When biomass is heated in the absence of oxygen, it produces a pyrolysis liquid (bio-oil or biocrude), char (biocharcoal or biochar) and noncondensable gases (synthetic gas [syngas] or biogas) in various proportions. The resultant bio-oil is a complex and unique mixture of organic compounds and water, closely resembling the elemental composition of the parent biomass. It is a brown, free-flowing, highly oxygenated, dense and viscous polar liquid (Bridgwater 2011). It has a distinctive acrid and smoky odour due to the presence of low molecular weight aldehydes and acids, and can irritate the eyes upon prolonged exposure (Bridgwater 2012). Bio-oil can be considered as a microemulsion, with a continuous phase of an aqueous solution of holocellulose decomposition products that stabilise the discontinuous phase of pyrolytic lignin macromolecules through mechanisms including hydrogen bonding (Bridgwater 2012). Ageing and instability seen in bio-oil is thought to result from the breakdown of this microemulsion (Meier et al. 2013).
|Title of host publication||Biomass processing technologies|
|Editors||Vladimir Strezov, Tim J. Evans|
|Place of Publication||Boca Raton, FL|
|Publisher||CRC Press, Taylor & Francis Group|
|Number of pages||21|
|Publication status||Published - 2015|
- fast pyrolysis