THE EFFECT OF AGING ON THE MICROWAVE SYNTHESIS OF ZEOLITE NAA

In the microwave synthesis of zeolite NaA ageing of the synthesis mixt ure is a prerequisite for fast crystallization. The rapid heating in m icrowave synthesis requires better preparation of the synthesis mixtur e compared to conventional synthesis methods. Sufficiently aged mixtur es can yield NaA, with crystal sizes ranging from 0.1 to 0.3 mu m, aft er 1 min in the microwave. It was also found that the synthesis of an unaged mixture can be improved dramatically by adding aged synthesis m ixture to it. This suggests that the rearrangement of the synthesis mi xture to yield nuclei is the bottleneck in a microwave synthesis. (C) 1997 Elsevier Science B.V.