Two feeds have been considered: pure and pretreated crude
glycerol. Normally, 1:6e1:9 M ratios of oil-to-methanol are
used in the transesterification of vegetable oil to biodiesel with
catalyst NaOH. After the reaction is finished, large amount of
the methanol is unreacted. Since methanol and glycerol both
have carbon-to-alcohol ratios of 1:1 with associated high
degrees of hydrogen bonding, the methanol preferentially
distributes into glycerol phase, and only a relatively small
amount dissolves in biodiesel, as experimentally verified [25].
Indeed, the main components of crude glycerol are glycerol
and methanol [26], and also water [27], which is used to reduce
its viscosity and allow the crude glycerol to be pumped.
Anyway, in order to better perform the reforming process, an
economic solution for the partial purification of crude glycerol
stream should be done, especially to reduce the negative
impact of a few impurities on catalyst and reactor material
under supercritical conditions. Thus, in this study it is