Co-Processing of Used Cooking Oil in Hydrocracker: Refinery-Scale Trial for Sustainable Aviation Fuel Production

This study presents a field-scale demonstration of Used Cooking Oil (UCO) co-processing in a commercial hydrocracker, with the primary objective of evaluating its viability as a pathway for producing Sustainable Aviation Fuel (SAF) and renewable diesel. Key performance indicators assessed include reactor thermal behaviour, catalyst stability, biogenic carbon integration, and product quality. The trial supports the broader refinery objective of aligning with decarbonisation mandates using existing infrastructure and minimal capital investment. Among the process units in a typical refinery, Hydrocrackers stand out for their versatility and superior adaptability to handle renewable bio-feeds. A controlled co-processing trial was executed in Hydrocracker Unit with UCO fed at up to 3 vol% of total feedstock. UCO, a second-generation biofeeds rich in long-chain triglycerides and oxygenates, was introduced via a filtered, dedicated pump system connected to the main feed line. Reactor bed temperatures, pressure drops, hydrogen partial pressure, off-gas composition, and sour water generation were monitored in real-time. Analytical evaluation of product fractions included cold flow properties, distillation behaviour, and biogenic carbon quantification using ASTM D6866. Particular emphasis was placed on temperature profiles across the catalyst beds, detection of trace gases, and water production behaviour to assess the extent of hydrogenolysis, decarboxylation, and hydrodeoxygenation reactions. While hydrotreaters have been widely used for co-processing, hydrocracking units offer distinct advantages. Their multi-bed configuration, higher hydrogen partial pressures, and robust temperature management systems make them better suited to handle the operational challenges posed by biofeeds—notably high hydrogen demand, exothermic reactions, and the presence of contaminants. In addition, hydrocrackers have integrated fractionation systems, enabling effective separation of renewable-derived molecules into desired fuel product streams such as jet and diesel. The trial validated the hydrocracker's capability to process oxygenated renewable feedstocks under commercial operating conditions. A moderate exothermic rise was observed in reactor Bed-1 and Bed-2 due to hydrodeoxygenation, decarboxylation and saturation reactions, while downstream beds exhibited minimal impact, indicating rapid reaction kinetics of UCO components compared to fossil VGO. Gross conversion improved and middle distillate yield increased, with a product shift toward kerosene and diesel. Biogenic carbon was successfully traced (ASTM D6866) in ATF fraction and diesel fraction, supporting the effectiveness of co-processing for renewable content integration. Though ATF freezing point and diesel pour point increased, still remained within product specification, with slight improvement in cetane index. These results affirm the viability of SAF production from co-processing routes using existing refinery infrastructure.