Navegando por Palavras-chave "Deactivation"

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    On the reasons for deactivation of titanate nanotubes with metals catalysts in the acetalization of glycerol with acetone
    (Elsevier Science Sa, 2018) Gomes, Igor S.; de Carvalho, Davi C.; Oliveira, Alcineia C.; Rodriguez-Castellon, Enrique; Tehuacanero-Cuapa, Samuel; Freire, Paulo T. C.; Filho, Josue M.; Saraiva, Gilberto D.; de Sousa, Francisco F.; Lang, Rossano [UNIFESP]
    Pt-containing titanate nanotubes (PTNT) catalyst had PtOx and chlorined-Pt species dispersed on the alkali trititanate nanotube phase (TNT). This solid was morphologically and structurally stable during glycerol acetalization of glycerol with acetone. In contrast, a significant transformation of Ni2+ and Co3+/Co2+ surface species dispersed on TNT provoked morphological, textural and surface changes affecting the catalytic performance of these samples, as observed with the help of HRTEM, XPS, Raman and textural properties measurements. Leaching of Co and Ni species was identified as the main mechanism for the deactivation respectively on Co-containing titanate nanotubes (CTNT) and Ni-containing titanate nanotube (NTNT) catalysts. On the contrary, PTNT performed very well giving rise to 28% of conversion and 11% selectivity to solketal over three reaction cycles of 24 h. This was thanked to the suitable tuning of pore-structure and proper surface acidity of PTNT, resulting in a stable solid for the reaction.