Alternative microchannel reactors

The Cytos Pilot System is a 10-fold parallelized version of the Cytos Lab System [18] with identical fluidic behavior. Thus, nine Cytos microreactors were used for production with a cumulative product mass flow of 0.6 kg h , while alternately one reactor was treated with tetrahydrofuran in a rinsing cycle at a mass flow rate of 0.4kgh to avoid clogging of the microchannels. The continuously running Cytos Pilot System was cooled by an electrically tempered cooling system. 

An alternative to filling or coating with a catalyst layer the microcharmels, with the related problems of avoiding maldistribution, which leads to a broad residence time distribution (RTD), is to create the microchannels between the void space left from a close packing of parallel filaments or wires. This novel MSR concept has been applied for the oxidative steam reforming of methanol [173]. Thin linear metallic wires, with diameters in the millimeter range, were close packed and introduced into a macro tubular reactor. The catalyst layer was grown on the external surface of these wires by thermal treatment. 

As an alternative to the above-mentioned reactor, Pattekar et al. [39] designed a radial flow packed-bed MSR to reduce the pressure drop compared to randomly packed microchannels. This design provides an order of magnitude reduction in pressure drop while maintaining the compact design of the microreactor, and seems to be easier to construct. 

Mixing in microreactors is almost exclusively assumed to be laminar dne to the small flow channel width. Laminar flow through microchannels reqnires the phase flow to be alternated in some fashion in order to create the mixing environment. This operation is important because mass transfer, in this case, is driven only by molecular diffusion. Hence, the creation of larger gas-liquid interfaces is the only practical course of action for gas-limited operations. Miniaturized bubble columns are able to accomplish this task well. For example, a standard reactor can create... 

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