What type of catalyst is commonly used in the catalytic cracking process?

The catalytic cracking process primarily employs zeolite catalysts, which are silicon and aluminum oxide structures that have a porous framework. Zeolites are particularly suited for this process because their unique properties facilitate the breaking down of larger, more complex hydrocarbons into smaller, more valuable products like gasoline and diesel. Their high surface area and tunable acidity enhance the reactions by providing more active sites for the feedstock to interact.

In catalytic cracking, the zeolite catalyst also contributes to selectivity, allowing for the production of specific hydrocarbons while minimizing unwanted byproducts. The shape selectivity of zeolites means that they can preferentially adsorb certain molecules based on size and shape, affecting the efficiency and yield of the desired products.

While other catalysts, like platinum, are effective in different types of reactions (such as reforming), they are not employed in catalytic cracking as extensively due to their cost and effectiveness primarily in reactions needing different conditions and mechanisms. Similarly, zinc oxide and alumina play roles in other catalytic processes but do not possess the characteristics ideal for cracking large hydrocarbons as effectively as zeolites do.