Process for the preparation of doped pentasil-type zeolite using doped seeds
View Patent ↗The present invention relates to a process for the preparation of doped pentasil-type zeolite, which process comprises the steps of: a) preparing an aqueous precursor mixture from a silicon source, an aluminium source, and doped non-zeolitic seeds; and b) thermally treating the precursor mixture to form a doped pentasil-type zeolite. The term “non-zeolitic seeds” includes seeds made from materials selected from the group consisting of (i) X-ray amorphous materials, (ii) milled crystalline materials, such as milled zeolites, that have a relative crystallinity of not more than 75%, and (iii) crystalline materials other than zeolites, such as clays (e,g, bentonite and kaolin) and (low) crystalline aluminas.
1. Process for the preparation of doped pentasil-type zeolite, which process comprises the steps of:
a) preparing an aqueous precursor mixture from a silicon source, an aluminium source, and doped non-zeolitic seeds, and
b) thermally treating the precursor mixture to form a doped pentasil-type zeolite.
2. The process of claim 1 wherein the doped pentasil-type zeolite is doped ZSM-5.
3. The process according of claim 1 wherein the non-zeolitic seeds are X-ray amorphous.
4. The process according of claim 1 wherein the non-zeolitic seeds are milled crystalline materials that have a relative crystallinity of not more than 75%.
5. The process of claim 4 wherein the milled crystalline materials have a relative crystallinity of not more than 60%.
6. The process of claim 5 wherein the milled crystalline materials have a relative crystallinity of not more than 50%.
7. The process of claim 1 wherein the non-zeolitic seeds are crystalline materials other than zeolites.
8. The process of claim 1 wherein the non-zeolitic seeds are doped with a dopant selected from the group consisting of Ce, La, Zr, Mn, Fe, Ti, Cu, Ni, Zn, Mo, W, V, Sn, Pt, Pd, Ga, B, and P.
9. The process of claim 1 wherein the silicon source is selected from the group consisting of sodium (meta)silicate, stabilised silica sols, silica gels, polysilicic acid, tetra ethylortho silicate, fumed silicas, precipitated silicas, and mixtures thereof.
10. The process of claim 1 wherein the aluminium source is selected from the group consisting of Al 2 (SO 4 ) 3 , AlCl 3 , AlPO 4 , Al 2 (HPO 4 ) 3 , Al(H 2 PO 4 ) 3 , aluminium trihydrate (Al(OH) 3 ), thermally treated aluminium trihydrate, (pseudo)boehmite, aluminium chlorohydrol, aluminium nitrohydrol, and mixtures thereof.
11. The process of claim 1 wherein a shaping step is performed between steps a) and b).