DEPENDENCE OF SELECTIVITY ON THE PREPARATION METHOD OF COPPER ALPHA-ALUMINA CATALYSTS IN THE DEHYDROGENATION OF CYCLOHEXANOL

An electroless copper plating method a precipitation method and an impregnation method were used in the preparation of eleven Cu/alpha-Al2O3 catalysts. The effects of the method of preparation on the dehydrogenation reaction of cyclohexanol were investigated. The results showed that the dehydrogenation activity increased as the copper loading increased up to a certain limit and then declined with further copper loading. The selectivity to cyclohexanone also increased as copper loading increased up to a certain limit, then decreased as copper loading increased for the catalyst prepared by the impregnation method. For the catalysts prepared by the electroless method the selectivity remained almost the same. For the precipitation method the selectivity was very poor. The activation energy was lowest for ELE-3, intermediate for IMG-2 and highest for PRE-2. According to our findings, the catalysts prepared by the electroless method are better than those prepared by the other two methods, and the catalyst ELE-3 is the best one among the eleven catalysts tested.