Since calcium glyceroxide is always generated during
the transesterification reaction, herein, calcium glyceroxide was
synthesized by heating the mixture of CSS, glycerol (WAKO, Japan)
and methanol at 60 C under mechanical agitation for 3 h [24]. For
comparison, a commercial CaO (WAKO, Japan), which was calcined
at 1000 C for 2 h in air before use , was also used at the same
reaction condition.