Acetic acid catalysed carbon xerogels derived from resorcinolfurfural for hydrogen storage

Abstract

Carbon xerogels were prepared from the sol-gel polymerisation of resorcinol with furfural followed by carbonisation and activation, and their hydrogen storage properties were studied. Acetic acid was used as a catalyst to adjust the initial pH value of the resorcinol-furfural solution. The acetic acid facilitates the condensation reaction by reducing the gelation time dramatically from a few days to several hours. The effect of precursor acidity on the final gels are chemically distinguishable (by 13C CPMAS NMR) from the acetic acid catalysed organic gels compared with uncatalysed gel. The connectivity of the primary carbon particles and particle size are related to the degree of acidity, as were found from SEM photographs. The pore structures were studied by small angle X-ray scattering and nitrogen adsorption techniques after carbonisation and activation in order to determine the effect of precursor pH variables on the resulting samples. A catalysed carbon xerogel prepared with pH ∼ 4.8 has a surface area of 1924 ± 26 m2 g−1, a micropore volume of 0.86 ± 0.08 cm3 g−1 and a hydrogen uptake of 4.65 wt.% at 77 K and 3.9 MPa, showing it to be a promising material for hydrogen storage.