Synthesis of microporous faujasitic zincophosphates in novel environments.

摘要

Zeolitic microporous materials are an important part of our everyday life. They are utilized in detergents to soften water through an ion exchange mechanism and as a catalyst to crack crude oil into more desirable fuel sources as well as for a variety of other purposes. Methods for creating new microporous materials, increasing yields and the purity and understanding the mechanisms by which they form are being studied. A low temperature growth of faujasitic zincophosphate (ZnPO-X) is reported here that implicates a preexisting structure of DABCO-phosphate when the templating agent DABCO and the phosphorus-containing source (H3PO4) are mixed prior to adding a zinc source. DABCO-phosphate crystals have been isolated and when they are utilized for zincophosphate growth, the reaction produces nearly pure ZnPO-X crystals. Hopeite, a condensed zincophosphate, is the preferential product when the reactant species are mixed in a different order that does not combine the DABCO and phosphate sources as a precursor. Also reported is a microwave irradiated reverse micellar growth of ZnPO-X. If a short microwave burst (1 minute at 150 W) is introduced during the nucleation stages of a 48-hour synthesis procedure, P6, an impurity, is the primary product. At later stages in the growth, after the initial 4-hour nucleation stage, competition between ZnPO-X and P6 leads to a mixed product. When the short microwave pulse is added to the reaction after complete crystallization, or after about 15 hours, ZnPO-X growth is promoted and increased yields are noted. A microwave irradiated reverse micellar gold nanoparticle growth by the reduction of HAuCl4 with hydrazine hydrate was studied as a model of microwave irradiated reverse micelle growth.