Dehydrogenation Oxidation Study Of Diethanolamine To Iminodiacetic Acid Over Cu/ZrO₂ Catalyst

Iminodiacetic acid (IDA) is an important chemical industrial intermediate, which is widely used in many aspects including pesticide, pharmacy, rubber, electroplating and metal manufacture. Among of these, the most important application is used in producing herbicide Glyphosate. There are many producing processes of IDA in industry, but the production of IDA through dehydrogen oxidation of Diethanolamine (DEA) is a simple and clean process. Moreover, the cost of using this method to produce IDA is low, the yield and purity of product are high, therefore, this reaction exhibits significant scientific research value.In this paper, a series of Cu/ZrO2 complex oxides were prepared by cis-plus and inverse coprecipitation method, and then activated through the treatment of H2 or potassium borohydride. We focused on the effect of calcination temperature, activation method, activation temperatures and activation time on the structure and the property of catalyst, combined with TG-DTA, XRD, BET, SEM, N2O titration and H2-TPR techniques.The XRD results showed that calcination temperature significantly affected the crystal of catalyst, and the phase transition temperature of catalyst prepared by inverse coprecipitation method was lower than that prepared by cis-plus coprecipitation method. N2O titration results showed that the catalyst calcined at 400℃had the biggest Cu surface area and the smallest crystallite size. The lower temperature shift of CuO reduction peak through TPR results indicated that there existed strong interaction between Cu and ZrO2.It was found that the Cu/ZrO2 catalyst prepared by inverse coprecipitation method could kept Cu content of 20 wt%and exhibited high reactivity, which was first calcined at 400-500℃and then reduced by H2 (the mol ratio of H2/N2 was 1/3) at 230℃for 1.5 h; Besides, the Cu/ZrO2 catalyst was prepared with the cis-plus coprecipitation method could also kept Cu content of 20 wt%and exhibited the same high reactivity after calcined at 500℃and reduced by potassium borohydride for 4 h at room temperature.