Preparation Of Supported Noble Metal Catalysts And Research For Their Performance In Catalytic Hydrogenation And Dehydrogenation

Supported noble metal catalysts have obvious advantages in metal particle size,morphology,physical and chemical properties,catalytic performance and other aspects,and can greatly improve the rate and selectivity of organic reactions.They have broad application prospects in the fields of hydrogenation,dehydrogenation,selective oxidation,alkylation and other organic catalytic reactions.The catalytic properties of supported noble metal catalysts in catalytic hydrogenation and dehydrogenation were studied.Firstly,the preparation method of Pd-Er2O3 and its catalytic hydrogenation performance were explored.At room temperature and pressure,the hydrogenation efficiency of Pd-Er2O3 series catalysts were extremely high,and the conversion frequency values(TOF)of catalytic hydrogenation of styrene were all higher than 5000 h-1.Among them,1.75 wt%Pd-Er2O3 catalyst had the highest reaction activity,reaching 9013 h-1.The reaction rate constant of the hydrogenation of 4-nitrophenol was 0.0058 s-1.The 1.75 wt%Pd-Er2O3 catalyst had good stability and chemical selectivity as well.According to the characterization results of HR-TEM and XPS,the excellent performance of the catalyst is mainly attributed to the enhanced chemisorption of H2 by the catalyst and the strong metal-support interaction(SMSI)between Pd metal nanoparticles and Er2O3.Secondly,Pt-TiO2 catalyst was prepared and its catalytic dehydrogenation performance was studied using the photocatalytic reforming of methanol as the model.Under the condition of 300 W Xenon lamp illumination,the photocatalytic activity of Pt-TiO2 was high,and the hydrogen production efficiency reached 19.87?mol/h.This is mainly due to the formation of strong metal-support interaction(SMSI)between Pt and TiO2 carrier,which can promote the rapid migration and transformation of photogenerated electrons between the carrier and the metal,and improve the photocatalytic activity of Pt-TiO2 catalyst.The hydrogen production efficiency increased by 3.55 times to 70.62 ?mol/h after adding PAG.According to the analysis of the reaction products by FT-IR and GC-MS,this may be because PAG produced H+ under light,which increased the content of H+ in the solution and promoted the combination of H+and photogenic electrons,thus greatly improved the efficiency of catalytic hydrogen production.In general,the Pd-based and Pt-based supported catalysts designed and synthesized in this paper can efficiently catalyze a series of hydrogenation and dehydrogenation reactions,such as the hydrogenation of styrene,4-nitrophenol and the photocatalytic reforming of methanol to produce hydrogen gas,with excellent catalytic performance under mild reaction conditions.