Catalytic reactors multifunctional reactor

Noeres C, Benvenuti C, Hoffmann A, Gorak A. Reactive distillation nonideal-flow behavior of the liquid phase in structured catalytic packings. Proceedings of International Symposium on Multifunctional Reactors (ISMR-2), Nuremberg, 2001. 

At first sight, adsorption and reaction are well-matched functionalities for integrated chemical processes. Their compatibility extends over a wide temperature range, and their respective kinetics are usually rapid enough so as not to constrain either process, whereas the permeation rate in membrane reactors commonly lags behind that of the catalytic reaction [9]. The phase slippage observed in extractive processes [10], for example, is absent and the choice of the adsorbent offers a powerful degree of freedom in the selective manipulation of concentration profiles that lies at the heart of all multifunctional reactor operation [11]. Furthermore, in contrast to reactive distillation, the effective independence of concentration and temperature profiles... 

The potential advantages of catalytic filters are those typical of multifunctional reactors (reduction of process units, space and energy savings, cost reduction, etc.). Later on some examples will elucidate these points (see Section IV). However, the following properties should be possessed by catalytic filters so that these opportunities actually can be exploited ... 

A membrane reactor is a particular type of multifunctional reactor where one or more chemical reactions, generally catalytically promoted, are carried out in the presence of a membrane this last, thanks to its permselectivity, affects the course of the reactions, allowing improvements of either the achievable conversion (e.g., equilibrium reactions) or the selectivity toward intermediate products (e.g., consecutive reaction schemes). 

Halloin VL, Wajc SJ. A multifunctional catalytic reactor suitable for the exothermal synthesis of condensable products. Chemical Engineering Science 1994 49 4691-4698. 

Petrachi, GA, Negro, G, Specchia, S, Saracco, G, Maffetone, PL, Specchia, V. Combining catalytic combustion and steam reforming in a novel multifunctional reactor for on-board hydrogen production from middle distillates. Ind. Eng. Chem. Res. 2005 44 9422-9430. 

Future Trends in Reactor Technology The technical reactors introduced here so far are those used today in common industrial processes. Of course, research and development activities in past decades have led to new reactor concepts that may have advantages with respect to process intensification, higher selectivities, and safety and environmental aspects. Such novel developments in catalytic reactor technology are, for example, monolithic reactors for multiphase reactions, microreactors to improve mass and heat transfer, membrane reactors to overcome thermodynamic and kinetic constraints, or multifunctional reactors combining a chemical reaction with heat transfer or with the separation in one instead of two units. It is beyond the scope of this textbook to cover all the details of these new fascinating reactor concepts, but for those who are interested in a brief outline we summarize important aspects in Section 4.10.8. 

Novel developments in reactor technology are multifunctional reactors, which couple different processes such as reaction and separation by membranes, adsorption, or distillation, catalytic or reactive distillation, monolithic reactors, microreactors, and adiabatic reactors with periodic flow reversal. 

The variety of functions of the catalyst is pronounced, in particular, in the technological catalytic oxidation of -paraffins to aliphatic acids [5]. This technology consists of several stages among which the central place is occupied by oxidation. It is conducted at 380 420 K in a series of reactors, with a mixture of salts of aliphatic acids of K+ and Mn2+ or Na+ and Mn2+ as the catalyst. The alkaline metal salt stabilizes (makes it more soluble and stable) the manganese salt [152]. Studies have revealed the multifunctional role of the catalyst (manganese ions) (Mn) [152-154]. 

The combination of reaction and separation in one multifunctional membrane reactor is an interesting option. In such a reactor the membrane could be catalytically active itself, or it could serve only as a separation medium. There are several types of operation for such a reactor [33]. It could be used to separate the formed products from the reaction mixture. In this way it is possible to overcome equilibrium limitations or to improve the selectivity of the reaction. Another possibility is the controlled addition of reactant via the membrane, which might be of use in, for example, oxidation reactions or sequential reactions. The advantage of using zeolitic membranes in a membrane reactor is that they have a high thermal stability and exhibit a good selectivity. Moreover, they can be made catalytically active. 

The concept of process intensification aims to achieve enhancement in transport rates by orders of magnitude to develop multifunctional modules with a view to provide manufacturing flexibility in process plants. In recent years, advancement in the field of reactor technology has seen the development of catalytic plate reactors, oscillatory baffled reactors, microreactors, membrane reactors, and trickle-bed reactors. One such reactor that is truly multifunctional in characteristics is the spinning disk reactor (SDR). This reactor has the potential to provide reactions, separations, and good heat transfer characteristics. 

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