Solvent effects in liquid-phase reactions: I. Activity and selectivity during citral hydrogenation on Pt/SiO2 and evaluation of mass transfer effects

A basic requirement in the analysis of catalytic reactors is a rate expression for the reaction concerned In the design of any equipment the equations to be used contain certain basic physical-chemical coefficients whose values must be known In the case of physical operations, these coefficients can usually be predicted from available correlations and the design of equipment is often carried out from first principles But there is no method available by which the kinetic rate parameters of a chemical reaction can be predicted; thus experimental determination of these parameters is unavoidable

Laboratory catalytic reactors

Catalysts with bidisperse pore structures are extensively used in chemical industries. In such catalysts, diffusion and reaction in the microporous particles are preceded by diffusion in the macropores. The relative significance of macro- and micropore diffusion resistances on the observed reaction rates with linear and nonlinear rate forms, heat effects, catalyst deactivation and selectivity problems in bidisperse catalysts are investigated in number of published works. In this article, a review of the models proposed in the literature is presented together with a critical analysis of assumptions involved. Criteria are presented to test the relative significance of transport limitations. Also, a review of experimental techniques and experimental values of micro- and macropore effective diffusivities of gases in solids with bidisperse pore structures, such as zeolite pellets and supported porous catalysts, is given.

R.R. Hudgins

Papers

A general criterion for absence of diffusion control in an isothermal catalyst pellet