Study of physisorbed and chemisorbed carbon dioxide (CO<sub>2</sub>) species was carried out on the NaX zeolite modified by cationic exchanges with bivalent cations (Ca<sup>2+</sup> and Ba<s...Study of physisorbed and chemisorbed carbon dioxide (CO<sub>2</sub>) species was carried out on the NaX zeolite modified by cationic exchanges with bivalent cations (Ca<sup>2+</sup> and Ba<sup>2+</sup>) by temperature-programmed desorption of CO<sub>2</sub> (CO<sub>2</sub>-TPD). Others results were obtained by infrared to complete the study. The results of this research showed, in the physisorption region (213 - 473 K), that the cationic exchanges on NaX zeolite with bivalent cations increase slightly the interactions of CO<sub>2</sub> molecule with adsorbents and/or cationic site. Indeed, the desorption energies of physisorbed CO<sub>2</sub> obtained on the reference zeolite NaX (13.5 kJ·mol<sup>-1</sup>) are lower than that of exchanged zeolites E-CaX and E-BaX (15.77 and 15.17 kJ·mol<sup>-1</sup> respectively). In the chemisorbed CO<sub>2</sub> region (573 - 873 K), the desorption energies related to desorbed species (bidentate carbonates: CO<sub>3</sub>2-</sup>) on the exchanged zeolites E-CaX and E-BaX are about 81 kJ·mol<sup>-1</sup>, higher than the desorbed species (bicarbonates: HCO<sub>3</sub>2-</sup>) on the reference R-NaX (62 kJ·mol<sup>-1</sup>). In addition, the exchanged E-BaX zeolite develops the secondary adsorption sites corresponding to bicarbonates species with desorption energies of 35 kJ·mol<sup>-1</sup> lower to desorption energies of bicarbonates noted on the reference zeolite NaX.展开更多
FT-IR spectrometry, TPD and adsorption isotherms of thiophene on NaY/NiY zeolites were carried out and the diffusion coefficient was obtained by means of its real-time dynamic curves. The loading of thiophene adsorbed...FT-IR spectrometry, TPD and adsorption isotherms of thiophene on NaY/NiY zeolites were carried out and the diffusion coefficient was obtained by means of its real-time dynamic curves. The loading of thiophene adsorbed on the NaY zeolite decreased with an increasing temperature, which was ascribed to the patterns of physical adsorption. Both physical and chemical adsorption phenomena were detected on the NiY zeolite, with the 0 complexation and S-M interaction existing during the chemical adsorption. The loading of thiophene adsorbed on the NiY zeolite at 302 K and 335 K was equal, but it decreased at 373 K. The diffusion coefficient of thiophene on the NaY zeolite decreased when the loading increased to more than 0.02 mmol/g, and on the contrary that of thiophene on the NiY zeolite did not change obviously with the loading adsorbed.展开更多
文摘Study of physisorbed and chemisorbed carbon dioxide (CO<sub>2</sub>) species was carried out on the NaX zeolite modified by cationic exchanges with bivalent cations (Ca<sup>2+</sup> and Ba<sup>2+</sup>) by temperature-programmed desorption of CO<sub>2</sub> (CO<sub>2</sub>-TPD). Others results were obtained by infrared to complete the study. The results of this research showed, in the physisorption region (213 - 473 K), that the cationic exchanges on NaX zeolite with bivalent cations increase slightly the interactions of CO<sub>2</sub> molecule with adsorbents and/or cationic site. Indeed, the desorption energies of physisorbed CO<sub>2</sub> obtained on the reference zeolite NaX (13.5 kJ·mol<sup>-1</sup>) are lower than that of exchanged zeolites E-CaX and E-BaX (15.77 and 15.17 kJ·mol<sup>-1</sup> respectively). In the chemisorbed CO<sub>2</sub> region (573 - 873 K), the desorption energies related to desorbed species (bidentate carbonates: CO<sub>3</sub>2-</sup>) on the exchanged zeolites E-CaX and E-BaX are about 81 kJ·mol<sup>-1</sup>, higher than the desorbed species (bicarbonates: HCO<sub>3</sub>2-</sup>) on the reference R-NaX (62 kJ·mol<sup>-1</sup>). In addition, the exchanged E-BaX zeolite develops the secondary adsorption sites corresponding to bicarbonates species with desorption energies of 35 kJ·mol<sup>-1</sup> lower to desorption energies of bicarbonates noted on the reference zeolite NaX.
文摘FT-IR spectrometry, TPD and adsorption isotherms of thiophene on NaY/NiY zeolites were carried out and the diffusion coefficient was obtained by means of its real-time dynamic curves. The loading of thiophene adsorbed on the NaY zeolite decreased with an increasing temperature, which was ascribed to the patterns of physical adsorption. Both physical and chemical adsorption phenomena were detected on the NiY zeolite, with the 0 complexation and S-M interaction existing during the chemical adsorption. The loading of thiophene adsorbed on the NiY zeolite at 302 K and 335 K was equal, but it decreased at 373 K. The diffusion coefficient of thiophene on the NaY zeolite decreased when the loading increased to more than 0.02 mmol/g, and on the contrary that of thiophene on the NiY zeolite did not change obviously with the loading adsorbed.
