Analysis of pyrolysis liquids obtained from the slow pyrolysis of a German brown coal by comprehensive gas chromatography mass spectrometry

Due to the upcoming shortage of crude oil and natural gas, alternative resources for the production of chemicals are needed and long-term research should be conducted. One of the future possible methods for the production of valuable chemicals is the utilization of coal and its conversion by pyrolysis. During pyrolysis, macromolecular organic compounds are decomposed into smaller compounds, which can be utilized. The development of these processes requires compositional knowledge of the products, which are very complex mixtures of organic compounds. In this study a series of pyrolysis liquids obtained in a fixed bed reactor at different pyrolysis temperatures between 400 and 700 °C is analyzed qualitatively and quantitatively by comprehensive gas chromatography mass spectrometry (GC×GC-MS). More than thousand compounds were observed in each of the samples. Selected compound classes (alkanes, alkenes, alkylbenzenes, phenols, carboxylic acids and thiophenes) are discussed in detail. Quantification results of 94 compounds are given, visualized and discussed in relation to the pyrolysis conditions. It is demonstrated, that the application of GC×GC-MS is highly beneficial for the analysis of pyrolysis liquids from coal.