Green solvent production of ethyl lactate via process intensification

Background: Ethyl lactate is a green solvent with many applications in the chemical industry. Several studies of ethyl lactate production can be found in the available literature, including conventional reactive distillation designs, but the green solvent design is not clearly defined in the open literature. Also, several thermodynamic models must be verified as it is important for predicting the binary interaction parameter. Moreover, process design arrangements are crucial for the process intensification proposed. Methods: Herein, the proposed green solvent designs are figured out with the various process design arrangements, including conventional design and three designs of reactive distillation column (RDC), named Design-1 to Design-3. The binary interaction parameters from three thermodynamic models (UNIQUAC, UNIFAC, NRTL) are validated. The process simulation and economic evaluation in terms of the total capital cost (TCC), total operating cost (TOC), as well as total annual cost (TAC) are analyzed using Aspen Plus. Significant findings: The thermodynamic model assessment found that the UNIFAC is applicable for RDC system, but NRTL is preferred for the extractive distillation system. RDC using side stream combined with direct separation (Design-1) is strongly recommended because the TCC and TOC reduce to 57.3% and 17.5%, respectively. The RDC using a side stream combined with extractive distillation separation (Design-2) has the lowest energy consumption (saved 26.3%) and less in TOC (saved 17.5%). Finally, the lowest TAC is Design-1 (saved 40.2%), followed by Design-2 (saved 30.9%) and Design-3 (saved 17.8%), as compared to conventional design.