The present invention relates to a process for preparing a pulverulent, porous crystalline metal silicate, comprising the following steps: a) hydrothermal synthesis in an aqueous mixture comprising (A) at least one silicon source, (B) at least one metal source and (C) at least one mineralizer to obtain an aqueous suspension comprising a porous crystalline metal silicate as reaction product; and b) calcination of the reaction product, characterized in that the calcination is conducted by means of flame spray pyrolysis at an adiabatic combustion temperature within a range of 450-2200° C., wherein the suspension having a solids content of 70% by weight which is obtained in step a) is sprayed into a flame generated by combustion of a fuel in the presence of oxygen to form a pulverulent, porous crystalline metal silicate.