The oxidative dehydrogenation of methanol over a novel low-loading Ag/SiO2-TiO2 catalyst

Catalytic oxidation of methanol to formaldehyde was carried out over Ag/TiO2-SiO2 catalysts prepared by chemical reduction. The catalytic activity was measured at the temperature interval 820-920 K, O-2/CH3OH molar ratio between 0.35 and 0.50 and at the space velocity of 1.2 x 10(5) h(-1). The optimal content of silver determined by chemical analysis was about 1.7 wt%. The yield of formaldehyde over this catalyst was similar to 13% higher than that of the industrial pumice-supported silver catalyst and even similar to 3.5% higher than that of electrolytic silver. The XRD patterns for silver particles supported on TiO2-SiO2 are corresponding to Ag(lll), (200) and (220), respectively SEM was used to determine its morphology and particle size. Isolated silver particles were observed on the surface of the catalyst. O-2 chemisorption by using the pulse technique was carried out to determine the free silver surface areas. The average silver particle size from the calculation of selective oxygen chemisorption was found to be in good agreement with that observed from SEM.