BASIC CATALYSIS ON BETA ZEOTYPES

From the catalytic activity for the Knoevenagel condensation of benzaldehyde with several malonic esters with different pKa, it has been found that sodium exchanged Beta zeolites containing Al, Ga, Ge and Si, show stronger basicity per site than sodium faujasite with a much higher framework Si/AI ratio. This has been related to the relatively smaller T–O–T angles formed when exchanging the H-Beta zeolite by Na+. It is postulated that in flexible structures, strong variations in T–O–T angles can be expected when changing the nature of the countercation. Then, the same zeolite but with different countercation can present relatively strong acid and base properties.