Preparation Of Cu-(/)SiO₂ Catalyst And Its Catalytic Performance In The Vapor Phase Dehydrogenation Of Cyclohexanol

Cyclohexanone,as an important chemical raw material and solvent,can be produced various processes.The production of cyclohexanone by cyclohexanol gas-phase dehydrogenation process is used extensively for the simple operation,high target product yield and high selectivity.Cu-based catalysts were mainly adopted in the reaction with the advantages of low reaction temperature and high selectivity.However,Cu particles were easy to agglomerate in the reaction,further resulted in deactivation of the catalyst.Therefore,it is of great significance to design Cu-based catalysts with high activity and stability.Therefore,a series of Cu-based catalysts were prepared by different methods with the target of anti-sintering of Cu-based catalysts.The catalytic performance of cyclohexanol gas-phase dehydrogenation reaction was systematically studied.The research contents and main conclusions are as follows:1.A series of Cu-(/)SiO2 catalysts were prepared by different methods using SiO2 as support and performed on cyclohexanol gas-phase dehydrogenation reaction.Cu-SiO2-EISA catalyst prepared by one-pot evaporation induced self-assembly method(EISA)has the advantages of large specific surface area,highly dispersed Cu particles and strong metal-support interaction,thus displays higher activity and selectivity.The initial conversion of cyclohexanol was over 72.6%and the selectivity of cyclohexanone was over 99.5%.2.The influence of CuO content,calcination temperature,reduction temperature and reaction temperature of Cu-SiO2-EISA catalyst on the dehydrogenation performance of cyclohexanol was systematically investigated.At the containing 10 wt.%CuO,the calcination temperature was 550℃,the reaction temperature was 300℃and the reduction temperature was 250℃,the catalyst performed superior activity and selectivity.The initial conversion of cyclohexanol was over 90%,and the selectivity of cyclohexanone was over 99%.Furthermore,the catalytic stability and regenerability were operated under this optimal condition.The results indicated that the catalytic activity increased continuously with the increase of the CuO loading content and reaction temperature,but the deactivation rate accelerated.Combined with the characterization results of TG-DSC,XRD and TEM,the sintering of the metallic Cu particles was revealed to be responsible for the catalyst deactivation.3.To restrain the agglomeration of Cu particles,a series of Cu-SiO2 catalysts were prepared by complex-decomposition method taking advantage of the special structure and complex effect of natural amino acid molecules.Cu-SiO2-Gly catalyst prepared with glycine(Gly)as complexing agent displayed high Cu dispersion and particle size。At the containing 15 wt.%CuO,the calcination temperature of 550℃,the reduction temperature of 250℃ and the reaction temperature of 300℃,the initial conversion of cyclohexanol was dropped from 93.1%to 77.0%in 80 h,and the selectivity of cyclohexanone was stabilized at 94%to 99%.4.The performance of other alcohols dehydrogenation reaction was further investigated on 15Cu-SiO2-Gly catalyst.It was shown that the conversion of 1,4-butanediol to y-butyrolactone was 91.9%and the selectivity of y-butyrolactone was 98.6%.In the reaction of producing methyl ethyl ketone by sec-butanol dehydrogenation process in gas-phase,the conversion of sec-butanol was 93.0%and the selectivity of methyl ethyl ketone was 98.5%.