Eco-efficient hydrolysis of coconut oil: a continuous hydrothermal and water-only process for the production of oleochemicals

Abstract

A continuous hydrothermal process using water as reaction medium was investigated for the selective hydrolysis of triglycerides under sub- and supercritical conditions. The process was operated in continuous flow at 250–400 °C and 22–25 MPa with residence times between <1 s and <60 s, enabling controlled partial or near-complete hydrolysis without added catalysts, organic solvents and expensive enzymes. At 380 °C and 25 MPa, selective partial hydrolysis yielded up to 51 wt% mono-diglycerides and 32 wt% fatty acids at a residence time of 23 s. The process was demonstrated at a pilot scale with a throughput of 30 kg h⁻¹ and stable operation at high oil concentrations up to 34 wt% in the reactor. Integration of counter-current heat recovery reduced the external energy demand by up to 61%, addressing the high energy intensity typically associated with supercritical water processing. Hydrolysates enriched in mono- and diglycerides exhibited strong emulsifying performance and long-term stability up to 1 year, comparable to that of a commercial emulsifier. These results show that continuous, water-only hydrothermal hydrolysis enables rapid and selective triglyceride conversion within an energy-integrated and scalable process configuration.