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Effects of the incorporation of Cr, Ni, Co, Ag, Al, Ni and Pt cations in titanate nanotubes (NTs) were examined on the NOx conversion. The structural and morphological characterizations evidenced that the ion-exchange reaction of Cr, Co, Ni and Al ions with the NTs produced catalysts with metals included in the interlayer regions of the trititanate NTs whereas an assembly of Ag and Pt nanoparticles were either on the nanotubes surface or inner diameters through an impregnation process. Understanding the role of the different metal cations intercalated or supported on the nanotubes, the optimal selective catalytic reduction of NOx by CO reaction (SCR) conditions was investigated by carrying out variations in the reaction temperature, SO2 and H2O poisoning and long-term stability runs. Pt nanoparticles on the NTs exhibited superior activity compared to the Cr, Co and Al intercalated in the nanotubes and even to the Ag and Ni counterparts. Resistance against SO2 poisoning was low on NiNT due to the trititanate phase transformation into TiO2 and also to sulfur deposits on Ni sites. However, the interaction between Pt2+ from PtOx and Ti4+ in the NTs favored the adsorption of both NOx and CO enhancing the catalytic performance.

This work addresses the main point, the synthesis of one-dimensional titanate nanostructures and their ion exchange with transition metals for application in photocatalysis. The catalysts tested in the photocatalytic process were titanate nanoribbons (NRTi) synthesized by hydrothermal method and ion exchanged with Sn2+. The structural and morphological analysis of the material was performed by XRD, Raman spectroscopy and TEM images, confirming the formation of the desired structures and the growth of SnO2 nanoparticles after the ion exchange process with average size smaller than 10 nm. The values of surface area were obtained by BET and showed a significant increment after the ion exchange process, making it favorable for application in photocatalysis. The NRTi was applied in the degradation of blue dye remazol, generating a total degradation in 120 minutes. The rate constants were calculated from the pseudo-first-order equation.

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