The effect of ageing on the microwave synthesis of zeolite NaA

In the microwave synthesis of zeolite NaA ageing of the synthesis mixture is a prerequisite for fast crystallization. The rapid heating in microwave synthesis requires better preparation of the synthesis mixture compared to conventional synthesis methods. Sufficiently aged mixtures can yield NaA, with crystal sizes ranging from 0.1 to 0.3 μm, after l min in the microwave. It was also found that the synthesis of an unaged mixture can be improved dramatically by adding aged synthesis mixture to it. This suggests that the rearrangement of the synthesis mixture to yield nuclei is the bottleneck in a microwave synthesis.