Application case

★ Industrial processes based on ionic liquids

BASF has developed industrial processes utilizing ionic liquids. These processes are called Basil™ processes. The abbreviation BASIL stands for “Biphasic Acid Scavenging utilizing Ionic Liquids.” BASF makes use of this technology for the synthesis of alkoxyphenylphosphines, These compounds are important raw materials for the production of BASF’s Lucirin© photoinitiators that are used to cure coatings and printing inks by exposure to UV radiation. HCl gas is formed during the synthesis of alkoxyphenylphosphines, and this gas has to be scavanged to avoid product decompostion. In the past, scavenging was done with with a tertiary amine. This resulted in a thick, non-stirrable slurry, which was difficult to filter off from the product. If 1-methylimidazole is used as an acid scavenger, an ionic liquid is formed: 1-methylimidazolium chloride, which has a melting point of 75 °C. After the reaction two clear liquid phases occur that can easily be separated. The upper phase is the pure product, the lower phase the pure ionic liquid.

Eastman Chemicals is using a phosphonium ionic liquid in a process for isomerization of epoxybutene to 2,5-dihydrofuran.

Air Products has developed an ionic-liquid-based technology for delivering hazardous gases for ion implantations in the electronics industry. The hazardous gases are stored in gas-cylinders filled with an ionic liquid. The [Rmim][Cu2Cl3] ionic liquids can absorb toxic gases like phosphine (PH3) and arsine (AsH3) by complex formation. [Rmim][BF4] ionic liquids can be used to absorb boron trifluoride (BF3). By application of vacuum to the gas-storage cylinders the gases can be released in the actual implantation process and no loss of ionic liquid is observed. Due to the superior heat transfer capability of ionic liquids, gases are easier to load and deliver compared to solid zeolite or carbon-based adsorption systems.

Linde Gas GmbH uses ionic liquids as liquid piston in pumps for the compression of gases (natural gas and hydrogen). A liquid piston has advantages over a solid metal piston. A solid piston has the disadvantage that they wear and become leaky with time. The ionic liquid seals the cylinder space, in which the liquid piston moves, completely and there is no wear. This technology, developed in partnership with proionics, saves a substantial proportion of the energy required to compress gases.

Several industrial processes take advantage of the low vapor pressure of ionic liquids.

★ List of Application case based on ionic liquids