Role of particle geometry and surface contacts in solid-phase reactions

J. Kostogorova, H. J. Viljoen, A. Shteinberg

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

Given the surface areas of three different species A,B, and C, what is the most likely contact area between A and B? This problem finds many applications, but it is of specific importance in solid-phase reactions. Reactions in powder mixtures depend strongly on contact area between reactants, even when one species may melt. The surface of particles is meshed with small "tiles," and a combinatorial problem is formulated to map all tiles onto each other. The number of different contacts of n constituents is (formula presented); if pores are present, they are considered a constituent. The combinatorial problem for n > 3 is computationally overwhelming, but for two or three species, the desirable contacts can be calculated. The model was developed for contact between three different species (two species are included as a special case). This could constitute three different powders at 100% MTD, or a mixture of two powders that includes pores where the latter phase acts as a third species. The combinatorial approach is used to find the discrete probability-distribution function (PDF), viz., p(z, A, B, C), where z is the number of desirable contacts (for example, A\B), given the surface areas (A, B, C). The first moment of the PDF gives the expectancy value Ψ (A\B, A, B, C) for contact between species A and B. The theory was demonstrated by two examples. A simple contact problem is solved for two powders that also contain pores. The second example compares kinetic rates for different shapes and sizes of particles.

Original languageEnglish (US)
Pages (from-to)1794-1803
Number of pages10
JournalAIChE Journal
Volume48
Issue number8
DOIs
StatePublished - Aug 1 2002

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ASJC Scopus subject areas

  • Biotechnology
  • Environmental Engineering
  • Chemical Engineering(all)

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