67
broadly divided into three sections on the basis of operation: the riser–reactor, the
regenerator, and the fractionator. The cracking and separation of catalyst and product occur in the riser–reactor section. Carbon generated during cracking reactions
gets deposited on the catalyst surface, and cracking activity progressively decreases.
At the exit of the reactor, the catalyst is separated from the reaction mass by
cyclones, and the spent catalyst is sent to the regenerator. In the regenerator, the
catalyst is continuously regenerated by burning off the coke using air. In the fractionator, the cracked gasses are fractionated into liquid and gaseous product streams.
Other auxiliary units such as feed preheater, air, and flue gas systems are required
for control and optimal operation of this unit for regenerating the catalyst.
3 History of the FCC Process
Internal combustion engines provide outstanding reliability and durability, with
more than 250 million highway vehicles in the country relying on it. Along with
gasoline or diesel, they can also utilize renewable or alternative fuels (e.g., natural
gas, propane, biodiesel, or ethanol) [14]. Initially, the motor gasoline used in these
primitive automobiles was mostly derived from straight-run products of crude distillation at atmospheric pressure. The typical yield of gasoline from such distillation
was around 20 vol.%. The increasing demand and low yield of gasoline by conventional distillation paved the way for the advent of thermal cracking. William Burton
of Standard Oil Company Indiana commercialized the first thermal cracking process in 1913 [15, 16]. This process involved destructive distillation of crude under
pressure. Subsequently, many other competitive designs were developed. The
Dubbs process [17] licensed by Universal Oil Products Co. (UOP) was one of the
most popular ones. It was also founded by T.Ogden Armour in the same year. In this
process, a light crude was continuously cracked in furnace tubes along with simultaneous removal of residue from the system. The gasoline yield placated the rapidly
increasing demand for gasoline; however, this gasoline was of relatively poorer
quality. It caused premature combustion or “knocking,” which would damage the
cylinders of the automobile engines. Additives like tetra ethyl lead were discovered
in 1920 that would improve the ignition quality of the gasoline. However, high olefinicity led to stability issues and gum deposits [26]. During this period, the invention of octane engine created a direct correlation between gasoline composition and
its performance.
The inherent limitations of thermal cracking and a French engineer named
Eugene Houdry’s long-standing fascination with racing cars led to the discovery of
catalytic cracking, now known as the Houdry process (Fig. 1), [18, 19] which he
developed in association with the Socony-Vacuum Oil Co (now Mobil). This process made use of a fixed bed reactor with two large motor-operated valves that
switched between vessels. The first commercialized Houdry process went on stream
in 1937 at Sun Oil’s refinery. Initially, the catalyst used was activated clay, which
was subsequently replaced by synthetic silica–alumina. This process developed
Recent Developments in FCC Process and Catalysts
broadly divided into three sections on the basis of operation: the riser–reactor, the
regenerator, and the fractionator. The cracking and separation of catalyst and product occur in the riser–reactor section. Carbon generated during cracking reactions
gets deposited on the catalyst surface, and cracking activity progressively decreases.
At the exit of the reactor, the catalyst is separated from the reaction mass by
cyclones, and the spent catalyst is sent to the regenerator. In the regenerator, the
catalyst is continuously regenerated by burning off the coke using air. In the fractionator, the cracked gasses are fractionated into liquid and gaseous product streams.
Other auxiliary units such as feed preheater, air, and flue gas systems are required
for control and optimal operation of this unit for regenerating the catalyst.
3 History of the FCC Process
Internal combustion engines provide outstanding reliability and durability, with
more than 250 million highway vehicles in the country relying on it. Along with
gasoline or diesel, they can also utilize renewable or alternative fuels (e.g., natural
gas, propane, biodiesel, or ethanol) [14]. Initially, the motor gasoline used in these
primitive automobiles was mostly derived from straight-run products of crude distillation at atmospheric pressure. The typical yield of gasoline from such distillation
was around 20 vol.%. The increasing demand and low yield of gasoline by conventional distillation paved the way for the advent of thermal cracking. William Burton
of Standard Oil Company Indiana commercialized the first thermal cracking process in 1913 [15, 16]. This process involved destructive distillation of crude under
pressure. Subsequently, many other competitive designs were developed. The
Dubbs process [17] licensed by Universal Oil Products Co. (UOP) was one of the
most popular ones. It was also founded by T.Ogden Armour in the same year. In this
process, a light crude was continuously cracked in furnace tubes along with simultaneous removal of residue from the system. The gasoline yield placated the rapidly
increasing demand for gasoline; however, this gasoline was of relatively poorer
quality. It caused premature combustion or “knocking,” which would damage the
cylinders of the automobile engines. Additives like tetra ethyl lead were discovered
in 1920 that would improve the ignition quality of the gasoline. However, high olefinicity led to stability issues and gum deposits [26]. During this period, the invention of octane engine created a direct correlation between gasoline composition and
its performance.
The inherent limitations of thermal cracking and a French engineer named
Eugene Houdry’s long-standing fascination with racing cars led to the discovery of
catalytic cracking, now known as the Houdry process (Fig. 1), [18, 19] which he
developed in association with the Socony-Vacuum Oil Co (now Mobil). This process made use of a fixed bed reactor with two large motor-operated valves that
switched between vessels. The first commercialized Houdry process went on stream
in 1937 at Sun Oil’s refinery. Initially, the catalyst used was activated clay, which
was subsequently replaced by synthetic silica–alumina. This process developed
Recent Developments in FCC Process and Catalysts