Preparation And Catalytic Behaviour Of Nanosized Nickel-Based Microwave-catalyst For The Microwave Catalytic Oxidation Of Cyclohexane

The selective oxidation of cyclohexane to cyclohexanol and cyclohexanone is one of the most representative reaction in the paraffin oxidation reactions, since its product is an important chemical raw materials and intermediates. In the industrial process, cyclohexane oxidation is mainly carried out at 423～433 K and 1.0 Mpa, resulting in about 4% conversion and 70～85% selectivity to K/A oil. Although the technology has been matured, a large number of recycling cyclohexane in the industrial production process caused the waste of energy consumption, and produced serious pollution and waste in the production process. From environmental protection and resource constraints viewpoint, there is an urgent need to optimize the transformation of traditional routes, seeking a mild, environmentally friendly cyclohexane oxidation method.In recent years, microwave catalytic technology has got great attention by researchers., and is widely used in chemical field. Microwave can accelerate the reaction rate, improve reaction selectivity, and can also with some catalyst to catalyze some reactions which cannot carry out in conventional processing, and reduce the reaction activation energy. Therefore, in this article, oxygen as oxidant, combining microwave and microwave catalyst, we studied in detail the process of cyclohexane oxidation in microwave field, and got results as follows:(1) We prepared nano-NiO catalyst by precipitation method, and the catalyst was characterized by TG-DSC, BET, XRD and TEM. We studied the effect of precipitation agent type and calcination temperature of catalytic performance, catalyst showed the best catalytic performance when catalyst prepared as Na2CO3 precipitant and roasted at 500℃.(2) The catalytic performance of nano-NiO catalyst. In the reaction system of microwave catalytic cyclohexane selective oxidation, we investigated the influence of microwave power, the initiator amount, the catalyst amount, reaction time and the reused of catalyst. The results showed that when oxygen as oxidant, microwave 400 W, initiator amount 1.25 g, catalyst amount 1.50 g, reaction 24 h at atmospheric pressure, we obtained 3.56% cyclohexane conversion and 100% selectivity of K/A oil and CHHP.(3) We prepared CuO-NiO catalyst by hydrothermal synthesis method. We studied the effect of Cu/Ni mole ratio and calcination temperature on catalytic performance, catalyst showed the best catalytic performance when catalyst of the Cu/Ni mole ratio of 1:2 and roasted at 500℃. We also investigated the influence of microwave power, the initiator amount, the catalyst amount, reaction time and the reused of catalyst. The results showed that reaction 1 h at atmospheric pressure, we obtained 1.88% cyclohexane conversion and 100% selectivity of K/A oil and CHHP.(4) Combing nanosized nickel-based metal oxide as microwave-catalyst with microwave catalytic technology, the route of realizing the selective oxidation of cyclohexane to cyclohexanol and cyclohexanone under mild conditions is feasible.