Methanol conversion over a Pd5Cu/Al2O3–CeO2 catalyst: An FT-IR study and reaction mechanism

A catalyst composed of a Pd5Cu mixed oxide supported over Al2O3–CeO2 with general formula Pd5CuOx/Al2O3–CeO2 (Al/Ce atomic ratio = 1/1) has been prepared by a wet impregnation method and tested in the methanol conversion.The structural and morphological characterization of the catalyst evidences that it is a mesoporous material thermally stable up to 873 K. At that temperature the specific surface area value is 170 m2/g, and a CeO2 cubic phase is identified together with ill-defined diffraction peaks tentatively assigned to Cu–Pd clusters, suggesting that the active phase is well dispersed over the support.Infrared studies prove that methanol conversion takes place over the catalyst to a high extent yielding syngas as main product in the range 473–723 K and methane at higher temperatures. Oxygenated intermediates containing methoxy, carbonile or formiate species are not detected, which evidences that methanol conversion to methane very probably takes place according to a via-carbide mechanism.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Pd5CuOx/Al2O3–CeO2 is an active catalyst in the methanol conversion. ► Infrared studies prove that methanol conversion takes place over the catalyst to a high extent yielding syngas as main product in the range 473–723 K and methane at higher temperatures. ► Oxygenated intermediates containing methoxy, carbonile or formiate species are not detected, which evidences that methanol conversion to methane very probably takes place according to a via-carbide mechanism.