Applying microreactor technology in chemical product research and process development

The particular features of microreactors, such as the large driving forces for heat and mass transport and the high surface-area-to-volume ratio, stimulate the use of these devices as new tools in chemical product research and process development. For example, microreactors are well suited for rapid screening of materials and catalysts, for measuring intrinsic reaction kinetics, and for discovering new process chemistries. An additional advantage is that micro structured chemical systems may be easily integrated with dedicated instrumentation, sensors and actuators, in small bench top units, requiring less fume hood space and fewer utilities. Nowadays microreactor systems are also more and more combined with modern measurement technologies for real-time analysis of the system's performance and of the chemistry conducted in these reactors. Scale-up to production levels by replication of microreactor units used in the laboratory could subsequently eliminate costly redesign and pilot plant experiments, thereby shortening the development time from laboratory to commercial production. At present three areas of measurement needs can be identified: (1) the characterization of the microreactor itself in terms of its performance characteristics (e.g., flow distribution, temperature distribution), (2) the characterization of the chemistry being conducted in the microreactor (conversion, selectivity, product yield), and (3) the characterization of banks of microreactors which would be found in commercial production. In the lecture, various examples will be given of the characterization of the performance of microreactors as well as determining the kinetics and mechanism of various exothermic reactions (e.g., ammonia oxidation, preferential CO oxidation, ethane ammoxidation). Important issues will be covered such as flow distribution, isothermal operation, product gas sampling, etc. The characterization of different types of microreactors will be discussed, such as microchannel reactors and parallel-plate microreactors. It is demonstrated that real-time analysis in well characterized microreactor systems leads to better understanding of the chemistry which ultimately will lead to more efficient chemicals production.