Preparation Of Nano-Gold Catalyst Supported On Zeolite And Its Catalytic Performance For Cyclohexane Oxidation

The selective oxidation of cyclohexane to cyclohexanone and cyclohexanol(KA oil) is an important industral production process, cyclohexanone and cyclohexanol are easier overoxidized to a mixture of acid and ester than cyclohexane.In order to the high selectivity,the conversion of cyclohexane must be low.In the chemical industry the one-way conversion is controled lowly(4% approximately),the selectivity is not higy(80%approximately).They not only bring about energy consumpted largely,equip-ment utilized lowly,but also many problems and srtess to environment.Therefore it’s particularly important to develop highly activity and selectivity,environmental catalyst.As a result of the performance of low-temperature and high catalytic activity of nano-gold in microcrystalline scale,the selected type and unique porous of molecular sieve,nano-gold loaded on molecular sieve catalysts have surged on a vigorous mass campaign for the selectivity of cyclohexane.Many scholars have made a lot of research for this process through Au/MCM-41,Au/ZSM-5, Au/TS-1 prepared by different methods.But many of them have only used a little amount of cyclohexane 2-10 mL in the selective oxidation of cyclohexane.In this paper we have prepared Au@TiO2/MCM-41 by photocatalytic reduction method and Au/TS-1 by one-step method,used for the amplification reaction of the selective oxidation of cyclohexane.The catalytic performances and the optimal amplification reaction condition were investigated.Au@TiO2/MCM-41 TEM characterization indicated that nano-gold have loaded in the TiO2/MCM-41 carrier successfully,the particle size is 10 nm approximately with uniform distribution.IR and XRD characterization found that the introduction of gold and titanium dioxide did not change the order and crystallinty of molecular sieve.Au/TS-1 IR and XRD characterization found that the introduction of gold did not change basic MFI structure,the particle size is 10 nm approximately with uniform distribution. The catalyst present a neat uniform quadrangular with complete crystal size for 3×5×7μm discovered by SEM characterization.We investigated the optimal amplification reaction condition:initiator 0.048 g,at 148℃,1.0 MPa,reaction time 1h,the conversion of cyclohexanewas 10.99% with 84.75% selectivity of cyclohexanone,cyclohexanol and cyclohexyl hydroperoxide.Air as the oxidant, Au/TS-1(wt.0.17%) as the catalyst,700 mL cyclohexane was converted upto 6.97% with 88.5% selectivity of objective product at 1.3 MPa,150℃for 2 h in a solvent-free system.The good catalytic effect laid a foundation of the nano-gold catalyst used in the industry.