Controlling the Equilibrium of Formic Acid with Hydrogen and Carbon Dioxide Using Ionic Liquid

Abstract

The equilibrium for the reversible decomposition of formic acid into carbon dioxide and hydrogen is studied in the ionic liquid (IL) 1,3-dipropyl-2-methylimidazolium formate. The equilibrium is strongly favored to the formic acid side because of the strong solvation of formic acid in the IL through the strong Coulombic solute-solvent interactions. The comparison of the equilibrium constants in the IL and water has shown that the pressures required to transform hydrogen and carbon dioxide into formic acid can be reduced by a factor of approximately 100 by using the IL instead of water. The hydrogen transformation in such mild conditions can be a chemical basis for the hydrogen storage and transportation using formic acid.

Ionic Liquids and Dense Carbon Dioxide: A Beneficial Biphasic System for Catalysis

“…Indeed, Yasaka et al very recently investigated the equilibrium reaction of formic acid production from H 2 and CO 2 , with regard to using ILs as solvent. 220 They compared the equilibrium constants in [PPMIm][HCOO], water, and vacuum (to study the gas phase reaction), and they found that the Coulombic solvatation power present in the IL had a tremendously beneficial impact on the equilibrium toward the HCOOH side. The authors see in this method a possible future application for hydrogen storage, as formic acid can (unlike H 2 ) be easily stored and transported in the liquid state.…”

Continuous‐Flow Hydrogenation of Carbon Dioxide to Pure Formic Acid using an Integrated scCO2 Process with Immobilized Catalyst and Base

“…[4b,d] The resulting HCO 2 H/NHex 3 adduct can be separated and cleaved into free formic acid and amine by distillation. Yasaka et al proposed the use of imidazolium-based ILs with formate anions to stabilize HCO 2 H. [6] Herein we present a new concept that allows the continuous-flow hydrogenation of supercritical CO 2 (scCO 2 ) with integrated product separation from an immobilized catalyst and stabilizing base to produce pure HCO 2 H in a single processing unit. [5] After reaction, the solid catalyst is separated by filtration, and the formic acid can be distilled out from the basic IL.…”

Hydrogen Storage Using Ionic Liquid Media

“…[9,[47][48][49][50][51][52] Formic acid contains only 4.4 wt% hydrogen, less than the previous mentioned materials. The abundance of carbon dioxide as substrate enhances the attraction of formic acid as simple and cheap hydrogen storage material.…”