Whole sample analysis of bio-oils and thermal cracking fractions by Py-GC/MS and TLC–FID

Abstract

A combination of pyrolysis-GC/MS and TLC–FID techniques were used for whole sample analysis of bio-oil samples obtained from different liginocellulosic biomasses, (i.e., birch wood, pine wood, barley straw and forest residue and thermal-cracking fractions). Both techniques showed the ability to analyze the whole sample without cleanup or fractionation and to distinguish among the bio-oils based on their feedstock sources. The TLC–FID is a chromatographic method whereby the oil solution is spotted on a TLC rod, developed by a two solvent system and the chromatographic bands measured by flame ionization detection (FID). The Py-GC/MS instrument uses a sample cup and a vertical microfurnace to analysis bio-oils. The non-volatiles fraction remaining in the cup were weighed after thermal evaporation-GC/MS. The hardwood birch bio-oil was shown to have syringol and its derivatives compared to pine wood and barley straw bio-oils that were shown to have methoxyphenolic and non-methoxy-phenolic compounds, respectively. TLC–FID shows clear differences in the peak areas and shapes for the bio-oils fractions by solvent development on chromarods and are in agreement with the results obtained by Py-GC/MS. Furthermore, forest residue bio-oil and its thermal cracking fractions could be effectively characterized by TLC–FID (and Py-GC/MS) whereby the light fraction was composed of a wide range of lower polarity compounds while middle and heavy fraction had higher polarity compounds.