It was obvious that the 30% RHA800-800 catalyst had better stability and suffered less leaching problem compared to the CaO.
This was because CaO–SiO2 bonds in the 30% RHA800-800 catalyst were too strong to prevent lixiviation of calcium from the catalyst surface [24].
Additionally, the slight deactivation of the 30% RHA800-800 catalyst during the repeated experiments should be due to the small amount of water and CO2 in the reaction system.
Thus, for practical applications in the transesterification reaction, it was important to acquire a more stable
catalyst rather than a more active one [30].