Catalytic Cracking Processes

Increasing demand for gasoline, along with the need to produce high-octane gasoline for increasingly more powerful spark ignition engines, led to the development and maturation of catalytic cracking processes just before and during World War II. Following the development of a fixed-bed (Houdry process, 1936) and a moving-bed (Thermafor Catalytic Cracking, 1941) catalytic cracking process, fluid-bed catalytic cracking (FCC, 1942) became the most widely used process worldwide because of the improved thermal efficiency of the process and the high product selectivity achieved, particularly after the introduction of crystalline zeolites as catalysts in the 1960s.

The list below shows a timeline for the development of the catalytic cracking processes. The evolution of catalytic cracking processes is an exemplary showcase in chemical engineering for discussing the advancement of reactor configuration, driven by energy conservation and process kinetics. The evolution of these processes is discussed in the following subsections.

Historical Time-Line for Catalytic Cracking Processes

1.      McAfee (1915)

o    Batch reactor catalytic cracking to produce light distillates

o    Catalyst: A1Cl3 – A Lewis acid, electron acceptor

o    Alkane – electron(abstracted by A1Cl3)→ a carbocation⁽⁺⁾→ ionic chain reactions to crack long chains

2.      Houdry (1936) - a commercial process

o    Continous feedstock flow with multiple fixed-bed reactors

o    Cracking/catalyst regeneration cycles

o    Catalyst: clays, natural alumina/silica particles

3.      Thermafor Catalytic Cracking (TCC) (1942)

o    Continues feedstock flow with moving-bed catalysts

o    Catalyst: synthetic alumina/silica particles

o    Higher thermal efficiency by process integration

4.      Fluid Catalytic Cracking (FCC) (1942)

o    Continuous feedstock flow with fluidized-bed catalysts

o    Catalyst: synthetic alumina/silica+zeolites (1965)