Titer-plate reactor

S Reactor 22 [R 22] The Microstructured Titer Plate Reactor Concept... 

Miniaturization and parallelization key approaches for drug development apparatus for combinatorial chemistry UHTS 1536 titer-plate format modular construction of apparatus applications of UHTS fine-chemical synthesis by micro reactors numbering-up nature as model general advantages of micro flow vision of plants-on-a-desk [233]. 

Implementation of the above screening principle requires three main parts a thermosensitive IR camera capable of recording heat emissions of the catalysts contained in the reactor system, the reactor itself as central part and an xyz-posi-tionable sampling capillary, connected to the second analytical tool (MS or GC, etc.) (Fig. 2.4). To simplify matters, a reactor with a 4x4 matrix of reaction channels is illustrated here, the actual reactor formats used at hte Aktiengesellschaft are 96- and 192-fold reactor systems based on the 8xl2-MTP (micro-titer plate) matrix. 

Sample integrations similar to pharmaceutical approaches were already examined in 1997 [39]. Here, a chip-like microsystem was integrated into a laboratory automaton that was equipped with a miniaturized micro-titer plate. Microstructures were introduced later [40] for catalytic gas-phase reactions. The authors also demonstrated [41] the rapid screening of reaction conditions on a chip-like reactor for two immiscible liquids on a silicon wafer (Fig. 4.8). Process conditions, like residence time and temperature profile, were adjustable. A third reactant could be added to enable a two-step reaction as well as a heat transfer fluid which was used as a mean to quench the products. 

The parallel reactor for the screening of the titer-plates consists of several modules, each of them is responsible for just a single operation (Fig. 4.12). The gas flow for example is preheated and evenly distributed within the distribution module and delivered to the wells on the titer-plate. The latter is clamped between the distribution module and the insulation module and also treated as a separate reaction module. The insulation module separates the heated section of the parallel reactor from the unheated section and is further cooled by the heat exchanger module on top of it. The last module, just above the heat exchanger module, is a multi-port valve that delivers the product gas to the gas-chromatograph. 

Fig. 4.12 Modular concept of the steady reactor configuration with a 48-fold titer-plate [37, 38].

After coating, the titer-plates are inserted into the reactor to test their activity. The reaction conditions were held constant in the following experiments. The reactor was heated to 475 °C and held at a pressure of 0.2 bar (g). The heat exchanger was operated at 50 °C, and the throughput for a single well was adjusted to 1 ml min-1, resulting in a total space velocity of 9000 h 1. The residence time in the wells was 0.4 s. 

Catalysts prepared by the wash-coating method were first used to check the reproduction of the measured values. For this reason, six elementary metal salts (platinum, zirconium, molybdenum, nickel, silver, and rhodium) were dissolved and impregnated onto a titer-plate. The catalysts were pre-reduced inside the reactor with 5% hydrogen in 95% nitrogen at 250 °C. The results were recorded first before the pre-reduction and then after the pre-reduction. The repeated measurements indicated good reproducibility in both cases. The conversion of methane with the rhodium catalyst is better after the pre-reduction. Methane conversion after 18 h runtime was still stable. 

Reactor 23 [R 23] Microstructured Titer Plate Transient Reactor Concept... 

Chemical activities in the field of mass screening are often related to combinatorial chemistry [51,52]. One major goal, especially in the field of solid phase chemistry involving polymers like DNA or peptides, aims at the increase in the number of compounds per reactor volume and time. Commercially available microtiter plates are established as reactors in this case whereby robotic feed systems fit perfectly to their dimensions. A drastic reduction of reaction volume and increase in number of reaction vessels ( wells ) leads to the so-called nanotiter plates (e.g. with 3456 wells). Microfabrication methods such as the LIGA process are ideal means for the cost effective fabrication of nano-titer plates in polymeric materials by embossing or injection molding techniques so that inexpensive one-way tools are realized. 

Another reactor for fast catalyst testing is a modular microstructured device with up to 10 catalysts applied on titer plates. An advantage of this reactor is the composition of various modules such as flow distribution, reaction heat exchange and gas sampling, which can be interconnected in different ways. The reactor can be operated at maximum pressure and temperature of 30 bar and 600 °C in the reaction module, and flow rates up to 10 mL min are possible. Catalyst deposition can be carried out very rapidly by a sputtering method or by washcoating, which has already been tested for the oxidation of methane [107, 108]. 

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