Adsorbate-adsorbate interactions are universally present within adsorbed phases, especially at high fractional occupancy, but their role in increasing the delivery of adsorbed fuels above a given minimum effective pressure is often overlooked. This is because few adsorbents meet the requirements of both practical storage materials (high volumetric surface area, low mass, simple chemical synthesis) and homogeneous surfaces (where the distribution of binding energies is narrow enough to permit the detection of enhancement via adsorbate-adsorbate interactions). Zeolite-templated carbons (ZTCs) have been shown to meet both requirements with respect to their interactions with methane, the primary component of natural gas. In this work, we present a new Langmuir-type model of adsorption that consists of only five fitting parameters and employ it to assess the role of methane-methane interactions in the remarkable delivery of &gt;200 v/v by ZTC at between 5-100 bar. These results are supported by inelastic neutron scattering (INS) spectroscopic investigations as well as ab initio computational studies of methane adsorption on ZTC, and we also report on our latest efforts to densify ZTC powders by jolting volumetry. A critical assessment of the effects of adsorbate-adsorbate interactions on stronger binding heteroatom-modified surfaces shows that this effect is unlikely to remain detectable, even on highly substituted and homogeneous surfaces.

Effects of methane-methane interactions in increasing the volumetric delivery of adsorbed natural gas

ACS Spring 2022

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