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Reaction rates in fractal vs. uniform catalysts with linear and nonlinear kinetics
Author(s) -
Gavrilov C.,
Sheintuch M.
Publication year - 1997
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690430706
Subject(s) - fractal , porosity , kinetics , sierpinski triangle , knudsen diffusion , catalysis , branching (polymer chemistry) , diffusion , thermodynamics , materials science , knudsen number , chemistry , chemical engineering , chemical physics , composite material , mathematics , physics , mathematical analysis , organic chemistry , classical mechanics , engineering
Pore fractal objects are expected to be optimal catalysts, since material is supplied to the narrower pores, which are also shorter through the larger pores where diffusion resistance is smaller. To demonstrate this, diffusion and reaction were simulated on Sierpinski‐gasket‐type fractal objects and on the corresponding nonfractal uniform‐pore structures of the same size, porosity and reactive area. Positive order reactions limited by Knudsen diffusion were shown to exhibit larger rates in fractal than in uniform‐pore objects. Fractal catalysts also exhibited a new intermediate domain in which the rate depends only weakly on the kinetics parameters. In nonmonotomic kinetics the branching point (bifurcation point) was extremely sensitive to the pore structure.