7.6 Ag
+
-Exchanged Zeolite Catalysts for C–C Bond Formation
in the Conversion of Methane . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
7.6.1 Catalysis of Electrophilic Reactions by H
+
-Exchanged
Zeolites: Role of the Methoxy Species on the Zeolite
Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
7.6.2 Reaction of Surface Methoxy Species with Ethylene
to Produce C 3 H 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
7.7 Unique Properties of Silver Cations in the Zeolite-Based
Catalysis of the Reaction of Methane with Ethylene . . . . . . . . . . . 183
7.7.1 General Properties of Ag
+
-Exchanged Zeolites:
Reversible Reduction of Ag
+ Cations and Generation
of Brønsted Acid Sites . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
7.7.2 Generation of Hydrogen Species Over Ag
+
-Exchanged
Zeolites in the Presence of Hydrogen: Reversible
Heterolytic Dissociation of Hydrogen Molecules . . . . . . . . 186
7.7.3 Cleavage of the C–H Bond of CH 4 Over
Ag
+
-Exchanged Zeolites . . . . . . . . . . . . . . . . . . . . . . . . . . 189
7.7.4
13 C MAS NMR Evidence for the Formation
of Methoxy Species on Ag
+ -Exchanged Zeolites . . . . . . . . 190
7.7.5 Reaction of Methane with Ethylene Over
Ag
+
-Exchanged Zeolites . . . . . . . . . . . . . . . . . . . . . . . . . . 191
7.7.6 Reaction of Methane with Ethylene Over
Metal-Cations-Exchanged Zeolites . . . . . . . . . . . . . . . . . . 197
7.7.7 Differences Among the Catalytic Properties
of Ag
+
-, Zn
2+ -, and H
+
-Exchanged Zeolites
in the Activation of Lower Alkanes Including CH 4 . . . . . . 201
7.8 Summary of the Features of Carbocation-Mediated C–C Bond
Formation in Methane Conversion . . . . . . . . . . . . . . . . . . . . . . . . 215
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
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