Co-processing represents an opportunity to reduce the carbon intensity of transportation fuels by incorporating biocrude in refinery units. 5-10 vol% biocrude is expected to be co-processed in existing refinery units at some point, thus eliminating the need for a stand-alone biorefinery and post-blending facilities. To enable co-processing, biocrudes need to be compatible for blending with petroleum fractions, such as gas oils. Biocrudes are highly polar and contain 10–40% oxygen, resulting in challenges for mixing. This work focusses upon the mild upgrading of biocrude to the extent at which it can be blended with petroleum vacuum gas oil (VGO) for potential co-processing in fluid catalytic cracking or hydrocracking units. In this work, three different biocrudes derived from hydrothermal liquefaction (HTL), pyrolysis of forest biomass and organic wastes were mildly hydrotreated in a 300 mL autoclave unit. Tests were conducted using a pre-sulfided hydrotreating catalyst at reaction temperatures of 190–300 °C, an oil/catalyst ratio of 20-24 and a reaction time 6-9 h. Subsequently, the mixing compatibility of the hydrotreated biocrudes at a blending of 10 vol% hydrotreated biocrude in VGO was investigated using an in-house established method. Optical microscopy was employed to visualize the homogeneity of the blends after settling for 24 h. Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR; <sup>1</sup>H and <sup>13</sup>C) spectroscopy analyses of the original biocrudes, and their hydrotreated products, helped to identify compound classes that were resistant to mild hydrotreating. Table 1 lists the operating conditions and outcomes of the biocrude upgrading and mixing compatibility experiments. As shown in Table 1, 40-75% oxygen reduction was achieved through mild hydrotreating. It was found that lowering the oxygen content in two or three reaction steps was an effective approach to achieving miscibility.

Mild upgrading of biocrudes to enhance their co-processing in refinery units

ACS Fall 2020 Virtual Meeting

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