Naphthalene-based periodic nanoporous organosilicas: II. Hydrogen and methane adsorption and physicochemical study

Novel Periodic Nanoporous Organosilicas (PNOs) synthesized by direct co-condensation of tetraethylorthosilicate and triethoxy(naphthalen-1-yl)silane (as described in detail in part I) were evaluated for their hydrogen and methane storage ability. The naphthalene-based PNO materials exhibit regular hexagonal arrangement of uniform pores, high naphthalene content up to 17 wt.%, specific surface areas above 1000 m2/g and pore size distributions in the microporous/mesoporous boundary. Methane and hydrogen storage properties, at different temperatures, have been investigated for these samples by Sievert-type apparatus. The samples exhibit a reversible methane/hydrogen surface excess adsorption capacity, with measured maximum uptake of up to 5.27 wt.% at 298 K and 3.5 MPa and 2.05 wt.% at 77 K and 4.3 MPa respectively. The analysis of the obtained isotherm curves by Tόth equation shows high grade of surface homogeneity of the samples. Total storage capacities were also estimated. For methane a maximum 41.6 v/v at 298 K and 3.5 MPa was found, while for hydrogen a maximum 15.8 g/L at 77 K and 4.3 MPa was calculated.

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► Naphthalene Periodic Nanoporous Organosilicas for methane and hydrogen physisorption.
► Reversible methane/hydrogen storage capacity.
► Importance of samples’ pore characteristics on methane but not on hydrogen adsorption.
► High grade of samples’ surface homogeneity by Tóth analysis.