Spent fluid catalytic cracking (FCC) catalyst enhances pyrolysis of refinery waste activated sludge

Catalytic pyrolysis is an effective innocuity, volume reduction and resource recovery technology for petroleum refinery waste activated sludge (rWAS). However, the high cost of catalysts hinders its application. In the present study, the spent fluid catalytic cracking catalyst (sFCCc) was reused to catalytically pyrolyze rWAS for the first time. The pyrolytic kinetics, yields and characteristics of pyrolytic products were investigated. sFCCc reduced the low-temperature (139-390 degrees C) and high-temperature (390-540 degrees C) average activation energy by 12.9% and 6.6% compared to rWAS alone. sFCCc and metallic oxides in rWAS jointly catalyzed the decomposition of rWAS and primary vapor via a series of thermochemical reactions. sFCCc promoted the conversion of rWAS into bio-oil and non-condensable gases. The lowest yield of biochar was 40.6 wt % and the highest content of H-2 in non-condensable gases was up to 38.4 vol %. sFCCc significantly improved the quality of bio-oil. The content of saturated hydrocarbons increased from 37.3 wt % to 45.7 wt % and H/C molar ratios increased from 1.4 to 1.6. The O mobility from rWAS to bio-oil decreased from 22.1 wt % to 14.9 wt %. The pyrolytic residue presented a low environmental risk and showed a catalytic potential in ozonation treatment of refractory refinery wastewater. This study provides a new "wastes-treat-wastes" method for petroleum refinery waste management with the advantages of value-added energy recovery and resources reuse. (c) 2021 Elsevier Ltd. All rights reserved.