Application Of Supported Gold Based Catalysts In Selective Aerobic Cyclohexane Oxidation

The selective oxidation of cyclohexane to cyclohexanol and cyclohexanone(KA oil)is crucial in the chemical industry.Both oxidation products are the main industrial precursors of,respectively,e-caprolactam and adipic acid,building blocks of the nylon-6 and nylon-66 polymers.At present,the main synthesis of KA oil is cyclohexane oxidation.However,it suffers the drawbacks of low conversion and poor selectivity.Therefore,the development of catalysts with high conversion and selectivity is the key to improving industrial production.Supported nano gold catalysts were applied to catalyze selective oxidation of cyclohexane to cyclohexanol and cyclohexanone by using oxygen Some major work is listed as follows:1.AuNPs were loaded into various support by a colloid deposition method.Catalyst has the best activity when support is CeO2-rod.At the same time,the catalysts have obvious size effect,which 5nm Au/CeO2-rod had the highest activity(TOF is up to 8367 h-1).For Au144/CeO2-rod which shows the highest space time yield,under the mild conditions(135 ? and 1 MPa for 3 hours)exhibited cyclohexane conversion of 7.86%with the KA oil selectivity of 100%and the KA value of 0.86.Catalytic kinetic experiments showed that the reaction time,temperature and partial pressure of oxygen are not the key to determining the reaction.The key factor is that the cyclohexanol and cyclohexanone are hardly desorption on the catalyst surface,which resulting in the active sites covered and catalyst deactivation.2.A solid-mediated alloying strategy is applied for the rational synthesis of supported AuPd and AuAg bimetallic nanoparticles(BMNPs).The introduction of Pd component can enhance the selectivity of cyclohexanone in the product,thereby enhancing the KA value and reducing the difficulty of cycluliexanol oxidative dehydrogenation to cyclohexanone.For Au5Pd1/CeO2-rod,under the same reaction conditions,the KA value increased from 0.87 to 1.20 when the conversion rate of cyclohexane was almost unchanged.Catalytic kinetic experiments also suggest that the key factor is the competitive adsorption of raw materials and products,but alloying can slightly enhance the capacity adsorptionof cyclohexane.