Synthesis of fly ash-based microporous copper silicate for CO 2 capture from humid flue gases

Conventional microporous adsorbents suffer from CO 2 adsorption capacity reduction due to the presence of water vapor in real flue gases. Therefore, development of low-cost moisture-insensitive adsorbents is of great significance. In the present work, microporous copper silicate was synthesized from waste fly ash for the first time. The synthesis conditions were further optimized to obtain copper silicates with high purities. The as-synthesized product was characterized in terms of structural morphology, chemical composition, and surface properties. The CO 2 and H 2 O adsorption properties of the prepared copper silicate were also investigated by single-component isotherm measurements and dynamic CO 2 /H 2 O binary breakthrough experiments. The results show that the as-synthesized fly ash-based copper silicate exhibited excellent CO 2 adsorption properties even in the presence of water vapor, thus demonstrating promising potential as a moisture-insensitive adsorbent for directly capturing CO 2 from humid flue gases.