A comparative production and characterisation of fast pyrolysis bio-oil from Populus and Spruce woods

Highlights: • The effect of temperature on the production of bio-oil from hardwood and softwood has been comprehensively discussed. • The most efficient solvent extraction route for separating and analysing highly valued chemicals has been identified. • Effect of temperature on chemical distribution in bio-oil has been investigated. This study focuses on the production and characterisation of fast pyrolysis bio-oil from hardwood (Populus) and softwood (Spruce) using a bench-scale pyrolysis reactor at two different temperatures. In this study, a mixed solvent extraction method with different polarities was developed to extract different components of bio-crude oil into three fractions. The obtained fractions were characterized by using gas chromatography and mass spectrometry (GC-MS). The effect of temperature on the production of bio-oil and on the chemical distribution in bio-oil was examined. The maximum bio-oil yield (71.20%) was obtained at 873 K for bio-oil produced from softwood (Spruce). In contrast, at a temperature of 773 K, the bio-oil yields were 62.50% and 65.40% for bio-oil obtained from hardwood (Populus) and softwood (Spruce) respectively. More phenolic compounds were extracted at a temperature of 773 K for bio-oil derived from softwood (Spruce) whereas the bio-oil obtained from hardwood (Populus) produced mostly furans, acids and sugar compounds at this temperature. For both types of bio-oil, a wide variety of chemical groups were identified at a temperature of 873 K in comparison to 773 K.