(78d) Sustainable marine fuel production through mild hydrotreating of catalytic fast pyrolysis oil

Lignocellulosic biomass-derived biofuels have great potential to reduce sulfur and fossil carbon dioxide (CO₂) emissions from the maritime sector and help achieve the International Maritime Organization (IMO) GHG emission targets and, at the same time, offer an alternative fuel source for meeting the growing demand for marine fuel. Hydrotreating experiments of the heavy organic fraction (bottom layer) of woody biomass-derived catalytic fast pyrolysis (CFP) oil were conducted at 300-350 °C, 103 bar (1500 psi) with weight hourly space velocities (WHSV) of 0.12-0.24 g/(gh) to produce sustainable marine fuel. Analysis conducted following the ISO 8217 demonstrated that our hydrotreated product met selected standard marine fuel properties. The bottom CFP oil with 23 wt% oxygen on a dry basis became significantly deoxygenated with less than 5 wt% oxygen in the hydrotreated oils at all hydrotreating conditions studied. Increasing hydrotreating temperature or decreasing WHSV led to enhanced deoxygenation and hydrogenation, resulting in a product oxygen content below the detection limit (0.05 wt%) at the highest temperature. The hydrotreated oils were distilled at 140 °C to remove water and compounds with low flash points to obtain marine fuel cuts. Hydrotreating at 300 °C with a WHSV of 0.17 g/(gh) resulted in the highest yield of marine fuel fraction with fuel properties meeting all tested ISO 8217 specifications and miscible with very low sulfur fuel oil (VLSFO); this milder condition also leads to savings in hydrotreating costs.