Al_2O_3负载型Cu-Al类水滑石氧化物的NO_x吸附及分解性能
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摘要
采用水热法制备铜铝水滑石作为前体,经500℃焙烧得到Cu-Al复合氧化物,并利用X射线衍射、红外光谱对其进行表征;将Cu-Al复合氧化物负载于直径为3～5 mm球状Al_2O_3载体上,进行NO吸附和热稳定性试验。结果表明,NO、O_2、H_2O(g)在Cu-Al复合氧化物作用下在氧化物表面生成HNO3,并与Cu-Al复合氧化物中的CuO组分反应生成Cu(NO_3)_2,吸附率可达28%,再高温焙烧可以释放以NO为主体的氮氧化物,并且可以恢复到之前的金属氧化物结构。而吸附完成的化合物静置数天后会回到原来的水滑石层状结构。
Copper-aluminum hydrotalcite is made via hydrothermal method,then is roasted at 500℃ to prepare CuAl complex oxides that is characterized by X-ray diffraction and infrared-red spectrum. The prepared Cu-Al composite oxide is loaded onto the surface of spherical Al_2O_3 carrier with a diameter between 3 mm and 5 mm,and the sample is evaluated in the experiments about NO adsorption and heat endurance. The experimental results show that NO,O_2 and water steam forms HNO_3 on the surface of Cu-Al complex oxides,then HNO_3 reacts with Cu O in Cu-Al composite oxides to form Cu(NO_3)_2,and the adsorption efficiency can reach 28%.NOx,with NO as the main body,can be released when the product is roasted at a high temperature,and the structure of the former metal oxides can be restored. The adsorbed compounds will return to the original hydrotalcite-like layered structure after a few days of static storage.
Copper-aluminum hydrotalcite is made via hydrothermal method,then is roasted at 500℃ to prepare CuAl complex oxides that is characterized by X-ray diffraction and infrared-red spectrum. The prepared Cu-Al composite oxide is loaded onto the surface of spherical Al_2O_3 carrier with a diameter between 3 mm and 5 mm,and the sample is evaluated in the experiments about NO adsorption and heat endurance. The experimental results show that NO,O_2 and water steam forms HNO_3 on the surface of Cu-Al complex oxides,then HNO_3 reacts with Cu O in Cu-Al composite oxides to form Cu(NO_3)_2,and the adsorption efficiency can reach 28%.NOx,with NO as the main body,can be released when the product is roasted at a high temperature,and the structure of the former metal oxides can be restored. The adsorbed compounds will return to the original hydrotalcite-like layered structure after a few days of static storage.
引文
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[14]李大塘,郭军.Cu-Al-O氧化物催化剂酸碱性质的量热表征[J].燃料化学学报,2001,29(增刊):73-76.
[15]Li J G,Ikegami T,Lee J H,et al.Synthesis of Mg-Al spinel powder via precipitation using ammonium bicarbonate as the precipitant[J].Eur Ceram Soc,2001,21(2):139-148.
[2]Kannan S,Swamy C S.Catalytic decomposition of nitrous oxide over calcined cobalt aluminum hydrotalcities[J]. Catal Today,1999,53(4):725-737.
[3]Kannan S,Rivers V,Knozinger H.High-temperature transformations of Cu-rich hydrotalcities[J]. Solid State Chem,2004,177(1):319-331.
[4]王立秋,张守臣,刘长厚.类水滑石复合产物催化消除氮氧化物的研究进展[J].化工进展,2003,22(10):1076-1080.
[5]Corma A,PalomaresA A E,Reyf,et al. Simultaneous catalytic removal of SOxand NOxwith hydrotalcite derived mixed oxides containing copper and their possibilities to be used in FCC unites[J].Catal,1997,17(1):140-149.
[6]Chmielarz L,Kustrowski P,Rafalska Lasocha A,et al.Catalytic activity of Co-Mg-Al,Cu-Mg-Al and Cu-Co-Mg-Al mixed oxides derived from hydrotalcites in SCR of NO with ammonia[J]. Appl Catal,2002,35(3):195-210.
[7]Armor J N,Braymer T A,Farris T S,et al.Calcined hydrotalcites for the catalytic decomposition of N2O in simulated process streams[J].Appl Catal,1996,7(3-4):397-406.
[8]Seanimirova T,Kirvo G.Cation composition during recrystallization of layered double hydroxides from mixed(Mg,Al)oxides[J].Appl Clay Sci,2003,22(6):295-301.
[9]Palomares A E,Prato J G,Reyf,et al.Using the“memory effect”of hydrotalcites for improving the catalytic reduction of nitrates in water[J].Catal,2004,221(1):62-66.
[10]Ferreira O P,Alves O L,Gouveia D X,et al.Thermal decomposition and structural reconstruction effect on Mg-Fe-based hydrotalcite compounds[J].Solid State Chem,2004,177(9):3058-3069.
[11]吕君英,郭亚平,龚凡.以类水滑石为前体的Cu-Al复合氧化物氧化吸附NO2的机理[J].环境与化工,2005,34(12):1203-1207.
[12]Wang J B,Tsai D H,Huang T J. Synergistic catalysis of carbon monoxide oxidation over copper oxide supported on samariadoped ceria[J].Catal,2002,208(2):370-380.
[13]冯拥军,李殿卿,李春喜,等.Cu-Ni-Mg-Al-CO3四元水滑石的合成及结构分析[J].化学学报,2003,61(1):78-83.
[14]李大塘,郭军.Cu-Al-O氧化物催化剂酸碱性质的量热表征[J].燃料化学学报,2001,29(增刊):73-76.
[15]Li J G,Ikegami T,Lee J H,et al.Synthesis of Mg-Al spinel powder via precipitation using ammonium bicarbonate as the precipitant[J].Eur Ceram Soc,2001,21(2):139-148.
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