“…The heavy hydrocarbons are usually referred to as 'tar'; the usual definition is that the tar fraction includes hydrocarbons with a molecular mass greater than that of benzene. This fraction may represent 5-10% of the total energy content of the fed biomass [6]. These tar species start to condense already at temperatures of around 360°C, and they create operational problems, such as process shut-down and/or downstream catalyst deactivation [2,[7][8][9][10].…”