Reactor integrated microreactors

Integration of various components is an important issue for the DCF systems. The simple scale-up of microreactors is not enough as the DCF system. A DCF system should consist of not only reactors but also other factory parts like a mixer, separator, and temperature controller. Many integrated microreaction systems have been reported and some of these are commercially available. For example, K. F. Jensen s group has reported an integrated microreactor system for gas-phase catalytic reactions using microstructured reactors and other devices on a computer board [13]. They have achieved computer control over the reaction system through this device as shown in Fig. 6. 

For solvent-free ionic liquid synthesis from methylimidazole and diethyl sulfate, a reactor configuration with an integrated microreactor and two capillaries was developed [25]. This three-fold division of the reaction path serves to compromise... 

Many microreactors are at the research level but a few are already commercially available. Microwave-assisted flow processing in microreactors (MAFP) [93] or radiofrequency-heated flow reactors [94,95] are promising alternatives for conventionally heated, multistep production of fine chemicals in batch reactors. Realization of MAFP at an industrial scale requires a proper design of multitubular reactors integrated with microwave heating [96]. 

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

To build an efficient and compact microreactor, the fabrication technique must allow for three-dimensional structures and the use of the appropriate materials, and the technique should be low cost. Since reactants and products must flow in and out of the device, traditional standard thin film techniques are not suitable for the reactor framework. However, thin film techniques are very useful for integration, surface preparation, sensor integration, and finishing or packaging. Fortunately, traditional thin film techniques can be modified for microreactor fabrication other techniques, which will be discussed below, are also available. 

Fig. 3. Proposed integrated FIA system, with microreactor packed with immobilized AOD 1, buffer solution 2, sample solution 3, horseradish peroxidase and reagents solution 4, eight-channel distribution valve 5, coil 6, peristaltic pump 7, colorimeter 8, computer 9, micro reactor 10, eight-channel injection valve 11, waste.

A chip-based integrated precolumn microreactor with 1 nl reaction volume has been explored by Jacobson et al. [67]. The reactor is operated in a continuous manner by electrokinetically mixing of sample (amino acids) and reagent (o-phthaldialdehyde) streams. The reaction time is adjusted via the respective flow velocities. By switching of potentials, small plugs of the reaction product were injected into a 15.4 mm separation channel in a gated injection scheme (< 1.8% RSD in peak area). The separation efficiency achieved was relatively poor, however, electrokinetic control of reaction time (and yield) permitted to monitor the kinetics of the derivatization under pseudo first-order conditions. A similar integrated precolumn reactor operated in a stopped flow mode has been described by Harrison et al. [68]. 

In the second chapter, Anil Agiral and Han J.G.E. Gardeniers take us to a fascinating world wherein "chemistry and electricity meet in narrow alleys." They claim that microreactor systems with integrated electrodes provide excellent platforms to investigate and exploit electrical principles as a means to control, activate, or modify chemical reactions, or even preparative separations. Their example of microplasmas shows that the chemistry can take place at moderate temperatures where the reacting species still have a high reactivity. Several electrical concepts are presented and novel principles to control adsorption and desorption, as well as the activity and orientation of adsorbed molecules are described. The relevance of these principles for the development of new reactor concepts and new chemistry is discussed. 

Battelle Pacific Northwest National Laboratories (PNNL, Richland, WA) are developing microreactors that produce synthesis gas. These reactors can be mass-produced to yield efficient, compact and cost-effective systems, and they have been made from copper, aluminum, stainless steel, high-temperature alloys, plastics and ceramics. Conventional technologies cannot take full advantage of the intrinsically rapid surface reactions involved in the catalytic conversion of hydrocarbon fuels, but microreactors with integrated catalyst structures can61. 

Tonkovich and coworkers [42—47] used packed bed microreactors for the production of hydrogen. The authors constructed a reactor consisting of stacked stainless steel plates for the partial oxidation of methane [42]. The microchannels (which were 254 pm wide, 1500 pm deep, and 35 mm long) were filled with mesoporous silica that was impregnated with rhodium. The reactor plates were sandwiched between two integrated heat exchanger plates. 

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