Extension to complex reactions

We considered in Chapter 2 the mathematical treatment of complex reactions. It was also shown how some simpler reaction schemes like parallel, series, and parallel-series reactions are amenable to analytical solution. We consider in the present section the role of pore diffusion in these complex reactions. We omit the mathematical details and present in Table 6.5 the salient features of the effect of pore structure, that is, monomodal or bimodal distribution, on yield and conversion in a few selected types of complex reactions. Product R (bolded in the table) is considered to be the desired product. 

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The equations and plots presented in the foregoing sections largely pertain to the diffusion of a single component followed by reaction. There are several other situations of industrial importance on which considerable information is available. They include biomolecular reactions in which the diffusion-reaction problem must be extended to two molecular species, reactions in the liquid phase, reactions in zeolites, reactions in immobilized catalysts, and extension to complex reactions (see Aris, 1975 Doraiswamy, 2001). Several factors influence the effectiveness factor, such as pore shape and constriction, particle size distribution, micro-macro pore structure, flow regime (bulk or Knudsen), transverse diffusion, gross external surface area of catalyst (as distinct from the total pore area), and volume change upon reaction. Table 11.8 lists the major effects of all these situations and factors. 

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