Influence of ceria existence form on deactivation behavior of Cu-Ce/SBA-15 catalysts for methanol steam reforming

Abstract

Methanol steam reforming (MSR) is promising in hydrogen production. Cu-SBA-15 and Cu–Ce/SBA-15-I suffer poor selectivity owing to sluggish steam activation on Cu0-SBA-15. And small Cu0 tend to sinter due to Ostwald ripening. Sintering can be avoided by modifying SBA-15 with Ce ion exchange, where Si–OH groups are replaced by Si–O–Ce. Ceria existence form varies from patches to small particles as exchange times increase. In Cu–Ce/SBA-15, ceria patches strongly interact with Cu, which promotes steam activation, hence the catalyst exhibit remarkable activity and selectivity. In Cu–3Ce/SBA-15, ceria patches grow into small ceria particles (<5 nm) after repeated ion exchange. Ceria particles tend to be over-reduced, thus accounting for carbonaceous deposits on excessive Ce3+. Such deactivation is reversible, and catalytic performance can resume after air exposure. This study reveals that deactivation behavior of MSR catalysts can be modified by existence and size effect of ceria, which is worth referring to in further MSR catalyst synthesis.