Incorporation of Mo into the Vacant T-Atom Sites of the Framework of BEA Zeolite as Mononuclear Mo Evidenced by XRD and FTIR, NMR, EPR, and DR UV–Vis Spectroscopies

Abstract

A MoSiBEA zeolite has been prepared by a two-step postsynthesis procedure that consists of first creating the vacant T-atom sites with associated silanol groups by treatment of TEABEA zeolite with nitric acid and then incorporating Mo ions into the vacant T-atom sites by solid-state ion exchange at 773 K using molybdenum(II) acetate. The incorporation of Mo ions into the vacant T-atom sites of the framework of SiBEA zeolite as isolated mononuclear Mo(VI) species was evidenced by the combined use of XRD and FTIR, NMR, and diffuse reflectance UV–visible spectroscopies. The consumption of OH groups was monitored by FTIR spectroscopy. The reducibility of Mo was investigated by TPR and EPR spectroscopy. The size of very small well-dispersed Mo(0) nanoparticles formed upon treatment of MoSiBEA between 298 and 1240 K in hydrogen stream (5% H2/Ar) was measured by TEM.