氯碱工业析氯阳极研究
发布时间：2019-06-19 12:23
【摘要】：氯碱工业是重要的基础化学工业,其产品氯气、烧碱和氢气是基础性的化工原料,氯碱工业消耗世界10%的发电量,因此高效的析氯电极对节能意义巨大。本文简述了氯碱工业、析氯阳极的发展历程,详细介绍了Ru-Ti体系DSA形稳阳极的导电机理、析氯催化机理和阳极失活机理。综述了主要针对钌钛氧化物涂层中掺杂其他元素及氧化物形成二元或三元混合氧化物,通过改变掺杂物种的含量、制备条件等改变涂层的组成和形貌对其催化析氯效果影响的研究现状。比较了形稳阳极不同制备方法的优缺点。提出通过理论计算结合实验研究,设计、模拟DSA形稳阳极进行理论计算和实验制备,从微观的角度研究析氯效果和析氯机理,对研制新型的DSA形稳阳极具有重要的指导意义。采用广义密度泛函理论(GGA)的PW91方法结合周期平板模型进行了Cl在一元、二元和三元金属氧化物表面吸附的理论计算。包括Cl在一元金红石型TiO_2和RuO_2的(110)表面的吸附情况,不同Ti、Ru掺杂比例(Ti:Ru比分别为3:1,1:1,1:3)二元金属氧化物TinRumO_2表面,Ti-Ru金属氧化物与第三种元素X(X为Ir、Sn、Mn)掺杂比例(Ti:Ru:X为2:1:1)的三元金属氧化物Ti2/4Ru1/4X1/4O_2表面吸附进行计算。计算各氧化物(纯氧化物,掺杂氧化物)的吸附能、能带结构、前线分子轨道等,揭示掺杂金属氧化物对电子构型的影响。根据析氯机理,通过前线分子轨道理论对电化学反应和电化学脱附反应的反应活性进行理论计算分析。使用LST/QST方法寻找Cl_2在不同比例金属氧化物表面的析出过程的过渡态和相应的能量数据,比较在不同比例金属氧化物表面析出的Cl_2过渡态的活化能和反应热。结果表明:(1)Cl在TiO_2和RuO_2的(110)表面吸附位只有金属顶位和氧顶位。Ti:Ru比为3:1时金属氧化物O顶位对Cl的吸附能最小为1.524e V。(2)Cl原子吸附在Ti:Ru比为3:1时的金属氧化物表面金属顶位,吸附作用最小。过渡态计算得出Cl在活性位Ru被氧化为S-O中间物种(S表示形稳阳极表面的活性吸附位)位吸附并析出电极表面;Cl_2在Ti3/4Ru1/4O_2(110)表面的析出的反应热ΔHr为5.798kcal/mol,活化能Ea为25.862kcal/mol,比在Ti2/4Ru2/4O_2表面生成Cl_2的能量低,Cl_2在Ti3/4Ru1/4O_2(110)表面更容易析出。比较掺杂前后的能带情况,由于Ru的掺入,使其导电性得到增强,且掺杂体系的导电性与Ru的掺杂比例有关,且随着掺杂比例增大其掺杂催化剂的导电性越好。通过前线轨道理论对其析氯机理分析得出,掺杂后Ti:Ru比为3:1时较易发生电化学反应,生成S-Clads中间体,此时的能隙ΔE最小为2.323e V;掺杂后Ti:Ru比为3:1时较易发生电化学脱附反应,析出Cl_2,能隙ΔE最小为2.088e V,且在该比例时,Cl在Ti3/4Ru1/4O_2(110)表面上的吸附能最小Ea为2.514 e V。(3)对于三元金属氧化物Ti2/4Ru1/4X1/4O_2(X为Ir、Sn、Mn)掺杂比例(Ti:Ru:X为2:1:1),比较其能带情况,在Ru掺杂量一定的情况下,Ir、Sn、Mn三种掺杂结构导电性顺序为Ti2/4Ru1/4Ir1/4O_2Ti2/4Ru1/4Sn1/4O_2≈Ti2/4Ru1/4Mn1/4O_2。Ir对固体催化剂的导电性的加强作用明显,有利于反应过程中电子的传递,加快了反应的速率。通过过渡态计算得出Cl_2分别在Ti2/4Ru1/4Ir1/4O_2和Ti2/4Ru1/4Sn1/4O_2表面析出的活化能Ea分别为16.658 kcal/mol和45.795 kcal/mol,故Ti2/4Ru1/4Ir1/4O_2更有利于Cl_2的析出。通过前线轨道理论对其析氯反应机理反应计算可知,对于电化学反应,掺杂铱元素的电极其前线轨道LUMO能量比掺杂锡元素后的前线轨道LUMO降低,Ti2/4Ru1/4Ir1/4O_2(110)电极的能隙ΔE为1.249e V,比Ti2/4Ru1/4Sn1/4O_2(110)电极能隙ΔE1.461e V小。对于电化学脱附反应,Ti2/4Ru1/4Ir1/4O_2(110)电极氯吸附在O顶位后能隙ΔE为1.801e V,比Ti2/4Ru1/4Sn1/4O_2(110)电极Cl吸附在O顶位时能隙ΔE为2.046e V小。Ti2/4Ru1/4Ir1/4O_2(110)电极析氯催化活性比Ti2/4Ru1/4Sn1/4O_2好。根据计算模型的原子比例,采用高温分解法制备不同温度下的Ti-Ru-X(X为Ir、Sn、Mn)三元金属氧化物析氯电极,并对其进行SEM、XRD、EDS、LSV、CV表征和性能测试。实验结果表明:掺杂Ir、Sn、Mn元素制备Ti-Ru-X(X为Ir、Sn、Mn)三元金属氧化物析氯电极,在烧结温度为450℃时,形成的Ti-Ru-Ir混合氧化物电极表面龟裂最少,表面更加均匀,具有活性位数量最多。当烧结温度为450℃时,添加Ir、Sn、Mn元素制备的Ti-Ru-X(X为Ir、Sn、Mn)三元金属氧化物析氯电极,Ti-Ru-Ir电极具有最好的催化析氯活性。通过电化学性能测试,添加三种元素所得电极的活性从高到低依次为Ti-Ru-IrTi-Ru-SnTi-Ru-Mn。这与理论计算结果相吻合。
[Abstract]:The chlor-alkali industry is an important basic chemical industry, its product chlorine, caustic soda and hydrogen are the basic chemical raw materials, the chlor-alkali industry consumes 10% of the power generation, so the efficient chlorine evolution electrode is of great energy-saving significance. The development of the chlor-alkali industry and the chlorine evolution anode is described in this paper. The conductive mechanism of the DSA-shaped stable anode of the Ru-Ti system, the catalytic mechanism of chlorine evolution and the mechanism of the deactivation of the anode are introduced in detail. In this paper, the research status of the effect of the composition and morphology of the coating on the effect of the catalyst on the