Dong Mei, Wang Guofu, Qin Zhangfeng, Wang Jianguo, Liu Tao, Yuan Shuping, Jiao Haijun
State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, Shanxi 030001, P. R. China.
J Phys Chem A. 2007 Mar 1;111(8):1515-22. doi: 10.1021/jp066408l. Epub 2007 Feb 2.
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.
在结晶开始时，通过原位同步辐射X射线吸收光谱（XAS）和密度泛函理论（DFT）计算研究了Mn2+和Co2+掺入磷酸铝分子筛AlPO4-5骨架的过程。结果表明，MnAPO-5和CoAPO-5的合成在金属离子掺入机制上有所不同。对于CoAPO-5的合成，随着晶体形成，Co2+从八面体结构转变为四面体结构，而对于MnAPO-5，Mn2+向四面体结构的转变要困难得多，并且发生在长程有序微孔结构出现之后。合成过程中涉及的模型中间体的DFT计算表明，[Mn(OP(OH)3)4]2+比[Co(OP(OH)3)4]2+具有更高的转变能，这是掺入行为多样性的原因。
