Comparative adsorption study of EVS-10 and ETS-10

• EVS-10 has a structure and composition indistinguishable from ETS-10.
• EVS-10 and ETS-10 have comparable adsorption characteristics.
• EVS-10 has a defect-free pore structure due to its nano scale crystallites.

Vanadium silicate EVS-10 is analogous to ETS-10 except that vanadium completely substitutes for titanium in the structure. This study compares the structural and adsorptive characteristics of EVS-10 with ETS-10. The structures were characterized by powder XRD, EDX, argon physisorption, and SEM/TEM. The Henry law constants and heats of adsorption were calculated for both adsorbents from low pressure adsorption data using CH4, C2H6, C2H4, N2, O2, and CO2 for pressures up to 100 kPa and temperatures of 303, 323, and 343 K. The adsorption data were fit using Langmuir, Toth, and Redlich–Peterson isotherms. The best model was selected based on the quality of fit to the data and how closely the model predicted the saturation concentration compared to the value calculated from the measured pore volume data. The structural properties for EVS-10 are almost indistinguishable from ETS-10. The adsorption data reflects this similarity in that both adsorbents have similar heats of adsorption and selectivities for a wide range of gases. These results suggest that heteroatom substitution in ETS-10 does not necessarily affect its adsorption properties if the framework dimensions and composition remain similar.

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