Effect of pH in the preparation of Ni9Fe3Bi1Mo12O51 for oxidative dehydrogenation of n-butene to 1,3-butadiene: Correlation between catalytic performance and oxygen mobility of Ni9Fe3Bi1Mo12O51

A series of Ni9Fe3Bi1Mo12O51 catalysts were prepared by a co-precipitation method with a variation of pH value (pH 3–9), and were applied to the oxidative dehydrogenation of n-butene to 1,3-butadiene in a continuous flow fixed-bed reactor. O2-temperature-programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS) measurements were carried out to determine the oxygen mobility of Ni9Fe3Bi1Mo12O51 catalysts. It was revealed that the catalytic performance of Ni9Fe3Bi1Mo12O51 was closely related to the oxygen mobility of the catalysts. The yield for 1,3-butadiene was monotonically increased with increasing oxygen mobility of Ni9Fe3Bi1Mo12O51 catalysts. Among the catalysts tested, the Ni9Fe3Bi1Mo12O51 catalyst prepared at pH 8 showed the best catalytic performance due to its facile oxygen mobility. Thus, oxygen mobility played a key role in determining the catalytic performance of Ni9Fe3Bi1Mo12O51 catalysts in the oxidative dehydrogenation of n-butene.