BEHAVIOR OF COPPER-THORIUM PHOSPHATE CUTH2(PO4)3 IN BUTAN-2-OL CONVERSION

The phosphate Cu(I)Th2(PO4)3 was investigated in the decomposition of butan-2-ol. Its catalytic activity was observed to correspond mainly to a production of methyl ethyl ketone. This dehydrogenation process was related to the migration of Cu+ ions toward the surface and their replacement in the structure by protons under catalytic reaction conditions. This phenomenon occurred without a change in the crystallographic structure of the phosphate. Physical techniques provided evidence for this (i) X-ray diffraction showed peaks characteristic of (111) and (110) metallic copper diffractions (ii) UV-visible spectroscopy exhibited a conduction band at 570 nm and hydroxyl group combination bands at 1420 and 2220 nm (iii) IR spectra ascertained the protonation of the sample by the appearance of new hydroxyl bands at 895 and 590 cm-1. This result was also confirmed by H-1 nuclear magnetic resonance (iv) temperature-programmed reduction and temperature-programmed oxidation (TPO) analysis techniques provided, in agreement with the previous measurements, a quantitative description of the redox modifications occurring in the sample. Formation of copper particles was observed to be reversible upon a reoxidation at 650-degrees-C. TPO patterns revealed a possible existence at 385-degrees-C of a new phase Cu0.76(I)Cu0.08(II)H0.08Th2(PO4)3 which transforms at higher temperatures into the starting material Cu(I)Th2(PO4)3.