Modulating the Acidic and Basic Site Concentration of Metal‐Organic Framework Derivatives to Promote the Carbon Dioxide Epoxidation Reaction
Jinhua Ji, Hao Liu, Zewei Chen, Yajun Fu, Weijun Yang, Shuang‐Feng Yin
Abstract
Abstract Metal‐organic framework (MOF) is an ideal precursor/template for porous carbon, and its active components are uniformly doped, which can be used in energy storage and catalytic conversion fields. Metal‐organic framework PCN‐224 with carboxylporphyrin as the ligand was synthesized, and then Zn 2+ and Co 2+ ions were coordinated in the center of the porphyrin ring by post‐modification. Here, PCN‐224−ZnCo with different ratios of bimetallic Zn 2+ /Co 2+ ions were used as the precursor, and the metal‐nitrogen‐carbon(M−N−C) material of PCN‐224−ZnCo‐950 was obtained by pyrolyzing the precursor at 950 °C in Ar. Because Zn is easy to volatilize at 950 °C, the formed M−N−C materials can reflect different Co contents and different basic site concentrations. The formed material still maintains the original basic framework. With the increase of Zn 2+ /Co 2+ ratio in precursor, the concentration of N‐containing alkaline sites in pyrolysis products gradually increase. Compared with the precursor, PCN‐224−ZnCo 1 ‐950 with Zn 2+ /Co 2+ =1 : 1 has greatly improved basicity and suitable acidic/ alkaline site concentration. It can be efficiently used to carbon dioxide absorption and catalyze the cycloaddition of CO 2 with epoxide. More importantly, the current method of adjusting the acidic/basic sites in M−N−C materials through volatilization of volatile metals can provide an effective strategy for adjusting the catalysis of MOF derivatives with porphyrin structure.