Reactor 11 Chemical Processing Microsystem

Micro structured wells (2 mm x 2 mm x 0.2 mm) on the catalyst quartz wafer were manufactured by sandblasting with alumina powder through steel masks [7]. Each well was filled with mg catalyst. This 16 x 16 array of micro reactors was supplied with reagents by a micro fabricated gas distribution wafer, which also acted as a pressure restriction. The products were trapped on an absorbent plate by chemical reaction, condensation or absorption. The absorbent array was removed from the reactor and sprayed with dye solution to obtain a color reaction, which was then used for the detection of active catalysts by a CCD camera. Alternatively, the analysis was also carried out with a scanning mass spectrometer. The above-described reactor configuration was used for the primary screening of the oxidative dehydrogenation of ethane to ethylene, the selective oxidation of ethane to acetic acid, and the selective ammonoxidation of propane to acrylonitrile. 

Ni-Ta-Nb oxide catalysts also show high activity for the conversion of ethane to ethylene in primary screening tests. For further optimization bulk catalysts were prepared to perform secondary screening in an 48-channel fixed-bed reactor at 300 °C (see Table 3.4).The highest selectivity (86%) for ethylene was achieved with an Nio.62Tao.ioNbo.28°x catalyst [7]. 

Promising catalyst mixtures were tested over a 400 h run on-stream. Under the given reaction condition, no significant loss in activity or selectivity was observed 

Catalyst composition Ethane conversion (%) Ethylene selectivity (%) 

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The nitration of aromatic compounds is a fundamental reaction [7] of utmost importance to the chemical industry. Many different regimens for this unit-process are known [8]. Nitrations have been described in microreactors [9-11] and during our own work with microreactors we have also gained experience with nitrations [12]. We have shown that it is possible to generate, in the laboratory, smaller amounts of chemicals using micro reactors, exemplified by the continuous nitration of 8.6 g of N-methoxycarbonyl-l,2,3,4-tetrahydro-isoquinoline over 6 full days. In an unlimited period of time one could produce unlimited amounts of chemicals with a single microsystem. Since this is unrealistic we are not... 

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