A comprehensive comparison of zeolite-5A molecular sieves and amine-grafted SBA-15 silica for cyclic adsorption-desorption of carbon dioxide in enclosed environments

Abstract

This study investigated the performance of two adsorbent materials, namely commercially available zeolite-5A and an amine-grafted SBA-15 silica (“aminosilica”) synthesized in lab, for air revitalization in enclosed environments. Adsorbent performance metrics were evaluated, in the presence of 1 vol% CO2 in N2 at 25 °C, in terms of equilibrium CO2 uptake, CO2 adsorption kinetics, activation temperature and duration, regeneration temperature and duration, and cyclic stability. Aminosilica and zeolite-5A achieved similar performance in terms of equilibrium CO2 uptake (5.7 wt%) and cyclic stability (less than 2% CO2 uptake loss over 20 cycles). The main differences were that the aminosilica demonstrated (i) 43% faster CO2 adsorption kinetics in the first five minutes of adsorption cycle, (ii) lower activation temperature (80 versus 180 °C), (iii) lower regeneration temperature (90 versus 200 °C), (iv) 50% shorter activation duration, and (v) 35% shorter regeneration duration. The aminosilica also showed stable performance when regenerated in the presence of air at elevated temperature (8.6% CO2 uptake loss over 100 cycles). These indicators make the aminosilica material a potentially viable adsorbent for CO2 removal from dilute streams, including air revitalization applications.