FCC vs. Hydrocracking Interdependence

The downstream sector of the oil and gas industry relies heavily on effective conversion processes throughout the year. In order to protect the bottom-line, the refinery operator must understand the high temperature, rapid discharge catalytic conversion processes that determine the end products. Fluid catalytic cracking (FCC) and hydrocracking encompass the two most significant types of conversion processes in today’s refinery. Each possesses advantages in converting specific feedstocks to more desirable products.

FCC involves a carbon rejection. This endothermic process uses an acid catalyst to convert low-value feed to useable gas, gasoline, light and heavy cycle oil, and decant oil as well as petroleum coke. According to the EIA, FCC has greatly impacted the fuels industry in the U.S.’s gasoline-driven society. An important process feature involves the need for catalyst regeneration by means of burning off the catalyst coke. There are seemingly endless design configurations throughout the industry to limit the cost of this energy intensive process. This process produces higher octane products than thermal cracking products for gasoline production due to the isomerization mechanisms that produce iso-paraffins. This process may require some pre-hydrotreatment stage to protect the catalyst from poisoning.

Similarly, hydrocracking usually involves a two-stage conversion process. First, the feed is hydrotreated to remove heteroatoms that might poison the hydrocracking catalyst. Then, the feed completes an H/C ratio enhancement that hydrogentates the feed and removes impurities (cracking). This EIA article illustrates the general flow of the feed through the reactor, separator, and fractionator to produce jet fuel, diesel, and kerosene among other products. Compared to FCC, hydrocracking is much more suitable for processing heavy crudes with aromatic characteristics. The heteroatoms may be removed with this process and even utilized as a byproduct.

Both processes have strengths and weaknesses, and given the increase in demand for gasoline and distillates such as jet fuel and diesel, these processes will continue to be developed in tandem.

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