Microreactors reactors

Static mixing catalysts Operation Monolithic reactors Microreactors Heat exchange reactors Supersonic gas/liquid reactor Jet-impingement reactor Rotating packed-bed reactor... 

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. 

Spinning disk reactor Static mixer reactor Monolithic reactors Microreactors HEX reactors... 

Micro/milli-reactors A study by ECN in Holland suggests 20 PJ savings using heat exchanger-reactors. Microreactors extend this to 25 PJ Applications in 20% of processes in the sector saving 20% of energy - 1 PJ Reduce feedstock and additives by 30% in 10% of processes saving 5-7 PJ Spill-over from fine chemicals <1 PJ... 

Technologies Reactors spinning disk reactor, static mixer reactor, microreactors, heat exchange reactors, monolithic reactors, oscillatory flow reactors, trickle bed reactors... 

Additional demands are due to the fact that new types of reactors appear as very promising reverse-flow and ultrafast reactors, microreactors, reactors for photocatalysis, and so on. Suitable catalysts not only need new chemical formulations and textures, but also preparation processes adapted to the corresponding shaping techniques. Not all cases can be examined in this chapter. However, much emphasis will be laid on the role of a comprehensive approach in the scientific and chemical engineering research for catalyst fabrication. A few examples will illustrate the discussion. Suggestions may come from other fields of science and technology. 

Bioreactors. Bioreactors that utilize hving cells are typically called fermenters. There are several different types of bioreactors mechanically stirred or agitated tanks bubble columns (cylindrical tanks that are not stirred but through which gas is bubbled) loop reactors, which have forced circulation packed-bed reactors membrane reactors microreactors and a variety of different types of reactors that are not easily classified (such as gas-Uquid reactors and rotating-disk reactors). Biochemical engineers must choose the best bioreactor type for the desired purpose and outfit it with the right instrumentation and other features. 

Laminar flow is important in engineering systems, such as flow in pipes, fuel cells, chemical reactors, microreactors, microfluidic, and nanofluidic devices just to name some applications. 

Gas-solid (catalytic) Differential reactor Integral reactor Mixed (Carberry) reactor Microreactor Fluid-bed reactor Single-pellet reactor... 

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. 

Figure 9.23 Image of a numbered up 10-channel mini-packed bed reactor microreactor. Source By courtesy of IEEE) [69].

Shorter reaction times require for catalyst inside a microreactor to be more active than in traditional reactors. Microreactors employ less catalyst than their batch counterparts, because of their small size. The requirement for readily separable and recyclable catalysts leads often to the application of heterogeneous catalysts. Active catalysts have been coated on a microchannel wall supported by inorganic, polymer, or zeolite coatings [144,145]. 

Early studies with the detailed description of the so-called microstructured reactors (microreactors) are dated 1986 however, theoretical calculations of scientists of the former GDR were not put into practical application (1). A patent of that time describes, very generally, a miniaturized chemical engineering apparatus and systems made by simple fabrication methods. A stack-like arrangement of platelets carrying microchannels and fluid connecting structures was also proposed. 

Technical progress and implementation of microstmctured reactors (microreactors) have been described by an increasing number of publications over the past two decades. A number of book reviews [1-3] and dedicated conferences [4,5] have documented the progress in reactor development and chemical synthesis employing microreactors. The term microreactor usually defines a piece of equipment whose active components, that is, the structures in which mixing or a reaction occurs, are typically in the size range between 1 and 2000 [xm. These structural dimensions allow for well-defined continuous-flow conditions while the reactor unit itself is not necessarily on a micro- or millimeter scale [1,6]. 

Microstructured reactors (microreactors) represent a new type of reaction equipment for applications in chemistry. Small dimensions of microchannels provide a short diffusion time, better temperature and pressure control, large specific surface area, high heat exchanging efficiency, and a higher level of safety [1]. 

Ethylene oxide catalyst research is expensive and time-consuming because of the need to break in and stabilize the catalyst before rehable data can be collected. Computer controlled tubular microreactors containing as Httle as 5 g of catalyst can be used for assessment of a catalyst s initial performance and for long-term life studies, but moving basket reactors of the Berty (77) or Carberry (78) type are much better suited to kinetic studies. 

There are many descriptions of various microreactors for hydrogenation. Requirements for these reactors are more exacting because of the need to measure accurately small amounts of consumed hydrogen (22,30,31,36,45,46, 49,59,69,70,91,92,104,111). 

Viable operating eonditions were identified experimentally for maximising the produetion of ethylene, propylene, styrene and benzene from the pyrolysis of waste produets. Data are given for pyrolysis temperature, produet reaetion time, and quench time using a batch microreactor and a pilot-plant-sized reactor. 26 refs. CANADA... 

Microreactor scale-up is built upon the premise of numbering up channels. Figure 11.1. A single channel is demonstrated with the same geometry and fluid hydrodynamics as a full-scale reactor. Numbering up rehes on creating a massively... 

Degussa/Evonik (Germany) Falling film microreactors for ozonolysis and other chemical applications with IMM reactors [3] and DEMIS project collaboration [4, 5]... 

The advantages of microreactors, for example, well-defined control of the gas-liquid distributions, also hold for photocatalytic conversions. Furthermore, the distance between the light source and the catalyst is small, with the catalyst immobilized on the walls of the microchannels. It was demonstrated for the photodegradation of 4-chlorophenol in a microreactor that the reaction was truly kinetically controlled, and performed with high efficiency [32]. The latter was explained by the illuminated area, which exceeds conventional reactor types by a factor of 4-400, depending on the reactor type. Even further reduction of the distance between the light source and the catalytically active site might be possible by the use of electroluminescent materials [19]. The benefits of this concept have still to be proven. 

Recently, microstructured reactors have stepped into chemical production [4] and thus microreactor process and plant design, including economic incentives, is the issue at this time. For this purpose, large-capacity microstructured apparatus is needed ( micro inside, fist- to shoebox size outside ) and plant concepts have to be proposed which include all process steps. 

When the reaction was performed in the microreactor, the maximum conversion of 97.0 % was attained when the flow rate of Boc-AMP solution was 9 ml/min and the molar equivalents of KOH to Boc-AMP was 13 as shown in Fig. 1. Optimum operating conditions were obtained from a statistical method by using factorial design [6]. The yield decreased over the KOH equivalency of 13 in Fig. 1, since the phase separation between the t-Boc20 and the aqueous phase was observed due to the increased water content with increasing KOH equivalency. As the heat transfer performance of the microreactor was greatly improved compared with conventional reactors, higher reaction temperature could be admissible. 

In this experiment, the reaction temperature was isothermally controlled at 15 °C. The heat of reaction was completely removed using microreactor so that virtually no byproducts were produced during the reaction. It can be compared with other reactors described above, which should be operated at 0 °C or -20 °C to avoid side reactions. 

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