Intensified Glycerolysis of Palm Oil in a Spinning Disc Reactor for Continuous Monoglyceride Production

A traditional approach for synthesizing monoglycerides (MG) is the glycerolysis of triglycerides (TG) containing feedstocks, such as vegetable oil. As glycerol and palm oil are immiscible, the biphasic liquid–liquid reaction is limited by mass transfer. In this work, a spinning disc reactor (SDR), as an intensified reactor, was employed to generate a high-shear and thin liquid film, thereby enhancing micromixing and reaction performance. In the presence of an alkaline catalyst, the effects of operating parameters, including rotational disc speed (R), glycerol to oil molar ratio (Gly/TG), catalyst loading, and feed flow rate (Q), on productivity of glycerolysis, such as TG conversion (X_TG), MG selectivity (S_MG), and MG yield (Y_MG), were examined. Dimensionless numbers, including the Ekman number (E_k), Weber number (We), and Reynolds number (Re), relating different forces (centrifugal force, inertial force, and viscous force), were applied to explain the phenomena in the SDR. The intense centrifugal force zone, characterized by synchronization and a spiral wave (SW), plays a crucial role for achieving a high yield of MG. The results showed that the wider synchronization and centrifugal zones featuring a spiral wave (SW) are essential for achieving a high yield of MG. Increasing the Ekman number (E_k) and Weber number (We) expanded the SW zone. Additionally, the distribution rate of SW (F_a) reflects the effective mixing. High F_a aligns with increased R, indicating efficient SW generation, as seen in sawtooth waves and wavelets. At optimum conditions (reaction temperature of 200 °C, Gly/TG of 3:1, 0.3 wt % NaOH, rotational disc speed of 1000 rpm, and flow rate of 100 mL/min, equivalent to a residence time of 0.47 s), the TG conversion and MG yield were 91% and 51%, respectively. Compared with other reactors, a yield efficiency of MG as high as 47.04 × 10^–5 g/J was achieved in SDR, which is approximately 10-fold higher than the conventional mechanically stirred reactor (4.4 × 10^–5 g/J). Notably, SDR outperformed intensified reactors, achieving a 3.7-fold higher yield than a high-shear mixer (12.7 × 10^–5 g/J). It was demonstrated that SDR is the most promising intensification reactor for continuous MG production from palm oil.