Page 57 - Principles of Catalyst Development
P. 57

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
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