Research Of Efficient Spinel-type Catalyst Which Applied To Selective Catalytic Reduction Of Hydrogen

NOx is one of the world-recognized atmospheric pollutants, with the rapid development of industrialization level, the environmental problems caused by the NOx emission become more and more serious. In recent years, H2-SCR as a new method of flue gas denitration which gained widely attention. Catalyst is vital part of SCR technology, the rationality of the catalyst selection and performance are directly related to the efficiency of SCR denitration reaction, In order to explore the efficient catalyst in the H2-SCR reaction, This paper mainly revolves around spinel catalyst for research work. Specific content as follows:(1) Spinel-type complex oxide NiFe2O4was prepared by citric acid-ligand sol-gel method. The denitration activity of catalyst with different calcination temperature, H2/NO ratio and space velocity was studied. The results indicated that when the calcination temperature is700℃, the molar ratio of H2/NO was1, the space velocity was4500h’1, the denitration performance of catalyst is the best, the conversion of NO reached97%. Characterization methods with XRD, BET, SEM, TEM, TPR and TPD showed that the prepared NiFe2O4catalyst was intact spinel-type crystal structures and it with good performance of NO hydrogenation reduction, it is because of its good bifunctional oxidation-reduction quality and surface acidity.(2) With NiFe2O4spinel as carrier, Pt/NiFe2O4series catalysts were prepared by wet impregnation method. The effect of H2-SCR reaction activity of catalyst with different Pt load, concentration of H2and O2was investigated. The results showed that as the increase of Pt load, the NO removal rate increase at first and then decrease, the de-NOx activity increased significantly with the increase of H2concentration, while the impact with improvement of oxygen concentration on its catalytic activity was not obvious at low temperature. Compared with NiFe2O4spinel, as a result of the Pt load, its porosity decreased significantly, the acidity of the spinel was changed, the redox capacity of Pt/NiFe2O4was related not only with Fe and Ni, but also with Pt.(3) The NiFexPtyO4series catalysts were prepared by isomorphous substitution method, the H2-SCR reaction performance with different Pt doping in low temperature was researched through simulating the actual flue gas. And the influence on low temperature denitration activity with different space velocity, concentrations of H2, O2and NO was explored by change the kinetic parameters. Under the conditions of high concentration of NO and oxygen enrichment, NiFe1.95Pt0.05O4catalyst still keeped good denitration activity at low temperature. The Nitrogen adsorption/desorption isothermal curve showed a typical III isothermal curves of metal oxide, the doping of precious metal Pt improved the redox ability of original NiFe2O4spinel obviously, And it has L acid sites with two strong stripping peak and and B acid sites with a weak stripping peak, this was also why it can efficiently denitration at low temperature.