To obtain the subject zeolite excellent in absorptive performance with a specified silica/alumina molar ratio by aging a mixed gel shown by a specific compositional formula at a specified temperature followed by crystallization.
First, NaOH is added to an aqueous sodium aluminate solution to form a solution A which is then cooled to about ≤30°C; while an aqueous sodium silicate solution B is left to cool to about ≤30°C. Secondly, the aqueous solution B is added to the aqueous solution A under agitation to effect completion of gelatin while the whole system is kept at about ≤30°C, thus forming a mixed gel with the composition formula: 2.4-237Na2O.Al2O3.2.7-2.8SiO2.120-140 H2O. Thirdly, the mixed gel is aged at ≤35°C for about 24h and then heated to about 85-95°C and kept at that temperature for input 15h or longer to effect completion of the crystallization. Subsequently, the crystallized product is put to filtration, washed with water or warm water, and then dried at about 90-100°C, thus obtaining the objective low-silica X-type zeolite with the silica/ alumina molar ratio of 2.20-2.40.
| JP2003286013 | METHOD OF PURIFYING GASEOUS NITROGEN TRIFLUORIDE |
NISHIMURA TORU
INAOKA WATARU
