Cracking is the process of breaking straight chain alkanes into smaller straight chains hence the term “cracking.” This process was, and still is, and extremely important process in developing higher quality products such as gasoline that had an ever increasing octane number, something that is very desirable when producing gasoline. The two types of cracking processes are catalytic and thermal. In addition Catalytic cracking can be broken into catalytic cracking and catalytic hydrocracking.

Catalytic hydrocracking uses the same principles of catalytic cracking will also relying heavily on the elevated partial pressure of hydrogen gas. One positive attribute of catalytic hydrocracking is its ability to accept many different feeds that with minor adjustments can have a large effect on desired the product yields. FCC produces high octane gasoline from straight run gas oil. The long chains of n-alkanes in the feedstock are broken up through the process of catalytic cracking into smaller straight chain i-alkanes, or isoalkanes. Other products are cycloalkanes and other aromatic structures. As noted in the lesson, LPG, cycle oils, and olephin-rich light hydrocarbons are very important products of this cracking method as well.

The whole purpose with hydrocracking is the addition of hydrogen to keep the levels of coke productions under control. Without this, it would be much more difficult to introduce heavier crude oil fractions as a feedstock due to the high amounts of coking on the catalysts. So this is why hydrocracking was invented.

Catalytic cracking involves the presence of acid catalysts. This process has the effect of causing asymmetric breakage of bonds. Because of the use of free radicals in many cracking reactions, namely beta bond scission and hydrogen abstraction, the reactions are self-propagating as both free radicals and carbocations are formed. The formation of these two very highly unstable atomic and molecular structures respectively, result in the reaction proceeding until recombination is achieved.

Catalytic and catalytic hydrocracking are two very important processes that dominate the refining industry in their complexity and their yields of production of highly desirable products. These methods are constantly being heavily researched in order to better the products and the methods used in order to obtain them.