| Attempts to prepare carbon molecular sieves (CMSs) by carbon deposition from methane were unsuccessful. The effects of heat treatment alone were examined by heating the samples in N2. There was no evidence of carbon deposition from methane at 800°C. On the other hand, heat treatment significantly affected porosity. The surface areas and micropore volumes of the activated carbons from grain sorghum decreased by 39% and 37%, respectively, upon heat treatment. In contrast, the corresponding values of the commercial carbons increased by 60% and 62%, respectively, upon heat treatment alone.; The effects of experimental conditions on preparing CMSs by carbon deposition from methanol were explored. A thermodynamic analysis was carried out to establish that carbon decomposition would occur under the selected conditions. The surface areas and micropore volumes of the commercial activated carbons increased by 43% and 76%, respectively, upon carbon deposition, and by 62% and 101%, respectively, upon heat treatment alone. The corresponding values of the commercial CMSs modified by the former treatment were 50% and 60%, respectively, lower than those of the as-received CMSs when treated at 700°C; and vice versa when treated at 800°C. In contrast, the surface areas and micropore volumes of the commercial CMSs modified by the latter treatment were 687% and 1900%, respectively, higher than those of as-received CMSs when treated at either 700°C or 800°C.; An attempt was made to convert biomass residues into activated carbons by CO2 activation. The activated carbons produced had BET surface areas ranging from 400 and 1000 m2/g, and the ratios of micropore volume to total pore volume ranging from 0.38 and 0.66.; Experiments were performed to examine the technical feasibility of applying activated carbons for the storage of natural gas at 500 psig and 25°C. Activated carbons were prepared from sorghum through chemical activation with various agents. The highest storage factor (volume of methane adsorbed at STP/total volume of the tank) attained was 89 by the compacted activated carbons from grain sorghum, and was 106 by the compacted commercial activated carbons. |
