Page 57 - Principles of Catalyst Development
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44 CHAPTER 3
diffusional resistance requires changes in pore structure and particle formu-
lation. The methods for diffusional diagnosis given in Chapter 1 should be
used here, even if only limited data on comparable processes are available.
Equally important are problems in particle formulation. Particle shape,
size, strength, and stability must be considered. Often these features coexist
with chemical and diffusional difficuIties. t )4J
These first two steps require the talents of process engineers. Knowledge
of process design, reaction engineering, and economics is invaluable for
proper diagnosis and analysis. (79.KO.~1 J
3.4. CAT AL YST RESEARCH
In some cases, the problems and objectives are so obvious that the
path leads directly to catalyst design, for example, decreasing particle size
for higher conversion or modifying formulation for extra strength. However,
most situations divert to some extent into an area of research.
Catalysis research is a vast arena, utilizing specialties of many disci-
plines, from surface physicists and theoretical chemists on the one hand to
chemical engineers on the other. (82) Innovative and outstanding work is
being done at academic and industrial laboratories all over the world.
High-technology computers and equipment enable us to calculate and
observe the behavior of real molecules on well-characterized ideal sur-
faces.(8)) Preparation of powders is precisely controlled, properties exactly
measured, and kinetic experiments carried out with hitherto unknown
confidence. Modeling of catalyst particles and beds has reached a stage
where complex reaction schemes and deactivation regimes are handled with
ease.(84) The catalysis literature, documented in Appendix 1, has exploded
with an influx of books and articles, attesting to the high level of research
in progress.
The catalyst designer, seeking solutions to his problems, should not
overlook any source of information. Not only the open literature but also
patents and reports of experimental programs should be searched for
relevant data. This may be enough to proceed with catalyst design, in which
case the effort is justified. If nothing more, gaps in the literature indicate
experimental research worth doing.
For designing and developing catalysts, the focal point of aJl research,
the pay-off, is correlation between catalyst properties on the one hand and
mechanisms on the other. Choice of the active components, type of support
and promotion, method of preparation, pretreatment, and formulation must
be related to mechanism, kinetics, adsorption, or mass transfer. Often data
are incomplete or speculative. Correlations may be empirical but prove