H(2)O-prompted CO(2) capture on metal silicates in situ generated from SBA-15

A series of metal silicates, NaMSi(10)Ox (M = Cu, Mn and Ni), were prepared by in situ doping of metals into mesoporous SBA-15 under a hydrothermal process, displaying a continuous framework of SiO(4) structure with a narrow pore size distribution. These metal silicate materials were tested for CO(2) adsorption behavior in the absence and presence of water. The results exhibited that the effect of H(2)O on the CO(2) capture capability of metal silicates depends on the types of metal inserted into SBA-15. Compared to the dry condition, H(2)O addition enhances CO(2) uptake dramatically for NaCuSi(10)Ox by 25%, and slightly for NaNiSi(10)Ox (∼10%), whereas little effect is shown on NaMnSi(10)Ox. The metal silicate materials are stable after adsorption of CO(2) under wet conditions, which is benefited from their synthesis method, hydrothermal conditions. The improvement of CO(2) uptake on metal silicates by H(2)O is attributed to the competitive and synergistic adsorption mechanism on the basis of IR investigations, where initially adsorbed H(2)O acts as a promoter for further CO(2) capture through a hydration reaction, i.e., formation of bicarbonate and carbonates on the surface of the samples. These observations provide new possibilities for the design and synthesis of porous metal silicate materials for CO(2) capture under practical conditions where moisture is present.