Structure and catalytic activity of double oxide system: Cu-Cr-O supportedon MgF2

Two series of chromium-copper catalysts were prepared: co-impregnated and c onsecutively impregnated. On the basis of XPS, IR, EPR, X-ray investigation s, and catalytic tests, a conclusion was drawn, that on the surface of each sample, an interaction between copper and chromium ions occurred, leading to an electron transfer from chromium to copper. As a result: Cr6+ and Cu1 centres were formed. These sites were responsible for the catalytic activi ty of studied samples. The order of active phase deposition determined the properties of consecutively impregnated catalysts. The best performance was found for consecutively impregnated copper-chromium catalysts, which showe d the highest influence of copper-chromium interaction on the properties of such systems. The surface structures of particular catalysts were proposed . (C) 1999 Elsevier Science B.V. All rights reserved.