Synthesis Of MOFs And Their Low-temperature NH₃-SCR DeNO_x Performance

Nitrogen oxides emitted from fuel burning are the main factors of air pollutions such as acid rain and photochemical smog.Denitration of fuel, low NOx combustion and flue gas denitration are three main NOx control technologies. Selective catalytic reduction (SCR) technology has been used extensively in flue gas denitration fields because it possesses advantages such as high efficiency and no secondary pollution. In fact, catalyst is the most important factor of SCR denitration efficiency. as existing catalysts still have disadvantages such as low efficiency of low-temperature SCR, poor water resistance or sulfur resistance, and toxic component, development of a stable, non-toxic, and high low-temperature efficiency catalysis is a pressing matter of the moment.Because of their great specific surface area, strong adsorption capacity, long range ordered pore structure, and controllable topological structure, MOFs materials have been widely investigated in many research fields. Some MOFs possess exposed metal active sites or can display such exposed metal active sites after simple treatment. Therefore, they have potential catalytic properties.In view of the above premise, this paper took MOFs as SCR catalyst for low-temperature SCR processes. The main contents about the synthesis, characterization and mechanism results were as follows:(1) Octahedral, uniform size Cu-BTC crystal was synthesized by solvothermal method. The samples were characterized by a series of characterization techniques. The morphology, structure and main components of the impurity produced in the process of prepared Cu-BTC samples were studied by XPS, SEM and other characterization methods. The process of the removal of water molecules which adsorbed and coordinated to the Cu(II) under heating conditions was analyzed by means of FTIR testing and thermal analysis. An efficient activation method were used to expose Cu(II) center activity sites and so Cu-BTC displayed excellent catalytic activity.(2) Cu-BTC samples were activated by calcination under protection of inert gases. Catalytic performance test proved that Cu-BTC has good low-temperature catalytic performance, and230-Cu-BTC is the best sample. Cu-BTC catalysts were further characterized by BET, SEM and TEM. The changes of Cu2+between before and after the reaction were monitored by XPS and EPR characterization, and proved that Cu2+took part in the catalytic reaction. The process of NH3adsorption on Cu-BTC was also monitored by in-situ FTIR, and Cu(Ⅱ)… NH3species was found to be the NH3adsorption states on Cu(Ⅱ).(3) MOF-5and MIL-101(Cr) were also synthesized and characterized. It was found that MOF-5was unstable in air and MIL-101(Cr) showed huge surface area, thermo-stability and good water resistance. Catalytic test showed that MOF-5didn’t possess catalysis activity. MIL-101(Cr) exhibited catalytic activity.