Implementing ionics

BASF has set up a research partnership with the University of Alabama to study the dissolution and processing of cellulose by means of ionic liquids.

BASF has set up a research partnership with the University of Alabama(UoA), to study the dissolution and processing of cellulose by means of ionic liquids.

Occurring at a volume of some 700 billion tons, cellulose is the earth’s most widespread natural organic chemical and is highly important as a biorenewable resource. Out of the 40 billion tons nature renews every year, only 0.1 billion tons are used as feedstock for further processing.

A more intensive exploitation of cellulose as a biorenewable feedstock has to date been prevented by the lack of a suitable solvent that can be used in chemical processes. By means of ionic liquids, however, real solutions of cellulose can now be produced for the first time at technically useful concentrations, opening up great potential for cellulose processing.

BASF is in the process of evaluating a variety of ideas that might improve the use of cellulose. For example, making cellulose fibre from so-called dissolving pulp currently involves the use, and subsequent disposal, of great volumes of various chemical additives. A total of some 600,000 metric tons of carbon disulphide (CS2) is consumed each year for this application. For each ton of cellulose fibre, there are more than two tons of waste substances. Major volumes of wastewater are also produced for process reasons and need to be disposed of. These processes can be greatly simplified by the use of ionic liquids, which serve as solvents and are nearly entirely recycled. This can clearly reduce the amount of additives needed.

“By combining our knowledge of innovative ionic liquids with the specific expertise the University of Alabama possesses in the field of cellulose products, we are progressing into a fascinating area,” says Dr. Stefan Marcinowski, BASF’s Research Executive Director.

At its Ludwigshafen site, BASF has for some years been running the first large-scale industrial process worldwide that uses ionic liquids. The company says that this process allows fast and simple removal of acids from reaction mixtures. The reaction of an acid with a base results in a liquid salt instead of solid crystals, which frequently cause process problems in production. The use of ionic liquids means that time-consuming and expensive filtration is no longer necessary. These liquids can be easily separated from the desired products, like oil from water, and can also be recycled. 1-Methylimidazol, which replaces other bases used as additives, additionally acts as a catalyst, thus speeding up the reaction considerably.

BASF sells its ionic liquids under the brand name Basionics, and the corresponding processes are marketed under the name Basil. An Eco-Efficiency Analysis recently confirmed that the use of BASF’s Basil process for scavenging acids in the chemical synthesis of phosphorus compounds offers significant advantages over the conventional system.

Compared to amines, which have been used traditionally in this type of reaction, the BASF process based on 1 methylimidazole is less cost-intensive and at the same time easier on the environment. The new process for synthesising phosphorus compounds, which are used as chemical building blocks to produce photoinitiators in UV-curable coatings, avoids a number of problems encountered to date: Stability and product yield improve, and the process is less laborious.

“We believe ionic liquids hold many promises for the future,” says Dr. Matthias Maase, who works in the New Business Development unit of the BASF Intermediates operation division, “By their properties they will open up entirely new fields of application, even outside the classical chemical uses. For example, think of ionic liquids as new materials or as engineering liquids used in the mechanical and automotive industries, but also in oil and gas production, and they might even be used in the field of renewable resources.”

The road to use in practice is taking shape. Maase says, “We are currently talking to companies from the most varied industries all over the world who have recognised the benefits of ionic liquids and are discussing concrete applications with us.”