Catalyst Activity Modification during Catalytic Cracking Process

In this work, the evolution of the catalytic activity was studied by following the strength and distribution of active centers of the catalytic cracking catalyst since its introduction in the plant until its replacement due to high wear. This purpose was achieved by identification of the acid sites of the catalytic cracking catalysts. There are several methods of investigation and researchers opinion about the best methods for determining the acid sites. Therefore, we used temperature programmed desorption of ammonia (NH 3 -TPD), infrared spectroscopy of pyridine adsorption (Py-IR) and diethyl amine thermodesorbtion (TD-DA) to have a global image and to form our opinion on this subject. Experimental part Experiments were conducted on an industrial-type USY catalyst at various stages of its use in the FCC units, namely fresh, equilibrium, spent and calcined (for the total removal of coke deposited during the cracking process). The equilibrium catalyst is the spent catalyst, after being regenerated at 700 o C and 1.4 atm. Calcined catalyst is the spent catalyst which was burned in a calcinations furnace, in air at 800 o C for 2 h to completely eliminate the coke from the catalyst. Some physical and chemical properties of the catalysts were determined, namely surface area, matrix surface area, pore volume, pore size, carbon, sodium oxides, aluminums oxides, and rare earth content. Tables 1 and 2 present physical and chemical properties of the catalysts used in our experiments. Tests to determine specific surface BET, area of micropores and nitrogen adsorption-desorption isotherms were performed on an ASAP 2020 Analyzer V 3.00 H apparatus. Measurements took place at a temperature of 77 K using 0.1264 g equilibrium catalyst, 0.1423 g spent catalyst and 0.0944 g calcined catalyst respectively.