Desenvolvimento de materiais para captura de CO2 com estrutura zeolítica empregando fonte de sílica alternativa

Abstract

Emissions caused by polluting gases, such as carbon dioxide, are one of the main contributors to the generation of the greenhouse effect that causes global warming, responsible for climate change. An alternative to mitigate these emissions is the use of adsorbents capable of capturing and storing CO2. Zeolite is considered one of the most effective adsorbents in adsorption and gas separation technologies due to its higher adsorption capacity, abundant availability and low cost. Despite these advantages, reagents used in the synthesis as the source of silica make obtaining these materials more expensive. In this work, were developed materials for CO2 capture, with zeolitic structure, were fed using an alternative low-cost silica source from beach sand, MPI silica, to make the synthesis process eco-friendly. The materials obtained were characterized using X-ray diffraction (XRD), X-ray fluorescence (FRX), Fourier transform infrared absorption spectroscopy (FTIR), scanning electron microscopy (SEM), textural analysis adsorption and desorption of N2 and Ar, and thermal analysis. Studies were carried out on the crystallization time of zeolites obtaining for zeolite-A with silica MPI (ZAM 1h), the relative crystallinity of 74.26% in the time of 1 h with pure and crystalline phases. The MFI structure zeolite in basic medium with MPI silica (ZM 15 h) had a relative crystallinity of 92.90% for the time of 15 h, with pure and crystalline phases, but smaller crystals than the zeolite with standard silica (ZAP 2 h). The MFI structure zeolite in hydrofluoric medium with silica MPI (SM 3 d) had a relative crystallinity of 111.90% in 3 days with pure crystalline phases, but with smaller crystals than zeolite with standard silica (SP 9 d). The evaluation of the adsorptive study showed that standard zeolite-A and MPI (ZAM 1 h) had the best CO2 capture results with adsorption capacities of, 5.25 mmol/g and 4.83 mmol/g CO2, respectively. Silicalite had the second best result with the standard (SP 9 d) and the MFI structure zeolites in hydrofluoric medium, from MPI silica (SM 3 d), with capacities of 3.94 mmol/g and 3.78 mmol/g of CO2, respectively. The MFI structure zeolites in basic medium, standard (ZMP 3 d) and the one with MPI silica (ZM 15 h) had capacities of 3.72 mmol/g and 3.22 mmol/g of CO2, respectively. The evaluation of the mathematical models indicated that zeolite-A fitted better to Temkin model and those with MFI structure in basic medium to Freundlich model, and Silicalite (SP 9 d), and zeolites from MPI silica (SM 3 d) to Langmuir and a SM 6 d to Temkin.