Process for preparing a crystalline zeolite

摘要

The invention relates to a process for preparing a crystalline zeolite having a molar composition: (0.9-1.1)MO.X2O3.(5-20)SiO2.(0.7-0.02)trioxane.(0-10)H2O wherein M is one or two alkali or alkaline earth metal ions having a total valence of 2 and X is at least one of the metals aluminum, iron or gallium. The process comprises maintaining an aqueous mixture of a source of silica, a source of ions of the alkali or alkaline earth metal M, a source of an oxide of X and trioxane at an elevated temperature thereby forming the crystalline zeolite. The molar ratios initially present in the aqueous mixture are: X2O3:SiO2=0.06-0.12 H2O:SiO2=5-30 OH-:SiO2=0.05-0.6 trioxane:SiO2=0.1-2.0 MO:SiO2=0.15-0.