Synthesis of a water tolerant solid base of CaO covered with Al2O3

Solid base catalysts composed of CaO covered with 5–20 mol% of Al2O3 were prepared by decomposition of Al(OCH(CH3)2)3 over an Ca(OH)2 surface in an ethyl acetate solution, followed by thermal decomposition in air at 773–1023 K. The catalysts containing Al3+ and treated at 773–973 K showed sufficient activity for a retro-aldol reaction to convert diacetone alcohol (4-hydroxy-4-methyl-2-pentanone) into acetone at 299 K. The dissolution of the active component of CaO into a polar solvent was strongly inhibited by a covering of a small amount of Al2O3. The prepared catalysts showed excellent tolerance to H2O contained in the substrate. The catalyst reusability was also examined.