Separation of CO2 from CO2-CH4 mixtures is an important issue in natural gas and biogas purification. The design of such separation processes depends on the knowledge of the behavior of multicomponent adsorption, particularly that of CO2-CH4 mixtures. In this study, we present a series of experimental binary equilibrium isotherms for CO2-CH4 mixtures on an activated carbon at 293 K and compare them with predicted values using the Ideal Adsorption Solution Theory (IAST) and the Extended Langmuir (EL) model. Even at concentrations of ca. 20% for all binary isotherms, CO2 already presents higher adsorbed amounts with respect to CH4. A maximum selectivity of around 8.7 was observed for a nearly equimolar mixture at 0.1 MPa. The IAST in conjunction with the Toth equation showed slightly better results than IAST using the Langmuir equation and both showed better results than the EL model.

The synthesis and characterization of new molecular sieves of the MCM-41 type are presented in this study. Samples were obtained from the alkoxides of Si, Ti and Al and different long-chain amine and alkylammonium salts surfactants, by the sol-gel method, through moderate agitation at room temperature. The reactions were conducted in two steps, acid hydrolysis (pH=2) and alkaline condensation (pH=10), both taking about 90min. The synthesized crystals were characterized using infrared spectroscopy, thermogravimetry and X-Ray diffraction. Pore diameters and surface areas were measured by N2 adsorption at 77K. Catalytic tests were conducted for anthracene oxidation using different oxidants (H2O2, alkylhydroperoxide) and organic solvents (benzene, tetrahydrofuran).

This paper presents experimental results for adsorption equilibrium of methane, ethane, and butane on nanoporous activated carbon obtained from coconut shells. The adsorption data were obtained gravimetrically at temperatures between 260 and 300K and pressures up to 1 bar. The Toth isotherm was used to correlate the data, showing good agreement with measured values. Low-coverage equilibrium constants were estimated using virial plots. Heats of adsorption at different loadings were also estimated from the equilibrium data. Adsorption properties for this material are compared to the same properties for BPL activated carbon and BAX activated carbon.