| Carboxylic compounds are very important organic chemical materials and intermediates,which are widely applied in pharmacy,pesticide and dye industries.Studying on preparation of diglycolic acid by direct electrooxidation diethylene glycol offers a method to synthetic organic electrochemistry alcohols.In this dissertation,nickel-oxide hydroxide electrodes were prepared by electrochemical oxidation-reduction.Atomic force microscopy(AFM)and chronoamperometry,cyclic voltammetry and constant current electrolyte were used to study the surface characterization and real areas of nickel-oxide hydroxide electrode,study electrochemical performance toward oxidation of diethylene glycol and synthesize diglycolic acid,respectively.The reaction temperature, diethylene glycol concentration,current densities and voltage were studied in the reaction.In order to study the characteristic of nickel-oxide hydroxide electrode catalyze-oxidation alcohols,oxidation of methanol and glycerol on nickel-oxide hydroxide electrode were investigated,and the temperature,reaction concentrations and scan rates were studied in the process.The experimental results showed that the surface granule of nickel-oxide hydroxide electrodes prepared by electrochemical oxidation-reduction had a nano-configuration,which enhanced the real surface areas of electrodes.Compared to polished nickel electrode, nickel-oxy hydroxide electrode behaved as an efficient electro-catalyst for the oxidation of alcohols in alkaline medium.In the process of oxidation methanol(unitary alcohol),diethylene glycol(duality alcohol) and glycerol(ternary alcohol),we found that electrochemical behaves of methanol,diethylene glycol and glycerol were resemble.Electrode process was controlled by diffusion process,with increasing electrolyte concentration and temperature,which increased the current of alcohols. But nickel-oxide hydroxide electrode had low stability and easily lost activity.Synthetic electrochemical of diglycolic acid experiments showed:(1) The yield of diglycolic acid was 54.6 percent properly at 16.6 mA/cm2 in experimental.Current densities greater than certain densities could lead to electrode damaged while current densities less than certain densities could insufficient to generate practical amounts of nickel-oxide hydroxide. (2)The best electrolyze concentration was 2 mol·L-1NaOH in the process of synthesis.The electrolyze concentration higher than certain concentration could lead to electrode toxicosis and lose activity.(3)The best temperature was 60℃in the process,and increasing reaction temperature could accelerate reaction largely.If the temperature was too high in the reaction,it would accelerate side reaction and decrease the yields of diglycolic acid.
|
PDF Full Text Request