MATRIX ACIDITY DETERMINATION - A BENCH-SCALE METHOD FOR PREDICTING RESID CRACKING OF FCC CATALYSTS

Novel methods for determination of matrix acidity of cracking catalyst s are discussed. Virgin matrix acidity is determined after complete de struction of the zeolite phase by acid treating the catalyst at pH 2. Properties of acid-treated catalyst closely approximate those of pure matrix. However, the virgin matrix acidity does not correlate with res id cracking performance of the catalyst under commercial or pilot plan t conditions. A second method has been developed that facilitates the measurement of matrix acidity on a laboratory deactivated sample with properties similar to that in the commercial cracking unit. The approa ch is based on total destruction of the zeolite by steaming at 870 deg rees C for 5 h. Acidity of the steamed catalyst closely resembles that of steamed pure matrix and has a good correlation with the resid crac king activity in the pilot plant testing. Preservation of matrix acid sites during hydrothermal deactivation was shown to be an important re quirement for achieving high resid cracking activity.