Valter J. Fernandes

Catalytic degradation of high density polyethylene by HZSM-5 zeolite

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. From TG curves, the activation energies, calculated using an integral kinetic method, decreased 60.6% in the presence of the zeolite.

An improved gravimetric method applied to co-processing of polyethylene terephtalate and petroleum blend using HY zeolite as a catalyst

ABSTRACT The co-processing of petroleum and polyethylene terephthalate (PET) was carried out in the presence and absence of a catalyst in an open vessel batch reactor at temperatures of 200, 300, 400, and 500 °C, which corresponds to temperatures of distillation and cracking. The catalyst used was the acidic HY zeolite, which is widely used in petroleum refining. The catalytic co-processing was carried out with the PET–oil charge, at a mass ratio of 1:1, containing 10% of HY zeolite. The conversion degree was measured by knowing the initial sample mass and amount of degraded material for each temperature and reaction time, using an improved gravimetric method consisting of a precision balance and an oven with a heating rate controller. The conversion values obtained were compared for petroleum and PET samples with and without the zeolite catalyst. At temperatures of 200 and 300 °C, the PET showed low conversions, about 5–10%. However, for the catalytic co-processing of PET–oil/HY at these same temperatures, an increase in conversion to about 25–30% was observed. At temperatures of 400 and 500 °C, conversions above 90% were obtained for the two samples, with a subsequent reduction in the activation energy, from 76 kJ mol−1 (PET) to 56 kJ mol−1 (PET–oil/HY). The decrease in the activation energy proved the efficiency of the HY zeolite and the synergistic effect when PET was blended to the oil for the catalytic co-processing, proving to be a viable alternative for the chemical recycling of PET in the petroleum industry.

Hydrothermal synthesis and crystallographic properties of silicoaluminophosphate with different content of silicon

Abstract Silicoaluminophosphate molecular sieves of SAPO-11 type were synthesized with variation in the [Si/(Al + Si + P)] ratio, using the hydrothermal method, starting from silica, pseudobohemite, orthophosphoric acid and water, in the presence of a di-isopropylamine organic template. The samples were characterized by elemental analysis, X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG/DTA), and scanning electron microscopy (SEM). The incorporation of silicon into the framework of SAPO-11 is demonstrated by the variation of the unit-cell volume with the silicon content. CELREF software was used to index and refine the main lines of the XRD patterns. It is shown that the unit-cell volume decreases over a wide range of silicon content.