氯堿工業(yè)析氯陽極研究
發(fā)布時間：2019-06-19 12:23
【摘要】：氯堿工業(yè)是重要的基礎化學工業(yè),其產品氯氣、燒堿和氫氣是基礎性的化工原料,氯堿工業(yè)消耗世界10%的發(fā)電量,因此高效的析氯電極對節(jié)能意義巨大。本文簡述了氯堿工業(yè)、析氯陽極的發(fā)展歷程,詳細介紹了Ru-Ti體系DSA形穩(wěn)陽極的導電機理、析氯催化機理和陽極失活機理。綜述了主要針對釕鈦氧化物涂層中摻雜其他元素及氧化物形成二元或三元混合氧化物,通過改變摻雜物種的含量、制備條件等改變涂層的組成和形貌對其催化析氯效果影響的研究現(xiàn)狀。比較了形穩(wěn)陽極不同制備方法的優(yōu)缺點。提出通過理論計算結合實驗研究,設計、模擬DSA形穩(wěn)陽極進行理論計算和實驗制備,從微觀的角度研究析氯效果和析氯機理,對研制新型的DSA形穩(wěn)陽極具有重要的指導意義。采用廣義密度泛函理論(GGA)的PW91方法結合周期平板模型進行了Cl在一元、二元和三元金屬氧化物表面吸附的理論計算。包括Cl在一元金紅石型TiO_2和RuO_2的(110)表面的吸附情況,不同Ti、Ru摻雜比例(Ti:Ru比分別為3:1,1:1,1:3)二元金屬氧化物TinRumO_2表面,Ti-Ru金屬氧化物與第三種元素X(X為Ir、Sn、Mn)摻雜比例(Ti:Ru:X為2:1:1)的三元金屬氧化物Ti2/4Ru1/4X1/4O_2表面吸附進行計算。計算各氧化物(純氧化物,摻雜氧化物)的吸附能、能帶結構、前線分子軌道等,揭示摻雜金屬氧化物對電子構型的影響。根據(jù)析氯機理,通過前線分子軌道理論對電化學反應和電化學脫附反應的反應活性進行理論計算分析。使用LST/QST方法尋找Cl_2在不同比例金屬氧化物表面的析出過程的過渡態(tài)和相應的能量數(shù)據(jù),比較在不同比例金屬氧化物表面析出的Cl_2過渡態(tài)的活化能和反應熱。結果表明:(1)Cl在TiO_2和RuO_2的(110)表面吸附位只有金屬頂位和氧頂位。Ti:Ru比為3:1時金屬氧化物O頂位對Cl的吸附能最小為1.524e V。(2)Cl原子吸附在Ti:Ru比為3:1時的金屬氧化物表面金屬頂位,吸附作用最小。過渡態(tài)計算得出Cl在活性位Ru被氧化為S-O中間物種(S表示形穩(wěn)陽極表面的活性吸附位)位吸附并析出電極表面;Cl_2在Ti3/4Ru1/4O_2(110)表面的析出的反應熱ΔHr為5.798kcal/mol,活化能Ea為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。比較摻雜前后的能帶情況,由于Ru的摻入,使其導電性得到增強,且摻雜體系的導電性與Ru的摻雜比例有關,且隨著摻雜比例增大其摻雜催化劑的導電性越好。通過前線軌道理論對其析氯機理分析得出,摻雜后Ti:Ru比為3:1時較易發(fā)生電化學反應,生成S-Clads中間體,此時的能隙ΔE最小為2.323e V;摻雜后Ti:Ru比為3:1時較易發(fā)生電化學脫附反應,析出Cl_2,能隙ΔE最小為2.088e V,且在該比例時,Cl在Ti3/4Ru1/4O_2(110)表面上的吸附能最小Ea為2.514 e V。(3)對于三元金屬氧化物Ti2/4Ru1/4X1/4O_2(X為Ir、Sn、Mn)摻雜比例(Ti:Ru:X為2:1:1),比較其能帶情況,在Ru摻雜量一定的情況下,Ir、Sn、Mn三種摻雜結構導電性順序為Ti2/4Ru1/4Ir1/4O_2Ti2/4Ru1/4Sn1/4O_2≈Ti2/4Ru1/4Mn1/4O_2。Ir對固體催化劑的導電性的加強作用明顯,有利于反應過程中電子的傳遞,加快了反應的速率。通過過渡態(tài)計算得出Cl_2分別在Ti2/4Ru1/4Ir1/4O_2和Ti2/4Ru1/4Sn1/4O_2表面析出的活化能Ea分別為16.658 kcal/mol和45.795 kcal/mol,故Ti2/4Ru1/4Ir1/4O_2更有利于Cl_2的析出。通過前線軌道理論對其析氯反應機理反應計算可知,對于電化學反應,摻雜銥元素的電極其前線軌道LUMO能量比摻雜錫元素后的前線軌道LUMO降低,Ti2/4Ru1/4Ir1/4O_2(110)電極的能隙ΔE為1.249e V,比Ti2/4Ru1/4Sn1/4O_2(110)電極能隙ΔE1.461e V小。對于電化學脫附反應,Ti2/4Ru1/4Ir1/4O_2(110)電極氯吸附在O頂位后能隙ΔE為1.801e V,比Ti2/4Ru1/4Sn1/4O_2(110)電極Cl吸附在O頂位時能隙ΔE為2.046e V小。Ti2/4Ru1/4Ir1/4O_2(110)電極析氯催化活性比Ti2/4Ru1/4Sn1/4O_2好。根據(jù)計算模型的原子比例,采用高溫分解法制備不同溫度下的Ti-Ru-X(X為Ir、Sn、Mn)三元金屬氧化物析氯電極,并對其進行SEM、XRD、EDS、LSV、CV表征和性能測試。實驗結果表明:摻雜Ir、Sn、Mn元素制備Ti-Ru-X(X為Ir、Sn、Mn)三元金屬氧化物析氯電極,在燒結溫度為450℃時,形成的Ti-Ru-Ir混合氧化物電極表面龜裂最少,表面更加均勻,具有活性位數(shù)量最多。當燒結溫度為450℃時,添加Ir、Sn、Mn元素制備的Ti-Ru-X(X為Ir、Sn、Mn)三元金屬氧化物析氯電極,Ti-Ru-Ir電極具有最好的催化析氯活性。通過電化學性能測試,添加三種元素所得電極的活性從高到低依次為Ti-Ru-IrTi-Ru-SnTi-Ru-Mn。這與理論計算結果相吻合。
[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，
本文編號：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，
本文編號：2502346
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