chlorine evolution is reviewed, mainly for the formation of binary or ternary mixed oxides by doping other elements and oxides in the titanium oxide coating, and by changing the content of the doped species, the preparation conditions and the like. The advantages and disadvantages of different preparation methods of the shape-stable anode are compared. In this paper, the theoretical calculation and the experimental preparation of the DSA-shaped stable anode are presented by the theoretical calculation, and the analysis of the chlorine effect and the chlorine evolution mechanism from the micro point of view is of great significance to the development of a new DSA-shaped stable anode. The theoretical calculation of the adsorption of Cl in the surface of a single, binary and ternary metal oxide is carried out by using the PW91 method of the generalized density functional theory (GGA) in combination with the periodic plate model. including the adsorption of Cl in the (110) surface of one-element rutile-type TiO _ 2 and RuO _ 2, the doping ratio of Ti and Ru (Ti: Ru ratio of 3:1,1:1,1:3) and the doping proportion of the Ti-Ru metal oxide with the third element X (X is Ir, Sn, Mn) (Ti: Ru: The surface adsorption of the ternary metal oxide Ti2/ 4Ru1/ 4X1/ 4O _ 2 with X 2:1:1 was calculated. The influence of the doping metal oxide on the electronic configuration is revealed by calculating the adsorption energy, the energy band structure, the front line molecular orbital, and the like of each oxide (pure oxide, doped oxide). According to the mechanism of chlorine evolution, the reaction activity of the electrochemical reaction and the electrochemical desorption reaction is theoretically calculated and analyzed by the front line molecular orbital theory. The transition state and the corresponding energy data of the precipitation process of Cl _ 2 on the surface of different scale metal oxides were found by the LST/ QST method, and the activation energy and the reaction heat of the Cl _ 2 transition state precipitated on the surface of the metal oxide in different proportions were compared. The results show that (1) The adsorption of (1) Cl on the (110) surface of TiO _ 2 and RuO _ 2 is only the top and top of the metal. When the ratio of Ti to Ru is 3:1, the adsorption energy of the top of the metal oxide O to Cl can be at least 1.524 e V. (2) The adsorption of the metal oxide on the surface of the metal oxide at the time of Ti: Ru ratio of 3:1 by the Cl atom is the least. The reaction heat of Cl _ 2 on the surface of Ti3/ 4Ru1/ 4O _ 2 (110) was 5.798 kcal/ mol, the activation energy Ea was 25.862 kcal/ mol, and the energy of Cl _ 2 was lower than on the surface of Ti2/ 4Ru2/ 4O _ 2. The Cl _ 2 is more easily separated on the surface of Ti3/ 4Ru1/ 4O _ 2 (110). Compared with the energy band before and after doping, the conductivity of the doped system is enhanced due to the incorporation of Ru, and the conductivity of the doping system is related to the doping proportion of Ru, and the better the