title: A comparative investigation of Co2+ and Mn2+ incorporation into aluminophosphates by in situ XAS and DFT computation.
abstract: The incorporation processes of Mn2+ and Co2+ into the framework of aluminophosphate molecular sieve AlPO4-5, at the onset of crystallization, were investigated by in situ synchrotron X-ray absorption spectroscopy (XAS) and density functional theory (DFT) computation. The results indicated that the syntheses of MnAPO-5 and CoAPO-5 were different in the incorporation mechanism of metal ions. For the synthesis of CoAPO-5, Co2+ transferred from an octahedral into tetrahedral structure with crystal formation, while, for MnAPO-5, the Mn2+ transition to the tetrahedral structure was much more difficult and it occurred after the appearance of long-range ordered microporous structure. The DFT computations of model intermediates involved in the synthesis process suggested that much higher transformation energy of [Mn(OP(OH)3)4]2+ than that of [Co(OP(OH)3)4]2+ was responsible for the diversity of the incorporation behaviors.
authors.affiliation: State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, Shanxi 030001, P. R. China.
authors.forename: Mei
authors.initials: M
authors.lastname: Dong
authors.forename: Guofu
authors.initials: G
authors.lastname: Wang
authors.forename: Zhangfeng
authors.initials: Z
authors.lastname: Qin
authors.forename: Jianguo
authors.initials: J
authors.lastname: Wang
authors.forename: Tao
authors.initials: T
authors.lastname: Liu
authors.forename: Shuping
authors.initials: S
authors.lastname: Yuan
authors.forename: Haijun
authors.initials: H
authors.lastname: Jiao