Preparation Of Non-precious Metallic Cu-N/C Catalyst For Electrocatalytic Oxidation Of Glycerol

Glycerol is a by-product of the process of producing biodiesel.Due to its large output and single use,the current situation of glycerol has overcapacity.Therefore,it is of great significance to find a suitable method to convert glycerol into high value-added chemicals.Among them,driving the electrocatalytic oxidation of glycerol by sustainable renewable energy is an effective way to realize the conversion of glycerol.However,due to the complicated reaction process of electrocatalytic oxidation of glycerol,problems such as carbon-carbon bond cleavage and over-oxidation will occur,resulting in poor glycerol conversion efficiency with low product selectivity.In view of this situation,this thesis focuses on the non-precious metal Cu-N/C catalyst,from the aspects of innovation and optimization of preparation methods,selection of suitable catalytic reaction conditions,exploration of active sites and synergistic catalysis with Pt,etc.,and discusses the composition,The relationship between the structure and the performance of electrocatalytic oxidation of glycerin to formic acid and glyceric acid.The main research contents are as follows:(1)A series of transition metal-nitrogen/carbon(M-N/C,M = Fe,Co,Ni,Cu and Zn)catalysts were prepared by gelatin immobilization-thermal decomposition method.By comparing the catalytic activity and selectivity of glycerol electrooxidation,the Cu-N/C catalyst was selected as the main research object.By screening the types of copper salts,the amount of copper salts added,the calcination temperature,the ratio of melamine and other preparation conditions,the best performance Cu-N/C catalyst is obtained,and it has a higher conversion rate of glycerol(97.7%)and formic acid selection under alkaline conditions.Sex(91.0%).Through XPS and other characterizations,it is found that Cu particles are the main active sites of the catalyst.The core-shell structure of the catalyst can well protect the active sites from being destroyed during the electrocatalytic reaction,thereby improving the stability of the catalyst.(2)Pt/CuNC catalyst was prepared by using Cu-N/C catalyst as a carrier to support Pt,and electrocatalytic oxidation of glycerol to glyceric acid was carried out at a lower voltage(0.92 V vs RHE).By comparing the Pt loading sequence,loading method and loading amount and other conditions,it is found that 5wt.% Pt is loaded after the ethylene glycol reduction method,and the best performance Pt/CuNC catalyst is obtained,with 68.6% glycerol conversion rate and 61.2% glyceric acid selectivity.Through characterization,it is found that the Cu-N/C carrier can effectively reduce the agglomeration of Pt and increase the anti-poisoning ability of Pt.There is a strong interaction between Pt Cu,which makes electrons transfer from Pt to Cu,reducing the electron density of Pt,and adsorbing and activating negatively charged ones.Alkoxy groups reduce the breaking of carbon-carbon bonds and the production of lactic acid,thereby increasing the conversion rate of glycerol and the selectivity of glyceric acid.