Fig. 5. Methyl lactate yield
achieved using refined glycerol as starting material was about
45 mol%. In addition to methyl lactate, about 17 mol% LA (unconverted
calcium lactate) yield and about 28 mol% PG yield were achieved. The
glycerol conversion and methyl lactate yield from CG1 were lower
than those in the case of converting refined glycerol. Reaction using
CG2 showed similar glycerol conversion and methyl lactate yield to
those in the case of converting refined glycerol. The LA yields achieved from CG1 and CG2 were close to those in the case of converting refined
glycerol; however, the PG yields were lower, possibly due to side reactions
that partially consumed the produced PG during the long reaction
time. FromTable 1, it can be seen that thewater content is about 7 wt.%
in CG1 and 13% in CG2, much higher than that in refined glycerol (no
water was added in the conversion of refined glycerol). Soap content
in CG1 is much higher than that in CG2. These impurities in crude glycerol,
especially in CG1, caused the consumption or possible deactivation
of CaO, resulting in the decrease of glycerol conversion and product
yield.