Chinese Journal of Applied Chemistry

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Influence of Carbon Chain Length on the Structure-Directing Effect of Ethylenediamine in the Synthesis of Open-Framework Aluminophosphates

CHANG Xiaowen,LU Tingting,WEI Yingzhen,GUO Mingyue,YAN Wenfu(),XU Ruren   

  1. State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry,Jilin University,Changchun 130012,China
  • Received:2018-04-16 Published:2018-09-01
  • Contact: YAN Wenfu
  • Supported by:
    Supported by the National Natural Science Foundation of China(No.21571075, No.21320102001, No.21621001), the National Key Research and Development Program of China(No.2016YFB0701100), the 111 Project(No.B17020), Program for JLU Science and Technology Innovative Research Team

Abstract:

By heating the initial mixture with the molar ratio of n(Al2O3):n(P2O5):n(R):n(H2O)=1:1:1:277(R=ethylenediamine(EDA) or 1,3-propanediamine(1,3-DAP)) at 180 ℃, a highly crystalline three-dimensional anionic open-framework aluminophosphate of AlPO4-12 or UiO-26 was obtained. The crystallization processes of both initial mixtures were investigated by X-ray diffraction analysis(XRD), elemental analysis, and pH measurement. The volume and the Hirshfeld charge on the N atom of the diprotonated EDA and 1,3-DAP were calculated by the “atom volume and surface” module and the Dmol3 module in Materials Studio, respectively. Theoretical calculation shows that the charge on the N atom of diprotonated EDA or 1,3-DAP is 0.073 e and 0.064 e(Hirshfeld), respectively. The corresponding charge density is 1.8573 and 1.3400 e/nm3(Hirshfeld). The corresponding formal charge density is 25.44 and 20.94 e/nm3, respectively. The framework charge density of AlPO4-12 and UiO-26 is -6.1 e/nm3 and -4.6 e/nm3, respectively. These results indicate that the change in the length of carbon-chain connected to the N atom in the amino group can affect the amount of charge and the charge density on it, which accordingly affects its initial structure-directing ability, resulting the crystallization product changed from AlPO4-12 to UiO-26 with a smaller charge density.

Key words: zeolite, aluminophosphate, structure-directing effect, charge, charge density