Tracking renewable carbon in bio-oil/crude co-processing with VGO through 13C/12C ratio analysis

Abstract

Biomass-derived pyrolosis oil (aka. Bio-oil) contains high oxygen and other heteroatoms that prevent it from being directly used as a conventional fuel due to its thermal instability, non-volatility and corrosivity. Co-processing the bio-oil with vacuum gas oil (VGO, a petroleum refining feedstock) leverages the existing petroleum refining infrastructure which significantly reduces Capex for the bio-oil pathway. Increasing renewable carbon incorporation into conventional fuels is a critical step in biofuels development and adoption. To take advantage of this approach, a fast, economic and accurate method with a potenial online monitoring capability is needed for tracking the renewable carbon through processing and then using the information to guide optimization of the co-processing parameters to maximize renewable carbon incorporation in fuel products. Here, we have developed a high-precision analytical protocol that enables accurate 13C/12C ratio analysis for bio-oil/crude samples. Our study demonstrates that high-precision 13C/12C ratio analysis can be a viable way to track renewable carbon incorporation in bio-oil co-processing products including the feedstock derived from C3 plants and guide the optimization of the co-processing parameters. Comparison of δ13C with radiocarbon (14C) results obtained by an accelerator mass spectrometer (AMS) reveals a significant correlation (R2 = 0.998) and confirms δ13C applicability for tracking renewable carbon in co-processing systems. Because C4 plant-derived bio-oils (−13‰) possesess more distinct δ13C values than C3 plant-derived bio-oils (-26‰) relative to VGO (~−30‰), the use of C4 plant-derived feedstock will greatly increase the renewable C traceability through 13C/12C ratio analysis in bio-oil co-processing.