Electroless-plated Cl/Al2O3 catalysts prepared with different chelating agents and their activity on the dehydrogenation of 2-butanol

The properties of the electroless Cu/Al2O3 catalyst prepared by the electroless plating technique depend upon the kind of chelating agents in the preparation process. In this study, two various chelating agents, ethylenediaminetetraacetic acid (EDTA) and triethanolamine (TEA), were individually used to prepare seven Cu/gamma-Al2O3 catalysts of different copper contents, 8.44-24.56 wt % by EDTA and 7.09-25.92 wt % by TEA. Dehydrogenation of 2-butanol was used as a model reaction to test the activities of these catalysts. The dispersion of copper particle on the gamma-Al2O3 support and the crystalline phase of the catalyst were characterized by scanning electron micrography (SEM) and X-ray diffraction (XRD), respectively. The copper surface area and the acidity of the catalyst were determined by the decomposition of nitrous oxide (N2O) and the chemisorption of ammonia (NH3), respectively, using the volumetric method. The experimental results showed that the dehydrogenation rate of 2-butanol increased with increasing temperature and the number of exposed copper atoms. The dehydration reaction competed with the dehydrogenation reaction only at higher temperatures and catalysts with higher acidity. Among these two series of catalysts, copper dispersed homogeneously over the gamma-Al2O3 support by using EDTA as the chelating agent, resulting in a higher surface area and a higher dehydrogenation rate; however, bulky copper clusters aggregated on the gamma-Al2O3 support by using TEA as the chelating agent, displaying a lower surface area and a lower dehydrogenation rate.