Synthetic aluminosilicates and their use as heterogeneous equilibration catalysts

A process for preparing synthetic aluminosilicates, which comprises (I) forming a gel by hydrolysis, with water or a mixture of water and alkanol, at a pH of 7.0 to 9.5, of (a) 10 to 90 mol percent of monomeric and/or polymeric silicic acid ester and 90 to 10 mol percent of aluminum alcoholate, based on the total amount of silicon and aluminum atoms, and (b) a doping agent, which is a compound of boron or a metal other than aluminum, which is soluble in water, alkanol or a mixture of water and alkanol, in an amount of from 0.1 to 5.0% by weight based on the total weight of the silicon and aluminum compound, separating the gel from the solution, drying the gel, and (II) heating the previously dried gel to at least 200.degree. C.