Enzymatic synthesis of acylglycerides from agroindustrial residues: process design and simplified techno-economic assessment

Abstract

This study developed an enzymatic process to add value to palm oil fatty acid distillate (PFAD) and glycerol, resulting in the production of monoacylglycerides (MAG) and diacylglycerides (DAG). The biocatalyst loading (Novozym 435) and molar ratio of reagents were evaluated to obtain a suitable reaction condition in terms of space–time yield and catalytic productivity. A conversion of 80.3% was achieved after 4 h at 65 °C with an acid:glycerol molar ratio of 1:1, using 2.5% (wt/wt, total mass) Novozym 435 in a stoppered flask. In a bubble-column reactor prototype, conversion reached 91.8% after 5 h at 70 °C, reducing the biocatalyst loading to 1.5%. The same biocatalyst loading could be reused for 12 cycles, resulting in high catalytic productivity (458.4 g of main product per g of biocatalyst). The data obtained were used in preliminary process design, modeling, and simulation to estimate equipment sizing, capital investment expenditure (CAPEX), and operational expenditure (OPEX) for industrial-scale acylglyceride production from PFAD and glycerol. Preliminary technoeconomic assessment identified scenarios in which enzymatic MAG/DAG production from agroindustrial residues may be economically feasible, with a positive net present value (NPV) and a payback time of under 3 years.