Mild hydrotreatment of biocrude derived from hydrothermal liquefaction of agriculture waste: improving biocrude miscibility with vacuum gas oil to aid co-processing

The co-processing of biocrude in petroleum refineries is viewed as an economical and practical pathway to produce low-carbon fuels. A major challenge to co-processing is the poor miscibility of biocrudes with petroleum due to their high levels of oxygen. This study investigated the mild hydrodeoxygenation of biocrude derived from hydrothermal liquefaction (HTL) of agriculture waste as a means to enhance its miscibility with petroleum vacuum gas oil (VGO). Blending compatibility tests were performed to identify the extent of deoxygenation required to achieve blending of 10 wt% treated biocrude in VGO. The highest oxygen removal (similar to 72%) was achieved by increasing the temperature in three steps (240, 280, and 300 degrees C), with pressure kept at 1400 psi and a catalyst-to-feed ratio of 0.19g g(-1). Under such conditions, the hydrotreated biocrude was found to be miscible in VGO and the resulting blend was stable over 7 days. The hydrotreated biocrude products were characterized using nuclear magnetic resonance to identify changes in oxygenated compound classes, such as carboxylic acids, alcohols, ethers, carbohydrates, carbonyls, and phenolics. Carboxylics and phenolics were identified as important contributors to the miscibility of the biocrude. In further testing, two 10 wt% blends of hydrotreated and raw biocrude in VGO were co-processed through hydrotreating. These supplementary tests confirmed that the hydrotreated biocrude performed better in terms of catalytic activity than the raw biocrude. (C) 2022 Her Majesty the Queen in Right of Canada. Biofuels, Bioproducts and Biorefining (C) 2022 Society of Industrial Chemistry and John Wiley & Sons Ltd. Reproduced with the permission of the Minister of Natural Resources Canada.