Production of CO-free H2 from formic acid. A comparative study of the catalytic behavior of Pt metals on a carbon support

The vapor-phase decomposition of formic acid was investigated over Pt metals supported on inert carbon Norit with the aim of producing CO-free H-2. FTIR spectroscopic studies revealed that formic acid dissociated on Pt metals at 220-240 K, but the formate species formed was stable only below 300-350 K. Decomposition of formic acid started at and above 350 K on all catalysts and was complete at 473-523 K. Kinetic studies on Pt/Norit demonstrated that the decomposition was a zero-order process with an activation energy of 70.7 kJ/mol. Although dehydrogenation was the predominant process at lower temperatures, CO-free H-2 was not produced on any catalyst. The highest selectivity of 98.3-99% for H-2 formation was attained on Ir/Norit. For all catalysts, the selectivity was improved considerably by the addition of water to formic acid. The production of CO-free H-2 was achieved only on supported Ir at 383-473 K. Similarly, as regards the H-2 yield the outstanding catalyst was Ir/Norit, followed by Pt/Norit. (C) 2011 Elsevier Inc. All rights reserved.