THE OXIDATIVE DEHYDROGENATION OF METHANOL OVER A NOVEL LOW-LOADING AGSIO2-TIO2 CATALYST/

Catalytic oxidation of methanol to formaldehyde was carried out over A g/TiO2-SiO2 catalysts prepared by chemical reduction. The catalytic ac tivity was measured at the temperature interval 820-920 K, O-2/CH3OH m olar 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 analys is was about 1.7 wt%. The yield of formaldehyde over this catalyst was similar to 13% higher than that of the industrial pumice-supported si lver catalyst and even similar to 3.5% higher than that of electrolyti c silver. The XRD patterns for silver particles supported on TiO2-SiO2 are corresponding to Ag(lll), (200) and (220), respectively SEM was u sed to determine its morphology and particle size. Isolated silver par ticles were observed on the surface of the catalyst. O-2 chemisorption by using the pulse technique was carried out to determine the free si lver surface areas. The average silver particle size from the calculat ion of selective oxygen chemisorption was found to be in good agreemen t with that observed from SEM.