Organosulfur adsorbents by self-assembly of titania based ternary metal oxide nanofibers

Abstract

By doping with secondary and tertiary species, the electron configuration of titanium oxide can be tuned for the selective adsorption of natural gas contaminants such as thiols. In this study, we attempted to co-incorporate copper group metals/oxides and lanthanum oxide within titania nanofibers via linear poly-condensations of multiple metal acetate complexes. In all cases, a sol–gel synthesis in heptane allowed the nanofibers to randomly pack, forming 3 dimensional network bundles. The resulting nanostructures were characterized using electron microscopy, mass spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy, N₂ physisorption and Raman spectroscopy. Multicomponent breakthrough studies with three thiols, H₂S, CO₂ and CH₄ show that doping a TiO₂ matrix with copper group metals/oxides and La₂O₃ increased the thermal stability of anatase crystallites and nanostructures. We note that Au and Ag₂O accumulated on the surfaces of the doped materials, where the La₂O₃ doping contributed more to the materials thermal stability. The Cu and La doped material was found to be the best adsorbent for thiols with remarkably high selectivity, demonstrating potential applications in industrial gas treatment. In addition, xerogel adsorbents through the random packing of linear structures provide the advantage of a macro-porous bulk material, which is less susceptible to fouling.