Hydrothermal Liquefaction\nof Organic Waste Model Compounds:\nThe Effect of the Heating Rate on Biocrude Yield and Quality from\nMixtures of Cellulose–Albumin–Sunflower Oil

Hydrothermal liquefaction\n(HTL) is a promising technology\nfor the\nconversion of high-moisture biomass into a liquid biofuel precursor\nwithout predrying treatment. This study investigated the effects of\nthe heating rate (20–110 °C/min) and feedstock composition\non phase repartition of the HTL products. HTL tests were carried out\nusing as feedstocks cellulose, egg albumin, and sunflower oil as model\ncompounds for carbohydrates, proteins, and lipids, alone and in binary\nmixtures. The biocrude, solid residue, and aqueous phase were characterized\nin terms of composition and elemental percentage. The effects of binary\ninteractions were studied in terms of product yields and compositions.\nIt was observed that higher heating rates resulted in lower solid\nyields from all the cellulose-containing feedstocks and, in most cases,\nin higher biocrude yields and higher energy recovery. The results\nshowed that the heating rate influences also the oil composition.\nBiocrude and solid yields were compared with their prediction based\non the combination of the yields of single model compounds, showing\na general increase in biocrude yields and a decrease in solid yields.\nThe most significant deviation is observed with the mixture cellulose–albumin\nboth for the biocrude and solid yields. In fact, the main interactions\nwere recognized for carbohydrate–protein mixtures followed\nby carbohydrate–lipid and protein–lipid mixtures.