Industrial microreactor process reactions

Using a microreactor and a feed comprising also palladium acetate and sulfuric acid, the reaction time was shortened to 10 min at 70 °C as compared to the industrial semibatch process (see Figure 11.24) [71]. However, the selectivity was lower. This could be solved by process modification using peracetic acid, generated in situ from acetic acid and hydrogen peroxide. 

To study the coke formation during ultrapyrolysis of heavy oils, a Model 240 Elemental Analyzer has been employed to analyze the carbon deposited onto the ferromagnetic wire and/or the glass microreactor walls. The influence of temperature and total reaction times on the amount of carbon formed have been studied. The experimental results confirmed that the coke yield increases sharply with temperature and reaction time. However, at the upper boundary of the ultrapyrolytic regime, a maximum coke yield of 17 wt% has been observed at 1000°C with a total reaction time of 1 second. For the same total reaction time, coke yields of 10 wt% and 6.5 wt% have been measured at 900 and 800°C, respectively, sharply decreasing from those values with a decrease in reaction time. Compared to the above values, industrial pyrolysis processes produce very high yields of undesirable coke. 

Jahnisch, K., Ehrich, H., Linke, D., Baerns, M., Hessel, V, Morgen-scHWEis, K., Selective gas/liquid-reactions in microreactors, in Proceedings of tfie Inten. Conference on Process Intensification for tfie Cfiemical Industry (13-15 October 2002), Maastricht, The Netherlands. 

The device consisted of a 75 -pm thick polyimide foil containing microstructured slits (250 pm wide and 45 mm long) sandwiched between the working and counter electrodes (Scheme 4.34). The reaction took place inside the microchannels that were in contact with both electrodes. To maintain a constant reaction temperature, a heat exchanger block was also mounted above the working electrode. This microreactor-based electrolysis afforded 98% product selectivity, which was higher than that for common industrial processes (about 85%). 

Most industrial processes using the interaction of fluids to obtain chemical changes can be classified into one, or sometimes more of the preceding five liquid reactor types. Variations on these themes are used for gas-gas, gas-liquid, or gas-solid reactions, but these variations parallel many of the processing ideas used for liquid-liquid reactors [20]. A new continuous, spinning disk reactor concept has recently attracted interest for some intrinsically fast organic reactions and for possible application in crystallizations [21]. Modular microreactors have also become of interest to fine chemicals producers and pharmaceutical companies for their faster reactions, ease of scale-up, and low cost [22]. 

In Chapter 9, we mentioned that the use of microreactors leads to a significant improvement in the control of the molecular-weight distribution in free radical polymerization by virtue of superior heat-transfer efficiency.Free-radical polymerization reactions are usually highly exothermic, so precise temperature control is essential to carry out these reactions in a highly controlled manner. Thus, from an industrial viewpoint, a major concern with free-radical polymerization is the controllability of the reaction temperature. Temperature control often arises as a serious problem during the scale-up of a bench process to industrial production. In this section, we will discuss the numbering-up of microreactors to increase production volumes in radical polymerization in industry. 

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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