Preparation Of Nano-sized Gold Complex Catalyst And Its Catalytic Performance For Cyclohexane Oxidation

The oxidation of cyclohexane to cyclohexanol and cyclohexanone (both mixture called KA oil), and is a key process in the chemical industry. More than 90% of cyclohexanone are producted by this way in the world. However, the current processes are energy intensive, have low conversion coefficients and total selectivity, generate environmentally hazardous waste and byproducts, and in recent years, as environmental protection requirements of improving and energy shortage, so it continues to be a challenge to receive high conversion and selectivity simultaneously under mild conditions by discovering a novel and efficient catalyst.The gold elements is considered the lowest catalytic activity of precious metal, but there were some studies found that the nanometer scale gold have very good low-temperature catalytic activity. Reported load type gold catalysts mole-sieve carrier (such as ZSM-5, MCM-41, TS-1) is difficult to volume production or expensive causes such as catalyst was difficult to industrialization. But activated carbon is inexpensive, origin is widespread with the great of surface and strong of adsorption ability and suitable to serve as the carrier of nano-gold catalysts. Based on the photocatalytic property of TiO2, we introduce a photocatalytic reduction method to prepare an Au@TiO2/AC catalyst. The catalytic performance of these samples for the cyclohexane liquid-oxidation into cyclohexanone and cyclohexanol by O2 in the absence of solvents is investigated. The following results and conclusion have been obtained:(1) The complex catalyst Au@TiO2/AC was prepared by the photodeposition method, after XRD, FT-IR and TEM, etc, we can analyze the characterization, and the catalyst samples has better crystallinity, the nano-gold and the TiO2 are load to be successful, and gold particles on activated to nanoscale, size in 10nm around.(2) The nano-gold catalysts of Au@TiO2/AC catalytic selective oxidation of cyclohexane reaction to test the performance of catalyst in the process of carrying gold, specific examines the quantity, reaction temperature, reaction time and different cyclohexane oxidation catalyst to influence the reaction. Finally found the composite catalysts between the various components are equipped with the synergy, that is to say the Au@TiO2/AC is a kind of efficient cyclohexane selective oxidation catalyst. And under the condition of Au@TiO2/AC (wt.0.5%), O2 1.1 MPa,421 K, proceed cyclohexane selective oxidation reaction 50 min, the conversion of cyclohexane was 9.2% and the total selectivity of desired products was 83.5%.(3) The complex catalyst Au@TiO2/AC photocatalytic selective oxidation of cyclohexane reaction to test the performance of this catalyst in different catalysts, reaction temperature, sunshine time, carry the dosage of gold quantity and catalyst reaction factors such as the experimental research, and the conversion of cyclohexane was 3.1% and the total selectivity of desired products was 89.5% under the condiotions of 0.1 g Au@TiO2/AC (wt.1.0%),393 K, O2 1.1 MPa, illuminated by 250 W UV-lamp for 2 h and reaction 4.5 h.