Coprocessing of waste cooking oil and fatty acid model compounds with VGO in a pilot-scale FCC riser

Herein, the effects of reaction temperature, Catalyst to Oil ratio, reaction residence time, waste cooking oil (WCO) mixing ratio, WCO feed position, and the addition of a ZSM-5 additive on the product distribution and quality of WCO and vacuum gas oil (VGO) co-processing were investigated in the pilot-scale riser. The experimental results demonstrated that the synergistic treatment of any blending ratios of WCO with VGO in the FCC unit was feasible. As the WCO blending ratio increased, the degree of deoxygenation (DOD) gradually decreased while the aromatic content, research octane number, and motor octane number of gasoline increased. The addition of an additive and changes in the WCO feed position also improved the product distribution and product quality. The experimental results of model compounds indicate that increasing the level of unsaturation and the presence of carboxyl groups in feedstock promoted alkylation, cyclization, and aromatization. GCxGC-MS results indicated that the main oxygenates in the liquid products were carboxylic acids, ketones, and esters. Increasing the cracking severity and adding additives effectively enhanced the DOD and decreased the concentration of oxygenates. Through 14C isotope analysis, the high content of renewable carbon in gasoline was revealed, demonstrating the feasibility of WCO co-processing.