Comparative study of the W/USY and Ni/USY zeolitic catalysts deactivation.

The deactivation of W/USY and Ni/USY zeolitic catalysts, prepared at different pHs, was studied, and several relationships were used to describe the process and calculate the initial activities. The calculated amount of coke deposited on the catalysts follows Voorhies equation, and the deactivation is well described by a combined first and second order expression. No mechanistic conclusion concerning the deactivation process could be drawn but similarities with reported results show that it can be correlated to the coke deposition and to the samples acidity.