Catalysis by “Copper Chromite”. I. The Effect of Hydrogen Reduction on the Composition, Structure, and Catalytic Activity for Methanol Decomposition

Abstract

The effect of hydrogen reduction on the composition, structure, and catalytic activity of dichromium(III) copper(II) tetraoxide (copper chromite), CuCr2O4, was investigated. In this oxide, the surface and the bulk CuII was reduced into CuI and further to Cu0 by heating in hydrogen. The methanol decomposition on fresh copper chromite proceeded in a manner similar to that on metallic copper formed as the result of strong reduction and dispersed on chromium(III) oxide. The contribution of CuII, CuI, and Cu0 species to catalytic activity was examined and the similarity in the character of reaction on these two samples with different surface states was discussed. The role of Cr2O3 interacting with zerovalent copper was postulated.

Structural and theoretical study of six dinuclear Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) complexes containing ON-NO donor azodye ligand, 4,4’-(1E,1’E)-(5,5’-(propane- 2,2-diyl)bis(2-hydroxy-5,1-phenylene)bis(diazene-2,1-diyl)dibenzenesulfonic a

“…The order of decomposition reaction and the activation energy are found to be 1.22 and 4.728 J/mol, respectively. The calculated value of activation energy is found to be low attributable to auto-catalytic effect of the metal ion on the thermal decomposition of the complex [38]. The correlation factor(r) is found to be 0.99 and the thermal decomposition of the complex fits well with the experimental results.…”

Copper-modified mesoporous MCM-41 silica: FTIR and catalytic study

“…In the case of copper-containing catalysts the literature data concerning the role of various copper species in this process are rather controversial. Usually the participation of metallic copper is reported [11][12][13]16,[18][19][20][23][24][25][26]32,33,42,45,46] but the role of copper ions in this process is not completely clear [12,14,17,21,22,28,29,31,43,44,47,48]. In our previous studies [79][80][81][82][83][84], the nature of a catalytic active complex (CAC) of copper modified activated carbon in methanol decomposition has been discussed.…”

Synthesis, Potentiometric, Spectral Characterization and Microbial Studies of Transition Metal Complexes with Tridentate Ligand

“…The calculated free energy of activation is relatively low indicating the autocatalytic effect of metal ion on thermal decomposition of metal complexes. 36,37 Negative ∆S values indicate more ordered activated states that may be possible through chemisorptions of oxygen and other decomposition products. The more ordered nature may be due to the polarization of bonds in activated state which might happen through charge transfer electronic transitions.…”