Study On Activity And SO₂ Tolerance Over NiAl Hydrotalcite-derived Catalysts For Selevtive Catalytic Reduction Of NO With C₃H₆

The removal of nitrogen oxides?NOx?is important for environmental protection.Selective Catalytic Reduction with propylene?C₃H₆-SCR?has been extensively studied.The performance and principle of C₃H₆-SCR over ZrNiAlO and MnNiAlO catalysts which were prepared by hydrothermal synthesis were investigated.The sulfur resistance and the mechanism were also explored.The main findings are as follows:?1?ZrNiAlO and MnNiAlO with different doping amounts were prepared by hydrothermal method.The results of XRD,SEM and FTIR indicated that the transition metal were successfully doped and highly dispersed in the mixed metal oxide,and the doping of Zr and Mn did not change the morphology of the catalyst.?2?The doping of the metal significantly enhanced the catalytic ability of the catalyst,including the ability to adsorb and activate NO,and the capacity to promote the reaction of nitrogen-containing species and carboxylates.In the ZrNiAlO series,the catalytic activity was the strongest when the Zr loading was 5%.In the MnNiAlO series,the catalytic effect was best when the Mn loading was 1%.?3?SO₂ caused sulfur poisoning of the catalysts,and the catalytic activity was inhibited due to the sulfates which produced by activating of SO₂ preferentially occupied the active sites of the catalysts,and these sulfates inhibited the formation and adsorption of nitrates.The doping of Zr and Mn weakened the deposition of sulfate and increased the sulfur resistance of the catalyst.?4?It was found through regeneration experiments that thermal regeneration lead to more serious poisoning of the catalyst,and washing regeneration could remove part of the sulfate deposition and effectively restored the catalytic performance of the catalyst.?5?Combining XPS and Py-FTIR to explore the factors affecting the catalytic activity of the catalyst.The results showed that the adsorption of oxygen on the surface of the catalyst is the decisive factor affecting the activity of the catalysts,and the amount of acid sites has no direct influence for the catalytic performance.