MCM-41 molecular sieve based Li4SiO4 high temperature CO2 adsorption material

Considering that metal ions have a positive effect on the adsorption performance of Li4SiO4, the author also studied the effect of different metal ions Na+, Ti+, Ca2+, Al3+ doped MCM-41 molecular sieve on the adsorbent performance (Figure 2c,d). Among them, the presence of Na+ can significantly enhance the adsorption kinetics of MCM-41-Li4SiO4. The adsorption capacity of CO2 also increased from 29.1 wt% of pure MCM-41-Li4SiO4 to 36.7 wt% of Na-MCM-41-Li4SiO4.

In addition, considering that the adsorption performance of MCM-41-Li4SiO4 is greatly affected by the concentration of CO2, the adsorbent was further modified with molten salt. By loading two molten salts of K2CO3 and Na2CO3, the adsorption capacity of the adsorbent under low CO2 concentration is greatly improved (Figure 3).

Under the conditions of 550 oC and 20 v% CO2, the CO2 adsorption capacity of 15 wt% K2CO3-MCM-41-Li4SiO4 and 10 wt% Na2CO3-MCM-41-Li4SiO4 are 32.2 wt% and 34.7 wt%, respectively, which are significantly higher than 11.8 wt% of MCM-41-Li4SiO4. At the same time, when tested at a lower CO2 concentration (10 v% CO2), the cycle stability of the adsorbent remained almost unchanged.