Solvothermal Metal Metathesis on a Metal?Organic Framework with Constricted Pores and the Study of Gas Separation
作者：Liangjun Li,? Haitao Xue,? Ying Wang,? Pinhui Zhao,? Dandan Zhu,? Min Jiang,? and Xuebo Zhao*,?
關鍵字：Metal Metathesis
論文來源：期刊
具體來源：ACS Appl. Mater. Interfaces 2015, 7, 25402?25412
發(fā)表時間：2015年
Metal?organic frameworks (MOFs) with constricted pores can
increase the adsorbate density of gas and facilitate effective CO2 separation from
flue gas or natural gas due to their enhanced overlapping of potential fields of the
pores. Herein, an MOF with constricted pores, which was formed by narrow
channels and blocks of functional groups, was fabricated from the assembly of a
methyl-functionalized ligand and Zn(II) centers (termed NPC-7-Zn). Structural
analysis of the as-synthesized NPC-7-Zn reveals a series of zigzag pores with pore
diameters of ～0.7 nm, which could be favorable for CO2 traps. For reinforcing the
framework stability, a solvothermal metal metathesis on the pristine MOF NPC-
7-Zn was performed, and a new Cu(II) MOF (termed NPC-7-Cu) with an
identical framework was produced. The influence of the reaction temperatures on
the metal metathesis process was investigated. The results show that the
constricted pores in NPC-7-Zn can induce kinetic issues that largely slow the
metal metathesis process at room temperature. However, this kinetic issue can be
solved by applying higher reaction temperatures. The modified MOF NPC-7-Cu exhibits significant improvements in framework
stability and thus leads to a permanent porosity for this framework. The constricted pore structure enables enhanced potential
fields for these pores, rendering this MOF with high adsorbate densities for CO2 and high adsorption selectivity for a CO2/N2
gas mixture. The adsorption kinetic studies reveal that CH4 has a faster diffusion rate constant than CO2, showing a surface
diffusion controlled mechanism for CO2 and CH4 adsorption.