Large volume in situ H₂ production on fixed bed reactor by concentrated formic acid aqueous solution

Formic acid is a promising hydrogen storage material for its high H₂ capacity, easy transfer and moderate H₂ regeneration conditions. Active carbon supported Mo₂C with or without Co doping were used as the heterogeneous catalyst in the decomposition of a high concentrated aqueous solution of formic acid up to 50% on a fixed bed reactor. For a given flow rate and reaction temperature, though higher volume of H₂ is produced per unit time, the increase in formic acid's concentration reduces both H₂ selectivity and formic acid conversion rate. At 250 °C, a stream of 236 mL/min H₂ was generated continuously at a high H₂ selectivity (91%) and formic acid conversion rate (86%), from a 10% formic acid fed at the flow rate of 5 mL/min. High reaction temperature improved the conversion of formic acid feed at little expense of H₂ selectivity. The doping of Co in the Mo₂C lattice improves the H₂ selectivity to 100% at 100–200 °C. A life time study showed the stability of this system by the remained high H₂ selectivity in formic acid decomposition. This work of using active carbon supported molybdenum carbides and high concentrated aqueous formic acid, opens up a new route for the portable H₂ generator using formic acid as a hydrogen storage material at no environmental risk.