Page 88 - Principles of Catalyst Development
P. 88

CATALYTIC  MATERIALS                                              7S
                                   TABLE 4.10.  Reactions
                                   Catalyzed by  Solid Acids

                                  Cracking of C-C bonds
                                  Alkyl  group isomerization
                                  Double bond isomerization
                                  Dealkylation
                                  Dehydroxylation
                                  Dehydrogenation
                                  Polymerization
                                  Oligomization
                                  Cyclization
                                  Alkylation
                                  "Coke" formation



           excluded. Also called "molecular sieves," zeolites possess the ability to be
           shape and size selective in catalytic molecular rearrangements. (133)
               Second,  ions  within  the  cavities  are  easily  exchanged  with  a  large
           number of altervalent ions. These ions exert large electrostatic or polarizing
           forces across the small dimensions of the cavity. Electron distribution shifts
           in acidic hydroxyl groups may be tailored to give acidities  10 times larger
                                                                  4
           than in  SiO r AI 20 3 •  They are  indeed "super acids.,,(134)


                          (')
                           I
                           0
                           )(
                           >-
                           I-
                           >   2
                           i=
                           ()
                           oc(
                           z
                           0
                           l-
                           e:(
                           ....J
                           >-
                           :x::
                           ....J
                           oc(
                           W
                           Cl
                           W
                           Z
                           w
                          :2
                           ;:)
                          ()         0.1    0.2    0.3    0.4
                                    ACID  AMOUNT,  m  mole g-1
                           Figure 4.20.  Activity  patterns for  acid solids. 1t291
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