GB398517A - Improvements in or relating to the manufacture of adsorptive or catalytic gels - Google Patents

Abstract

Hard, granular, porous gels having catalytic or adsorbent properties are obtained by peptizing a hydrous oxide "precipitate" (as opposed to a true hydrogel) with an organic acid such as formic, acetic, or chloracetic acid, and nearly dehydrating the peptized mass, as by subjecting it to a current of air at 105-150 DEG C. The precipitate treated may be prepared in an acid or alkaline medium according to the character of the oxide and may contain a mixture of different oxides. Washing of the precipitate before peptization is preferred, and the latter operation, which may be performed at temperatures of 10-95 DEG C., is advantageously carried out with agitation, for instance the mixture is subjected to a combined rubbing and stirring action. Preferably the peptized mass is dried without washing and washed afterwards only if drying has been followed by activation at a temperature above 200 DEG C. Oxide precipitates which may be treated according to the invention include those of iron, aluminium, vanadium, copper, nickel, titanium, thorium, manganese, chromium, zirconium, bismuth, gallium, beryllium, indium, cerium, scandium, silicon, germanium, tin, tantalum, molybdenum, and tungsten. An alumina gel prepared according to the invention may be used to extract water vapour from gases containing carbonaceous matter, since heating to 800-1200 DEG F. to burn out the carbon does not destroy its efficiency for further adsorption. The Specification as open to inspection under Sect. 91 comprises also the following subject-matter: the use of any peptizing agent, including an alkaline substance when the precipitate is prepared in an acid medium, or in the case of alumina, when it is prepared in an alkaline medium. This subject-matter does not appear in the Specification as accepted.