Structural modification and heat transfer enhancement on HKUST-1 for adsorbed natural gas

Abstract

HKUST-1 is being considered as a promising storage medium for adsorbed natural gas (ANG), but the practical application still calls for the improvement on the adsorption capacity for methane, hydro-stability and apparent thermal conductivity. Here, incorporation and carbonization were employed to ameliorate the performances of HKUST-1, and the effect of mixing graphene oxide (GO) and graphite intercalation compounds (GIC) as well as equipping honeycomb heat exchanging device (HHED) on mitigating the thermal effect was also evaluated. Researches were conducted in terms of adsorption equilibrium of methane on the samples and the dynamic characteristic of a storage vessel during a typical flow rate of charge/discharge which is in correspondence with the typical consumption rate of the fuel required by the power unit. Results show that, in comparing with those of the sample (GOH-5) prepared by incorporating with 5% (mass) GO, the sample (EH-2) incorporated with the same mass of composite formed by mixing GO and GIC in a mass ratio 2:1 had 2.0%, 4.4%, 1.2% and 28.4% increment in specific surface area, specific microporous volume, mean pore width and thermal conductivity. Results also reveal that, within the temperature-pressure range 273–323 K and 0.3–3.5 MPa, the mean useable capacity (UC) of methane on EH-2 and GOH-5 samples consolidated under pressure 2 MPa is nearly equal, and the average useable capacity ratio (UCR) on the storage system obtained the largest value while HHED + GOH-P (formed by GOH-5 under pressure 2 MPa) was filled into the system. It suggests that incorporating HKUST-1 with composite contained certain amount of GIC is conducive to improving the thermal conductivity, but equipping HHED within the storage system is more effective in improving the performance of the ANG system.