Preparation Of Carbon Supported Metal Electrode For Synthesis Of Dimethoxymethane By Methanol Oxidation

In this paper,a carbon material activated by concentrated nitric acid was used as a carrier to impregnate a certain proportion of chloroplatinic acid solution,and the Pt/C-X-T material was reduced by H₂ /N₂ atmosphere at different pyrolysis temperatures?X is the theoretical loading of Pt;T is the calcination temperature?.The synthesis conditions of Pt/C-X-T materials were optimized: During the calcination process,the material temperature was 5 K/min,the temperature was 300 °C,the calcination was 3 h,and the platinum loading was 5 wt.%.The material Pt/C-5%-300 was prepared.The materials were characterized by XRD? N₂ adsorption-desorption? SEM? TEM? XPS? Raman and ICP-OES.It was determined that the metal Pt grains were uniformly dispersed on the surface of the carbon support,and the grain size of Pt was calculated by Debye-Scherrer formula.Using Pt/C-5%-300 as the working electrode,platinum electrode as the counter electrode and saturated calomel electrode as the reference,the cyclic voltammetry test of the imidazolium salt type ionic liquid and the anhydrous methanol system showed that the experiment showed no water.Methanol undergoes a redox reaction at the Pt/C-5%-300 working electrode.Based on this,the anhydrous methanol-ionic liquid system was studied by controlled potential electrolysis coulometric method.The catalytic reaction results show that the prepared electrode material Pt/C-5%-300 has good catalytic performance.The reaction conditions of working electrode Pt/C-5%-300 constant potential electrolysis anhydrous methanol were optimized,and the best process conditions were obtained: The reaction constant potential is 4.5 V,the reaction temperature is 30 °C,the molar ratio of anhydrous methanol and ionic liquid Emim BF4?1-ethyl-3-methylimidazolium tetrafluoroborate?is 14:1,and the reaction time is 24 h;Under the optimal conditions,the conversion rate of anhydrous methanol reached 27.64 %,and the selectivity of DMM reached 95.23 %.In addition,in situ infrared spectroscopy of adsorption of anhydrous methanol on the surface of Pt/C-5%-300 material was studied.The test results show that anhydrous methanol is easy to adsorb on the surface of the electrode,and the signal of hydroxyl stretching vibration in the molecule is weakened with the increase of adsorption time.The carbonyl stretching vibration peak appears at 1741.3 cm^-1.It is indicated that the anhydrous methanol reacts on the surface of the catalyst and then undergoes surface conversion under the action of surface active groups.Based on this research,the reaction mechanism of electrochemical oxidation of anhydrous methanol was discussed and proposed.