| 摘要 |
A layer structure type, clay-like, synthetic silicate has the empirical formula nSiO2: Al2O3 : mAB : x.H2O, the layer lattice comprisin the silica, the alumina and the ions B, where n is from 2.4 to 3.0; m is from 0.2 to 0.6, A is one equivalent of an exchangeable cation having a valency of not greater than 2 and is external to the lattice, B is a negative ion FOH- or 1/2 O= or mixtures thereof; x is from 2.0 to 3.5 at 50% relative humidity, and said material is characterized by a d001 spacing at said humidity which extends from a lower limit of 10.4 </>rA to an upper limit of 12.0 </>rA when A is monovalent, to 14.7 </>rA when A is divalent and to a value intermediate between 12.0 and 14.7 </>rA when A includes both monovalent and divalent cations. A can be H+, NH4+, Na+, Zi+, K+/h 1/2 Ca++ 1/2 Mg++, 1/2 Sr++ or 1/2 Ba++ or mixtures thereof. Preferred values of the variable parameters are n = 2.5, m = 0.52, x = 2.7, A is NH4+ or Na+, B is 1/2 O= and the d001, spacing is 10.7 </>rA. Calcination of the ammonium derivative produces the hydrogen form. The above materials are produced by a hydrothermal treatment in an autoclave, at a temperature in the range 280-315 DEG C. under its autogenous pressure of a mixture comprising water, Al2O3, SiO2, together with NH4+, Na+, Li, K, Ca++, Ba++, Sr++ or mixtures thereof with an equivalent amount of OH-, F- or mixtures thereof in which mixture Al2O3:SiO2 = 2.7 to 3.3 and OH- or F-: Al2O3 is 0.2 to 0.6. The hydrothermal treatment preferably does not exceed 72 hours being most preferably 48 hours. The alumino silicates of the invention may be dehydrated preferably at a temperature of 500-700 DEG C. to produce catalysts. They may also be used as drilling mud additives, insecticide carriers and as a desiccant, but they are particularly useful as hydrocarbon cracking catalysts after being subjected to further treatment e.g. calcination or treatment with steam. |
