Production of pyrolytic oils by catalytic pyrolysis of Malaysian refuse-derived fuels in continuously stirred batch reactor

摘要

Malaysian refuse derived fuels (RDF) as valuable fraction of waste recycling were pyrolyzed in continuously stirred batch rig at 450 °C in the presence and absence of catalysts. Different types of catalysts were used for upgrading both quantity and quality of pyrolysis products: Y-zeolite, equilibrium FCC, ZSM-5, Ni-Mo-catalyst, Co-Mo-catalyst, silica-alumina and alumina. Gas-chromatography, Fourier-transformed infrared spectroscopy, X-ray spectroscopy and other standardized methods were used for the identification of product. RDF pyrolysis has produced gases with yields of 15.7-27.8%, pyrolytic oils of 9.8-17.8% and water (9.2-12.8%) depending on the types of applied catalyst. Data showed that the volatile fraction (both gas and pyrolytic oils) slightly increased with the catalyst, especially for Y-zeolite and ZSM-5. Gases consisted of CO, CO2, hydrogen and hydrocarbons. Main chemical compounds, such as aromatic, branched and non-branched in pyrolytic oils have been affected by catalysts, e.g. isomerization of main carbon frame and aromatization have been shown increasing in yields especially when Y-zeolite and ZSM-5 were applied. The phenol, benzene 1,3-diol and methyl-phenol content of pyrolytic oil obtained from non-catalytic pyrolysis decreased at 45.0%, 40.9% and 38.0%, respectively in the presence of Y-zeolite and at 39.4%, 36.9% and 26.9% over Co-Mo-catalyst compared to the catalyst free pyrolysis, respectively. Sulphur, nitrogen and chlorine were found as contaminants in pyrolytic oils, but their contaminants concentration could be significantly decreased by the use of catalysts. The activity of catalysts in the decrease of impurity followed the order of Ni-Mo-cat.>Co-Mo-cat.>Y-zeolite>FCC>ZSM-5>Al2O3/SiO2>Al2O3. According to EDXRFS analysis, char consisted of impurities such as Ca, Ti, Fe, Cu, Zn and Pb elements.