Slurry reactor industrial reactions with large

To produce a highly selective catalyst it is necessary to prepare the catalyst as a fine powder or to prepare a catalyst in which only the outer surface contains active sites. The decrease in size will cause problems with an RD column as reactor. Fine powders can only be handled in a slurry reactor, but this is not advantageous because we have a reaction that is equilibrium limited. For such a reaction a distillation column is superior. So the catalyst particles should be large enough to give a low pressure drop. The preparation of a shell catalyst will result in high selectivity but also in low activity because the outer surface of suitable catalyst particles is too low to make this concept attractive for an industrial application. 

The stirred tank with a jacket for heating or cooling (also called autoclave or digester) is the workhorse of the pharmaceutical, fine-chemicals, mineral and paper industries. It is used as a reactor, mixer, decanter, heater and cooler. The bubble and slurry-bubble columns too are akin to the STR. It is used as a batch reactor or semi- or fed-batch reactor for those reactions requiring a large residence time, as the tubular reactor would be too long and unwieldy. The STR is bulky, and the yield and selectivity could be low. 

The catalyst particle sizes and shapes (Figure 5.1) vary considerably depending on the reactor applications. In fixed beds, the particle size varies roughly between 1 mm and 1 cm, whereas for liquid-phase processes with suspended catalyst particles (slurry), finely dispersed particles (<100 xm) are used. Heterogeneous catalysis in catalytic reactors implies an interplay of chemical kinetics, thermodynamics, mass and heat transfer, and fluid dynamics. Laboratory experiments can often be carried out under conditions in which mass and heat transfer effects are suppressed. This is not typically the case with industrial catalysis. Thus, a large part of the discussion here is devoted to reaction-diffusion interaction in catalytic reactors. 

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