Fast, low-pressure, low-temperature microwave synthesis of ABW cesium aluminosilicate zeolite nanocatalyst in organotemplate-free hydrogel system

Cs-ABW zeolite nanocrystals were synthesized using a microwave-assisted hydrothermal technique without an organic template. Using powder X-ray diffraction Rietveld refinement and spectroscopy, we found that pure ABW-type CsAlSiO4 zeolite nanocrystals (Si/Al ratio = 1.08) with an orthorhombic structure (space group Pc21n, a = 9.4425(21) angstrom; b = 5A437(11) angstrom; c = 8.9152(19) angstrom) can be crystallized from a clear precursor solution of 4SiO(2):1Al(2)O(3):16Cs(2)O:160H(2)O (180 degrees C, 6 min). The Cs-ABW nanoparticles had a mean particle size of 68 nm and were thermally and colloidally stable. The nanocrystals-which had high accessible basic sites, (Si-O-Al)Cs--(+), located at their external surface-were active in catalyzing the cyanoethylation of aliphatic alcohols under non-microwave instant heating, with 100 % selectivity to the desired product and high catalyst reusability. Furthermore, the cyanoethylation of methanol catalyzed by nanocrystalline Cs-ABW under instant heating had equal or better reactivity than those catalyzed by other solid base catalysts.