Ionic liquids industrial process applications

However, little has entered the public domain concerning the use of ionic liquids on an industrial scale, and nothing has been claimed, even in general terms, to suggest that room-temperature ionic liquids are being used in a viable chemical process being operated commercially. Recent emphases on ionic liquid research and applications could change this. 

There is little doubt that intrepid entrepreneurs will continue to champion ideas for the application of ionic liquids. Without a doubt, further uses of these materials will be found and justified for commercial use. However, the perceived disadvantages, and particularly the toxicity issues, will temper enthusiasm until the data obtained provide reassurances that an ionic-liquid-based process satisfies all the economic, toxicological, safety, and (in the pharmaceutical industry) FDA regulatory criteria to justify implementation. 

Ionic liquids IIII Fundamentals, Process, Challenges, and Opportunities edited by R. D. Rogers and K. R. Seddon (ACS, Symposium Series, Washington DC, 2005). Ionic liquids Industrial Applications to Green Chemistry, by R. D. Rogers and K. R. Seddon (ACS, Symposium Series, Washington DC, 2002). Ionic Liquids in Synthesis edited by P. Wasserscheid and T. Welton (Wiley-VCH Weinheim, 2003). 

Weyershausen B, Hell K, Hesse U (2005) Industrial application of ionic liquids as process aid. Green Chem 7 283... 

The few examples where SILP catalysis has been tested so far showed highly encouraging results. It is very likely that other applications where ionic catalyst solutions were tested in liquid-liquid biphasic reactions could be reinvestigated under SILP conditions. If very high catalyst stability over time can be realised or simple catalyst regeneration protocols can be developed than SILP catalysis can be expected to make its way into industrial processes. 

The ionic liquid investment could be further reduced if future research enables the application of ammonium based alkylsulfate or arylsulfonate ionic liquids. For these systems bulk prices around 15 /kg are expected. Ammonium based alkylsulfate or arylsulfonate ionic liquids usually show melting points slightly above room temperature but clearly below the operating temperature of the hydroformylation reaction. Therefore these systems may be less suitable for the liquid-liquid biphasic process in which the ionic liquid may be involved in process steps at ambient temperature (e.g. phase separation or liquid storage). In contrast, for the SILP catalyst a room temperature ionic liquid is not necessarily required as long as the film becomes a liquid under the reaction conditions. Assuming an ammonium based SILP catalyst, the capital investment for the ionic liquid for the industrial SILP catalyst would add up to 105,000 . 

With the continued explosion of academic and industrial activities surrounding ionic liquids for many different applications, the potential for catalytic processes using ionic liquids has been increasingly recognized 1,15-18). A number of excellent reviews have appeared 19), including the reviews related to biocatalytic applications of ionic liquids 20,21). 

Ionic liquids (ILs) are, together with water and supercritical fluids, one of the few alternative media for environmentally friendly processes, which seem to have more possibility of industrial application in the next 10 years. The range of demonstrated or proposed applications of ILs is extraordinary, going from their use as nonvolatile, non-flammable solvents in organic synthesis to catalysts, materials for aiding separations and gas capture, advanced heat transfer fluids, lubricants, antistatics, and so on [2 ]. Surpassing in magnitude the number of potential uses is the number of possible IL compositions, estimated to be in the billions [5]. The term ionic liquids includes all compounds composed exclusively by ions that are liquid... 

Other groups are working on the use of ionic liquids for chemical and industrial processes. In order to push the development of the industrial application of ionic liquids, a European consortium was formed several years ago (Seddon, 1999). This three-year arrangement between academics and industry has three major goals ... 

Finally, the author would like to make some general points. When an area of chemistry has such potential for application and becomes fashionable discussion around it often polarizes. That seems very much to be the case with ionic liquids. Ionic liquids are not a panacea for all of the problems of chemical industries, but that equally well does not mean that they are a waste of time. It is just over a decade since the modern generation of ionic liquids were first discovered.83 This is a remarkably short period of time and it is not surprising that large-scale processes that use these ionic liquids are not yet in place. However, in this short time, huge advances have been made in understanding how they might be useful. 

Notwithstanding the numerous advantages of ionic liquids as reaction media for catalytic processes widespread industrial application has not yet been forthcoming. The reasons for this are probably related to their relatively high prices and the paucity of data with regard to their toxicity and biodegradability. The replacement of conventional VOCs with ionic liquids is an obvious improvement with regard to atmospheric emissions but small amounts of ionic liquids will... 

Of some concern in this field is the issue of intellectual property, as there are a large number of patents protecting the area in terms of the preparation, identities and uses of these solvents. For example, one patent claims broad coverage of cheap phosphonium ionic liquids, and this might prevent their use in many applications. However, the large number of patents also demonstrates significant industrial interest in these media and industrial processes using them are now online. ... 

For the industrial application of ionic liquids, as selective solvents for separation processes or other applications, a reliable knowledge of the pure component properties and mixture data (phase equilibria, excess properties) is required. Although... 

In many publications, an effect of the ionic liquid solvent on the rate or selectivity of organic and catalytic reactions has been reported [129], For industrial applications, it has been recognised that process intensification using ionic liquids is in most cases not a question of retrofitting by simply substituting a solvent by an ionic liquid, but further tuning strategies, such as the immobilisation of catalysts... 

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