Dehydration of 1,4-butanediol over rare earth oxides Original Research Article

Vapor-phase catalytic dehydration of 1,4-butanediol was investigated over rare earth oxides (REOs) calcined at different temperatures. In the dehydration of 1,4-butanediol over REOs, 3-buten-1-ol was mainly produced, together with tetrahydrofuran (THF). Weakly basic heavy REOs, such as Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, Lu2O3, and Y2O3, showed high selectivity to 3-buten-1-ol, while strongly basic light REOs, such as La2O3, Pr6O11, Nd2O3, Sm2O3, and Eu2O3, produced more THF and γ-butyrolactone. Heavy REOs exhibited different catalytic activities in the dehydration of 1,4-butanediol depending on their crystal structures. Cubic C-type REOs selectively produced 3-buten-1-ol; in particular, cubic Er2O3, Yb2O3, and Lu2O3 showed the highest formation rates of 3-buten-1-ol. Since the formation rate of 3-buten-1-ol was suppressed over Er2O3 in acidic CO2 or basic NH3 carrier gas flow, it is probable that the active centers for the formation of 3-buten-1-ol are composed of both basic and acidic sites.