| 摘要 |
PURPOSE:To easily obtain an L-type zeolite economically on an industrial scale, by producing a homogeneous compound from an aqueous solution of an alkali silicate and an aluminum-containing aqueous solution, dissolving the compound in an aqueous solution of an alkali metal hydroxide and crystallizing the resultant reaction mixture under agitation. CONSTITUTION:A aqueous solution of an alkali silicate is made to continuously react with an aluminum-containing aqueous solution (e.g. aqueous solution of AlCl3) at a specific ratio under agitation to obtain a slurry of 5-9 pH. Filtration and separation of the slurry gives a homogeneous compound (A) having an SiO2/Al2O3 (molar) ratio of 10-20 and an R2O/Al2O3 ratio of 0.8-1.2 (R2O is K2O+Na2O). The component A is dissolved in an aqueous solution of an alkali metal hydroxide (e.g. a mixed aqueous solution of NaOH and KOH) at 40-100 deg.C for 1-6hr to obtain an L-type precursor (B) wherein SiO2/Al2 O3=10-20, R2O/SiO2=0.4-1.0, K2O/R2O=0.5-0.9 and H2O/R2O=11-30. The component A is mixed with the component B at a ratio (B/A) of (10-30)/(90-70) (based on Al2O3) and the obtained reaction mixture is crystallized at 110-200 deg.C under stirring.
|
