Electrochemical Oxidation Of Shenmu Bituminous Coal In Alkaline Medium

Electrochemical oxidation of coal is a new clean coal technology that uses electrochemical methods to carry out the electrolytic oxidation of coal slurry to prepare high value-added industrial products.This technology is of great significance for the efficient and clean utilization of coal.In this paper,the electrochemical oxidation of Shenmu bituminous coal in alkaline medium was studied by using the H-type diaphragm electrolyzer in the three electrode system.The relationship between oxidation conditions and anodic oxidation products was obtained by systematically investigating the influence of oxidation conditions on the electrochemical oxidation process of coal.The cyclic voltammetric curve of the electrode was measured with the Ni electrode as the working electrode.The results showed that the oxidation current density of the Ni electrode was higher at the same potential than that of the electrolytic KOH solution experiment.The analysis of the oxidation products after anodic reaction shows that the anodic oxidation products arc mainly water-insoluble acid(WIA)and water-soluble acid(WSA),mainly water-insoluble acid.The analysis of anode gas phase products showed that the anode gas phase products were oxygen,and the purity was close to 100%.On the basis of Ni electrode as working electrode,the effects of coal slurry concentration,reaction time,electrolysis temperature and ash content on coal electrochemical oxidation process were investigated.It is found that with the increase of coal slurry concentration,the electrochemical current oxidation efficiency will increase,but the yield of corresponding anodic oxidation products will decrease,indicating that the higher the coal slurry concentration is,the better.Within the set range,the anodic oxidation products obtained by 25 g/L coal slurry electrochemical oxidation are the highest.With the increase of reaction time,the degree of oxidation reaction deepened,and the yield ratio of anodic oxidation product WIA/WSA increased.The influence of electrolysis temperature on oxidation process conforms to Arrhenius equation.The higher the electrolysis temperature,the greater the current oxidation rate.Under the constant voltage of 0.8 V(vs.SCE),the apparent activation energy of coal electrochemical oxidation reaction is 28.80 kJ/mol.The ash in coal has a certain influence on the electrochemical oxidation process of coal slurry.It is found that the ash in coal will hinder the electrochemical oxidation process of coal.A kind of BDD electrode with high oxygen evolution potential was used as the working electrode for coal electrochemical oxidation.Compared with Ni electrode,it was found that under the premise of other conditions,the current density of BDD electrode was smaller than that of Ni electrode,and the yield of anodic oxidation product was higher than that of Ni electrode.Comparing the gas phase products of the two electrodes,it is found that the gas volume of BDD electrode is about 1/4 less than that of Ni electrode,and the content of CO2 in the gas component of BDD electrode is more than that of Ni electrode.Comparing the infrared spectra of residual coal under BDD electrode and Ni electrode,it is found that the C=C Tensile vibration absorption peak in residual coal obtained by Coal Electrochemical Oxidation with BDD electrode as working electrode is stronger.In conclusion,BDD electrode is more suitable as anode material for coal electrochemical oxidation than Ni electrode.On the basis of BDD electrode as working electrode,the effects of reaction time,electrolysis temperature and oxygen conditions on coal electrochemical oxidation process were investigated.It was found that the yield of anodic oxidation products reached the maximum when the reaction time was 7 h;When the electrolysis temperature is 50℃,the yield ratio of WIA/WSA produced by electrochemical oxidation of coal was smaller when the BDD electrode was used compared with the Ni electrode;It is found that oxygen can promote the deep oxidation of coal.By analyzing the infrared spectra of coal samples and anodic oxidation products WIA and WSA before and after coal electrochemical oxidation,it is speculated that the structural change of coal electrochemical oxidation is that the ring opening of aromatic ring structure in coal is oxidized to WIA,while WIA continues to be oxidized to WSA,resulting in a large number of aromatic ring structures in WIA and WSA.