CATALYTIC ACTIVITIES OF ELECTROLESS-PLATED CU ALUMINA CATALYSTS FOR THE DEHYDROGENATION OF CYCLOHEXANOL

A systematic study was made of the variables involved in the Cu catalysts supported either with gamma-Al2O3 or with alpha-Al2O3, prepared by a newly developed electroless plating method, in the dehydrogenation reaction of cyclohexanol. According to the experimental results catalyst prepared by electroless method had high activity and selectivity, with homogeneous dispersed active sites. The results have shown that the dehydrogenation activity increased with increase in copper loading up to about 18.25 wt.% for gamma-Al2O3 Series and 13.23 wt.% for alpha-Al2O3 series, and then declined with further deposition. The selectivity to cyclohexanone significantly increased as the copper loading increased up to a certain value and then remained almost constant with further copper loading for the catalysts supported with gamma-Al2O3. When the catalysts were supported with alpha-Al2O3, the selectivity slightly increased as the copper loading increased and then remained almost constant. The selectivity decreased with increasing temperature for the catalysts supported with gamma-Al2O3 whereas the catalysts supported with alpha-Al2O3 were independent of temperature. The conversion was higher for the GAS series than for AAS series catalysts. The activation energy decreased up to a certain copper loading, further increasing the copper loading caused the activation energy to rise for both series of catalyst. Among the eleven catalysts tested in this study, the activation energy obtained was lowest, 9.512 kcal/mol, for GAS-4, while that for AAS-3 was 11.724 kcal/mol.