Renewable-carbon recovery in the co-processing of vacuum gas oil and bio-oil in the FCC process – Where does the renewable carbon go?

Abstract

This study aims to quantify the renewable-carbon content in the products produced by co-processing vacuum gas oil with up to 20 wt% bio-oil in the fluid catalytic cracking (FCC) process. The renewable-carbon content of 40 product samples collected at a demonstration-scale FCC unit was quantified by 14C isotopic analysis.The renewable-carbon mass balance closure ranged between 90% and 110%. The biogenic-carbon content of the liquid effluent increased linearly as a function of the amount of bio-oil fed to the FCC. Most of the biogenic carbon was recovered as coke. Moreover, the renewable-carbon recovery in the liquid effluent remained at approximately 30 wt%, independent of the percentage of bio-oil fed to the FCC process. The FCC process is generally considered the largest single source of greenhouse gas (GHG) emissions in a petroleum refinery. These results will enable the life-cycle assessment from the co-processing of bio-oil in an FCC.The renewable carbon present in the coke deposited on the FCC catalyst, which is later burned during catalyst regeneration in the FCC, would contribute to GHG emission abatement. Additionally, the use of bio-oil as an FCC feed could contribute to reducing the carbon intensity of gasoline, diesel, and fuel oil.