Enhanced removal of hydrogen sulfide from a gas stream by 3-aminopropyltriethoxysilane-surface-functionalized activated carbon

A commercial activated carbon was functionally modified by silylation with 3-aminopropyltriethoxysilane (APTES). The silylation led to the fixation of weakly basic functional groups, –NH2, on the surface as indicated by pH titration, Boehm titration, N \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$_{2^{-}}$\end{document} BET analysis and X-ray photoelectron spectroscopic (XPS) analysis. Despite reducing the specific BET area and the pore volume, silylation improved the H2S removal capacity so that APTES modified activated carbon (APTES-AC) was 3.55 times more effective than the original activated carbon. XPS results indicate that H2S removal may be associated with the amino (–NH2) group and the presence of sulfur in the four oxidation states S2−, S0, S4+ and S6+. The effects of moisture, oxygen content and temperature on the performance of APTES-AC for H2S removal were investigated. The presence of moisture in the gas stream was found to have an adverse effect on the H2S removal, whilst the presence of oxygen favored the removal of H2S by APTES-AC. The higher removal capacity of APTES-AC relative to the original activated carbon indicates that APTES-AC is a potential candidate for the removal of H2S from gas streams. The H2S removal efficiency of APTES-AC was proved be superior to that of Na2CO3-impregnated AC by the pilot-scale test of purification H2S containing industrial waste gas, yellow phosphorus off-gas.