Study On The Character And Catalytic Performance Of Cu Or Fe Pillared Sepiolite

Pillared intercalated layered clay(PILCs)is a kind of sandwich clay with different metal oxides in the layers. So it has larger surface area and acidity.It is also a kind of catalatic carrier for selective catalytic reduction of NO_x. In present, the reseaches of pillared clay focused on the preparation and characterization of Al, Ti or Zr pillared bentonites. More researches pay more attention on the texture of pillared clay as carrier, not on their catalytic characterization, especially ion pillared sepiolite. More papers focused on modifying the structure of pillared clays such as pore and surface area. PILCs used as carriers and absorbents attract more attention than their catalytic activity.This paper ameliorated the pore distribution and improved the thermal stability of sepiolite via acid modifation and Na ion exchange reaction. Copper and ion pillared sepiolite are synthesized for SCR-HC. At the same time, Fe-Al-Ce, Fe-Al-Sm and Cu-Fe-Ce pillared sepiolite are synthesized for oxidation of CO. Many analyzing techniques including BET, XRD, SEM, TG/DTG, XRF and XPS were employed to characterize the changes of structure and property of pillared sepiolite.The results as follows:1. From the result of BET, the surface area changed from90.755m²Â·g-1 to 158.0 m²Â·g-1with the sharp increase after acid modification. The percentage of mesopore increased notably. Connection of layers has been changed, the number of spicules decreased. However, the cation exchange capacity (CEC) decreased to 14.40 mmol/100g clay. The special surface area of Na exchanged sepiolite dreased to 55.731 m²Â·g-1. The aggregation of spicules and fasciculus are also existed. The CEC of Na2CO3-sepiolite is 26.4 mmol/100g。2. Surface area and micropore surface area increased to 167.04m²Â·g-1and 58.357 m²Â·g-1 respectively of Fe pillared acid modified sepiolite. There are clearly sandwich in Fe-pillared acid modified sepiolite.The particles are dispersed, the size of particle is about 12μm. It was shown that Fe and Cu-Fe pillaring increased the thermal stability which improved the capability of support from the spectrogram TG-DTG.3. Surface area and micropore surface area of Fe and Cu-Fe pillared Na-sepiolite increased, especially Fe pillared Na-sepiolite whose special surface area and micropore surface area increased to 101.55 m²Â·g-1 and 4.962 m²Â·g-1 respectively.The size of most pores are 20nm to 50nm. Aggregation is also can be found, but pillared sepiolite thermal stabilities are improved.4. Fe pillared Na-Sepiiolite have a good behavior in selective catalytic reduction of NO_x, the best NO_x conversion is 28.95% which achieved at 393℃. NO_x conversion of Cu-Fe pillared Na-Sepiolite is better than Fe pillared Na-Sepiolite when Cu content is more than 10%. The highest NO_x conversion of Cu-Fe pillared Na-Sepiolite is 33.4% which is achieved at 450℃when Cu content is 15%.5. The NO_x conversion of Fe pillared acid modified sepiolite is lower than 10 percent in this paper. However, Cu-Fe pillared acid modified sepiolite did better than Fe pillared acid modified sepiolite in selective catalytic reduction of NO_x. From the result of XRD, it can be found that ion is existed in dispersion.6. Fe or Cu-Fe pillared sepiolite which contains Ce or Sm is applied for oxidation of CO. It can be found that Fe or Cu-Fe pillared sepiolite which contains Ce or Sm did better than Fe or Cu-Fe pillared sepiolite. It was showed that the surface of sepiolite existed by CuO and Cu2O for Cu while Fe₂O₃ and Fe3O4 for Fe by the spectrogram of XPS.Copper, ion pillared sepiolite are synthesized in this paper. Not only study on the structure character but also on the catalytic activity of pillared sepiolite. This study of property and application of pillared sepiolite can be seen as primary research for a new kind of carriers which have activity in SCR and oxidation of CO.