The Zosel Patent

As we related in the introduction to Appendix A, this patent should be read by everyone involved in research and process development using supercritical fluids. In his examples, Zosel describes results on neat solubility, separations of liquids and solids, fractionations, etc. A wealth of information is given on the performance of various gases, e.g., ethylene, ammonia, ethane, carbon dioxide, in dissolving a variety of compounds. Several interesting experiments carried out in a plexiglass autoclave are descrited, and certain phase separations are noted. Some of the information can be found in other references, of course, but not in such succinct form. It is of pedagogical value to reproduce one of the examples here. 

Many such observations and a quite detailed Invention section make this patent a valuable source of information. There are, however, a few examples which are not accurate. The following is one such example. 

Zosel s explanation is generally accurate concerning the ratio of the hydrocarbon radical to the hydroxyl group. However, ethanol can be extracted from ethanol-water solutions by supercritical ethylene (Paulaitis, Gilbert, and Nash, 1981) and so can acetone from acetone-water solution (Elgin and Weinstock, 1959) a few such inaccuracies still do not detract from the vast amount of data that Zosel provides. 

The first claim of the patent is also reproduced here because of its pedagogical value. What is claimed is  

Note that the claim covers only the retrograde region of solubility behavior. 

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The Zosel patent (U.S. 3,969,196). The description of this patent could fill a separate appendix. This patent is 30 pages long and it includes 68 examples that describe all sorts of extractions and separations. The discussion of this patent is terse because of consU aints on space however, the patent is must reading for serious researchers and managers. 

Katz goes on to present a detailed account of the phenomenon, and he gives a number of examples of separating oil and gas mixtures by applying the phenomenon. This patent like the Zosel patent is must reading in this case it is not for the many examples described but for the fundamentals that Katz develops. 

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