Proton Transfer to Substrate Molecules within Zeolite Cavities

Proton Transfer to Substrate Molecules within Zeolite Cavities 

It is assumed that, after adsorption into the zeolite, the initial activation of substrate molecules for further conversion is by proton transfer from the zeolite. 

Inspired by the chemistry in superacidic media, it has been speculated that zeolites may be superacids and able to protonate even saturated hydrocarbon molecules to yield carbonium ions as a first step in catalytic cracking. Later, doubts have been raised as to whether carbenium ions obtained by protonation of unsatu- 

There may also be additional deactivation channels for protonated species, for example carbenium ions can attach via C-O bonds to the zeolite framework and form alkoxides, as shown in Fig. 22.1 for isobutene. 

Whether or not the neutral adsorption complex or the ion-pair structure is more stable depends on the energy of the proton transfer reaction, ATp,  

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