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In this manuscript, MCM-41 and Co-MCM-41 were synthesized to evaluate the effect of the metal incorporated in the structure of the mesoporous material used in the benzene removal in aqueous medium containing hydrogen peroxide (H 2 O 2 ). The decomposition of H 2 O 2 in the medium containing MCM-41 and Co-MCM-41 was investigated. The techniques used to characterize these materials showed satisfactory results, proving that the synthesis was effective. The decomposition of hydrogen peroxide carried out in the ultraviolet/visible molecular absorption spectrophotometer revealed that the pH of the medium and the presence of cobalt influence its decomposition. In the reaction containing benzene + Co-MCM-41 + H 2 O 2 , it was possible to confirm this information, because there was practically no decomposition at pH = 1.5, 3.0 and 5.0, whereas decomposition was considerable at pH = 7.0 and 10.0 and all H 2 O 2 was decomposed at pH = 12. Tests containing benzene + H 2 O 2 + MCM-41 resulted in a higher removal of analytes in an alkaline medium. The last catalytic tests contained benzene + Co(II) + H 2 O 2 in the aqueous reaction medium; compared to benzene + Co-MCM-41 + H 2 O 2 , it was found that the influence of Co-MCM-41 can be better viewed in pH = 10.0 and 12.0, because 82.1% of benzene was removed after 5 h.

The catalytic degradation of high density polyethylene (HDPE) was studied in the presence of HZSM-12 zeolites with different Si/Al ratio, by thermogravimetry and pyrolysis coupled to gas chromatography and mass spectrometry. The NaZSM-12 zeolite was synthesized by the hydrothermal method using methyltriethylammonium chloride as template. The HZSM-5 was obtained by ion exchange of NaZSM-12 with ammonium chloride, drying and subsequent calcination. The materials characterization were carried out by chemical analysis, X-ray diffraction, scanning electron microscopy, BET measurements and acidity by n-butylamine adsorption. The obtained HZSM-12 zeolites were physically mixed with HDPE in the proportion of 50%wt and submitted to thermogravimetric analyses at heating rates of 2.5; 5; 10 and 20 °C min −1 . The addition of HZSM-12 to HDPE produced a decreasing in the temperature of polymer degradation, which was proportional to the zeolite acidity. The activation energy (Ea) for the process was determined from the non-isothermal model-free kinetic model proposed by Vyazovkin. The Ea decreases linearly with the concentration of acid sites on the HZSM-12 materials. From the pyrolysis data, the obtained products were typically light gases (C 2 -C 3 ); liquid petroleum gases (C 4 -C 5 ); and gasoline (C 6 -C 10 ). This results suggest that acid zeolites are excellent materials for obtaining alternative fuels from catalytic recycling of plastics.

The pyrolysis of vacuum gasoil (VGO) was studied alone and in presence of HZSM-5/AlMCM-41 hybrid catalyst. This micro–mesoporous material was synthesized by the hydrothermal method using dual templates of tetrapropilamonium and cetyltrimethylammonium ions at different crystallization times. The obtained materials were washed and calcined for remotion of the organic templates. The characterization by X-ray diffraction, nitrogen surface area by the BET method, scanning and transmission electron microscopies, evidenced that typical MFI structure was embedded into the bulk of the MCM-41 matrix, in order to obtain the hybrid micro–mesoporous phase. The protonic form of the material was obtained by ion exchange with ammonium chloride solution and subsequent thermal treatment. The total acidity, as determined by n -butylamine adsorption, was equivalent to 0.75 mmol g −1 , in the temperature range of 300–500 °C, corresponding to strong acid sites. For catalytic reaction, a physical mixture of 10% of catalyst/VGO was decomposed in a thermobalance at heating rates of 5; 10 and 20 °C min −1 , from 100 to 550 °C. From TG/DTG data, applying the model-free kinetics, it was observed that the activation energy for the pyrolysis of VGO alone was ca. 125 kJ mol −1 . For VGO physically mixed to both AlMCM-41 and HZSM-5, the value decreased to ca. 80–90 kJ mol −1 , whereas for the hybrid, the value was the lowest, ca. 65 kJ mol −1 , evidencing the efficiency of the combined effect of the acid sites, crystalline phase and microporosity of ZSM-5 zeolite with the accessibility of the mesoporous of the AlMCM-41 ordered material. For determination of the catalytic properties, the samples of VGO and catalyst/VGO were submitted to pyrolysis-GC–MS system at 500 °C using helium as gas carrier. The VGO alone suffers decomposition to a wide range of hydrocarbons, typically C 17 –C 41 , while in the presence of catalyst, light fraction of hydrocarbons, in the range of liquefied petroleum gas (C 3 –C 5 ), gasoline (C 6 –C 10 ) and diesel (C 11 –C 16 ) were obtained, evidencing that the HZSM-5/AlMCM-41 hybrid material is an effective catalyst for pyrolysis of VGO.

This work describes the covalent grafting of 3,4,9,10-perylenediimides (PDI), which are fluorescent dyes with very interesting optical properties, onto the walls of mesoporous molecular sieves MCM-41 and SBA-15. The mesoporous materials were first treated with 3-aminopropyltriethoxysilane (APTES) in anhydrous toluene, generating amine-containing surfaces. The amine-containing materials were then reacted with 3,4,9,10-perylenetetracarboxylic dianhydride (PTCA), generating surface-grafted PDI. Infrared spectra of the materials showed that the reaction with amino groups took place at both anhydride ends of the PTCA molecule, resulting in surface attached diimides. No sign of unreacted anhydride groups were found. The new materials, designated as MCMN 2 PDI and SBAN 2 PDI, presented absorption and emission spectra corresponding to weakly coupled PDI chromophores, in contrast to the strongly coupled rings usually found in solid PDI samples. The materials showed a red fluorescence, which could be observed by the naked eye under UV irradiation or with a fluorescence microscope. The PDI-modified mesoporous materials showed electrical conductivity when pressed into a pellet. The results presented here show that the new materials are potentially useful in the design of nanowires.

This work describes the encapsulation of N , N ′-bis(2-phosphonoethyl)-3,4,9,10-perylenetetracarboxylic diimide (PPDI), a water-soluble perylene dye, in the channels of mesoporous silica MCM-41. The incorporation of the dye was achieved by stirring MCM-41 with aqueous solutions of PPDI. The solid material obtained by this process exhibited a red fluorescence. Diffuse reflectance and emission spectra of the fluorescent powder suggested a highly organized arrangement with the PPDI molecules self-assembled in a 1D stack inside the channels of the mesoporous silica. The new materials described here have potential applications as nanoscale optoelectronic devices, such as conducting nanowires and fluorescent gas sensors.