Molecular simulation of the accumulation of alkanes from natural gas in carbonaceous materials

The accumulation of heavier alkanes is a significant drawback in the use of activated carbon for the storage of natural gas. Thus far, no predictive method has been developed that can describe bed deactivation beforehand. We propose a new methodology that uses atomistic simulation and only carbon pore size distribution as the input to predict bed deactivation caused by natural-gas alkanes. We validated our model by comparing the calculated results with experimental data for alkane monocomponent isotherms and bed deactivation for WV 1050 activated carbon. Using this methodology, we estimated bed deactivation for three other species of activated carbon (Maxsorb, BPL and Norit R1) within the values found in the literature. We then predicted the optimal pore size for achieving maximum storage capacity and for minimizing the retention of heavier fractions. The suggested method will assist both fast screening and new synthesis routes for carbonaceous materials with diminished heavier-alkane selectivity. Carbon-based adsorbents used in CO2 removal during the processing of raw natural gas can also be improved. (C) 2013 Elsevier Ltd. All rights reserved.