Advances in the study of methane storage in porous carbonaceous materials

Abstract

This paper presents an overview of the results of our research group in methane storage, in which the behaviour of different carbon materials in methane storage has been studied. These materials include physically activated carbon fibres (ACFs), chemically activated carbons (ACs) and activated carbon monoliths (ACMs), all of them prepared in our laboratories. These results have been compared with those corresponding to commercial ACFs, commercial activated carbon cloths and felts, and a commercial activated carbon. An in depth analysis (different raw materials, activating agent and preparation variables) has been done in order to obtain the carbon material with the best methane adsorption capacity by unit volume of adsorbent. The important effect of the micropore volume, micropore size distribution (MPSD) and packing density of the carbon materials in the methane adsorption capacity and delivery has been analysed. After this study, activated carbons with volumetric methane uptake as high as 166 v/v and delivery of 145 v/v have been prepared. In addition, ACM with methane uptake of 140 v/v and a delivery of 126 v/v has also been obtained. Moreover, the results corresponding to preliminary in situ small angle neutron scattering (SANS) study of CD 4 adsorption under pressure in different porous carbons and a zeolite are also included. These experiments have established SANS as a viable technique to investigate high-pressure methane adsorption. CD 4 adsorption at supercritical conditions produces changes in the SANS curves. The changes observed are in agreement with theoretical speculations that the density of the adsorbed phase depends upon the pore size.