High-temperature Microreactors

Paul, B. K., Hasan, H., Dewey, T., Ahman, D., Wilson, R. D., Development of aluminide microchannel arrays for high-temperature microreactors and micro-scale heat exchangers, in Proceedings of the 6th International Conference on Microreaction Technology, IMRET 6 (11-14 March 2002), AIChE Pub. 

Tiggelaar et al. [263] deposited a 150-nm-thick layer of silicon-rich silicon nitride on a microstructured silicon surface by low-pressure CVD by using SiH2Cl2 and NH3 gases. The silicon nitride membrane was part of a high-temperature microreactor with integrated heater and sensor patterns. 

A Pd-catalyzed aminocarbonylation was performed above the boiling point of the solvent toluene up to 150 °C [44]. Two reaction products can be generated, an amide and an a-ketoamide, depending on the insertion of one or two equivalents of carbon monoxide. It was demonstrated that high-temperature microreactor operation favors the amide formation and high pressures lead to the a-ketoamide, according to prior literature experience with conventional technology. 

Tiggelaar, R.M., Berenschot, J.W., de Boer, J.H., Sanders, R.G.P., Gardeniers, J.G.E., Oosterbroek, R.E., van den Berg, A., and Elwenspoek, M.C. (2005) Eabrication and characterization of high-temperature microreactors with thin film heater and sensor patterns in silicon nitride tubes. 

Veser G., Experimental and theoretical investigation cf H2 oxidation in a high-temperature catalytic microreactor, Chem. Eng. Sd. 56 (2001) 1265-1273. 

M., Zengerle, R., a modular microreactor design for high-temperature catalytic oxidation reactions, in Ehreeld,... 

Several examples of oxidation reactions, both in the liquid and in the gas phase, have been investigated in microreactors. Often the use of the microstructured device allows a better selectivity to the product of partial oxidation, because of a better temperature control on the catalyst surface (see, for instance, several examples in reviews [61a,b]). Indeed, several gas-phase oxidations can be completed in milliseconds, at significantly high temperatures. 

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. 

The Newman-Kuart rearrangement is an example of a high-temperature reaction [34]. With the use of a microreactor, the reaction temperature could be extended up to 200 °C. 0-(2-Nitrophenyl)-N,N-dimethylthiocarbamate was converted to S-(2-nitro-phenyl)-N,N-dimethylcarbamothioate at 170 °C in 14 min at 90% yield. Quantitative conversion with a throughput of 34 g/h was achieved with sulfolane as solvent at the same temperature and reaction time. 

For high-temperature systems, radiative heat loss can be very significant. In conventional systems, reflective shields or radiation mirrors and low-emissivity material are commonly used to mitigate radiative heat loss. It is expected that similar approaches would be effective in microreactors as well. ... 

Many speciahzed laboratory reactors and operating conditions have been used. Sinfelt has alternately passed reactants and inert materials through a tubular-flow reactor. This mode of operation is advantageous when the activity of the fixed bed of catalyst pellets changes with time. A system in which the reactants flow through a porous semiconductor catalyst, heated inductively, has been proposed for studying the kinetics of high-temperature (500 to 2000°C) reactions. An automated microreactor... 

A similar procedure was developed to grow ZSM-5 crystals in situ on a molybdenum support [245]. The high thermal conductivity (138 W mK 1) and the high mechanical stability at elevated temperatures of the molybdenum support allow the application of ZSM-5 coatings in microreactors for high temperature processes involving large heat effects. The effect of the composition of the synthesis mixture on... 

C. Alepee, R. Maurer, L. Paratte, L. Vulpescu, P. Renaud, A. Renken, Fast heating and cooling for high temperature chemical microreactors, Microreaction, Technol. Ind. Prospects 514 (2000). 

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