METHOD FOR PREPARING A HIGHLY HOMOGENEOUS AMORPHOUS SILICA-ALUMINA COMPOSITION

摘要

Improved silica-alumina catalyst compositions are methods for preparing such catalystcompositions are disclosed. The present invention relates to a method for preparinga highly homogeneous, amorphous silica-alumina cogel catalyst. Silica-aluminaaccording to the present invention may be prepared by a variety of methods employingbatch and continuous processes in different combinations. In one embodiment,a batch process, the present invention provides a method for preparing a highlyhomogenous silica-alumina cogel catalyst comprising: vigorously mixing anaqueous silicate solution with a gradual addition of an aqueous solution of anacid aluminum salt while maintaining the pH of the solution less than 3.0 and ensuringvigorous and complete mixing of the aluminum salt and silicate solutions to forman acidified silica sol in the aluminum salt solution; gradually adding a basicprecipitant to the acidified silica sol/aluminum salt solution while vigorouslymixing the solution to raise the pH of the cogel solution to greater than 3.0, producinga cogel; continuing the addition of basic precipitant and vigorous mixing ofthe cogel solution while maintaining a uniform pH of the cogel solution in therange of from 5­-9 until precipitation of the cogel is complete; washingthe precipitated cogel; and processing the precipitated cogel into a finishedcatalyst.