Production of Renewable Liquid Fuels by Coprocessing HTL Biocrude Using Hydrotreating and Fluid Catalytic Cracking
Yi Zhang, Anton Alvarez‐Majmutov
Abstract
In this study, we explore coprocessing of hydrothermal liquefaction (HTL) biocrude with vacuum gas oil (VGO) in the fluid catalytic cracking (FCC) process. Coprocessing experiments were conducted using an advanced cracking evaluation FCC laboratory unit. Four sets of experiments were conducted: one with pure VGO to set the baseline performance and three sets with different VGO/HTL biocrude blends (5, 10, and 15% biocrude). Each set of tests covered a range of catalyst-to-oil ratios with temperature fixed at 510 °C. Prior to the FCC tests, the VGO and biocrude blends were hydrotreated in a continuous pilot plant to reduce the levels of heteroatoms, in an attempt to represent a refinery scheme with an FCC pretreat hydroprocessing unit. During the FCC tests, the biocrude blends showed lower conversion levels with respect to the baseline as a result of having more nitrogen and oxygen compounds that could have acted as catalyst inhibitors. Nevertheless, at a given conversion, the selectivity toward gasoline improved when the coprocessing ratio was 5%. The coprocessed gasoline products were nearly identical in terms of hydrocarbon type composition to the one from VGO at high conversion. The 10 and 15% biocrude blends showed a pronounced tendency to yield more light cycle oil, dry gas, and coke than VGO. As a whole, the study suggests that the coprocessing ratio for HTL biocrude should optimally be around 5% to minimize impacts on product yield distribution.