A method for purifying a spent acid catalyst from an acid catalyzed chemical reaction that generates a mixture of a product, spent add and tar, includes the steps of separating the mixture of product, spent acid, and tar into a product fraction and a spent acid fraction, said spent acid fraction comprising a mixture of spent acid and tar, and separating the spent acid fraction, by flotation separation, centrifugation, or liquid-liquid coalescence, into a tar fraction and a de-tarred spent acid fraction. The fluidized tar and the de-tarred spent acid can each be further processed to produce concentrated acid.