Template Removal from SBA-15 by Ionic Liquid for Amine Grafting: Applications to CO₂ Capture and Natural Gas Desulfurization

A new ionic liquid treatment method has been developed for removing the organic template from mesoporous silica SBA-15. Compared with conventional template removal by air calcination, the novel ionic liquid treatment method efficiently removed the organic template at a low temperature and preserved the surface silanol groups. The significantly increased silanol density led to higher amine loadings on amine grafted SBA-15. Consequently, the ionic liquid treated sample showed 63% more CO₂ capacity at conditions relevant to CO₂ capture from flue gas. Moreover, the ionic liquid treated sample exhibited significantly higher capacities for H₂S capture from natural gas as well as CO₂ adsorption capacities for direct air capture which were nearly 3 times higher than the conventionally treated sample. The adsorbent stability, the isosteric heats of adsorption, and the effect of moisture were also investigated for the ionic liquid treated sample. The mechanism of template removal by ionic liquid is discussed, and the feasibility of recovery/reuse of the ionic liquid and the template is shown.