HZSM-5 zeolite was screened as catalyst for high density polyethylene degradation at 450‡C, under nitrogen static atmosphere.
Two different samples were studied in this condition: HDPE alone and mixed with HZSM-5. The reactor was connected on line
to an HP 5890-II gas Chromatograph. Sample degradation was investigated using a Perkin-Elmer Delta 7 Thermobalance, from room
temperature to 800‡C, with heating rates of 5.0, 10.0 and 20.0‡C min−1. From TG curves, the activation energies, calculated using an integral kinetic method, decreased 60.6% in the presence of
Authors:Edjane F. B. Silva, Marcílio P. Ribeiro, Ana C. F. Coriolano, Ana C. R. Melo, Anne G. D. Santos, Valter J. Fernandes Jr., and Antonio S. Araujo
properties and other characterization techniques [ 3 ]. In the case of catalyticdegradation lower temperatures are required and chemical product distribution is fewer than in thermal degradation, leading to more valuable products.
Authors:Ana C. R. Melo, Edjane F. B. Silva, Larissa C. L. F. Araujo, Mirna F. Farias, and Antonio S. Araujo
fuels. The emphasis given to the use of fuels from biomass needs a higher understanding of the kinetic parameters involved in the reactions of conversion [ 3 , 4 ]. The catalyticdegradation is a process that provides lower temperatures and distribution
Authors:Anabela Coelho, Luís Costa, Maria Marques, Isabel Fonseca, Maria Lemos, and Francisco Lemos
High-density polyethylene (HDPE) was cracked over HZSM-5 and HY zeolites and the reaction was followed using simultaneous
thermogravimetry (TG) and differential scanning calorimetry (DSC) and was compared with the degradation of the same material
in the absence of an added catalyst. The products obtained in the degradation reaction were analyzed by gas chromatography.
The simultaneous use of the signals from the TG and DSC allowed an accurate description of the thermal and catalytic degradation
of the polymer by application of a novel kinetic model that correlates the two signals that are measured. The kinetic parameters
were estimated by fitting this model to the experimental data obtained by TG and DSC. For both zeolites, the polymer degradation
takes place at lower temperatures when compared with pure thermal degradation. It was also observed that the two zeolites
have a distinct influence on the product distribution.
Authors:A. Marcilla, A. Gómez-Siurana, and S. Menargues
A study of the catalytic degradation of EVA copolymers under air atmosphere has been carried out using thermogravimety (TG). Three commercial EVA copolymers and five zeolites and related materials catalysts have been selected. The degradation process in air atmosphere involves four main decomposition steps (as observed in TG), being more complex than the corresponding process in inert atmosphere. The presence of MCM-41, HY and H-β does not seem to noticeably affect to the overall degradation temperature, despite the temperature of maximum reaction rate for the second decomposition step being slightly displaced towards lower temperatures. Contrarily, the presence of HZSM-5 and HUSY zeolites seems to displace the main stage of the oxidative degradation process towards higher temperatures. Moreover, the relative importance of the second and third decomposition step is different depending on the amount and the nature of the zeolite mixed with the EVA sample. The results obtained show that the presence of the catalyst also enhances the formation of the carbonous residue.
Authors:Edjane F. B. Silva, Marcílio P. Ribeiro, Luzia P. F. C. Galvão, Valter J. Fernandes, and Antonio S. Araujo
residues can be converted in valuable products through thermal or catalyticdegradation [ 1 ]. Consequently, polymer degradation became an increasing and important method to convert plastic residues into chemical products such as fuel and petrochemicals [ 2
Authors:Juan Zhang, Feng-Tian Hu, Qian-Qian Liu, Xin Zhao, and Shou-Qing Liu
catalyticdegradation of organic pollutants utilizing molecular oxygen under visible light irradiation. However, tris(1,10)-phenanthroline iron(II) has not been reported as a photo-Fenton catalyst up to now. In this study we loaded tris(1,10)-phenanthroline