Role of chlorides in reactivation of contaminant nickel on fluid catalytic cracking (FCC) catalysts

Abstract

Abstract Nickel, a common contaminant in crude oil, deposits on Fluid Catalytic Cracking (FCC) catalysts and induces unwanted dehydrogenation reactions. These lead to an increase in hydrogen and coke which inhibits the FCC unit from reaching its optimal operation. Modern catalyst technologies can include nickel passivation strategies to minimize such detrimental effects, and, over time, aging of the nickel on catalyst also diminishes its deleterious activity to some extent; however, reactivation of nickel due to chemical interactions within the FCC unit can retard aging and further penalize the catalytic performance. For the first time, we attempt to demonstrate and characterize the physiochemical and catalytic effects of chloride ions on contaminant nickel in the FCC environment. Equilibrium catalyst (Ecat) samples obtained from industrial FCC units are exposed to chloride ions, and changes in physicochemical characteristics, catalytic selectivity, and the reducibility of nickel are analyzed. These changes indicate the reactivation of nickel and an increase in unwanted dehydrogenation reactions following exposure to chloride ions. Spectroscopic analyses show that the interaction with chloride ions alters the electronic environment of nickel, which makes it easier to be reduced in the FCC riser, and Advanced Cracking Evaluation (ACE) studies show equilibrium catalysts that were exposed to chloride ions gave higher coke and H2 yields. These results bridge the gap between existing literature and the FCC environment by demonstrating that chloride ions can interact and reactivate nickel contaminant on FCC catalysts.