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 CO2 adsorption. To that end, the simplex-centroid design was applied to optimize CO2 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 CO2 adsorption was investigated using thegravimetric method at 298 K and pressures up to 40 bar. The resulting materials, labelled C17, C19, C21, C17C19, C19C21, C17C21 and C17C19C21, were characterized by XRD, FTIR, TG and SEM and showed significant differences in structure as well as in the mass of CO2 adsorption. The response models showed that the best combination of the surfactants resulted from C17C19 sample, which presented synergistic interactions reaching the highest value of CO2 adsorption (0.62 g CO2/g adsorbent), compared to other samples.

This work aimed to study the kinetics of thermal and catalytic pyrolysis using Ti-MCM-41 as catalyst in order to assess the catalytic pyrolysis efficiency compared to thermal pyrolysis of elephant grass. Ti-MCM-41 molecular sieve was synthesized by hydrothermal method from hydrogel with the following molar composition:1.00 CTMABr: 4.00 SiO2:X TiO2: 1 + X Na2O: 200.00 H2O, whichstructure template used was cetyltrimethylammonium bromide (CTMABr). The materials synthesized were characterized by X-ray diffraction, IR spectroscopy, thermogravimetric analysis and specific area by the BET method, for subsequent application in the biomass pyrolysis process. The kinetic models proposed by Vyazovkin and Flynn-Wall were used to determine the apparent activation energy involved in the thermal and catalytic pyrolysis of elephant grass and the results showed that the catalyst used was effective in reducing the apparent activation energy involved in the thermal decomposition of elephant grass.