Patent GB-1082131-A (GB)
Title: Manufacture of zeolites
Inventor: ANDREWS EDWIN BOLWELL
IPC: C01B33/46
Filed: 1964-05-20
Abstract: Crystalline zeolites are produced by preparing aqueous sodium aluminosilicate reaction mixtures having oxide mol. ratios as defined by one of the following sets of ranges (a), (b) and (c): (a) SiO2/Al2O3 = 0.06-4.0, Na2O/SiO2 = 0.7-20.0, H2O/Na2O = 15-200.0, (b) SiO2/Al2O3 = 2.0-3.0, Na2O/SiO2 = 0.4-6.5, H2O/Na2O = 10-150.0, (c) SiO2/Al2O3 = 8.0-30.0, Na2O/SiO2 = 1.0-3.0, H2O/Na2O = 10-120, at least part of the siliceous component being an "active" sodium metasilicate pentahydrate and of the formula Na2O. SiO2.5H2O, the ratio of the pentahydrate to any inactive siliceous component present (e.g. sodium silicate or free silica) expressed as Na2O.SiO2.5H2O: SiO2 ranging from 1.0:0 to 1.0:76.0, and effecting crystallization at a temperature of 30-120 DEG  C. without ageing of the reaction mixture at a temperature below the crystallization temperature.  The "active" sodium metasilicate pentahydrate is defined as one which yields Zeolite X within 3 hours under the following conditions: 8 grams of the sodium metasilicate pentahydrate dissolved in 20 grams of water at ambient temperature is mixed with 24 grams of aqueous sodium aluminate containing 0.75g Na2O and 1.0g Al2O3, the mixture is heated with stirring at 90-100 DEG  C. for 3 hours under reflux, and the precipitate filtered, washed, and dried at 80-140 DEG  C.  The process is described in connection with the production of Zeolites A, X and Y, wherein the preferred oxide mol. ratios in the sodium aluminosilicate reaction mixture for Zeolite A production are: SiO2/Al2O3 = 0.19-2.7, Na2O/SiO2 = 0.85-9.7, H2O/Na2O = 30-200.0, for Zeolite X production are: SiO2/Al2O3 = 2.8-8.0, Na2O/SiO2 = 0.7-5.0, H2O/Na2O = 35.0-120.0, and for Zeolite Y production are SiO2/Al2O3 = 8.0-20.0, Na2O/SiO2 = 1.0-3.0 and H2O/Na2O = 35.0-90.0, the reaction mixtures being maintained at 30-120 DEG  C. until crystals having the desired composition and X-ray diffraction patterns have formed. Examples are given by way of tables in which the use of "active" sodium metasilicate pentahydrate according to the invention is compared with the use of other siliceous components in the production of Zeolites A, X and Y, utilizing the oxide mol. ratios quoted above; not all the mixtures given led to the required Zeolite.  For comparison with the invention for Zeolite A production there is mixed with the water and sodium aluminate; (i) sodium disilicate (at 50 DEG C.), (ii) sodium disilicate and sodium hydroxide (at 50 DEG  and 90 DEG  C.), (iii) sodium metasilicate nonahydrate and sodium hydroxide (at 50 DEG  and 90 DEG  C.), and (iv) anhydrous sodium metasilicate and sodium hydroxide (at 50 DEG  and 90 DEG  C.).  For Zeolite X production in comparison with the invention there is used in admixture with the water and sodium aluminate at 90-100 DEG  C., (i) sodium disilicate and sodium hydroxide, (ii) waterglass and sodium hydroxide, (iii) sodium metasilicate nonahydrate, and (iv) anhydrous sodium metasilicate.  For Zeolite Y production in comparison with the invention there is mixed with the water and sodium aluminate at 90 DEG  C. colloidal silica and sodium hydroxide.