Modulation of ODH Propane Selectivity by Zeolite Support Desilication: Vanadium Species Anchored to Al-Rich Shell as Crucial Active Sites.

The commercially available zeolite HY and its desilicated analogue were subjected to a classical wet impregnation procedure with NHVO to produce catalysts differentiated in acidic and redox properties. Various spectroscopic techniques (in situ probe molecules adsorption and time-resolved propane transformation FT-IR studies, XAS, V MAS NMR, and 2D COS UV-vis) were employed to study speciation, local coordination, and reducibility of the vanadium species introduced into the hierarchical faujasite zeolite. The acid-based redox properties of V centres were linked to catalytic activity in the oxidative dehydrogenation of propane.

On the Role of Protonic Acid Sites in Cu Loaded FAU31 Zeolite as a Catalyst for the Catalytic Transformation of Furfural to Furan.

The aim of the present paper is to study the speciation and the role of different active site types (copper species and Brønsted acid sites) in the direct synthesis of furan from furfural catalyzed by copper-exchanged FAU31 zeolite. Four series of samples were prepared by using different conditions of post-synthesis treatment, which exhibit none, one or two types of active sites. The catalysts were characterized by XRD, low-temperature sorption of nitrogen, SEM, H-TPR, NMR and by means of IR spectroscopy with ammonia and CO sorption as probe molecules to assess the types of active sites.

Reduction and Oxidation of Cu Species in Cu-Faujasites Studied by IR Spectroscopy.

The process of reduction (by hydrogen and ethanol) and oxidation (by oxygen and NO) of Cu sites in dealuminated faujasite-type zeolites (of Si/Al = 31) was studied by infrared (IR) spectroscopy with CO (for Cu) and NO (for Cu) as probe molecules. Two zeolites were studied: one of them contained mostly Cu, whereas another one contained mostly Cu and Cu The susceptibility of various forms of Cu for reduction were investigated. IR experiments of CO sorption evidenced that Cu was more prone for the reduction than Cu According to NO sorption studies, Cu was reduced in the first order before Cu Ethanol reduced mostly Cu and, also, some amounts of Cu.