Liquid-phase reactants monolithic catalysts

Processes with liquid-phase reactants dominate in a large part of the chemical industry, in particular in fine chemicals manufacture. A good example of fhe applicafion of acidic cafalysts in fine chemistry is work done by Beers et al. (179,180,200). They prepared (3-zeolite-containing monolithic catalysts and evaluated them in an acylation reaction. The dipcoating technique gave satisfactory results, in particular for silica monoliths. 

When a very high degree of conversion of a liquid phase reactant is desired, and the catalyst has a high selectivity, one of the varieties of the three phase packed bed will generally be preferable. When the conversion in the liquid and in the gas have to be high, the two-phase monolith (parallel passage reactor) can be considered. 

The various aspects that are to be considered to achieve a proper and efficient catalyst testing approach are presented. This applies to heterogeneous systems in which the catalyst is the solid phase and the reactants are in the gaseous and/or the liquid phase. The presence of a solid phase introduces complicating phenomena on which this chapter focuses. In this respect, homogeneous catalysis is a limiting case and does not need separate treatment. The solid catalyst can be present as either a packed bed of particles, a wash-coated monolith, a fluid bed, an entrained bed, or in a liquid-phase slurry. 

There are many different reactor designs but the two most commonly used are fixed bed and batch slurry phase. For a fixed bed reactor a given volume of solid particulate or monolith supported catalyst is fixed in a heated tube located within a furnace and liquid and/or gaseous reactants flow through the bed. This type of process is commonly used for large continuous-volume production where the reactor is dedicated to making only one product such as a bulk chemical or petroleum product. 

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