conductivity of the doped catalyst is increased with the doping proportion. According to the analysis of the chlorine evolution mechanism of the front-line track theory, an electrochemical reaction is easy to occur when the ratio of Ti to Ru is 3:1, and the S-Clads intermediate is generated. At this time, the energy gap coefficient E is at a minimum of 2.323 e V, and the post-doping Ti: Ru ratio is 3:1, the electrochemical desorption reaction is easy to occur, and the Cl _ 2 is separated out. The minimum Ea at the surface of Ti3/ 4Ru1/ 4O _ 2 (110) is 2.05e V. (3) For ternary metal oxide Ti2/ 4Ru1/ 4X1/ 4O _ 2 (X is Ir, Sn, Mn) doping ratio (Ti: Ru: X is 2:1:1), the energy band can be compared. The conductivity of the three doping structures of Sn and Mn is Ti2/ 4Ru1/ 4Ir1/ 4O _ 2Ti2/ 4Ru1/ 4Sn1/ 4O _ 2Ti2/ 4Ru1/ 4Mn1/ 4O _ 2.Ir has obvious reinforcing effect on the conductivity of the solid catalyst, and is beneficial to the transfer of electrons in the reaction process, and the reaction rate is accelerated. In the transition state, the activation energy Ea for the precipitation of Cl _ 2 on the surface of Ti2/ 4Ru1/ 4Ir1/ 4O2 and Ti2/ 4Ru1/ 4Sn1/ 4O _ 2 is 16.658 kcal/ mol and 45.795 kcal/ mol, respectively, so that Ti2/ 4Ru1/ 4Ir1/ 4O _ 2 is more favorable for the precipitation of Cl _ 2. It can be found that the energy gap of the front-line track LUMO of the electrode with the doping element is lower than that of the front-line rail LUMO after the doping of the tin element, and the energy gap ratio E of the Ti2/ 4Ru1/ 4Ir1/ 4O _ 2 (110) electrode is 1.249e V, which is smaller than that of the Ti2/ 4Ru1/ 4Sn1/ 4O _ 2 (110) electrode, and the energy gap of the electrode of the Ti2/ 4Ru1/ 4Sn1/ 4O _ 2 (110) electrode is smaller than that of the Ti2/ 4Ru1/ 4Sn1/ 4O _ 2 (110) electrode. The energy gap of Ti2/ 4Ru1/ 4Ir1/ 4O _ 2 (110) electrode was 1.801e V and 2.046e V when the electrode Cl of Ti2/ 4Ru1/ 4Sn1/ 4O _ 2 (110) was adsorbed on the O-top position for the electrochemical desorption reaction. The catalytic activity of Ti2/ 4Ru1/ 4Ir1/ 4O _ 2 (110) is better than that of Ti2/ 4Ru1/ 4Sn1/ 4O _ 2. Ti-Ru-X (X is Ir, Sn, Mn) ternary metal oxide-containing electrode at different temperatures is prepared by high-temperature decomposition method according to the atomic ratio of the calculated model, and the SEM, XRD, EDS, LSV, CV characterization and performance test are carried out. The experimental results show that the Ti-Ru-X (X is Ir, Sn, Mn) ternary metal oxide chlorine-removing electrode is prepared by doping Ir, Sn and Mn elements, and at the sintering temperature of 450 鈩，
本文编号：2502346
