There is a growing concern on the relationship between anthropogenic carbon dioxide and climate changes. A promising approach is the adsorption technology using mesoporous MCM-41 materials that can be easily synthesized to depict structures adequate to the flow of gas. The aim of this study was to improve the synthesis of MCM-41 using cationic surfactant mixtures and apply the resulting materials to CO 2 adsorption. To that end, the simplex-centroid design was applied to optimize CO 2 adsorption from seven mesoporous MCM-41 materials synthesized by the hydrothermal method using surfactants from hydrophobic chains of different sizes. The cationic surfactants used were tetradecyltrimetylammonium bromide, cetyltrimethylammonium bromide, trimethyloctadecylammonium bromide and their mixture at ratios of 1:1 and 1:1:1. The CO 2 adsorption was investigated using thegravimetric method at 298 K and pressures up to 40 bar. The resulting materials, labelled C 17 , C 19 , C 21 , C 17 C 19 , C 19 C 21 , C 17 C 21 and C 17 C 19 C 21 , were characterized by XRD, FTIR, TG and SEM and showed significant differences in structure as well as in the mass of CO 2 adsorption. The response models showed that the best combination of the surfactants resulted from C 17 C 19 sample, which presented synergistic interactions reaching the highest value of CO 2 adsorption (0.62 g CO 2 /g adsorbent), compared to other samples.

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Materials such as MgAl 2 O 4 and ZnAl 2 O 4 assessed in the reaction of dry reforming of methane to produce syngas were synthesized by microwave-assisted combustion method using urea as fuel. Samples of synthesized oxides were calcined at 800 °C for 2 h and impregnated with 5% nickel. The impregnated samples were calcined at 850 °C for 4 h to obtain the desired phases. The results of the catalytic tests showed that the catalysts are active for the reaction of dry reforming of methane, and the catalyst that showed the best performance for methane conversion was 5% Ni/MgAl 2 O 4 calcined at 850 °C/4 h. Keywords: chemical synthesis, powder diffraction, oxides, dry reform, nickel catalysts. Resumo Materiais

The CO2 adsorption technology using solid adsorbent shas been considered as a promising approach to reduce CO2 emissions. Therefore, research has been developed to obtain efficient and economically viable adsorbents. The mesoporous materials of the MCM-41 type are among the candidates for effective adsorbents as a result of easy synthesis and structure which favors the flow of gas. The aim of this study was to improve the synthesis of MCM-41 using mixtures of cationic surfactants and apply in CO2 capture. The cationic surfactants used weretetradecyltrimetylammonium bromide (TTMABr - C17H38NBr) and cetyltrimethylammonium bromide (C19H42NBr) and their mixture in a ratio of 1:1. The CO2 adsorption was investigated using the gravimetric method at 298K and pressure varying up to 40 bar. The resulting materials, C17, C19 and C17C19, were characterized by XRD, FTIR, TG and SEM. The results revealed significant differences in the structure of the materials and amount of of CO2 adsorbed.