Methylation of cyclopentadiene on solid base catalysts with different surface acid-base properties

The methylation of cyclopentadiene with methanol has been studied over Al₂O₃ and KOH promoted MgO and unpromoted MgO. The dehydrogenation of methanol to formaldehyde was found to be a key-step in the generation of the active methylating species on these solid bases. The modification with Al₂O₃ or KOH favors the formation of methylcyclopentadienes and elevates the activity of MgO based on different reasons: introduction of acidic sites for Al₂O₃/MgO and superbasic effect for KOH/MgO. These catalysts present different deactivation behaviors due to the different surface acid-base properties. The heavy coking of cyclopentadiene on basic sites is responsible for the rapid deactivation of KOH/MgO along the catalytic test at 773 K. However, the coking can be well suppressed at 723 K, and KOH/MgO exhibits the catalytic performance apparently superior to MgO and Al₂O₃/MgO.