Preparation of amorphous silica-alumina particles by acid-treating spherical P-type zeolite particles crystallized from a sodium aluminosilicate gel

A process for the preparation of amorphous silica-alumina spherical particles, which comprises the steps of:

• (a) mixing sodium silicate or active silicic acid gel, sodium aluminate and sodium hydroxide in aqueous solution in the component molar ratios of:
• Na.sub.2 O/SiO.sub.2 =0.2 to 8;
• SiO.sub.2 /Al.sub.2 O.sub.3 =3 to 20;
• and H.sub.2 O/Na.sub.2 O=20 to 200, to form a gel of sodium aluminosilicate;
• (b) homogenizing the gel obtained in step (a) and effecting crystallization at a temperature of 85.degree. to 200.degree. C. under atmospheric pressure or under hydrothermal conditions to form zeolite particles having an X-ray diffraction pattern inherent to P type zeolite, individual particles having a definite spherical shape as a whole and a notched surface;
• and
• (c) subjecting the zeolite particles to a one-staged or multi-staged acid treatment to remove the sodium component sufficiently to render the particles amorphous.