An extension of the general criterion for importance of pore diffusion with chemical reactions

✍ Scribed by K.B. Bischoff

• Publisher: Elsevier Science
• Year: 1967
• Tongue: English
• Weight: 439 KB
• Volume: 22
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(67)80035-6

✦ Synopsis

The genera1 criterion for the importante of pore diffusion with reaction in porous solids as developed by Weisz and Prater is one of the most useful practical results of the effectiveness factor concept. This criterion uses only observable quantities and so can often be easily estimated. However, it was developed for only tïrst order reactions and does not give proper results for other reaction types. Using recent work on generalized effectiveness factors, the criterion is here extended to include any reaction rate form.

ONE OF the most useful aspects of the effectiveness factor concept for reaction in porous solids is its use to defìne conditions such that pore diffusion is net important. For practical applications, particularly in development work, the exact details of any diifusion limitations are usually not desired beyond this assurance. WEISZ and PRATER [l] developed a criterion for this purpose such that the (usually unknown) reaction rate constant need not be used and only observable quantities were required. Their derivation, however, was for fitst order reactions only and PETERSEN [2] has recently pointed out that for other cases, particularly adsorption mechanisms, the details can be rather drastically different.