Potential applications catalyst recovery

Ionic liquids represent a unique class of reaction media for catalytic processes, and their application in catalysis has entered a period of exploding growth. The number of catalytic reactions involving ionic liquids continues to increase rapidly. These liquids offer promising solutions to the problems associated with conventional organic solvents the potential advantages may include enhanced reaction rates, improved chemo- and regioselectivities, and facile separation of products and catalyst recovery. 

The present procedure evolved from our previous work on the conversion of allenals, allenones, and allenylcarbinols to furans and 2,5-dihydrofurans with catalytic silver nitrate (AgN03) in acetone.5-10 It has also been shown that allenylcarbinols can be converted to 2,5-dihydrofuran under these conditions.11 0- and y-Alkynyl allylic alcohols can also be isomerized to furans under strongly basic conditions with potassium tert-butoxide in tetrahydrofuran-tert-butyl alcohol-18-crown-6 or hexamethylphosphoramide (KO-t-Bu in THF-t-BuOH-18-crown-6 or HMPA).12 The AgNOa/silica gel method is milder, faster, and more efficient than the previously reported procedures.13 Moreover, it offers the potential advantage of catalyst recovery and possible applicability to a flow system in which a packed column, protected from light, could serve as the reactor.4... 

The future of cathodic metal removal seems to be fruitful, since it is a mature technology, and there is a wide variety of cell designs commercially available nowadays. A promising field of application is recovery of precious metals from, e.g., spent catalysts and printed circuit boards, in which cell design and cell potential are usually not critical due to the value of the metal. Selective metal electrodeposition from a mixture of different ions is still a challenge, especially when the electrodeposition overpotentials are very close. 

Nanofibers have yield potential applications in areas such as filtration, recovery of metal ions, drug release, dentistry, tissue engineering, catalysts... 

Despite the great potentialities of the photocatalytic processes, their application at the industrial level is limited by different factors. Besides the problems regarding the high reactivity of the system and the low selectivity of the classical catalysts on which, as previously described, many studies have been realized in recent years, one of the main problems is the recovery of the catalyst from the reaction environment. 

The applications mentioned demonstrate the potential of membrane reactors for the recovery and repeated use of homogeneously soluble catalysts. For some of the examples a strong increase in the total turnover number has been achieved. First publications indicate that this technique is also being investigated by industry [58]. Due to the additional steps required for coupling as well as for the equipment necessary it might be applicable in the majority to high value-added products. On... 

Microemulsions are thermodynamically stable isotropic dispersions of oil in water (o/w) or of water in oil (w/o) containing domains of nanometer dimensions stabilized by an interfacial film of surfactant(s). The most typical oil phases are alkanes, the choice of cyclic or aromatic hydrocarbon being dependent on further application. Extensive study of microemulsions has been stimulated by their great potential for practical applications in different fields [1,2] such as pharmaceuticals, cosmetics, enhanced oil recovery and material science (catalysts, semiconductors, etc.). 

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