solid sampling method ETV-ICP OES is well suited for the fast determination of oxygen in coals, varying in rank from lignite to semianthracite, in a content range of about 100 ppm up to 27% using 1.5 mg sample weight. This direct analysis method represents an accurate, advantageous alternative to currently used methods for estimation of total oxygen contents in coals.

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