Estimación de Constantes de Difusión de CO2 en Materiales Microporosos

SIBY GARCÉS; JHONNY VILLARROEL-ROCHA; KARIM SAPAG; SOPHIA A. KORILI; ANDONI GIL

San Luis

Simposio; 2° Simposio sobre Adsorción, Adsorbentes y sus Aplicaciones; 2013

Universidad Nacional de San Luis - INFAP - CONICET

In this work adsorption rates, uptake-curves, of CO2 on two commercial zeolites (5A and 13X), a commercial MOF (ZIF-8) and a pillared clay (Zr-PILC) [1] were measured volumetrically at 273 K and gas pressure up to 800 mmHg. The diffusion time constants were calculated using the isothermal and non-isothermal models [2] in order to evaluate the heat effects. The results found were discussed from the pore size distribution and the strength of the interaction of CO2 with the adsorbent, evaluated from the Henry’s Law constants. The pressure-dependence of the diffusion time constants was predicted with the Darken-relation, structural [3], and supercritical-structural [4] diffusion models combined with several isotherm models. All materials presented a fast sorption rate of CO2 and the isothermal models were unable to describe the experimental uptake curves. Therefore, the reliable diffusion time constants were obtained from the heats effects and this constant increased with the pressure and the pore size. The zeolites presented the slow diffusion time constants due to the small pore size and the very strong adsorption with CO2.