Enhanced Catalysis of Mechano-Chemically Synthesized KMgF 3 Catalysts for the Knoevenagel Condensation

The catalytic activity of KMgF 3 catalysts for a Knoevenagel condensation reaction was enhanced by synthesizing the catalysts mechano-chemically. The Brunauer–Emmett–Teller specific surface area and number of strongly basic site on KMgF 3 were increased by applying greater mechanical energy (i.e. a higher rotation rate) during the mechano-chemical process. These increases were caused by stronger mechano-chemical effects such as micronization of the particles and the introduction of lattice defects onto the surface, which resulted in an enhancement of the catalytic activity of KMgF 3 toward a Knoevenagel condensation reaction. X-ray photoelectron spectroscopic analysis revealed that the elemental composition of the KMgF 3 surface was similar to that for K 2 MgF 4 , indicating the possibility that the true active component for this reaction was K 2 MgF 4 rather than KMgF 3 . Kinetic measurements revealed that Knoevenagel condensation catalyzed by KMgF 3 was a first-order reaction with an estimated apparent activation energy of 55.8 kJmol −1 . A soluble component capable of acting as a catalyst was not present in the solution; the KMgF 3 acted as a true solid catalyst.