Catalytic cracking has been widely used since the early 1900’s for production of a range of fuels, predominantly light distillates, gasoline. Three types of Catalytic cracking exist, Houdry Catalytic Cracking, Thermafor Catalytic Cracking, and Fluid Catalytic Cracking. Fluid Catalytic Cracking has been widely adopted because of its thermal efficiency compared to the other two processes as well as its little to no down time during running. Catalytic cracking generally uses gas oil as a feed for the cracking processes. The gas oil is run through a column where steam is introduced and uses catalysts such as a zeolite or aluminum/silica catalysts for the separation process. The catalysts tend to build coke an inherently become deactivated requiring activation by heated air and/or steam. The products that come from these processes are Gas, Gasoline, Light Cycle Oil, and Heavy Cycle Oil. For the Fluid Catalytic Cracker, a product is also Decant Oil which can be used for fuel oil or for feedstock to produce needle coke or carbon black. Light Cycle Oil can be processed to produce diesel fuel. The Fluid Catalytic Cracker is used not only for its efficiencies but also because of its use of better catalysts and reactivation of the catalysts. These processes have a downfall in handling a wide range of feedstocks, primarily the heavier factions.

Hydrocracking has begun to be used in the late 50’s because of this growing demand for middle and light distillates as well as its flexibility to handle wide range of feedstocks. The hydrocracking plants have the ability to crack aromatics to produce paraffinic compounds without losing carbon, which increases the yields of the desired distillates without producing low-grade byproducts, such as coking. This is a major issue that wasted time and energy in the catalytic cracking plants. The catalyst used were typically metals such as nickel and copper as well as silica/alumina as in catalytic cracking. Since the process is bi-functional it also required highly active noble metals such as platinum and palladium. This process sheds the unwanted heteroatoms and increasing the H/C ratio. Hydrocracking can be used to treat the products that were resistive to cracking from the Fluid Catalytic Cracking plant such as Light Cycle Oil.

Hydrocracking costs more to perform which leads to the reasoning of performing both the Fluidized Catalytic Cracking for what it can do and using the Hydrocracking for what the FCC cannot do to supply the necessary amounts of fuels in demand. Although Hydrocracking is more flexible with feed, produces less coke, and gives use to the byproduct produced hydrogen, Fluidized Catalytic Cracking still serves its purpose for a cost effective way to produce light distillates such as gasoline, as well as coke that can be used for heating in plants and other purposes.