Materiais de sílica mesoporosa modeladas com sacarose para adsorção de CO2

Abstract

The capture and storage of carbon dioxide (CO2) has been indicated as an effective strategy to reduce the emissions of this gas with the greatest impact on the greenhouse effect. Several studies have focused on the application of mesoporous silica materials in CO2 adsorption processes. And SBA-15 has stood out as a CO2 capture capture agent to its large pore volume and diameter and high thermal and hydrothermal performance. However, the synthesis of these materials still has a high cost due to the complexity in the processing to obtain tetraethylorthosilicate and the use of synthetic surfactants to model these materials. The objective of the present work was the synthesis of several mesoporous silica materials, using several sources of biomass as a structure modeler, for the adsorption of CO2. The materials were synthesized with sucrose, D-glucose, starch, cellulose, carboxymethylcellulose, lignin and chitosan with TEOS and then with an alternative and cheaper silica source, sodium silicate (Na2SiO3). Preliminary results showed sucrose as a promising modeling agent for these mesoporous structures, thus, a study of the synthesis with different molar ratios of sucrose (0, 0.3, 1, 2 and 3) in relation to silica (SiO2) was carried out. The structures of mesoporous were prepared and characterized by X-ray diffractometry (XRD), thermogravimetric analysis (TG/DTG) and nitrogen adsorption at -196°C, confirming the formation of a mesoporous silica structure and showing that increasing sucrose composition during synthesis resulted in improved properties and textures of these materials. The samples prepared with higher sucrose composition obtained the best results obtained the best results for surface area, 322 and 343 m2 ∙g-1 , and pore diameter, 7 and 9 nm, respectively. The results obtained in the adsorption tests found that the structures synthesized with sucrose correlated better with the Elovich Kinetic model, indicating that chemisorption is a rate-limiting step in the CO2 adsorption process of these materials. The adsorbents prepared with higher sucrose composition showed better adsorption capacities, 44.37 and 47.81 mg.g-1 , respectively, reaching adsorption capacity superior to other mesoporous silica structures.