Reactor and Setup

To achieve a homogeneous temperature distribution across the library is a challenging problem. Homogeneity is essential due to the temperature dependence of chemical reactions (Arrhenius law). With increasing reactor diameters, temperature gradients increase. Fig. 7.2 (see page 180) shows the temperature distribution 

At a reactor temperature of 300 °C the temperature gradient between reactor centre and edge was about 40 °C and thus not acceptable. Different heat sources had been studied. The best solution proved to be a commercial heating plate used in Ceran top stoves. For libraries of 10 cm diameter a heating plate of 1,2 kW and outer diameter of 17 cm has been used. This heat source heats an air pad, which in turn heats the reactor bottom mounted above the heater (see Fig. 7.9 below). With this setup the temperature gradient has been reduced to 4°C at 300 °C (Fig. 7.3), which was found acceptable for a primary screening technique. 

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