isomerization of normal butane to isobutane. Isomerization of C 5 –C 6 paraffins for
motor fuel blending was introduced in the late 1950s.
UOP developed the Butamer™ process for the isomerization of n-butane to
isobutane, typically used as a feedstock to produce motor fuel alkylate. Isobutane
produced from isomerization can also be converted to isobutylene via catalytic
dehydrogenation using a process such as the UOP Oleflex™ process. Isobutylene is
used to produce gasoline blending components such as MTBE and ETBE and for
making petrochemicals such as butyl rubber.
The aforementioned processes are some of the most widely used in industry and
form the basis of this discussion. Developments in light-naphtha isomerization are
usually based on the introduction of new, more active or more stable catalysts, some
of which will be discussed in more detail below.
The skeletal isomerization of paraffins is one of the many important industrial
applications of acid function-promoted catalysis. Other examples of the wide
commercial applications of acid-catalyzed industrial hydrocarbon reactions are
the alkylation of paraffins and aromatics with olefins, transalkylation and disproportionation of aromatics, metathesis of olefins, oligomerization of olefins,
etherification and hydration of olefins, and hydrocracking. Although these various
applications have some similarities, they are all promoted by an acidic catalyst and
often by a metal function. The specific catalytic requirements for achieving a
favorable economic result have led to the proliferation of specialized catalytic
materials.
History
In the 1930s, Vladimir Ipatieff and his team from UOP discovered that they could
transform normal butane molecules in gasoline to isobutane using an aluminum
chloride catalyst with hydrogen chloride as a cocatalyst (Remsberg and Higdon
1994). While scientifically interesting at the time, refiners did not want isobutane in
their gasoline due to its high volatility. But before the decade was over, high-octane
aviation fuel was being produced from alkylation and isomerization processes and
became a significant factor in the war effort during World War II. The UOP
Butamer™ process was the predominant process used for n-butane isomerization
then, as it is today. HF alkylation was subsequently used to produce higher-octane
motor fuel for automobiles by combining isobutane with isobutylene to form highly
branched isooctane molecules with eight carbon atoms. This gasoline had a high
octane number and burned cleanly in combustion engines.
Demand for high-octane fuels for automotive use continued to increase in the
late 1950s and 1960s as part of postwar economic expansion. It was recognized that
the light straight-run naphtha portion of crude oil, consisting of predominantly
pentanes and hexanes, negatively affects gasoline quality. A catalyst similar to what
was used in the Butamer process was applied by UOP scientists to pentane- and
hexane-rich naphtha and found to increase octane by 12–20 numbers. This UOP
process, named the Penex™ process, was soon being used in nearly all refineries.
Isomerization in Petroleum Processing
481
motor fuel blending was introduced in the late 1950s.
UOP developed the Butamer™ process for the isomerization of n-butane to
isobutane, typically used as a feedstock to produce motor fuel alkylate. Isobutane
produced from isomerization can also be converted to isobutylene via catalytic
dehydrogenation using a process such as the UOP Oleflex™ process. Isobutylene is
used to produce gasoline blending components such as MTBE and ETBE and for
making petrochemicals such as butyl rubber.
The aforementioned processes are some of the most widely used in industry and
form the basis of this discussion. Developments in light-naphtha isomerization are
usually based on the introduction of new, more active or more stable catalysts, some
of which will be discussed in more detail below.
The skeletal isomerization of paraffins is one of the many important industrial
applications of acid function-promoted catalysis. Other examples of the wide
commercial applications of acid-catalyzed industrial hydrocarbon reactions are
the alkylation of paraffins and aromatics with olefins, transalkylation and disproportionation of aromatics, metathesis of olefins, oligomerization of olefins,
etherification and hydration of olefins, and hydrocracking. Although these various
applications have some similarities, they are all promoted by an acidic catalyst and
often by a metal function. The specific catalytic requirements for achieving a
favorable economic result have led to the proliferation of specialized catalytic
materials.
History
In the 1930s, Vladimir Ipatieff and his team from UOP discovered that they could
transform normal butane molecules in gasoline to isobutane using an aluminum
chloride catalyst with hydrogen chloride as a cocatalyst (Remsberg and Higdon
1994). While scientifically interesting at the time, refiners did not want isobutane in
their gasoline due to its high volatility. But before the decade was over, high-octane
aviation fuel was being produced from alkylation and isomerization processes and
became a significant factor in the war effort during World War II. The UOP
Butamer™ process was the predominant process used for n-butane isomerization
then, as it is today. HF alkylation was subsequently used to produce higher-octane
motor fuel for automobiles by combining isobutane with isobutylene to form highly
branched isooctane molecules with eight carbon atoms. This gasoline had a high
octane number and burned cleanly in combustion engines.
Demand for high-octane fuels for automotive use continued to increase in the
late 1950s and 1960s as part of postwar economic expansion. It was recognized that
the light straight-run naphtha portion of crude oil, consisting of predominantly
pentanes and hexanes, negatively affects gasoline quality. A catalyst similar to what
was used in the Butamer process was applied by UOP scientists to pentane- and
hexane-rich naphtha and found to increase octane by 12–20 numbers. This UOP
process, named the Penex™ process, was soon being used in nearly all refineries.
Isomerization in Petroleum Processing
481