Pyridine, CO and SO 2 were used as probes to characterize the mixed oxides Al 2O 3/SiO 2 by TPD technique. XRD study showed mullite was the major composition of the mixed oxides. The tail gases were analyzed by gas ch...Pyridine, CO and SO 2 were used as probes to characterize the mixed oxides Al 2O 3/SiO 2 by TPD technique. XRD study showed mullite was the major composition of the mixed oxides. The tail gases were analyzed by gas chromatography. The results showed that the nanocrystal mixed oxides exhibited a good adsorbability for pyridine, CO and SO 2. During desorption of pyridine and CO, CO 2 was detected in desorbed mixtures and in the case of SO 2 solid sulphur was found.展开更多
A series of CexPr1-xO2-δ mixed oxides were synthesized by sol-gel met hod and characterized by Raman and XRD techniques. When x value was changed from 1.0 to 0.5, only a cubic phase CeO2 was observed. The samples wer...A series of CexPr1-xO2-δ mixed oxides were synthesized by sol-gel met hod and characterized by Raman and XRD techniques. When x value was changed from 1.0 to 0.5, only a cubic phase CeO2 was observed. The samples were very well cr ystallized on decreasing x from 0.50 to 0.99. For CexPr1-xO2-δ samples 465 cm-1 and 1 150 cm-1 Raman peaks are attributed to the Raman active F2g mode of CeO2. The broad peak at about 570 cm-1 in the region of 0.3 ≤ x ≤ 0.99 can be linke d to lattice defects resulting in oxygen vacancies. The new band at about 195 cm -1 may be attributed to the asymmetric vibration caused by the formation of oxyg en vacancies. Calcination temperatures had great effect on the peak intensity fo r CeO2 but less effect on Ce0.8Pr0.2O2-δ in Raman spectra. It might be due to t he transformation of the colors for the mixed oxides, the insertion of Pr atom i nto the ceria lattice could enhance the sintering resistance and thermal stabili ty of the mixed oxides.展开更多
文摘Pyridine, CO and SO 2 were used as probes to characterize the mixed oxides Al 2O 3/SiO 2 by TPD technique. XRD study showed mullite was the major composition of the mixed oxides. The tail gases were analyzed by gas chromatography. The results showed that the nanocrystal mixed oxides exhibited a good adsorbability for pyridine, CO and SO 2. During desorption of pyridine and CO, CO 2 was detected in desorbed mixtures and in the case of SO 2 solid sulphur was found.
文摘A series of CexPr1-xO2-δ mixed oxides were synthesized by sol-gel met hod and characterized by Raman and XRD techniques. When x value was changed from 1.0 to 0.5, only a cubic phase CeO2 was observed. The samples were very well cr ystallized on decreasing x from 0.50 to 0.99. For CexPr1-xO2-δ samples 465 cm-1 and 1 150 cm-1 Raman peaks are attributed to the Raman active F2g mode of CeO2. The broad peak at about 570 cm-1 in the region of 0.3 ≤ x ≤ 0.99 can be linke d to lattice defects resulting in oxygen vacancies. The new band at about 195 cm -1 may be attributed to the asymmetric vibration caused by the formation of oxyg en vacancies. Calcination temperatures had great effect on the peak intensity fo r CeO2 but less effect on Ce0.8Pr0.2O2-δ in Raman spectra. It might be due to t he transformation of the colors for the mixed oxides, the insertion of Pr atom i nto the ceria lattice could enhance the sintering resistance and thermal stabili ty of the mixed oxides.
