Light olefin production from catalytic pyrolysis of waste tires using nano-HZSM-5/γ-Al2O3 catalysts

Nano-HZSM-5/gamma-Al2O3 composite catalysts were prepared by employing mesoporous gamma-Al2O3 as supports. Their structures, morphologies and acidity were characterized using powder X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR) analysis, N-2 adsorption and desorption measurement, scanning electron microscope and the NH3 temperature-programmed desorption. Nano-HZSM-5 was uniformly dispersed and grown on the surface of gamma-Al2O3 carrier. Nano-HZSM-5/gamma-Al2O3 also showed a proper acidity with the uniform acid density distribution. The catalytic pyrolysis of waste tires was carried out in a micro-reactor system, and the composition of the product was analyzed on-line by gas chromatography. The selectivity to light olefins of nano-HZSM-5/gamma-Al2O3 reached 29.9%, which was higher than that of nano-HZSM-5 zeolites, gamma-Al2O3 and the mixture of nano-HZSM-5 and gamma-Al2O3 with the same composition as nano-HZSM-5/gamma-Al2O3.