Facile fabrication of effective Cerium(III) hydroxylated species as adsorption active sites in CeY zeolite adsorbents towards ultra-deep desulfurization

Abstract

Ce-containing materials attracted much attention in adsorption desulfurization due to their excellent adsorption selectivity. Identification and fabrication of specific Ce species as effective adsorption active sites, however, still remained ambiguous which had impeded the development of a potential desulfurization adsorbent. In this paper, series of CeY zeolites were synthesized via liquid phase ion exchange method. The implication of Ce loadings and calcination temperatures on the nature of Ce species active sites that can be present in the Y zeolite was a major focus of this work. Specially, the chemical speciation and location of Ce species in the CeY adsorbents were analyzed by the intelligent gravimetric analyser (IGA), XRD, in situ FTIR spectroscopy, and XPS techniques. The prepared CeY adsorbents were tested in terms of their sulfur breakthrough adsorption capacities using a fixed-bed column and model fuels. The experimental results indicate that more effective Ce(III) hydroxylated species as adsorption active sites, located in the supercages of CeY0.075C150 zeolite, are facilely fabricated as low as the calcination temperature (ca. 150 °C) and the suitable Ce loading (ca. 12.31 wt%). Remarkable sulfur breakthrough adsorption capacity can be achieved by using the new CeY0.075C150 adsorbent, which is no less ca. 5 folds than that of the reported CeY adsorbents to the best of our knowledge, especially for the 2-methylthiophene capture (ca. 18 folds). After regenerated with two cycles, the adsorbent still remains high sulfur breakthrough adsorption capacity. Importantly, this controllable method to construct specific Ce species as active sites in the CeY zeolites should play an instructive role for the development of the directional design of effective adsorption active sites in other excellent desulfurization adsorbents.