Unusual catalytic behavior of β-Bi 2Mo 2O 9 in the oxidative dehydrogenation of n-butene to 1,3-butadiene

Abstract

A β-Bi 2Mo 2O 9 catalyst was prepared by a co-precipitation method and applied to the oxidative dehydrogenation of n-butene to 1,3-butadine. It was found that the β-Bi 2Mo 2O 9 catalyst retained lower oxygen mobility than γ-Bi 2MoO 6. It was also revealed that the β-Bi 2Mo 2O 9 was thermally unstable and decomposed into α-Bi 2Mo 3O 12 and γ-Bi 2MoO 6 at a reaction temperature of 420 °C. However, the β-Bi 2Mo 2O 9 showed a higher catalytic performance than the α-Bi 2Mo 3O 12 and γ-Bi 2MoO 6 catalysts in the oxidative dehydrogenation of n-butene, in spite of its thermal instability and low oxygen mobility. Moreover, the β-Bi 2Mo 2O 9 showed a stable catalytic performance with time on stream without catalyst deactivation. The high and stable catalytic performance of β-Bi 2Mo 2O 9 can be attributed to the synergy effect of α-Bi 2Mo 3O 12 and γ-Bi 2MoO 6 formed via the decomposition of β-Bi 2Mo 2O 9 during the catalytic reaction, to the high intrinsic catalytic activity of β-Bi 2Mo 2O 9, and to the well-crystallized parts of β-Bi 2Mo 2O 9.