Effect of pH in the preparation of ZnFe2O4 for oxidative dehydrogenation of n-butene to 1,3-butadiene: Correlation between catalytic performance and surface acidity of ZnFe2O4

A series of zinc ferrite (ZnFe2O4) catalysts were prepared by a co-precipitation method with a variation of pH value (pH 3–12), and applied to the oxidative dehydrogenation of n-butene to 1,3-butadiene. It was found that a zinc ferrite phase was formed at pH 6–12. Conversion of n-butene, selectivity for 1,3-butadiene, and yield for 1,3-butadiene were very high at low pH value (pH 6–10), but were drastically decreased with increasing pH value (pH 11–12). NH3-TPD experiments were conducted to correlate the acid property with the catalytic performance of zinc ferrite catalysts. It was revealed that the catalytic performance was closely related to the surface acidity of the catalysts. Conversion of n-butene was increased with increasing surface acidity of the catalysts. Among the catalysts tested, the zinc ferrite catalyst prepared at pH 9 with the largest surface acidity showed the best catalytic performance in the oxidative dehydrogenation of n-butene.