Page 98 - Principles of Catalyst Development
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DESIGN  OF  CATALYSTS                                             85


                                  TARGET        REACTION

                                   STOICHIOMETRIC   ANALYSIS











                                  SURFACE       MECHANISM



                                   REACTION        PATH


                                  CATALYST     PROPERTIES










                               Figure 5.1.  Steps in  the  catalyst design.

            5.2.  EXAMPLE-OXIDATION OF METHANE TO FORMALDEHYDE

                The target reaction is the partial oxidation of methane to formaldehyde:
                              CH 4  + O 2  = CH 20  + H 20
                                 t:..H~,25 = -76.8 kcal mole-I            (5.1)

                                 t:..G~.25 = -70.9 kcal mole-I
           This  reaction  is  exothermic  and  thermodynamically  feasible  with  large
           conversions  possible even  up to  high  temperatures.
                Formaldehyde is now made from CH 4 ,  but through a series of separate
           processes:  steam  reforming,  methanol  synthesis,  and  methanol  oxidation.
           This  complex  process  route  leads  to  low  efficiency  and  high  cost.  Direct
           partial  oxidation to  formaldehyde  is  a  worthy  process objective.  We  need
           a  catalyst with  high activity and selectivity for  reaction  (5.1).
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