38
H. K. Timken et al.
The paraffin alkylation process requires a very high acidity catalyst. An ionic
liquid catalyst with mole ratio of AlCl 3 to amine chloride close to 2:1 was selected
for enhanced performance in producing higher octane number alkylate gasoline. The
ionic liquid catalyst shows the highest Lewis acidity when the mole fraction of AlCl 3
in the ionic liquid, x(AlCl 3 ) is 0.67 (2:1 mole ratio of AlCl 3 to amine chloride). The
catalyst for the commercial process was selected for its overall performance, i.e.,
activity and selectivity for alkylation process as well as for long-term stability.
In addition, a trace amount of anhydrous hydrogen chloride (HCl) co-catalyst is
needed for the high activity of the ISOALKY Catalyst system, and a constant supply
of HCl is required to maintain the reactivity of the catalyst system for extended,
continuous operation of the alkylation process [6]. For the commercial process, the
HCl is generated in situ by the addition of an organic chloride promoter.
The fundamental aspects of chloroaluminate ionic liquid and the nature of its
acidity were studied by Johnson et al. [7, 8] and Smith et al. [9]. Other characteristics
of halometallate ionic liquids have been well reviewed by Estager et al. [10]. Catalysis
for paraffin alkylation using an ionic liquid catalyst and the effect of HCl addition
for the process were studied by Jess et al. [11–13].
Independently, the China University of Petroleum developed a composite ionic
liquid catalyst containing CuCl, trialkyl ammonium hydrochloride, and anhydrous
aluminum chloride for the paraffin alkylation process and commercialized the
technology in China [3, 14, 15].
Other researchers have studied many different ionic liquid catalysts for the paraffin
alkylation process. A recent review article by Wong et al. has a comprehensive list
[16].
2.5 Characteristics of Ionic Liquid Catalyst and Its Use
in a Refinery
The ionic liquid catalyst is a liquid salt (consisting of positive and negative ions
only) at ambient temperature. It has the typical properties of a salt, such as no
measurable vapor pressure, stability for long-term storage, and low solubility in
hydrocarbon. These properties allow for easier handling of the catalyst in a refinery.
Ionic liquid catalyst spills can be contained and managed with no concern of the
catalyst vaporizing.
In addition, hydrocarbon product separation from the ionic liquid is facile due to
low solubility of ionic liquid in the hydrocarbon. Efficient separation and recovery of
the ionic liquid catalyst minimize the loss of the ionic liquid catalyst via carry-over
to the distillation section.
The ISOALKY Catalyst is very hydrophilic and easily hydrolyzed in the presence of water. To protect the catalyst from hydrolysis, high-performance dryers are
installed to dry the feeds to less than 1 ppm moisture level.
H. K. Timken et al.
The paraffin alkylation process requires a very high acidity catalyst. An ionic
liquid catalyst with mole ratio of AlCl 3 to amine chloride close to 2:1 was selected
for enhanced performance in producing higher octane number alkylate gasoline. The
ionic liquid catalyst shows the highest Lewis acidity when the mole fraction of AlCl 3
in the ionic liquid, x(AlCl 3 ) is 0.67 (2:1 mole ratio of AlCl 3 to amine chloride). The
catalyst for the commercial process was selected for its overall performance, i.e.,
activity and selectivity for alkylation process as well as for long-term stability.
In addition, a trace amount of anhydrous hydrogen chloride (HCl) co-catalyst is
needed for the high activity of the ISOALKY Catalyst system, and a constant supply
of HCl is required to maintain the reactivity of the catalyst system for extended,
continuous operation of the alkylation process [6]. For the commercial process, the
HCl is generated in situ by the addition of an organic chloride promoter.
The fundamental aspects of chloroaluminate ionic liquid and the nature of its
acidity were studied by Johnson et al. [7, 8] and Smith et al. [9]. Other characteristics
of halometallate ionic liquids have been well reviewed by Estager et al. [10]. Catalysis
for paraffin alkylation using an ionic liquid catalyst and the effect of HCl addition
for the process were studied by Jess et al. [11–13].
Independently, the China University of Petroleum developed a composite ionic
liquid catalyst containing CuCl, trialkyl ammonium hydrochloride, and anhydrous
aluminum chloride for the paraffin alkylation process and commercialized the
technology in China [3, 14, 15].
Other researchers have studied many different ionic liquid catalysts for the paraffin
alkylation process. A recent review article by Wong et al. has a comprehensive list
[16].
2.5 Characteristics of Ionic Liquid Catalyst and Its Use
in a Refinery
The ionic liquid catalyst is a liquid salt (consisting of positive and negative ions
only) at ambient temperature. It has the typical properties of a salt, such as no
measurable vapor pressure, stability for long-term storage, and low solubility in
hydrocarbon. These properties allow for easier handling of the catalyst in a refinery.
Ionic liquid catalyst spills can be contained and managed with no concern of the
catalyst vaporizing.
In addition, hydrocarbon product separation from the ionic liquid is facile due to
low solubility of ionic liquid in the hydrocarbon. Efficient separation and recovery of
the ionic liquid catalyst minimize the loss of the ionic liquid catalyst via carry-over
to the distillation section.
The ISOALKY Catalyst is very hydrophilic and easily hydrolyzed in the presence of water. To protect the catalyst from hydrolysis, high-performance dryers are
installed to dry the feeds to less than 1 ppm moisture level.