Reactions of halobenzenes with methanol on the microporous solid acids hbeta, HZSM-5, and HSAPO-5: halogenation does not improve the hydrocarbon pool.

The reactions of fluorobenzene, 3-fluorotoluene, and three isomers of difluorotoluene, chlorobenzene, and bromobenzene with excesses of methanol were investigated on the large-pore catalysts HBeta (*BEA) and HSAPO-5 (AFI), and on the medium-pore HZSM-5 (MFI). Flow reactor studies in pulse mode with GC-MS detection revealed that the fluorobenzene derivatives were readily methylated at, for example, 375 degrees C, but not even pentamethylfluorobenzene was obviously active as a reaction center for methanol-to-olefin (MTO) catalysis. Carbon-labeling studies revealed that small amounts of methylbenzenes were formed by defluorination, and these aromatic hydrocarbons seemed to account for the small yields of olefins (and their secondary reaction products) observed.