Design and optimization of reactive distillation for enhancing supercritical transesterification process to produce biodiesel

The present study explored the optimization of a reactive distillation column (RDC) for biodiesel production using supercritical transesterification (SCTE). The SCTE process at high pressure and temperature, is known for water-sensitive flexibility and catalyst-free operation, and has shown promising advantages in biodiesel production. The steady-state simulations were conducted using Aspen Plus, with two RDC configurations: RDC-1, employing a single feed of oil and methanol, and RDC-2, utilizing separate feeds. Surprisingly, high conversion rates were achieved at only 8.5 MPa pressure. The study aiming to identify an optimized RDC design, systematically examined the impact of design parameters such as reflux ratio, feed temperature, and the number of reactive stages on conversion and energy requirements. Internal column specifications and species flow through each stage were investigated to comprehend reaction and separation processes. Temperature analysis revealed that preheating to 380 °C significantly improved conversion and reduced reboiler heat duty. RDC-1, with 9 reactive stages, demonstrated greater conversion efficiency, while RDC-2, with 11 stages, exhibited better biodiesel separation. By optimizing reflux ratios, the study achieved remarkable conversions with enhanced methanol separation. Cost estimation revealed that RDC-1 promoted lower capital and operating costs, making it a preferred design and an efficient option for SCTE-based biodiesel production.