Preparation And Properties Of Ammonia-and Ammonia-Free SCR Composite Denitrification Catalysts

Nitrogen oxides?NOx?are one of the main causes of environmental pollution,and also an important contributor to environmental problems such as haze and acid rain.The technique of selective catalytic reduction?SCR?can remove nitrogen oxides effectively.And low temperature denitrification catalyst and ammonia free denitrification catalyst have become the research trend.The main research works are as follows:?1?A series of novel denitrification catalysts of M/ZrO₂-CeO₂?M:Cu,Fe?with different molar ratios of M/ZrO₂-CeO₂ were prepared by coprecipitation method.The BET,the XRD,Raman spectra and XPS were used to characterize the structures and properties of the catalysts.The results revealed that the specific surface area of Cu_1-0.5/ZrO₂-CeO₂ and Fe_0.5-1/ZrO₂-CeO₂ catalyst were highest and the diffraction peak of the active component is the weakest in the same series catalysts.?2?The catalytic activity was investigated in selective catalytic reduction with ammonia?NH₃-SCR?.The results showed the NO conversion get to 100%between 150?and 250?with the catalyst of Cu_1-0.5/ZrO₂-CeO₂,and the same to the catalyst of Fe_0.5-1/ZrO₂-CeO₂ during 140-250?.Comparison of traditional NH₃-SCR catalysts,the Cu_1-0.5/ZrO₂-CeO₂ or Fe_0.5-1/ZrO₂-CeO₂ have showed good catalytic performance during 150-440?(Cu_1-0.5/ZrO₂-CeO₂)or 140-470?(Fe_0.5-1/ZrO₂-CeO₂),and the NO conversion can keep above 70%.?3?A novel ammonia-free denitrification catalyst was prepared by combining chitosan?CS?with Ti-W-V-Mn metal oxides.The structures and properties were characterized by scanning electron microscope?SEM?,Fourier transform infrared spectroscopy?FT-IR?,X-ray diffraction?XRD?and Microporous analyzer.And the catalytic denitrification activities of catalysts were collected by gas analyzer.The results indicated that the CS/Ti-W-V-Mn composite catalysts not only showed good catalytic activity at low temperature?180-250??,but also performed well at high temperature?350-400??.Especially,the NO conversion could up to 100%within 180-400?when the weight ratio between CS and Mn-V-W-Ti oxides was 1:1 and its repeatability of activity testing at low temperature without ammonia was good.