ABSTRACT
I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 601
A. General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 601
B. Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 602
C. Pore Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 603
D. Capillary Condensation in Pores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 605
II. Possible Features and Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 606
III. Mass Transfer in Pellets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 607
A. Approximate Calculations of the Effect of Capillary Condensation . . . . . . . . . 607
B. Transport Phenomena inside Catalyst Particle . . . . . . . . . . . . . . . . . . . . . . . . 610
1. Types of Diffusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 610
2. Diffusion and Flow in Surface Adsorbed and Capillary
Condensed Adsorbate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 610
C. Estimation Using Fick’s Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 611
D. Mass Transfer Calculations Using Dusty Gas Model . . . . . . . . . . . . . . . . . . . 616
IV. Reaction Kinetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 618
V. Transient Regimes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 623
A. Flow Rate Variation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 624
B. Temperature Variation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625
C. Mathematical Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625
VI. Catalyst Deactivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 627
VII. Capillary Condensation in Industrial Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . 631
VIII. Concluding Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 635
Notations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 636
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 637
Solid heterogeneous catalysts are typical finely dispersed systems. Depending on the manufacturing
method, the porous structure of catalyst grain is formed by numerous microparticles or nano-
particles bound together. The diameter of these particles varies from a few nanometers to
hundred nanometer. For example, mixed hydroxide or carbonate catalysts are normally prepared by
precipitation, leading to a final crystallite size of 3-15 nm in the precipitated catalyst [1]. The void
space between particles in the catalyst represents the pore-structure, where active centers such as
metal nanoparticles are located. Such a structure can be random (irregular), which is typical for
most porous catalysts, or well-ordered, that is characteristic for zeolites.
