【作者】 张超；

【导师】 李志林； 张良虎；

【作者基本信息】 北京化工大学 ， 材料工程（专业学位）， 2022， 硕士

【摘要】 湿法冶金作为目前主流的炼锌方式,由此得到的金属锌占到了锌总产能的80%。在传统电沉积锌工艺中,铅基合金阳极上发生的析氧反应带来了高反应电位,导致整个过程电能消耗较大。使用氢气扩散阳极(HDA)代替传统铅基阳极进行锌电积,通过改变阳极反应可以降低槽电压,达到节能的效果。本文着重研究用以催化HDA上氢氧化反应(HOR)的铂催化剂,从对铂催化剂进行表面形貌设计入手,并对其掺杂量进行调控,研究它们对电沉积锌的影响。本文还对HDA的制备工艺进行了探索。本文以氯铂酸、乙二醇、二甲基甲酰胺和商业炭黑作为原料,用水热法制备了碳载铂催化剂。通过调节各组分的比例,诱导铂催化剂形成特定的表面结构。构造了具有八面体形貌和四面体形貌的铂纳米颗粒催化剂,对这些催化剂的形貌、含量和催化性能间的关系进行表征和研究;以碳布、铂催化剂、商业炭黑、异丙醇和聚四氟乙烯为原料,制备了气体扩散电极。通过在电极上掺杂不同形貌的催化剂以及对催化剂的掺杂量进行调控,并将电极应用于电沉积锌的反应中,对其槽电压、电流效率以及直流单耗进行了相关研究。取得的主要研究结果如下:(1)制备出具有四面体形貌和八面体形貌的铂纳米粒子催化剂,其中四面体铂纳米粒子催化剂具有较好的HOR催化性能,极限电流密度达到3.28 m A/cm~2,反应过电位仅为10 m V,在40 m V超电势下具有42.9 m A/mg的质量活性;在经过5000次电位循环后,其极限电流密度还能保持循环前的86%,在一氧化碳沉积毒化后仍保留约60%的质量活性,相比于商业铂碳催化剂有着明显优势,具有一定的应用前景。(2)制备了不同铂负杂量下的碳载铂催化剂,对其HOR电化学性能进行研究后发现:制备的铂质量分数为5%的铂催化剂与铂质量分数为20%的商业铂碳催化剂的极限电流密度相当,表明在保证HOR催化性能的前提下采用本文制备的制备方法可减少铂使用量,降低反应成本。(3)通过涂覆、冷压、烧结、热压制备了不同催化剂形貌、含量下的HDA并用于锌电积。经参数调整优化表明,催化剂在电极上的掺杂量为5%的时候,电极的成型性能和经济效益最高。用四面体铂催化剂所制备的电极进行锌电积时,槽电压仅为1.19 V,电流效率达到89%,直流单耗为1180 k Wh/t,节能效果优于用商业铂碳催化剂制备的电极。更多还原

【Abstract】 Hydrometallurgy,as the current main way of zinc refining,produces 80%metal zinc of the total zinc production.In the traditional electrowinning process of zinc,the oxygen evolution reaction on the anode of lead alloy leads to a high reaction potential,which causes large energy consumption in the whole process.The hydrogen diffusion anode(HDA)can be used instead of the traditional lead anode for zinc electrowinning.By changing the reaction on the anode,the cell voltage can be reduced to save energy.This thesis focuses on the platinum catalyst for the catalysis of the hydrogen oxidation reaction(HOR)on HDA,The surface morphology of platinum catalysts is designed and their doping content is regulated to study their influence on electrowinning of zinc.In addition,the preparation process of HDA was also explored in this thesis.In this thesis,using chloroplatinic acid,ethylene glycol,dimethylformamide and commercial carbon black as materials,using hydrothermal prepared platinum catalyst.By adjusting the proportion of each component to induce the surface structure of platinum catalyst,and the platinum nanoparticles with octahedral morphology and tetrahedral morphology were constructed.Then,we characterized and studied the relationship between the morphology,content and catalytic performance of these catalysts.Using carbon cloth,platinum catalyst,commercial carbon black,isopropyl alcohol and polytetrafluoroethylene as materials,the gas diffusion electrode were prepared and applied to electrowinning of zinc.Then we studied the electrochemical parameters related to the electrowinning process,which are cell voltage,current efficiency and direct current unit consumption.The main research results are as follows:(1)The platinum nanoparticle catalysts with tetrahedral morphology and octahedral morphology are prepared.And tetrahedral platinum nanoparticle catalysts have good application performance in HOR,with limiting current density reaching 3.28 m A/cm~2,reaction overpotential of 10 m V,and mass activity of 42.9 m A/mg at 40 m V superpotential.After 5,000 potential cycles,the limiting current density of platinum tetrahedral catalyst can still retain 86%of the original state,and the mass activity of tetrahedral platinum catalyst retains about 60%after carbon monoxide poisoning.Compared with commercial platinum catalyst,it has obvious advantages.(2)Carbon supported platinum catalysts with different doping content were prepared.After studying the electrochemical performance of HOR on these catalysts,we were found that the limiting current density of the platinum catalyst prepared with 5%platinum mass fraction is comparable to that of the commercial platinum carbon catalyst prepared with 20%platinum mass fraction,indicating that the catalyst prepared in this thesis can reduce the amount of platinum and the reaction cost on the premise of ensuring the catalytic performance of HOR.(3)Hydrogen diffusion anodes with different catalyst morphology and content were prepared by coating,cold pressing,sintering and hot pressing for electrowinning of zinc.The optimized parameters show that the electrode has the highest forming performance and economic benefit when the catalyst doping fraction on the electrode is 5%.When the electrode prepared by tetrahedral platinum catalyst is used for electrowinning of zinc,the cell voltage is only 1.19V,the current efficiency is 89%,and the direct current unit consumption is 1180 k Wh/t,which is better than the electrode prepared by commercial platinum carbon catalyst.更多还原