Kouzu et al. [8,9] verified that this compound is the active phase
of the collected catalyst rather than other unknown calcium compounds
present as minor constituents. CaD prepared as a reference
sample was proven to be as active as the catalyst recovered after
the transesterification process. They found that glycerol was more
reactive with CaO than methanol, as the immersion of CaO in
methanol reflux in the presence of glycerol only produced CaD.
To facilitate the handling of the solid base catalyst, Kouzu et al. recommended
the previous conversion of CaO into CaD by immersion
in a methanol solution of glycerol [8].