Liquid-Liquid Extraction of Formic Acid with 2-Methyltetrahydrofuran: Experiments, Process Modeling, and Economics

Antero T Laitinen; Vyomesh M Parsana; Olli Jauhiainen; Marco Huotari; Leo J P van den Broeke; Wiebren de Jong; Thijs J H Vlugt; Mahinder Ramdin

doi:10.1021/acs.iecr.1c00159

Liquid-Liquid Extraction of Formic Acid with 2-Methyltetrahydrofuran: Experiments, Process Modeling, and Economics

Ind Eng Chem Res. 2021 Apr 21;60(15):5588-5599. doi: 10.1021/acs.iecr.1c00159. Epub 2021 Apr 7.

Authors

Antero T Laitinen¹, Vyomesh M Parsana², Olli Jauhiainen¹, Marco Huotari¹, Leo J P van den Broeke³, Wiebren de Jong⁴, Thijs J H Vlugt³, Mahinder Ramdin³

Affiliations

¹ VTT Technical Research Centre of Finland, Tietotie 4 E, Espoo FI-02044, Finland.
² Department of Chemical Engineering, V.V.P. Engineering College, Gujarat Technological University, Rajkot 360005, Gujarat, India.
³ Engineering Thermodynamics, Process & Energy Department, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Leeghwaterstraat 39, Delft 2628CB, The Netherlands.
⁴ Large-Scale Energy Storage, Process & Energy Department, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Leeghwaterstraat 39, Delft 2628CB, The Netherlands.

Abstract

Formic acid (FA) is an interesting hydrogen (H₂) and carbon monoxide (CO) carrier that can be produced by the electrochemical reduction of carbon dioxide (CO₂) using renewable energy. The separation of FA from water is challenging due to the strong (cross)association of the components and the presence of a high boiling azeotrope. For the separation of dilute FA solutions, liquid-liquid extraction is preferred over conventional distillation because distilling large amounts of water is very energy-intensive. In this study, we use 2-methyltetrahydrofuran (2-MTHF) to extract FA from the CO₂ electrolysis process, which typically contains <20 wt % of FA. Vapor-liquid equilibrium (VLE) data of the binary system 2-MTHF-FA and liquid-liquid equilibrium (LLE) data of the ternary system 2-MTHF-FA-water are obtained. Continuous extraction and distillation experiments are performed to test the extraction power and recovery of 2-MTHF from the extract. The VLE and LLE data are used to design a hybrid extraction and distillation process to produce a commercial grade product (85 wt % of FA). A detailed economic analysis of this hybrid extraction-distillation process is presented and compared with the existing FA separation methods. It is shown that 2-MTHF is a cost-effective solvent for FA extraction from dilute streams (<20 wt % FA).