Comprehensive database of Manufactured Gas Plant tars – Part B Aliphatic and aromatic compounds

摘要

Rationale Coal tars are a mixture of organic and inorganic compounds and were produced as a by-product from the manufactured gas and coke making industries. The composition of the tar produced varied depending on many factors; these include the temperature of production and the type of retort used. As different production processes produce different tars, a comprehensive database of the compounds present within coal tars from different production processes is a valuable resource. Such a database would help to understand how their chemical properties differ and what hazards the compounds present within these tars might pose. This study focuses on the aliphatic and aromatic compounds present in a database of 16 different tars from 5 different production processes. Methods Samples of coal tar were extracted using accelerated solvent extraction (ASE) and derivatized post extraction using BSTFA with 1% TMCS. The derivatized samples were analysed using two-dimensional gas chromatography combined with time-of-flight mass spectrometry (GCxGC/TOFMS). Results A total of 198 individual aliphatic and 951 individual aromatic compounds were detected within 16 tar samples produced by 5 different production processes. The PAH content of coal tars varies greatly depending on the production process used to obtain the tars and this is clearly demonstrated within the results. The aliphatic composition of the tars provided an important piece of analytical information that would have otherwise been missed with the detection of petrogenic compounds such as alkyl cyclohexanes. Conclusions The aromatic compositions of the tar samples varied greatly between the different production processes investigated and useful analytical information ws obtained about the individual production process groups. Alkyl cyclohexanes were detected in all samples from sites known to operate Carbureted Water Gas plants and not detected in those that did not. This suggests that petrogenic material may be expected at many UK gaswork sites.