Catalytic Production of Liquid Fuels from Organic Residues of Rendering Plants

Anaerobic low temperature conversion (LTC) converts organic residues such as animal meal or meat and bone meal (MBM) to bio‐crude, a solid product, containing carbon and phosphorus, reaction water and non‐condensable gases. The yield of bio‐crude increases with the content of volatile solids. The efficiency of the conversion as well as the calorific value of the liquid fuel produced are favorably affected by the partial recycling of inorganic constituents, high amounts of volatile solids and a low percentage of heteroatoms present in the feeding material. Heating values are 32.3 MJ/kg for bio‐crude from animal meal and 19.5 MJ/kg for bio‐crude from MBM. Both bio‐crude and animal fat produced were effectively converted in a vertical reactor construction with a fixed bed of aluminosilicates of the zeolite family or acidic clays, respectively. Products are bio‐fuels of varying chemical qualities. Depending on the reaction temperature and the catalyst type, aliphatic hydrocarbons (T = 400 °C, ～97 %) or alkylbenzenes (T = 550 °C) are the main products. The calorific values of these bio‐fuels are in a range from 40.1 to 41.9 MJ/kg and the kinematic viscosities are between 0.9 and 2.29 mm²/s. The solid products of LTC from different biomass (sludge, animal meal, MBM) contain a significant amount of phosphorus. In the case of the solid product from MBM it was as high as 242 mg P₂O₅/g. Solubility in citric acid showed that in the case of MBM, 98.8 % of total phosphorus is potentially available to plants. Pot experiments demonstrated a similar plant growth as with other organic fertilizers.