6.7 Active Species and Reaction Mechanism for the Formation
of Aromatic Hydrocarbons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
6.7.1 Active Mo Species and C–C Bond Formation
to Give C 2 H 6 and C 2 H 4 During the Initial Stage . . . . . . . . 151
6.7.2 Reaction Mechanism and Role of the Catalyst
in the Formation of Benzene from Ethylene . . . . . . . . . . . 153
6.8 Various Attempts to Improve the Production of Aromatic
Hydrocarbons by Mo/H-ZSM-5 . . . . . . . . . . . . . . . . . . . . . . . . . . 154
6.8.1 Promotion of the Catalytic Performance of Mo/H
+ -
Exchanged Zeolite Catalysts Using Various Additives . . . . 154
6.8.2 Suppression of Brønsted Acid Sites on the External
Surface of H
+
-Exchanged Zeolites . . . . . . . . . . . . . . . . . . 155
6.8.3 Effect of the Addition of Small Amounts of CO
and CO 2 to the Methane Feed . . . . . . . . . . . . . . . . . . . . . 156
6.8.4 Effect of the Addition of Small Amounts of O 2 , H 2 ,
and H 2 O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
6.9 Summary of the Catalytic Features of Mo/H
+
-Exchanged
Zeolite Catalysts for MDA Reaction . . . . . . . . . . . . . . . . . . . . . . 157
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
7 C–C Bond Formation via Carbocations in the Methane
Conversion Under Non-oxidative Conditions . . . . . . . . . . . . . . . . . . 165
7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
7.2 Superacid Catalysts for the Activation of CH 4 and Other
Lower Alkanes for C–C Bond Formation . . . . . . . . . . . . . . . . . . . 166
7.2.1 Definition of Brønsted Superacids . . . . . . . . . . . . . . . . . . . 166
7.2.2 Definitions of Carbocations as Key Reaction
Intermediates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
7.2.3 Outline of the Formation of Carbenium Ions . . . . . . . . . . . 168
7.3 Formation of Carbocations in Superacid Solutions . . . . . . . . . . . . 169
7.4 Reaction of Alkanes with Carbenium Ions to Produce
C–C Bonds in Superacid Reaction Systems . . . . . . . . . . . . . . . . . 171
7.4.1 Conversion of Methane into Higher Hydrocarbons
in FSO 3 H–SbF 5 Solution . . . . . . . . . . . . . . . . . . . . . . . . . 173
7.5 Role of Penta-Coordinated Carbonium Ion Intermediates
in C–C Bond Formation in the Reaction of Alkenes
with Alkanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
7.5.1 Application of the Concept of a Penta-Coordinated
Carbonium Ion to Alkane Cracking Reactions Over
H
+
-Exchanged Zeolites . . . . . . . . . . . . . . . . . . . . . . . . . . 176
7.5.2 Reaction of Methane with Ethylene to Produce
Propane Using Superacid Catalysts . . . . . . . . . . . . . . . . . . 177
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