Solvent technology

Textile Solvent Technology— Update 73", Proceedings of Symposium American Association of Textile Chemists and Colorists, Research Triangle Park, N.C., 1973. 

Originally, extractive distillation was limited to two-component problems. However, recent developments in solvent technology enabled applications of this hybrid separation in multicomponent systems as well. An example of such application is the BTX process of the GTC Technology Corp., shown in Figure 6, in which extractive distillation replaced the conventional liquid-liquid extraction to separate aromatics from catalytic reformate or pyrolysis gasoline. This led to a ca. 25% lower capital cost and a ca. 15% decrease in energy consumption (170). Some other examples of existing and potential applications of the extractive distillations are listed in Table 6. 

Many of these novel solvent technologies have particular advantages that are as important as their environmental profile. Of particular relevance are the ease of product isolation and catalyst recycling, the cost, and the potential to carry out reactions which are not possible under more conventional conditions. These technologies may all lead to potential commercial benefits that are so important in the industrial sector. 

Jones, AATCC Symposium Textile Solvent Technology , Jan 1973, p 103. 

Supercrihcal solvent technology supercritical solvents, especially carbon dioxide, offer novel synthetic ophons owing to their unusual solvating properties... 

Nevertheless, since the earliest days of solvent technology attempts have been made to systematise solvency and to quantify differences in interaction of solvents with other solvents and solutes. One of the oldest rules in use for this purpose is that a solvent will be miscible with other solvents or dissolve solutes which are similar in chemical character, or alike dissolves alike . The first attempts to provide a system tabulated miscibility. However, with the growing understanding of solvent action, this approach is hardly used today with the exception of miscibility with water, which is still an important factor both from an end-use and a safety point of view. Water immiscible solvents, for instance, often float on water and this can, when they are flammable, easily cause spread of flames in case of fire. Upon spillage, dilution of toxic solvents is more easy when they are water miscible. 

In principle, BAT(NEEC) and RACT offer the user flexibility in choosing an emission reduction strategy -choice between a variety of end-of-pipe abatement techniques, low solvent technologies, waste minimisation or any combination of these. It recognises that the most appropriate solution will vary from one application to another with size, product quality required and the age and location of a plant. 

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