solidified upon heating. When the solid mass was cooled, broken up, and placed
inside a reactor, the propylene and/or butenes condensed into a liquid in the
gasoline boiling range. This discovery was scaled up and eventually commercialized (Ipatieff et al. 1938).
Shortly after the introduction of the catalytic condensation process came the
catalytic cracking process, initially as a fixed-bed process and later as the fluidizedbed catalytic cracking process, or FCC. These catalytic cracking processes, and in
particular FCC, yielded even more olefins than thermal cracking, principally
propylene and butenes, which at that time had very little commercial value. Thus,
further application of the catalytic condensation process ensued.
Early units operated at about 10 atmospheres, since that was the pressure level of
many liquefied petroleum gas (LPG) recovery systems. However, it was soon
discovered that, if the reactor was operated at 30 or more atmospheres, catalyst
lives could be extended by a factor of 4–6 times, thus began the evolution of higher
pressure units. Some units that employed tubular reactors at 60 atmospheres were
constructed and were found to be even more successful.
SPA catalyst was also tried for other reactions. In the late 1930s, it was
discovered that SPA would catalyze the reaction of olefins with aromatic compounds to yield alkyl aromatics. This discovery was widely used to make cumene
(isopropylbenzene) for aviation fuel used in World War II. Cumene has a very high
performance number necessary for the aviation gasoline used in internal combustion
engines in aircraft. After the war, use of cumene in aviation fuel declined, but
cumene found an even more important outlet as feedstock for the production of
phenol and acetone. This petrochemical use of cumene continues to dominate this
industry, even though in recent years there has been a significant shift from SPA to
acid zeolite catalysts for this aromatic alkylation. During World War II, there was
also a high demand for ethylbenzene and styrene. Some units were built to produce
ethylbenzene by reacting ethylene with benzene over SPA catalyst. The reaction was
slow and fairly inefficient, so SPA never gained relevance for this application; most
ethylbenzene units at the time made use of aluminum chloride catalysts. Today,
practically all existing ethylbenzene capacity makes use of acid zeolite catalysts.
World War II also led to increased demand and production of polyvinyl chloride
(PVC). PVC is an excellent plastic material but lacks the flexibility required for many
applications. It was discovered, however, that octyl phthalates and the esters of higher
alcohols could be used to “plasticize” PVC, that is, to make it more flexible and
supple. Octyl to decyl alcohols could be obtained by the “oxo” reaction (hydroformylation reaction) of olefins with carbon monoxide and hydrogen. The corresponding
olefins, with one carbon less than the desired alcohols, could be recovered as
by-products from the gasoline operation simply by fractionating the desired olefins
out of the olefinic gasoline blend obtained by the catalytic condensation process. To
this date, this is still the way that these olefins, from heptenes to nonenes, are produced,
except that now these olefins are the main products from this operation, and the
remaining lighter and heavier fractions are blended back into the gasoline pool.
A further application that derived from World War II was the advent of synthetic
detergents to overcome the shortage of soap caused by the diversion of glycerin
460
R.L. Mehlberg et al.
inside a reactor, the propylene and/or butenes condensed into a liquid in the
gasoline boiling range. This discovery was scaled up and eventually commercialized (Ipatieff et al. 1938).
Shortly after the introduction of the catalytic condensation process came the
catalytic cracking process, initially as a fixed-bed process and later as the fluidizedbed catalytic cracking process, or FCC. These catalytic cracking processes, and in
particular FCC, yielded even more olefins than thermal cracking, principally
propylene and butenes, which at that time had very little commercial value. Thus,
further application of the catalytic condensation process ensued.
Early units operated at about 10 atmospheres, since that was the pressure level of
many liquefied petroleum gas (LPG) recovery systems. However, it was soon
discovered that, if the reactor was operated at 30 or more atmospheres, catalyst
lives could be extended by a factor of 4–6 times, thus began the evolution of higher
pressure units. Some units that employed tubular reactors at 60 atmospheres were
constructed and were found to be even more successful.
SPA catalyst was also tried for other reactions. In the late 1930s, it was
discovered that SPA would catalyze the reaction of olefins with aromatic compounds to yield alkyl aromatics. This discovery was widely used to make cumene
(isopropylbenzene) for aviation fuel used in World War II. Cumene has a very high
performance number necessary for the aviation gasoline used in internal combustion
engines in aircraft. After the war, use of cumene in aviation fuel declined, but
cumene found an even more important outlet as feedstock for the production of
phenol and acetone. This petrochemical use of cumene continues to dominate this
industry, even though in recent years there has been a significant shift from SPA to
acid zeolite catalysts for this aromatic alkylation. During World War II, there was
also a high demand for ethylbenzene and styrene. Some units were built to produce
ethylbenzene by reacting ethylene with benzene over SPA catalyst. The reaction was
slow and fairly inefficient, so SPA never gained relevance for this application; most
ethylbenzene units at the time made use of aluminum chloride catalysts. Today,
practically all existing ethylbenzene capacity makes use of acid zeolite catalysts.
World War II also led to increased demand and production of polyvinyl chloride
(PVC). PVC is an excellent plastic material but lacks the flexibility required for many
applications. It was discovered, however, that octyl phthalates and the esters of higher
alcohols could be used to “plasticize” PVC, that is, to make it more flexible and
supple. Octyl to decyl alcohols could be obtained by the “oxo” reaction (hydroformylation reaction) of olefins with carbon monoxide and hydrogen. The corresponding
olefins, with one carbon less than the desired alcohols, could be recovered as
by-products from the gasoline operation simply by fractionating the desired olefins
out of the olefinic gasoline blend obtained by the catalytic condensation process. To
this date, this is still the way that these olefins, from heptenes to nonenes, are produced,
except that now these olefins are the main products from this operation, and the
remaining lighter and heavier fractions are blended back into the gasoline pool.
A further application that derived from World War II was the advent of synthetic
detergents to overcome the shortage of soap caused by the diversion of glycerin
460
R.L. Mehlberg et al.