FCC is considered a carbon rejection process because the coke deposited on the catalyst surface and eventually burned off for heat is rich in carbon and thus enables the production of large quantities of a light distillate crackate in the process without the addition of hydrogen.
The source of the large hydrocarbon molecules is often the naphtha fraction or the gas oil fraction from the fractional distillation of crude oil petroleum. Semih Eser. The breaking of the large hydrocarbon molecules into smaller molecules is more technically referred to by organic chemists as scission of the carbon-to-carbon bonds.
The catalyst material, on which a certain amount of carbon, better known as coke, has been deposited during the cracking process, is transported to the regenerator, where the coke is burned off.
The catalyst is separated from the product mixture and stripped of remaining useful product by steam treatment. Patent No. If you are studying a UK-based syllabus and haven't got one, follow this link.
Use of a catalyst in the cracking reaction increases the yield of high-quality products under much less severe operating conditions than in thermal cracking.