The Design of a Uniform Pore Structure Is Favorable to Improve Gas Absorption

974 Words Feb 2nd, 2018 4 Pages
The curves of all three samples show hysteresis behavior and belong to type IV isotherms31. It suggests that our samples exhibit mesoporous structure with pore sizes larger than 5.6 nm (Table 2). The pore diameter of thiol-functionalized SBA-15 calculated by the BJH theory is smaller than that of SBA-15, which is attributed to the anchoring of thiol moiety to the silanol group in the interior wall of SBA-1540. The decrease of pore size, while maintaining type IV isotherm characteristics in thiol-functionalized SBA-15, is one possible reason that thiol moieties are located along the interior pore channels of SBA-15, not in the internal framework of SBA-15. The further decrease of pore size in Bi-thiol-functionalized SBA-15 can be explained by the attachment of bismuth to the thiol group, narrowing the inner pore channel of SBA-15.
The BET surface areas of SBA-15, thiol-functionalized SBA-15, and Bi-thiol-functionalized SBA-15 are 847, 512, and 347 m2/g, respectively. The pore volumes of those are 1.03, 0.85, and 0.62 cm3/g, respectively (shown in Table 2). The gradual decrease of the surface area and pore volume can also be understood in the attachment of thiol group to the inner wall of SBA-15 or bismuth to the thiol group as discussed above. Interestingly, the pore diameter of Bi-SBA-15 is similar to that of SBA-15, indicating that bismuth is not impregnated to the…