| Activated carbon plays an important role in the fields of environmental protection,chemical industry,catalyst carrier and double capacitor preparation due to its unique advantages of high specific surface area.In the preparation of activated carbon,the activation parameters and the selection of activators have a great effect on the pore structure of activated carbon,which determines the adsorption and electrochemical performance of activated carbon,therefore,based on the preliminary study of KOH activation mechanism,the parameters of simple KOH activation and complex activation were optimized in order to obtain high specific surface area activated carbon and improve its properties.By using comprehensive thermal analyzer,Sinopec petroleum coke as raw material and KOH as activator,the regulation rule of pore structure of activated carbon under different final activation temperature was revealed.The conventional activation process of petroleum coke under different coke alkali ratio was studied in the temperature window of 0-1000℃,and the mechanism of KOH on the regular activation of petroleum coke was preliminarily explored:In the KOH activation process,the activation process of petroleum coke based activated carbon mainly includes two stages:low temperature activation stage(below 400℃)and high temperature activation stage(above 600℃),The low-temperature activation stage belongs to the activation induction stage.The pre activation and pore forming of raw petroleum coke are carried out.The high-temperature activation stage is mainly the reaction between the carbonaceous substance on the surface of raw material and the intermediate substance generated by KOH,which leads to the introduction of longitudinal activation.In this paper,the effects of activation time,microwave power and coke alkali ratio on the pore structure of activated carbon were studied and the optimal activation parameters were determined,constant current charge discharge,cyclic voltammetry and AC impedance tests were carried out on the activated carbon to reveal the quantitative relationship between the electrochemical performance of the activated carbon and the active parameters,the experimental results show that:The pore structure,adsorption performance and electrochemical performance of activated carbon obtained by the comparison of activation time,microwave power and caustic soda play a decisive role.Under the optimal activation parameters of microwave power of 640 W,activation time of 30 min and coke-alkali ratio 1:2,the specific surface area of the activated carbon was 1914.56 m2/g,the water absorption was 151.5%,and the iodine adsorption value was 1654.6 mg/g.At 0.1 A/g,the specific capacitance is 237.74 F/g,the capacity retention rate is 58.9%,and it has good rate performance.With KOH as the main compound activator,ZnCl2,Fe(OH)3 and KCl as auxiliary agents,the petroleum coke was activated under the optimal microwave power and activation time,the research focuses on the effect of the compound form and mass ratio of activator on the pore structure parameters and electrochemical properties of activated carbon,determines the optimal compound activator,and preliminarily reveals the compound activation mechanism of petroleum coke under microwave conditions,The results show that:Compared with activated carbon obtained by KOH activation alone,the addition of ZnCl2 resulted in a decrease of specific surface area of 500.18m2/g,with the worst effect;The added specific surface area of KCl increased by 105.05 m2/g,but the maximum impedance was due to the large number of micropores;the auxiliary effect of Fe(OH)3 was the best.When the quality ratio of KOH:Fe(OH)3 was 2:1,the specific surface area was increased to 2107.82 m2/g,at the current density of 0.1 A/g,the specific capacitance reached 261.81 F/g,and at 10 A/g,the specific capacitance was 166.17 F/g,with A capacitance retention rate of 63.5%.The pore structure and electrochemical performance of the activated carbon obtained were the best. |
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