Gold catalyzed one-pot myrtenol amination: effect of catalyst redox activation

The effect of the gold catalysts redox treatment on the formation of active catalysts for one-pot myrtenol amination with aniline was studied. A series of nanosized gold catalysts over metal oxides such as ZrO₂, CeO₂, La₂O₃ different in their basicity were synthesized by the deposition–precipitation method and characterized using TEM, XPS and TPR-, TPO-MS. One-pot myrtenol amination was carried out in a batch reactor at 180 °C under nitrogen pressure 9 bar. The catalytic activity and selectivity were shown to depend on the catalyst redox treatment. Pre-reduced gold catalysts supported on zirconium or cerium oxides were shown to be more effective in alcohol activation while once pre-oxidized catalysts promoted formation of the target amine with high selectivity. It was shown that thermal activation of catalysts in oxygen resulted in higher efficiency of ammonia removal compared to treatment in hydrogen. Difference in activity and selectivity for pre-reduced and pre-oxidized catalysts was proposed to be mainly related to the different degree of the support basic properties modification by residual ammonia.