Vanadium oxide loaded tin–titanium phosphates: Surface structures and performance for the oxidative dehydrogenation of ethane

Abstract Mixed crystalline tin–titanium phosphates with nominal Ti:Sn ratios of 0.5 and 3.0 have been prepared by precipitation of Sn(IV) and Ti(IV) soluble salts with H 3 PO 4 . Vanadium was then incorporated by chemical grafting with a VOCl 3 precursor up to levels of 2% vanadium. Both the tin–titanium phosphates (TS) and their V-loaded counterparts (V/TS3 and V/TS0.5) were characterized by X-ray diffraction, Raman spectroscopy, differential scanning calorimetry and X-ray photoelectron spectroscopy, and their reactivity was tested for the C 2 H 6 oxydehydrogenation reaction. It was shown that a part of vanadium segregates as V 2 O 5 in the V/TS3 sample, while Sn segregation occurs in V/TS0.5 and this system shown no formation of V 2 O 5 crystallites. Both the TS and V/TS systems were found to be active for this reaction, although significant differences were observed depending on the crystallinity and surface enrichment of tin. The V/TS0.5 system displayed the best performance. Selectivity for dehydrogenation decreased only slightly with increasing ethane conversion, whereas the selectivity to CO 2 increased to the detriment of the selectivity to C 2 H 4 because CO selectivity remained close to zero. The high selectivity to C 2 H 4 along the C 2 H 6 interval explored appears to be related to highly dispersed vanadium species on the catalyst surface.