Effect of potassium on the physicochemical properties of molybdenum oxide catalyst supported on sol–gel alumina–zirconia

Potassium-promoted molybdenum oxide/alumina–zirconia catalysts were prepared by the sol–gel method. The catalysts were characterized by nitrogen physisorption, X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and Fourier transform spectroscopy measurements. It was observed that potassium addition did not drastically disturb the textural properties and led to a redispersion of the molybdenum oxides composed both of octahedral and tetrahedral structures. Molybdenum oxide mainly led to the formation of Brönsted acid centers while alumina–zirconia support contained Lewis acid centers. Potassium led to a decrease in the number of Brönsted acid centers rather than that of Lewis centers.