ABSTRACT
The main catalytic characteristics of acid zeolites in hydrocarbon reactions are their selectivity as molecular sieves, their high acid strength, and their electrolytic properties which influence reaction kinetics. The changes in acid-site distributions were achieved by high temperature calcination and steaming and these processes might be expected to introduce significant structural changes resulting in the increase of coke and gas yield and a decrease in gasoline production. Dealumination of zeolite cracking catalysts results in increased activity but lower yields of gasoline and higher yields of gas and coke. In many acid-catalyzed reactions the reaction rate depends on the rate of carbonium ion formation. In the industrial catalytic cracking process, the acidic Y zeolite-based catalysts show certain new features not found with earlier-used acid catalysts. First, the activity of Y-type zeolite catalysts is much higher relative to silica alumina gel.
