The synergism of cadmium on the catalytic activity of Cd-Cr-O system I. Preparation, characterization and electrical properties

Cadmium-containing catalysts were obtained by calcining a parent mixture of chromia and cadmium nitrate precursor materials in atomic ratio Cd/Cr = 0.5. The thermal genesis of the catalysts was explored by means of thermogravimetric analysis (TGA) in different atmospheres (air, nitrogen, and hydrogen) and in the temperature range 25-1000 degreesC. The calcination products were characterized by adopting many techniques such as differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), estimation of surface excess Cr6+ concentration, surface area, and electrical conductivity measurements. It was demonstrated that raising the calcination temperature of Cd/Cr mixture results in many effects on the structural as well as the electrical properties of the calcination products. The role of Cd2+ ions in improving the electrical behavior of such a mixture was discussed. The results of the present study offer the advantageously usage of Cd/Cr catalysts over the net chromia catalyst in the dehydration/dehydrogenation of alcohols as it will be discussed in the next paper. (C) 2001 Elsevier Science B.V. All rights reserved.