Structure and Catalytic Activity of a Raney-type Copper-Aluminium-Chromium Oxide

Abstract

In order to improve the durability of Raney-type copper oxide catalysts, CuOCu-Al-Cr oxide catalysts were prepared by oxidation and calcination in air of Raney copper, which was prepared by leaching Cu-Al alloy with dilute sodium hydroxide aqueous solution containing (NH₄)₂CrO₇. The yield of Cu-Al-Cr oxide rises to a maximum at 530°C in the c alcination temperature range of 400 to 550°C. The catalytic actjkvity of CuOCu-A1-Cr oxide for oxidation of CO was found to increase with increasing content of Cu-Al-Cr oxide. Though the catalytici activity for oxidation of CO is rather lower than that of CuO, the Cu-Al-Cr oxide is excellerit in thermostability and durability under hydrothermal conditions. In the case of IPA decomposition, the catalytic activity for dehydrogenation of Cu-Al-Cr oxide was nearly equal to that of CuCr₂O₄. The crystal structure of Cu-Al-Cr oxide, CuAl_1.09Cr_0.91O₄, was found to be dependent on temperature; in the range of 400 to 700°C, - lattice constant α=8.23 A (cubic), and lattice strain η= 0.016, while in the range 700 to 900°C, α=8.37Å, c/α= 0.940 (tetragonal), η=0.0064. The amount of active oxygen of the latter, measured by hydrazine m ethod, was less than that of the former.