Niobiosilica Materials as Attractive Supports for Sb–V–O Catalysts

Abstract

Since niobium species have been described as being able to increase the catalytic properties of the Sb-V-O catalytic system, the main objective of the present paper is to design a non ordered-mesoporous Nb-containing material useful to be used as a support for this kind of catalysts. Such a material has been used as support for Sb-V-O active phases and the catalysts have been characterized and tested for the propane ammoxidation reaction. For comparative purposes, and in order to evaluate the role of niobium species, the study has been also performed with a support without niobium. The results have shown how the incorporation of niobium species into the support matrix with the procedure described here leads to the formation of a very promising catalytic support. The Nb species incorporated into the support cooperate with vanadium species of the SbVOx active phase increasing its performance for nitrile insertion into propane. Since Nb is a common additive that improves the catalytic behavior of different catalytic systems, the mesoporous Nb-containing support described in the present paper could be useful for other catalysts and/or catalytic processes.

The fascinating effect of niobium as catalytic promoting agent

“…Ziolek team also described a Niobiosilica material that demonstrated to be a good catalytic support also for the Sb-V-O active species [56], in this case, they described a synthesis method for a non-ordered porous niobiosilica material, without the use of a template, and the use of such material as support for VOx active species during the propane ammoxidation reaction. Fig.…”

“…For all the Sb-V catalysts, the selectivity to acrylonitrile increases with the use of the Nb-containing support, being higher for the catalysts with lower coverage. In this case the Nb promoting effect if related to the formation of larger particles of rutile VSbO 4 phase, as identified by XRD (56), that have structural defects in the structure, which enhances the catalytic properties. This results are in line with previous studies on ammoxidation over Sb-V-O catalytic system that showed that the SbVO4 rutile structure stabilizes cation vacancies in its structure [57], and with the ability of Nb species to incorporate into the rutile lattice [58].…”