Síntese de materiais mesoporosos impregnados com zircônia e aminas para adsorção de CO2

Abstract

New technologies for CO2 capturing and separating are considered necessary to reduce the emission of gas with greater impact without greenhouse effect. Several studies have focused on an application of mesoporous silica materials in adsorption processes. The aim of the present work was the synthesis of several mesoporous silica materials, through different types of surfactants and in the functionalization of these structures with basic groups for CO2 adsorption. The materials were impregnated with zirconium dioxide (ZrO2), polyethyleneimine (PEI) and (3-Aminopropyl) trimethoxysilane (APTS) by a post-synthesis method through the contact process, in proportions of 10%, 30% and 50% wt. They were characterized by X-ray diffractometry (XRD), thermogravimetric analysis (TG / DTG), nitrogen adsorption at -196 ° C, absorption spectroscopy in the infrared region with Fourier transform (FT-IR) and scanning electron microscopy (SEM). The adsorbents prepared were subjected to an assessment of the adsorption capacity of carbon dioxide (CO2) by the thermogravimetric method. The highly ordered mesoporous silica structures SBA-15, SBA-16 and other SBA-like structures using different surfactants, such as Igepal CO630, BrijO20 and Brij93, were synthesized. The average pore diameters by the BJH method measuring 5 to 10 nm for a SBA-15 (SBA-P123) sample, 2 to 20 nm for a SBA-16 (SBA-F127 and SBA-Brij93) sample and values ranging from 2 to 4 nm for the SBA-Igepal and SBA-BrijO20 samples. The SBA-Igepal and SBA-BrijO20 samples obtained the best surface área results, 1074 and 1075 m2∙g-1, respectively. The results obtained in the adsorption tests showed that there was a reduction in the amount of CO2 adsorbed as the impregnated zirconium dioxide content increases due to the blocking of the pores of the structures by ZrO2. For the samples impregnated with PEI, there was a tendency for the higher the amine content, the greater the CO2 adsorption capacity of the material, but for the samples synthesized with Igepal CO630 and BrijO20 there was a distinct behavior, possibly due to obstruction of the pores of these materials by the organic, since these materials, despite having the largest surface areas, presented the smallest pore size values. The materials impregnated with the aminosilane had the same adsorption behavior of the samples impregnated with the polyethyleneimine and the SBA-15 sample impregnated with 50% APTS obtained the best adsorption capacity of 58 mgCO2∙g-1ads, corresponding to an increase of 87% in CO2 adsorption when compared to the pure SBA-15 sample.