Solid-phase and precipitation synthesis of Ti-pyrophosphate for the catalytic oxydehydrogenation of n-butane

Abstract

In this article, the effect of the preparation methods of titanium pyrophosphate (TiPO) catalysts on their catalytic performances via the oxydehydrogenation (ODH) of n -butane has been investigated. The TiPO-A, TiPO-B, and TiPO-S catalysts have been prepared, respectively, by three synthesis methods: (1) liquid–solid, (2) coprecipitation, and (3) solid-state methods. The samples have been characterized by N 2 -sorption, X-ray diffraction, inductively coupled plasma through the atomic emission spectroscopy, Fourier transform infrared, thermogravimetric analysis, differential scanning calorimetry, field emission scanning electron microscopy, and temperature-programmed desorption (NH 3 or CO 2 ). Fourier transform infrared and X-ray diffraction data indicate the presence of a pure TiP 2 O 7 phase in TiPO-A and TiPO-S samples, whereas TiPO-B revealed the presence of an amorphous TiP 2 O 7 and rutile TiO 2 phase. The coupled TGA/DSC curves showed that all catalysts are stable up to 600 °C. The catalytic testing, performed at 500 °C in ODH of n -butane, shows that the best yield (11.6%) is obtained over the TiPO-A catalyst, with 22.7% of butane conversion and 51.2% of total butene selectivity (whose 94.6% is the trans -2-butene), and seems to be an important result in this work. Only the TiPO-B1 catalyst produced butadiene with 1.7% (14.2% of ODH product) selectivity; this result is no less crucial. • TiP 2 O 7 synthesized in nanoscale to ODH of n -butane. • The catalyst is prepared by solid-phase, solid–liquid, and coprecipitation methods. • The catalyst activity is shown by high density of acid–base sites. • The best yield 11.6% is obtained with 22.7% conversion and 51.2% butenes selectivity. • Coprecipitation catalyst produced butadiene with 14.2% selectivity of all butenes product.