Study On The Catalytic Performance On Cyclohexane Oxidation Of Silicon-based Gold Catalyst

Cyclohexanone is a kind of important intermediate, which are mainly used for synthesis of adipic acid and caprolactam and it is being used widely in market, but the traditional cyclohexanone production process has obvious flaws, so the development of new cyclohexanone production process has received much concern. Nano-gold catalyst is nonpoisonous and harmLess, which has higher reactivity at low temperature and strong tolerance to acid and alkali reaction environment, and its catalytic oxidation of cyclohexane is a very worth exploring topic. This paper mainly studied the two aspects of content: The effection of second modification on the catalytic performance of supported nano-gold catalyst Au/TiO2@SiO2; Preparation of Au/TiO2@SBA-15 through using mesoporous molecular sieve SBA-15 as carrier,study the influence of the catalytic oxidation performance of cyclohexane and reaction conditions. Catalysts were characterized by TEM, XRD, XPS, AAS and other means, investigate the loadings of gold and particle size distribution etc of the catalyst.The main results and conclusions are as follows:Second modification appropriately had little effect on catalytic performance of Au/TiO2@SiO2 but helpful in enhances the stability of catalyst. The best catalytic performance of 10%TiO2/Au/TiO2@SiO2 was got under calcination temperature of300 ? for 1h and 10% TiO2 loading of second modification. the conversion rate of cyclohexane reached 16.93%, total selectivity of cyclohexanol and cyclohexanone reached 82.9%, reaction of TOF reached 10567.84 h-1. The activity and selectivity of catalyst can be maintained and the catalyst stability was better without second modification through the circulation experiment. And the effect of the modifier TiO2 is better than the effect of the modifier SiO2.In the Au/10%TiO2@SBA-15 samples, the introduction of Au and titania did not substantially destroy the regular ordered structure of the parent SBA-15. The gold nanoparticles of catalyst on carrier surface were highly dispersed and had good nanometer size effect. Uniform distribution of gold particles on the carrier were only8 nm on average. Catalytic oxidation of cyclohexane with 0.5%Au/10%TiO2@SiO2under 150 ? and 1.5 MPa,cyclohexane conversion rate reached 14.1%, selectivity of cyclohexanol and cyclohexanone reached 95.6%, TOF reached 3426 h-1, this is the best reaction in the experimental process.The carriers of ordinary silica and mesoporous silica were used to research the catalytic performance of Au-catalyst and achieved good result. High-performance Au catalyst plays positive role in enhancing the development of cyclohexanone production process and becomes more and more worthy of our exploration and contemplation.