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  • Author or Editor: V. J. Fernandes Jr. x
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Abstract  

In this work was studied the acid properties of a series of HZSM-12 zeolites with different Si/Al molar ratio. The samples of ZSM-12 were synthesized by the hydrothermal method starting from a gel with the following molar composition: 20MTEA:10Na2O:xAl2O3:100SiO2:200H2O, where: x=2, 1, 0.67 and 0.50, respectively. After the synthesis, the samples of ZSM-12 were ion-exchanged NH4Cl solution to obtain zeolite in the acid form (HZSM-12). The acid properties were evaluated by n-butylamine thermodesorption in a TG equipment at three different heating rates. The model-free kinetic model was applied in the TG integral curves to estimate the apparent activation energy (E a) of the n-butylamine desorption process. The results obtained showed that the HZSM-12 zeolite presents two kinds main of acid sites: one with E a in the range of 115-125 kJ mol-1 classified as weak and other kind with E a varying of 230-250 kJ mol-1 classified as strong.

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Journal of Thermal Analysis and Calorimetry
Authors: A. M. Ramalho, M. M. Conceiçăo, V. J. Fernandes Jr., J. C. Machado, L. E. B. Soledade, and A. G. Souza
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Journal of Thermal Analysis and Calorimetry
Authors: Marta M. Conceição, V. J. Fernandes Jr., F. S. M. Sinfrônio, J. C. O. Santos, M. C. D. Silva, V. M. Fonseca, and A. G. Souza
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Journal of Thermal Analysis and Calorimetry
Authors: F. S. M. Sinfrônio, J. C. O. Santos, L. G. Pereira, A. G. Souza, M. M. Conceiçăo, V. J. Fernandes Jr., and V. M. Fonseca
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Journal of Thermal Analysis and Calorimetry
Authors: J. C. O. Santos, I. M. G. Santos, F. S. M. Sinfrônio, M. A. Silva, E. V. Sobrinho, M. M. Conceiçăo, V. J. Fernandes Jr., and A. G. Souza
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Journal of Thermal Analysis and Calorimetry
Authors: Ana Carla S. L. S. Coutinho, Solange A. Quintella, A. S. Araujo, Joana M. F. Barros, Anne M. G. Pedrosa, V. J. Fernandes Jr., and M. J. B. Souza

Abstract

Nanoporous silica with narrow pore size distribution has attracted increasing attention as a novel material for separations and reactions involving large molecules. SBA-15 has been synthesized in an acidic medium using a triblock copolymer as template. In this work, the SBA-15 was synthesized by the hydrothermal treatment at 373 K for 48 h, of a gel with the following overall molar composition: 1.0TEOS:0.017P123:5.7HCl:193H2O, where TEOS is tetraethyl orthosilicate and P123 is poly(ethylene oxide, propylene oxide and 1,4-dioxane). The obtained material was characterized by thermogravimetry, X-ray diffraction, infrared spectroscopy and BET surface area. A kinetic study using the model free model was accomplished in the stage of decomposition of the template (P123). The obtained value of the apparent activation energy was ca. 131 kJ mol−1.

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Journal of Thermal Analysis and Calorimetry
Authors: Késia K. V. Castro, Ana A. D. Paulino, Edjane F. B. Silva, Thiago Chellappa, Maria B. D. L. Lago, Valter J. Fernandes Jr., and Antonio S. Araujo

Abstract

Thermogravimetry (TG) was used in this study to evaluate thermal and catalytic pyrolysis of Atmospheric Petroleum Residue (ATR) which can be found in the state of Rio Grande do Norte/Brazil, after a process of atmospheric distillation of petroleum. The utilized sample in the process of catalytic pyrolysis was Al-MCM-41, a mesoporous material. The procedures for obtaining the thermogravimetric curves were performed in a thermobalance with heating rates of 5, 10, and 20 °C min−1. From TG, the activation energy was determined using the Flynn–Wall kinetic method, which decreased from 161 kJ mol−1, for the pure ATR, to 71 kJ mol−1, in the presence of the Al-MCM-41, showing the efficiency of the catalyst in the pyrolysis of Atmospheric Petroleum Residue.

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Journal of Thermal Analysis and Calorimetry
Authors: S. C. Souza, M. A. F. Souza, S. J. G. Lima, M. R. Cassia-Santos, V. J. Fernandes Jr., L. E. B. Soledade, E. Longo, A. G. Souza, and I. M. G. Santos
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