Construction Of Copper-based Nanocatalyst For Selective Catalytic Oxidation Of 1,2-Propanediol

In recent years,with the depletion of traditional fossil energy and the serious environmental pollution caused by its irrational use,people have an urgent need for renewable energy and green chemical energy.Therefore,catalytic conversion of biomass and its derivatives into high value-added chemicals has attracted extensive attention.1,2-propanediol is a renewable dihydric alcohol,which can be selectively converted into high value-added fine chemicals such as lactic acid,formic acid,acetic acid,pyruvate or hydroxyacetone by catalytic oxidation.However,most of the existing catalysts are supported noble metal catalysts,and their high cost seriously restricts their application.Copper-based catalysts have lower cost and better catalytic oxidation activity,but their selectivity is much lower than that of noble metal catalysts.It has become one of the important challenges in this field to develop an efficient new copper-based catalyst for highly selective 1,2-propanediol conversion.In this paper,Cu@Ag/?-HAP,nano-copper?Cu NPs?and CuFeO_x magnetic nanoparticles?CuFeO_x MNs?catalysts were designed and constructed,respectively,and used for the study of selective catalytic oxidation of 1,2-propanediol.The structure-activity relationship between catalyst and catalytic oxidation of 1,2-propanediol was studied by optimizing the reaction conditions.The main research contents and achievements are as follows:1.Hydroxyapatite nanowires doped with different metal ions??-HAP,in which the name is La,Bi,or Sn?were prepared by hydrothermal method,and a series of supported bimetal nanometer catalysts?Cu@Ag/?-HAP?were prepared by in-situ reduction method.The results showed that Cu@Ag bimetal nanoparticles could improve the conversion of 1,2-propanediol and the selectivity of lactic acid under the synergic action.In the process of catalytic oxidation of 1,2-propanediol,Cu@Ag/?-HAP catalysts doped with different metal ions can significantly improve the catalytic activity of the catalyst.In addition,highly selective lactic acid,acetic acid and hydroxyacetone can be prepared by adjusting the NaOH concentration with different catalysts.2.The single metal copper nanocatalysts?Cu NPs?with uniform particle size were prepared by organic phase oleylamine method.In the presence of O₂,the catalytic oxidation of 1,2-propanediol and the catalytic action of Cu NPs catalyst were studied.The catalytic effects of CuO and Cu₂O were compared.It can be found that Cu NPs catalyst has higher catalytic activity than CuO and Cu₂O.While,the selectivity of Cu NPs to lactic acid is basically the same as that of Cu₂O.The results show that Cu has higher product selectivity under pure phase state?Cu⁰?and low oxidation state?Cu⁺?.3.A spinel CuFeO_x magnetic nanoparticle?CuFeO_x MNs?with Cu?I?and Cu?II?co-existed was developed to catalyze the highly selective preparation of lactic acid from1,2-propanediol.It is found for the catalytic 1,2-propanediol conversion over spinel CuFeO_x MNs,the lactic acid selectivity can be significantly improved in absence of O₂as compared to that in presence of O₂.The cooperative Cu?I?and Cu?II?centres and spinel structure CuFeO_x MNs contribute to their enhanced activity and selectivity as compared to pristine CuO and Cu₂O with single Cu?I?or Cu?II?centres.Meanwhile,by fitting the reaction kinetic equation of Cu₁Fe₁O_x MNs and comparing with CuO and Cu₂O catalysts,it can be found that the reaction activation energy?Ea?and preindex factor?A?of Cu₁Fe₁O_x MNs are between CuO and Cu₂O catalysts.The results showed that Cu₁Fe₁O_x MNs surface had different catalytic activity sites from those of CuO and Cu₂O catalysts due to the presence of Cu?I?or Cu?II?centers at the same time.In addition,CuFeO_x MNs can be easily recovered through magnetic force,with good recovery performance.