Physical Parameter Screening Reactor

The majority of studies have concentrated on the screening of chemical properties. Screening of physical parameters such as the condensation behavior of a liquid 

With the introduction of micro reactors, transient reactor operations also became of interest for production owing to their low internal reactor volume and thus fast dynamic behavior. In 1999, liauw et al. presented a periodically changing flow to prevent coke development on the catalyst and to remove inhibitory reactants in a micro channel reactor [88], This work was preceded in 1997 by Emig and Seiler, of the same group, who presented a fixed-bed reactor with periodically reversed flow [89]. In 2001, Rouge et al. [27] reported the catalytic dehydration of isopropanol in a micro reactor. 

Despite recent promising strategies, the principle of micro process engineering is still not widely used in combinatorial catalysis. One drawback certainly is the increasing distance to industrial applications with decreasing dimensions. On the other hand, the small structures possess laminar flow conditions, which are fully 

Screening in the stationary mode will only give information about the activity of a single catalyst or a catalyst mixture. When a proper catalyst for a certain reaction is found, the next important information is the reaction kinetics. To obtain this information, a number of methods and reactors are recommended in the recent literature [10, 91, 96-101], Most of them apply transient reactor operations to find detailed kinetic information. Micro reactors are particularly suited for such an operation since their low internal reaction volumes permit a fast response to process parameter changes, for example, concentration or temperature changes. This feature has been applied by some authors to increase the product yield in micro reactors [34, 98, 102], 

Micro reactors operated in the pulsed mode were introduced by Kokes et al. in 1955 [91], but have been intensively used only in the last 10 years. Such transient studies to obtain insight into reaction mechanisms were undertaken by Cleaves et al. with the temporal analysis of products (TAP) reactor 1997 [100], They observed rate coefficients of elementary reaction steps such as adsorption and desorption by applying pulses of reactants to a catalytic micro reactor combined with a quadrupole mass spectrometer. 

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As noted in the introduction, a major aim of the current research is the development of "black-box" automated reactors that can produce particles with desired physicochemical properties on demand and without any user intervention. In operation, an ideal reactor would behave in the manner of Figure 12. The user would first specify the required particle properties. The reactor would then evaluate multiple reaction conditions until it eventually identified an appropriate set of reaction conditions that yield particles with the specified properties, and it would then continue to produce particles with exactly these properties until instructed to stop. There are three essential parts to any automated system—(1) physical machinery to perform the process at hand, (2) online detectors for monitoring the output of the process, and (3) decision-making software that repeatedly updates the process parameters until a product with the desired properties is obtained. The effectiveness of the automation procedure is critically dependent on the performance of these three subsystems, each of which must satisfy a number of key criteria the machinery should provide precise reproducible control of the physical process and should carry out the individual process steps as rapidly as possible to enable fast screening the online detectors should provide real-time low-noise information about the end product and the decision-making software should search for the optimal conditions in a way that is both parsimonious in terms of experimental measurements (in order to ensure a fast time-to-solution) and tolerant of noise in the experimental system. 

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