The yields of the remaining functional groups are lower than
3 wt.%. Furthermore, aldehydes are hardly affected by pyrolysis
temperature, but acetaldehyde and formaldehyde yields increase
slightly at high temperatures due to the cracking reactions leading
to light aldehydes [64]. There are also saccharides in the bio-oil of
RH, but their yield is lower than in the pyrolysis of other lignocellulosic
materials [21]. The major compound is levoglucosan and is
formed from cellulose degradation at intermediate temperatures
(between 300 and 400 C). The poor thermal stability of sugars
and the high ash content in the char are the cause of the low yield
of this lump of components in the bio-oil. It should be noted that
this bio-oil also contains nitrogen compounds, whose amount is
in the 1–1.5 wt.% range. These yields are much higher than those
corresponding to other bio-oils derived from wood, which usually
are below 0.5 wt.% [65]. This is a disadvantage for the use of this
bio-oil as fuel due to NOx emissions in its combustion. Certain
authors also found other nitrogen containing compounds, such as
pyridine, amides and amines, in the bio-oil obtained from the fast
pyrolysis of RH