ACo_2O_4/HZSM-5催化剂上N_2O的直接分解

分别采用柠檬酸络合燃烧法和低温络合浸渍法制备尖晶石型复合金属氧化物催化剂ACo2O4(A=Mg,Ni,Zn)和分子筛负载尖晶石型复合金属氧化物催化剂ACo2O4/HZSM-5(A=Mg,Fe,Ni,Cu,Zn,Zr,La).采用X射线衍射(XRD)、氨程序升温脱附(NH3-TPD)、扫描电子显微镜(SEM)和X射线能谱(EDS)等手段对催化剂进行表征,并在固定床微型反应器中评价其催化分解N2O活性.实验结果表明,A位离子种类影响ACo2O4/HZSM-5催化剂活性,以Ni、Fe、Zr或La为A位离子时,催化剂的活性较好,N2O分解温度低.ACo2O4/HZSM-5催化剂的活性高于ACo2O4尖晶石型复合氧化物,一方面是ACo2O4在分子筛HZSM-5载体上高度分散,使其以超细颗粒形态存在,另一方面ACo2O4/HZSM-5催化剂具有适宜的酸性,可提高催化剂的活性.

Decomposition of N2O on ACo2O4/HZSM-5 Catalysts

ACo₂O₄(A=Mg, Ni, Zn)andACo₂O₄/HZSM-5 (A=Mg, Fe, Ni, Cu, Zn, Zr, La) catalysts were synthesized by the citric acid -ligated combustion method and by low -temperature complex impregnation, respectively. The catalysts were characterized by X-ray diffraction (XRD), ammonia temperature -programmed desorption (NH₃-TPD), scanning electron microscopy (SEM), and energy dispersive X-ray microanalysis (EDS). The performance of the catalysts was evaluated with micro fixed bed reactor. The results showed that the catalytic activity was affected by the A-site ion, and when theA -site ion was Ni, Fe, Zr, or La, the catalysts had better catalytic activity and the temperature of N₂O decomposition was lower. Compared with ACo₂O₄, the ACo₂O₄/HZSM -5 catalyst had better catalytic activity. ACo₂O₄ was present as ultrafine particles on the HZSM-5 zeolite and the ACo₂O₄/HZSM -5 catalyst had good acidity. All these factors are useful in improving the performance of these catalysts.