CO₂ Capture with Mesoporous Silicas Modified with Amines by Double Functionalization: Assessment of Adsorption/Desorption Cycles

• Published in: Materials Vol. 11; no. 6; p. 887
• Main Authors: Sánchez-Zambrano, Kléver Santiago, Lima Duarte, Lairana, Soares Maia, Débora Aline, Vilarrasa-García, Enrique, Bastos-Neto, Moisés, Rodríguez-Castellón, Enrique, Silva de Azevedo, Diana Cristina
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI 25.05.2018; MDPI AG
• Subjects: CO2 adsorption; double functionalization; silica; CO2 adsorption; silica; double functionalization
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma11060887

CO₂ adsorption on mesoporous silica modified with amine by double functionalization was studied. Adsorption microcalorimetry was used in order to investigate the influence of increasing the nitrogen surface density on double functionalized materials with respect to the only grafted materials. The distribution of sites and the rate-controlling mechanism of adsorption were evaluated. A Tian Calvet microcalorimeter coupled to a manometric setup was used to evaluate the energy distribution of adsorption sites and to calculate the thermokinetic parameters from the differential enthalpy curves. CO₂ and N₂ adsorption equilibrium isotherms at 50 and 75 °C were measured with a magnetic suspension balance, allowing for the computation of working capacity and selectivity at two temperatures. With these data, an Adsorbent Performance Indicator (API) was calculated and contrasted with other studied materials under the same conditions. The high values of API and selectivity confirmed that double functionalized mesoporous silica is a promising adsorbent for the post combustion process. The adsorption microcalorimetric study suggests a change in active sites distribution as the amine density increases. Maximum thermokinetic parameter suggests that physisorption on pores is the rate-controlling binding mechanism for the double-functionalized material.