AN FTIR STUDY OF THE ADSORPTION OF METHANOL AND METHYL FORMATE ON POTASSIUM-PROMOTED CU/SIO2 CATALYSTS

FTIR spectra are reported for methanol and methyl formate on silica-supported potassium, potassium-promoted reduced copper/silica, and a potassium-promoted copper/silica catalyst which had been reoxidised by nitrous oxide. Adsorption of methanol on potassium/silica resulted in the formation of methoxy species on potassium. The corresponding adsorption of methanol on potassium-promoted reduced copper/silica catalyst produced copper methoxy groups in addition to K+OMe groups. Reoxidation of the copper component enhanced the quantity of methoxy species formed on copper. The concentration of potassium methoxy species was apparently unaffected. Adsorption of methyl formate on potassium/silica gave formate and methoxy species on potassium. The addition of copper caused a noticeable decrease in the amount of formate and methoxy groups on potassium. Furthermore, bridging formate was detected on the copper surface. Reoxidation of the copper component enhanced the quantity of formate species on potassium. An explanation is given in terms of adsorption of methyl formate at special sites located at the copper/potassium oxide interface. © 1993 Academic Press, Inc.