Prepn. of cubic sodium zeolite - by reacting glassy waste from power station with alkali under specific conditions

摘要

In prepn. of cubic Na-Pc zeolites by hydrothermal reaction of glassy waste materials from power stations using solid, fossil fuels, with aq. alkalis, opt. mixed with alkaline earths and/or (in)organic NH4 cpds., to give the required molar ratio of M2/mO:Al2O3 and H2O:Al2O3, for up to one day, opt. with stirring and with heating at a predetermined temp., followed by sepn. of the prod. and other solid components from the aq. phase, washing and opt. drying, (a) the molar ratio of SiO2:Al2O3 in the reactor mixt. is 3-10 (3-6), (b) the molar ratio of Na2O:Al2O3 in the reactor mixt. is 0.3-10 (0.6-6), (c) the molar ratio of H2O:Al2O3 in the reactor mixt. is 30-250 (50-80), (d) reaction temp. is 90-100 deg.C, (e) reaction time is 3-16 h, and (f) the solids content of the reactor mixt. is 10-50%. USE/ADVANTAGE - Yield of Na-Pc zeolite is high (70-80%), and the content of amorphous and crystalline impurities, e.g. analcim, is low. The raw materials are cheap; dusty wastes from pumice and perlite processing can also be used. Reaction is at low temp. and without application of pressure, and the temp. can be held constant over long periods, e.g. by use of a boiling water bath. Vigorous stirring is not needed. Aluminate-silicate glass and crystalline components, e.g. quartz sand, remain as unchanged inert components in the end prod. The zeolite is used as ion-exchanger in aq. solns., partic. for removing NH4 ions from industrial waste water; the selectivity for NH4 ions is high.