Synthesis of metal–organic frameworks (MOFs) and their application in the selective catalytic reduction of NOx with NH3

Abstract

Metal–organic framework (MOF) materials have attracted much attention as catalysts because of their high surface area, controllable pore size and desirable chemical functionalities. Hence, the fields of energy storage, sensing, gas storage, adsorption and catalysis have found substantial applications of MOF composites. Only a few researchers have conducted limited studies on the application of MOFs in the selective catalytic reduction of NO_x with NH₃ (NH₃-SCR). This review article aims to provide accurate information on the application of MOFs and their derivatives in the selective catalytic reduction of NO_x with NH₃. The following areas have been briefly reviewed: (1) the morphology, structure, metal ions, ligands, and pore characteristics of MOFs affect their catalyst performance for the NH₃-SCR, and these can be controlled by adjusting the pH, reaction time, reaction temperature, solvent and metal ion concentration. (2) MOF catalysts show notable SCR performance at low temperatures. The resistance to SO₂ poisoning of bimetallic MOFs is higher than that of single-metal MOFs. The water resistance of MOFs for NH₃-SCR performance can be improved by introducing the appropriate hydrophobic group and layer. (3) In order to overcome the limitations of MOF materials with low thermal stability, it is required to manufacture derivatives that maintain the structure and properties of MOFs. (4) There is an urgent need for research to reveal the difference in the interfacial chemistry process of SCR de-NO_x over ordinary catalysts and MOF materials. We hope this review will help researchers understand more about the research progress of MOFs in the NH₃-SCR process. (5) An in-depth study on the synthesis of MOF derivatives according to the confinement–pyrolysis–oxidation strategy should be conducted to synthesize MOF derivatives with high activity even at high GHSV and open the prospect of the industrial application of MOF materials.