Effect of the structure of the support and the aminosilane type on the adsorption of H2S from model gas

In the present work, three different porous supports, i.e. MCM-41, SBA-15 and UVM-7 were synthesized and functionalized with three different aminosilanes (C9H23NO3Si, C8H22N2O3Si and C10H27N3O3Si). All the synthesized samples were characterized using XRD, nitrogen physisorption, elemental analysis and acid-base titration, SEM and TEM. The obtained results revealed that all the samples have a well-ordered structure and amine groups were successfully grafted on their pore surfaces. Then, the ability of amine-functionalized samples to adsorb H2S was investigated. In the case of MCM-41, changing the aminosilane functional group did not change tbp (the time at which the outlet concentration of H2S reaches its maximum admissible value in the effluent). SBA-15 functionalized with C8H22N2O3Si showed enhanced tbp in comparison with C9H23NO3Si, but C10H27N3O3Si showed very low tbp (even lower than C9H23NO3Si) which might be attributed to pore blocking originating from the very large size of C10H27N3O3Si. UVM-7 had the highest tbp for all three of the aminosilane functional groups. This might be attributed to the very large pore size of UVM-7 with respect to those of SBA-15 and MCM-41. In addition, nanosize particles of UVM-7 facilitate the adsorption of H2S for this type of adsorbent, which should be due to the unconstrained diffusion of H2S within the mesopores of UVM-7. The efficiency of an aminosilane functional group strongly depends on the pore size of the support rather than its surface area.