Catalysis flow system

Immobilization by adsorption onto a surface such as activated carbon or to an ion-exchange resin gives a reversible and relatively weak bond, but this can be sufficient to increase the retention time in a flow system to acceptable levels. Recall Section 10.6 where it is shown that the residence time of an adsorbed species can be much larger than that of the mobile phase, in essence giving more time for catalysis. 

Circulation flow system, measurement of reaction rate, 28 175-178 Clausius-Clapeyron equation, 38 171 Clay see also specific types color tests, 27 101 compensation behavior, 26 304-307 minerals, ship-in-bottle synthesis, metal clusters, 38 368-379 organic syntheses on, 38 264-279 active sites on montmorillonite for aldol reaction, 38 268-269 aldol condensation of enolsilanes with aldehydes and acetals, 38 265-273 Al-Mont acid strength, 38 270-271, 273 comparison of catalysis between Al-Mont and trifluorometfaanesulfonic acid, 38 269-270... 

One of the most attractive features of the IL/CO2 approach to homogeneous catalysis is the development of continuous processes [7]. Consequently it needs to be demonstrated that the combination of a suitable IL and compressed CO2 can offer more potential for process optimisation than just a simple protocol for batch-wise catalyst recycling. As an example we were able to activate, tune and immobilise Ni catalyst 13 in a continuous-flow system for the hydroviny-lation of styrene (Scheme 3). Styrene is co-dimerised with ethene yielding 3-substituted 1-butenes [26,27]. We could show that this powerful carbon-carbon bond-forming reaction can be achieved with high enantioselectivity in batch-wise operation and in continuous-flow systems. 

Al-Shamma, E., Naman, S.A. 1989. Kinetie study for thermal production of hydrogen from H S by heterogeneous catalysis of vanadium sulfide in a flow system. Int J Hydrogen Energy 14 173-179. 

Plastourgou, M. and Hoffman, M.R. Transformation and fate of organic esters in layered-flow systems the role of trace metal catalysis. Environ. Sci Techno , 18(10) 756-764, 1984. 

Pioneering studies by Huntsman,Ohloff and others 78 demonstrated that cyclization of unactivated 1,6-dienes occurs in a flow system at 400-500 °C or on heating for longer times at 250-350 °C. Despite the apparently harsh conditions, good yields of product are usually obtained if no thermally sensitive functional groups are present. Lewis acid catalysis of these reactions is not possible since there is no basic site on the enophile. 

Over the past 20 years, fundamental studies of catalysis by metals have been carried out more and more over evaporated metal films which, at least in ultra-high vacuum, provided the guarantee of an atomically clean surface at the beginning of the reaction. Unfortunately, films do not lend themselves readily to investigations in flow systems and to kinetic studies. Nevertheless, films appear more reliable than supported metals unless any interaction between metal and support can be safely ruled out for the particular reaction under study. 

Batch reactors are not common in experimental catalysis since flow systems are so simple. They are most often found with liquid phase reactors using slurried catalysts. Good mixing is essential and checks should be made to eliminate external diffusion problems. Also it is necessary to vary catalyst loading during the experiment as a means of detecting vapor-liquid interfacial effects. ... 

Plastourgou, M., and M. R. Hoffmann (1984), Transformation and Fate of Organic Esters in Layered-Flow Systems The Role of Trace Metal Catalysis, Environ. Set. Technol. 18, 756-764. 

A PolyHIPE was employed in the form of a disk as support for the immobilization of flavine for further catalysis of the oxidation of benzyldi-hydronicotinamide in a flow system, demonstrating very good results [369]. PolyHIPE polymers also proved to be a usefiil support for solid-phase peptide synthesis [372]. In this case, large cells of the monolith were filled... 

Alkylation of methane by olefins under superacid catalysis was demonstrated both in solution chemistry under stable ion conditions and in heterogeneous gas-phase alkylations over solid catalysts using a flow system. Not only propylene and butylenes but also ethylene could be used as alkylating agents. 

---