Catalytic cracking - Evolution of fcc catalysts

Catalytic cracking is the most important refining process in terms of the annual amount of feedstock treated and catalyst consumed. Over its 50 year history, this process has ceaselessly undergone changes and major improvements related to the technology as well as the catalyst. Today, catalytic cracking is by far the refining process which uses the most diversified set of catalysts. Y-zeolite present in FCC catalysts undergoes deep modifications due to the severe hydrothermal conditions in the FCC regenerator and the action of metallic contaminants in the feedstock. Hydrothermal modifications of Y-zeolite can also be purposely provoked by the catalyst manufacturers. These modifications, the means to control them and the catalytic properties of modified Y-zeolites are briefly discussed. The important role of the matrix is also emphasized. This paper presents a revue of the principal catalyst components and illustrates how component characteristics can be adapted to tune catalyst performances with the FCC unit specificity. This specificity depends not only on the refiner's objectives (more liquid products, more gasoline, better gasoline octane etc.) but also on the FCC unit's constraints (regenerator blower, cracked gas compressor etc.).