The present invention relates to heterogeneous acid catalysts comprising or consisting of mixed metal salts, of lithium and aluminum phosphates and sulfates, and combinations with metallic cations, such as magnesium, titanium, zinc, zirconium and gallium, to provide adequate Lewis acidity; organic or inorganic porosity promoters, such as polysaccharides; and agglomerates, such as clays, kaolin and metal oxides of the type MxOy, where; M=Al, Mg, Sr, Zr or Ti, and other metals of groups IA, IIA and IVB, x=1 or 2 and y=2 or 3, for the formation of particles. A process is disclosed for obtaining from the catalyst by the hydrolysis of aluminum lithium hydride with water and oxygenated solvent, such as an ether. The catalysts are used in batch reactor and continuous flow systems in reactions that require moderate Lewis acidity, such as refining, petrochemical and general chemistry, including the transesterification of glycerides to produce alkyl esters.