The Thermofor Catalytic Cracking (TCC) process was developed from the Houndry process and, after its enhancement, the Fluid Catalytic Cracking (FCC) was achieved.
FCC units process intermediate and heavy oil fractions generating lighter products (gasoline and other intermediate products) with greater added-value by molecule-breaking chemical reactions with the help of zeolitic catalysts. Such catalysts usually present different levels of zeolite Y, a synthetic aluminum silicate.
Many compounds are formed in such process. The process takes place satisfactorily when sufficient heat is provided for an efficient molecular breakage (endothermic reactions) so that the catalysts involved in the process can be regenerated.
Based on experiments performed at the Massachusetts Institute of Technology (MIT), Professors Lewis and Gilliand confirmed the stabilized operation of a pneumatic circuit of fluidized beds and transport lines. Therefore, Exxon engineers noticed that the support tube was crucial for the circulation of solids, increasing the flow rate in a pilot plant. Along with the work of MW Kellog Company and Standard Oil of Indiana (currently Amoco) engineers, the efforts resulted in the 1942 first FCC commercial unit with a daily capacity of 13,000 feeding barrels. In order to reduce the powder load in the collectors, the mobile beds were replaced by fluidized beds, leading to the second model.
Two basic units are involved with the FCC: a reactor fed with gas oil operating at 480-540°C, where the gas oil is cracked when in contact with the hot catalyst particles. After a while, such catalyst particles are taken to a regenerator operating at 570-590°C, where the carbon content deposited in the particles is decreased from 1-2% to 0.4-0.8%. The catalyst returns to the reactor after this process takes place.