Interaction of spent FCC catalyst and asphalt binder: Rheological properties, emission of VOCs and immobilization of metals

Abstract

Spent fluid catalytic cracking (FCC) catalyst and its reutilization in asphalt mortar was investigated. The interaction between spent FCC catalyst and Pen 60/80 asphalt binder has been evaluated by simultaneously discussing volatile organic compounds (VOCs) released from asphalt binder and mobility of selected metals elements existed in spent catalyst. Dynamic shear rheological test results showed that the high temperature performance of asphalt mortar was significantly improved by coarse spent FCC catalyst. Consequently, a higher rutting factor and lower fatigue factor can be obtained under similar filler to binder ratio. However, the low temperature performance reduced with an increase of spent catalyst compared with limestone powder asphalt mortar due to fluidity reduction of asphalt binder in pores of catalyst. Addition of spent FCC catalyst leaded to a reduction of VOCs released from asphalt binder in respect of relative content and categories, especially for polycyclic aromatic hydrocarbons (PAHs), such as naphthalene, anthracene, phenanthrene and its derivatives. Spent FCC catalyst influences emission of VOCs in the manner of adsorption and assisted catalytic reaction by resident zeolite structure and rare earth elements. On the basis of better understanding about migration of metals from spent catalyst to asphalt matrix and to aqueous solutions, immobilization of vanadium, nickel, lanthanum and cerium was enhanced by possible chemical reactions asphalt binder as well as physical wrapping effect.