dispersity otherwise dispersion (rus. дисперсность) — 1) size characteristic of particles distributed in a different phase; generally defined as the ratio of the total surface of all particles to their total volume (weight); 2) in catalysis – characteristic of accessibility of the deposited phase (usually metal) for reagents, defined as the ratio of the number of surface atoms of the deposited particles to the total number of atoms in such particles.

Description

1. Conventionally all dispersion systems are classified into coarse (low) dispersion systems with a particle size of 1 micron and greater and fine (high) dispersion systems with particle sizes below 1 micron. The specific surface is the average dispersity indicator. A more complete representation of dispersity is provided by the volume or mass distribution curve for the dispersed phase by particle size. For porous bodies the term "porosity" is used instead of "dispersion". Dispersity is an important technological indicator in the production and application of various powdered and fine-grained products, such as pigments, plastic fillers, construction materials, pharmaceuticals, food products, etc.

2. One of the most important characteristics of catalysts, showing the effectiveness of the active catalytic phase. Expressed in fractions or percentages. It is a widely used method for determining the dispersity of a deposited phase based on a comparison of the total number of metal atoms in the catalyst with the number of surface atoms determined by the selective chemisorption of molecular probes (H2, O2, CO, etc.).

Author

  • Smirnov Andrey V.

Sources

  1. Disperse systems // Chemical encyclopedia (in Russian). V. 2. — Moscow: Sovetskaja ehnciklopedija, 1990. - 77 p.
  2. Ch. Satterfield. Heterogeneous Catalysis in Practice. — McGraw-Hill Inc. 1980. — 416 pp.

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