Ultramarine Blue Derived from Linde A Molecular Sieves

Abstract

Ultramarine blue (I) was derived from Linde 5A and Linde 4A mol. sieves by the following sequence: (1) impregnation with Na2S in a satd. aq. soln. and drying the product in N, (2) absorption of S vapor at 500° in N, (3) heating up to 820° in N at 17°/min, and (4) oxidn. at 500° in air. The oxidized products from Linde 5A and Linde 4A were sky-blue and green, resp., and they became blue by reheating in air for a few hours at 820°. The formation of I from Linde 4A was easier than that from the sintered product between kaolin and Na2CO3 with decompn. of NaAlSiO4, which had no sodalite-like structure. The formation of ultramarine green was caused by intrusion of polysulfides into the sodalite-type cages in Linde 4A.