Zeolites have attracted considerable interest because of their narrow and uniform pore sizes, high surface areas, adjustable hydrophobic/hydrophilic balance, ion exchange capacity and acidity. Because of the high selectivity of various zeolites for CO₂, they are frequently used in PSA systems. However, zeolites with high aluminum content, such as Zeolite 13X, become poor adsorbents in the presence of steam because of their high affinity for H₂O. Recently, RITE has developed several types of all-silica zeolites that are unaffected by steam, and the CO₂ adsorption properties of these materials under high pressure conditions in mixed gas systems are currently being evaluated.
 

The all-silica zeolite RITEsorb-1 has a significant capacity for CO₂ absorption, superior to that of Zeolite 13X in the presence of steam. Its CO₂ uptake also increases sharply at a CO₂ partial pressure of 1.6 MPa and its effective CO₂ adsorption capacity has been estimated at 3.6 mol/kg, a value that is considerably higher than those of other adsorbents (Figure 1). The CO₂ adsorption capacity of RITEsorb-1 is also comparable to the capacities of standard zeolites under dry conditions, even when it is pre-treated with saturated H₂O vapor. Moreover, we have confirmed that RITEsorb-1 is a separable adsorbent with high selectivity for CO₂ from a CO₂/N₂ gas mixture.

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