[Abstract]:The chlor-alkali industry is an important basic chemical industry, its product chlorine, caustic soda and hydrogen are the basic chemical raw materials, the chlor-alkali industry consumes 10% of the power generation, so the efficient chlorine evolution electrode is of great energy-saving significance. The development of the chlor-alkali industry and the chlorine evolution anode is described in this paper. The conductive mechanism of the DSA-shaped stable anode of the Ru-Ti system, the catalytic mechanism of chlorine evolution and the mechanism of the deactivation of the anode are introduced in detail. In this paper, the research status of the effect of the composition and morphology of the coating on the effect of the catalyst on the chlorine evolution is reviewed, mainly for the formation of binary or ternary mixed oxides by doping other elements and oxides in the titanium oxide coating, and by changing the content of the doped species, the preparation conditions and the like. The advantages and disadvantages of different preparation methods of the shape-stable anode are compared. In this paper, the theoretical calculation and the experimental preparation of the DSA-shaped stable anode are presented by the theoretical calculation, and the analysis of the chlorine effect and the chlorine evolution mechanism from the micro point of view is of great significance to the development of a new DSA-shaped stable anode. The theoretical calculation of the adsorption of Cl in the surface of a single, binary and ternary metal oxide is carried out by using the PW91 method of the generalized density functional theory (GGA) in combination with the periodic plate model. including the adsorption of Cl in the (110) surface of one-element rutile-type TiO _ 2 and RuO _ 2, the doping ratio of Ti and Ru (Ti: Ru ratio of 3:1,1:1,1:3) and the doping proportion of the Ti-Ru metal oxide with the third element X (X is Ir, Sn, Mn) (Ti: Ru: The surface adsorption of the ternary metal oxide Ti2/ 4Ru1/ 4X1/ 4O _ 2 with X 2:1:1 was calculated. The influence of the doping metal oxide on the electronic configuration is revealed by calculating the adsorption energy, the energy band structure, the front line molecular orbital, and the like of each oxide (pure oxide, doped oxide). According to the mechanism of chlorine evolution, the reaction activity of the electrochemical reaction and the electrochemical desorption reaction is theoretically calculated and analyzed by the front line molecular orbital theory. The transition state and the corresponding energy data of the precipitation process of Cl _ 2 on the surface of different scale metal oxides were found by the LST/ QST method, and the activation energy and the reaction heat of the Cl _ 2 transition state precipitated on the surface of the metal oxide in different proportions were compared. The results show that (1) The adsorption of (1) Cl on the (110) surface of TiO _ 2 and RuO _ 2 is only the top and top of the metal. When the ratio of Ti to Ru is 3:1, the adsorption energy of the top of the metal oxide O to Cl can be at least 1.524 e V. (2) The adsorption of the metal oxide on the surface of the metal oxide at the time of Ti: Ru ratio of 3:1 by the Cl atom is the least. The reaction heat of Cl _ 2 on the surface of Ti3/ 4Ru1/ 4O _ 2 (110) was 5.798 kcal/ mol, the activation energy Ea was 25.862 kcal/ mol, and the energy of Cl _ 2 was lower than on the