Chemical‐bonding aspects of heterogeneous catalysis. II. Solid acids

Acid properties of clays are examd. by using recently published data. An anal. of electrovalent chemisorption based on purely electrostatic interactions is given. The difference in acidities between zeolites and clays cannot be understood if adsorption is considered to be purely local. Model calcns. for beidellite indicate that acidity in clays is much less than that predicted by using Pauling electrostatic valences. For Ni-substituted-mica-montmorillonite acidity increases due to creation of acid sites in the octahedral plane. Therefore, catalytically active sites will be located in the lateral plane or edges of the clay