Screening Reactors for Steady Continuous Operation

Various laboratory reactors have been described in the literature [3, 11-13]. The most simple one is the packed bed tubular reactor where an amount of catalyst is held between plugs of quartz wool or wire mesh screens which the reactants pass through, preferably in plug flow . For low conversions this reactor is operated in the differential mode, for high conversions over the catalyst bed in the integral mode. By recirculation of the reactor exit flow one can approach a well mixed reactor system, the continuous flow stirred tank reactor (CSTR). This can be done either externally or internally [11, 12]. Without inlet and outlet feed, this reactor becomes a batch reactor, where the composition changes as a function of time (transient operation), in contrast with the steady state operation of the continuous flow reactors. 

For initial screening, we have operated our micro-catalytic reactor in a pulsed mode. As is shown below (Results Discussion, Figure 2), the catalyst appears to rather quickly achieve steady-state response, after the first few samples of wood (e.g., <100 mg wood per gram of catalyst). This is confirmed by the approximate mass closures (>80 % typically) from summation of all gaseous species evolving from each wood-vapor pulse, plus measured char yields for each pulse, and overall coke yields of 5-10 weight percent (See Table II under Results Discussion). There is some evidence of absorption of water and light aromatics when vapor first contacts the catalyst, so that the reported yields of liquid products are probably conservative. We plan to insert wood dowels in a continuous manner to verify the behavior under steady state of wood addition. 

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