Abstract
Formic acid is a promising liquid organic hydrogen carrier (LOHC) since it has relatively high hydrogen content (4.4 wt%), low inflammability, low toxicity and can be obtained from biomass or from CO2. The aim of the present research was the creation of efficient 1 wt% Pd catalysts supported on mesoporous graphitic carbon (Sibunit) for the hydrogen production from gas-phase formic acid. For this purpose, the carbon support was modified by pyrolysis of deposited precursors containing pyridinic nitrogen such as melamine (Mel), 2,2′-bipyridine (Bpy) or 1,10-phenanthroline (Phen) at 673 K. The following activity trend of the catalysts Pd/Mel/C > Pd/C ~ Pd/Bpy/C > Pd/Phen/C was obtained. The activity of the Pd/Mel/C catalyst was by a factor of 4 higher than the activity of the Pd/C catalyst at about 373 K and the apparent activation energy was significantly lower than those for the other catalysts (32 vs. 42–46 kJ/mol). The high activity of the melamine-based samples was explained by a high dispersion of Pd nanoparticles (~2 nm, HRTEM) and their strong electron-deficient character (XPS) provided by interaction of Pd with pyridinic nitrogen species of the support. The presented results can be used for the development of supported Pd catalysts for hydrogen production from different liquid organic hydrogen carriers.
Highlights
IntroductionAmong them are reducing non-renewable sources of energy and high CO2 emission, which are suspected to excite global warming with all related problems
According to research performed for the US Department of Energy [1], it is expected that despite growth in non-fossil fuel consumption will be greater than that of fossil fuels, the fossil fuels will still account for 78% of energy use in 2040
The goal of the present work was the creation of efficient Pd catalysts for the hydrogen production from formic acid based on the N-doped carbon supports obtained by deposition of melamine, 1,10-phenanthroline and 2,20 -bipyridine on a mesoporous graphitic carbon
Summary
Among them are reducing non-renewable sources of energy and high CO2 emission, which are suspected to excite global warming with all related problems. For this reason, interest in eco-friendly and renewable sources like hydrogen, water, solar or wind energy grows every year. The main problems with the hydrogen use are its storage and transportation. The various methods based on physical or chemical storage have been developed to solve these problems. The physical methods assume storage of molecular hydrogen in vessels at high pressure and low temperatures or Energies 2019, 12, 3885; doi:10.3390/en12203885 www.mdpi.com/journal/energies
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