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Titanium silicate porous materials for carbon dioxide adsorption / José N. Primera-Pedrozo in Industrial & engineering chemistry research, Vol. 49 N° 16 (Août 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 16 (Août 2010) . - pp. 7515–7523 Titre : Titanium silicate porous materials for carbon dioxide adsorption : synthesis using a structure directing agent, detemplation and inclusion of alkaline earth metal cations Type de document : texte imprimé Auteurs : José N. Primera-Pedrozo, Auteur ; Brenda D. Torres-Cosme, Auteur ; Meghan E. Clardy, Auteur Année de publication : 2010 Article en page(s) : pp. 7515–7523 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Porous  materials  Adsorption Résumé : A titanium silicate variant named UPRM-5 was prepared using tetraethylammonium hydroxide as a structure-directing agent (SDA). Characterization of the material by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques showed a homogeneous and crystalline solid powder phase, with unit cell dimensions of a = 6.8 Å, b = 11.7 Å, c = 13.4 Å, α = 102.9°, β = 92.8°, and γ = 91.1°. Successful detemplation was achieved via ion exchange with NH4Cl as evidenced by thermal gravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopy data. Effective functionalization was obtained after ion exchanging the detemplated material using SrCl2 and BaCl2. These ion exchanged variants were also characterized using XRD and porosimetry techniques. Thermal-vacuum activation of Sr-UPRM-5 at 90 °C resulted in a material with a surface area of ca. 240 m2/g, while activation at higher temperatures resulted in low surface areas and plausible structural distortion. On the other hand, the barium variant exhibited the best thermal stability, with an average surface area on the order of 250 m2/g after employing activation temperatures up to 180 °C. The differences in thermal stability may be a result of structurally coordinated water. Adsorption of CO2 at 25 °C in Sr- and Ba-UPRM-5 materials activated at different temperatures also co-corroborated the aforementioned thermal stability observations in addition to what appears to be cation relocation. Fitting of the CO2 adsorption data with the Dubinin−Astakhov model revealed a heterogeneous surface, which was corroborated by isosteric heats of adsorption estimated from the uptake data. For low partial pressures, the observed CO2 adsorption capacities increased as follows: NH4-UPRM-5 < Sr-UPRM-5 < Ba-UPRM-5. Both the Sr- and Ba-UPRM-5 materials exhibited outstanding selectivity for CO2 over CH4, N2, and O2. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100331q?journalCode=iecred [article] Titanium silicate porous materials for carbon dioxide adsorption : synthesis using a structure directing agent, detemplation and inclusion of alkaline earth metal cations [texte imprimé] / José N. Primera-Pedrozo, Auteur ; Brenda D. Torres-Cosme, Auteur ; Meghan E. Clardy, Auteur . - 2010 . - pp. 7515–7523. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 16 (Août 2010) . - pp. 7515–7523 Mots-clés : Porous  materials  Adsorption Résumé : A titanium silicate variant named UPRM-5 was prepared using tetraethylammonium hydroxide as a structure-directing agent (SDA). Characterization of the material by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques showed a homogeneous and crystalline solid powder phase, with unit cell dimensions of a = 6.8 Å, b = 11.7 Å, c = 13.4 Å, α = 102.9°, β = 92.8°, and γ = 91.1°. Successful detemplation was achieved via ion exchange with NH4Cl as evidenced by thermal gravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopy data. Effective functionalization was obtained after ion exchanging the detemplated material using SrCl2 and BaCl2. These ion exchanged variants were also characterized using XRD and porosimetry techniques. Thermal-vacuum activation of Sr-UPRM-5 at 90 °C resulted in a material with a surface area of ca. 240 m2/g, while activation at higher temperatures resulted in low surface areas and plausible structural distortion. On the other hand, the barium variant exhibited the best thermal stability, with an average surface area on the order of 250 m2/g after employing activation temperatures up to 180 °C. The differences in thermal stability may be a result of structurally coordinated water. Adsorption of CO2 at 25 °C in Sr- and Ba-UPRM-5 materials activated at different temperatures also co-corroborated the aforementioned thermal stability observations in addition to what appears to be cation relocation. Fitting of the CO2 adsorption data with the Dubinin−Astakhov model revealed a heterogeneous surface, which was corroborated by isosteric heats of adsorption estimated from the uptake data. For low partial pressures, the observed CO2 adsorption capacities increased as follows: NH4-UPRM-5 < Sr-UPRM-5 < Ba-UPRM-5. Both the Sr- and Ba-UPRM-5 materials exhibited outstanding selectivity for CO2 over CH4, N2, and O2. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100331q?journalCode=iecred