Hydrothermal Liquefaction Biocrude Stabilization via Hydrotreatment

Abstract

The main objective of the manuscript is to investigate mild hydrotreatment upgrading of hydrothermal liquefaction biocrude to improve its stability and energy content. To that end, biocrude hydrotreatment was performed, exploring three different operating windows in order to examine the effect of reaction temperature and hydrogen supply on deoxygenation reactions. A typical NiMo/Al2O3 hydrotreating catalyst was utilized while the experiments were performed in a continuous-flow TRL 3 hydrotreatment plant. The results show that the resulting product has a higher carbon content as compared to the raw feed. The oxygenated compounds were removed, leading to a product with almost zero oxygen and water content, with high energy density. The reaction pathways during the hydrotreatment upgrading of biocrude were investigated via GC-MS analysis and presented in detail in the manuscript. In general, the hydrotreating process was able to improve the quality of the initial biocrude, allowing easier handling and storing for further upgrading, or to be used as an intermediate refinery stream.