Formic acid (53 g H2/liter) is a promising liquid storage and delivery option for hydrogen gas. Hydrogen release from FA is exergonic but not exothermic. This thermodynamic property leads to a couple of distinct advantages; H2 can be released from the liquid carrier at (i) low temperature and (ii) high H2 pressure (P&gt; 600 bar) has been reported. In the past decade, significant advancements have been achieved in catalyst development for selective hydrogen generation from formic acid. Hence the focus of majority of the publications has been on catalysis of H2 release. However, the thermodynamics to make FA from carbon dioxide and H2 is unfavorable (ΔGo = +31kJ/mol). Hence, the direct formation of FA by hydrogenation of carbon dioxide is limited by its reaction equilibrium. Role of the solvent can have a significant effect on the position of this equilibrium. Thermodynamics and kinetics of these three reactions will be discussed with respect to challenges and opportunities for formic acid as a potential H2 carrier. HCOOH ↔ó H2 +CO2 (1) HCOO- +H2O↔ H2 +HCO3- (2) HCOOH ↔ H2O + CO (3)

Thermodynamics and kinetics of formic acid as a H2 carrier

2019 Spring National Meeting

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