surface of Ti2/ 4Ru2/ 4O _ 2. The Cl _ 2 is more easily separated on the surface of Ti3/ 4Ru1/ 4O _ 2 (110). Compared with the energy band before and after doping, the conductivity of the doped system is enhanced due to the incorporation of Ru, and the conductivity of the doping system is related to the doping proportion of Ru, and the better the conductivity of the doped catalyst is increased with the doping proportion. According to the analysis of the chlorine evolution mechanism of the front-line track theory, an electrochemical reaction is easy to occur when the ratio of Ti to Ru is 3:1, and the S-Clads intermediate is generated. At this time, the energy gap coefficient E is at a minimum of 2.323 e V, and the post-doping Ti: Ru ratio is 3:1, the electrochemical desorption reaction is easy to occur, and the Cl _ 2 is separated out. The minimum Ea at the surface of Ti3/ 4Ru1/ 4O _ 2 (110) is 2.05e V. (3) For ternary metal oxide Ti2/ 4Ru1/ 4X1/ 4O _ 2 (X is Ir, Sn, Mn) doping ratio (Ti: Ru: X is 2:1:1), the energy band can be compared. The conductivity of the three doping structures of Sn and Mn is Ti2/ 4Ru1/ 4Ir1/ 4O _ 2Ti2/ 4Ru1/ 4Sn1/ 4O _ 2Ti2/ 4Ru1/ 4Mn1/ 4O _ 2.Ir has obvious reinforcing effect on the conductivity of the solid catalyst, and is beneficial to the transfer of electrons in the reaction process, and the reaction rate is accelerated. In the transition state, the activation energy Ea for the precipitation of Cl _ 2 on the surface of Ti2/ 4Ru1/ 4Ir1/ 4O2 and Ti2/ 4Ru1/ 4Sn1/ 4O _ 2 is 16.658 kcal/ mol and 45.795 kcal/ mol, respectively, so that Ti2/ 4Ru1/ 4Ir1/ 4O _ 2 is more favorable for the precipitation of Cl _ 2. It can be found that the energy gap of the front-line track LUMO of the electrode with the doping element is lower than that of the front-line rail LUMO after the doping of the tin element, and the energy gap ratio E of the Ti2/ 4Ru1/ 4Ir1/ 4O _ 2 (110) electrode is 1.249e V, which is smaller than that of the Ti2/ 4Ru1/ 4Sn1/ 4O _ 2 (110) electrode, and the energy gap of the electrode of the Ti2/ 4Ru1/ 4Sn1/ 4O _ 2 (110) electrode is smaller than that of the Ti2/ 4Ru1/ 4Sn1/ 4O _ 2 (110) electrode. The energy gap of Ti2/ 4Ru1/ 4Ir1/ 4O _ 2 (110) electrode was 1.801e V and 2.046e V when the electrode Cl of Ti2/ 4Ru1/ 4Sn1/ 4O _ 2 (110) was adsorbed on the O-top position for the electrochemical desorption reaction. The catalytic activity of Ti2/ 4Ru1/ 4Ir1/ 4O _ 2 (110) is better than that of Ti2/ 4Ru1/ 4Sn1/ 4O _ 2. Ti-Ru-X (X is Ir, Sn, Mn) ternary metal oxide-containing electrode at different temperatures is prepared by high-temperature decomposition method according to the atomic ratio of the calculated model, and the SEM, XRD, EDS, LSV, CV characterization and performance test are carried out. The experimental results show that the Ti-Ru-X (X is Ir, Sn, Mn) ternary metal oxide chlorine-removing electrode is prepared by doping Ir, Sn and Mn elements, and at the sintering temperature of 450 鈩，
本文编号：2502346
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