The Research On Catalytic Oxidation Of Cyclohexane Over Al-Cu-Co Alloys Containing Quasicrystal

The selective oxidation of cyclohexane to cyclohexanol and cyclohexanone is the important step to produce nylon-6 and nylon-66 in the chemical industry. Currently, the production of cyclohexanol and cyclohexanone is still in the homogeneous reaction of cyclohexane oxidation. The processes of cyclohexane oxidation still suffer from low conversion(<5%) and low selectivity of cyclohexanol and cyclohexanone(<85%). The separation of products is difficult and the environmental problem has aroused great concern in the processes of homogeneous catalytic. To study the heterogeneous catalysis has important theoretical and practical significance in the process of cyclohexane oxidation.It was significant to discover quasicrystals in the 1980 s for the traditional crystallographic, which promoted the development of materials science, physics, chemistry, and other fields. The electrical, thermal, mechanical, and surface properties are unusually compared with other metal materials, because of their unique atomic arrangement structure. The unique atomic arrangement structure in sufrace of quasicrystals can produce specific activating effect, and alloys contains quasicrystalline have suitable properties for catalytic applications such as high hardness, resistance to loss, low cost and thermal stability.Al-Cu-Co alloys with different compositions were prepared by arc-melting method, and characterized by ICP-OES, XRD, SEM-EDX, TEM-SAED and XPS. The actual composition of the Al60Cu5Co35 alloy and theory are consistent. The composition of Al60Cu5Co35 alloy was confirmed to consist of Al Co cubic phase and decagonal quasicrystalline phase(D-phase). These alloys as a catalyst, oxygen as the oxidant, cyclohexane can be oxidized under solvent-free conditions. The mole content of Co in Al-Cu-Co alloys have an important influence on its catalytic activity in cyclohexane oxidation, and the presence of 5%Cu can improve the conversion of cyclohexane. When the content of Cu is more than 10%, activity of catalyst is suppressed. Al60Cu5Co35 alloy showed the best activity and selectivity in Al-Cu-Co alloys for cyclohexane oxidition. The catalytic reaction performance had been discussed by varying the reaction parameters of temperature, time, amounts and mesh of catalyst. The conversion of cyclohexane was 6.4% and the overall selectivity of cyclohexanol and cyclohexanone was 95.2% under the optimum reaction conditions. The catalyst of Al60Cu5Co35 could be recycled for five times without loss in activity and selectivity.The innovation of this research work is that a novel Al60Cu5Co35 containing decagonal quasicrystalline phase was the first time prepared and used as catalyst for the catalytic oxidation of cyclohexane. It is a heterogeneous catalyst with higher activity and selectivity, steady stability and low cost in catalyzing the oxidation of cyclohexane.