CRYSTALLINE GALLOALUMINOSILICATES, STEAM-MODIFIED CRYSTALLINIC GALLOALUMINOSILICATES, THEIR PREPARATION AND USE AS CATALYSTS AND CATALYSTS

摘要

Crystalline galloaluminosilicates which have an X-ray diffraction pattern which is essentially the same as the pattern for an MFI zeolite and a composition which, expressed as a molar ratio between oxides, is as follows: 0.9 +- 0.2 M2/nO.Al2O3.a Ga2O3.b SiO2.zH2O in which M is a cation, n is the valency of the cation, a has a value of between 0.0001 and 2, b has a value of at least 12, and z has a value of from 0 to 40. A process for preparing the crystalline galloaluminosilicates comprises crystallizing, at an elevated temperature, a gel which comprises (i) a silicon dioxide source (SiO2), (ii) an aluminium oxide source (Al2O3), (iii) a gallium oxide source (Ga2O3), (iv) a mineralizing agent selected from oxides, hydroxides and salts of alkali metals and alkaline earth metals (X2/nO, in which n is the valency of x), (v) an organic base (B) and (vi) ROH, where R is H and/or lower alkyl, in the following molar proportions: SiO2:M1/2O3, (in which M1/2O3 is defined as total molar quantity of Al2O3 + Ga2O3) = greater than 12:1 SiO2X2/nO = 1000:1 to 50:1 SiO2:B = 50:1 to 1:20 SiO2:ROH = less than 1:10 Al2O3:Ga2O3 = 500:1 to 1:100. Ion-exchanged forms, calcined forms and steam-treated forms of the crystalline galloaluminosilicates are also indicated. Such materials can be used as catalysts and catalyst supports. The steam-treated form can, in particular, be used as a catalyst for preparing aromatic hydrocarbons from a C2 to C12 hydrocarbon feed mixture.