Efficient Reversible Hydrogen Carrier System Based on Amine Reforming of Methanol.

A novel hydrogen storage system based on the hydrogen release from catalytic dehydrogenative coupling of methanol and 1,2-diamine is demonstrated. The products of this reaction, N-formamide and N,N'-diformamide, are hydrogenated back to the free amine and methanol by a simple hydrogen pressure swing. Thus, an efficient one-pot hydrogen carrier system has been developed. The H2 generating step can be termed as "amine reforming of methanol" in analogy to the traditional steam reforming. It acts as a clean source of hydrogen without concurrent production of CO2 (unlike steam reforming) or CO (by complete methanol dehydrogenation). Therefore, a carbon neutral cycle is essentially achieved where no carbon capture is necessary as the carbon is trapped in the form of formamide (or urea in the case of primary amine). In theory, a hydrogen storage capacity as high as 6.6 wt % is achievable. Dehydrogenative coupling and the subsequent amide hydrogenation proceed with good yields (90% and >95% respectively, with methanol and N,N'-dimethylethylenediamine as dehydrogenative coupling partners).