Characterization of Catalytic Cracking Catalysts Regenerated by Gasifying Deposited Coke

TE6; Partially or fully regenerated catalytic cracking catalysts were prepared by gasifying the coke deposited on coked catalysts with a gaseous mixture of oxygen and steam in a fixed fluidized bed (FFB). The resultant samples were characterized by different methods such as the nitrogen adsorption-desorption analysis, the X-ray diffractometry, the infrared spectroscopy, the ammonia temperature-programmed desorption (NH3-TPD) method, the X-ray fluorescence (XRF) analysis, the transmission electron microscopy and energy dispersive X-ray spectroscopy (TEM-EDX), the thermal-gravimetric analysis (TGA) and the differential thermal analysis (DTA). The results showed that exposure of catalyst to steam for about 10 minutes at temperature ≥ 800℃ could not cause too much destruction of the catalysts, and an amount of coke equating to about 0.27 m% was enough to block approximately all acid sites in micro-pores of the zeolite catalyst. Coke didn't show equal reactivity during coke burning-off that could be accelerated by the catalytic action of nearby metal atoms. However, when the carbon content on the catalyst reached about 2.44 m%, the catalytic action of metals on the catalyst was not evident. The severe thermal and hydrothermal environment during exposure of the catalyst to steam at a temperature in the range of about 860-880℃ for 30 minutes could lead to collapse of pore structure and transformation of crystal phase and consequently decrease of the surface area and acid amount on the catalyst.