Accelerated synthesis of zeolites via radicalized seeds

Abstract

By means of milling and heating, the zeolite crystals can be radicalized forming surface non-bridging oxygen hole center (NBOHC, ≡Si–O·). The corresponding g values of 2.0043 and 2.0048 unambiguously confirm the existence of the ≡Si–O· radicals in the milled and heated crystals via electron paramagnetic resonance. The active ≡Si–O· radicals can react with water to form hydroxyl free radicals to accelerate the crystallization of zeolite along with seeds. Radicalized crystals are used as seeds that show obvious accelerating effect in the crystallization of Na-A and nanosized silicalite-1 than the non-radicalized seeds. At the same crystallization time, solid products with much better crystallinity and more yields could be obtained using radicalized seeds compared with non-radicalized seeds. A new seeding-synthesis-related strategy is developed to accelerate the crystallization of zeolites.