Pellet partially wetted catalyst

Most common in practice is a trickling flow that occurs at relatively low gas and liquid flow rates. Under these conditions in trickle-bed reactors (TBRs) complete liquid films around the particles would break up into partial films, rivulets and droplets and a so-called partial wetting trickling regime exist. It is easier for hydrogen to enter the no wetted or very thin wetted part of partially wetted catalyst pellets because the mass-transfer resistance between a gas and the particle sur-... 

The purpose of this paper is to summarize previous interpretations of the effect of incomplete catalyst wetting on trickle-bed performance and to develop a model for the effectiveness factor for partially wetted catalyst pellets. In the case of a reaction... 

Recently (21) another approximate model for the catalysts effectiveness factor in trickle bed reactor has been proposed. In this model the effectiveness factor for a partially wetted catalyst pellet in a trickle-bed reactor for a reaction occurring only in the liquid filled pore region of the pellet is defined by ... 

FA Hessari, SK Bhatia. Reaction rate hysterisis in a single partially internally wetted catalyst pellet Experiment and modelling. Chem Eng Sci 51 1241-1256,1996. 

The tubular multiphase hollow membrane wall reactor briefly described before and sketched in Figure 24.1 h is a multiphase reactor design very similar to the trickle-bed reactor. In a regular trickle-bed reactor, the liquid flows over a partially wetted pellet as a thin film and supplies the liquid-phase reactant to the catalyst pores. This action, however, has the effect of hindering pore access to... 

Incomplete wetting of the catalyst causes a non-uniform reactant concentration on its surface. Sometimes the pellet may not be only externally but also partially wetted internally as a result of unsatisfactory liquid distribution and of liquid evaporation due to heat of reaction. 

Catalyst effectiveness factor in trickle-bed reactors is a function of the Thiele modulus, (fix, incomplete external wetting, ncE> fractional pore fill-up, nj[. Exact formulas for representation of the effectiveness factor in partially internally and externally wetted pellets can be derived only if the geometry of the wetted region and its boundary is known. In this paper a solution is derived for the case of total internal and partial external wetting. This seems to be the case in a number of trickle-bed reactors. 

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