Pyridine-pyrrole-ruthenium complexes, methods for their preparation, and their application as electrocatalysts for the oxidation of ammonia to produce hydrazine

Abstract

The present invention discloses a pyridine-pyrrole-ruthenium complex, a method for producing the complex, and its application as a catalyst that exerts an electrocatalytic action on ammonia oxidation to produce hydrazine. The pyridine-pyrrole-ruthenium complex has a highly active metal ruthenium as the central metal ion and a pyridine-pyrrole-containing compound having electron withdrawing / donating properties as a ligand. This gives the pyridine-pyrrole-ruthenium complex as a whole high catalytic activity for ammonia oxidation. By applying this to the electrocatalytic oxidation of ammonia in an organic solvent, it is possible to realize a high conversion rate and high selectivity of ammonia, and obtain H2, N2, N2H4, etc. as the main products.

Description

[Technical field]

[0001] The present invention relates to a catalytic material, in particular to a pyridine-pyrrole-ruthenium complex catalytic material, and further to a synthesis method thereof and its application as a catalyst for electrocatalysis of ammonia oxidation to produce hydrazine, which belongs to the technical field of catalysis. [Background technology]

[0002] Hydrogen gas (H 2 ) is recognized by everyone as one of the most ideal substitutes for fossil fuels. However, due to unfavorable factors such as extremely low volumetric energy density of hydrogen gas, extremely flammable and explosive nature, high storage and transportation costs, and low safety, large-scale direct use of hydrogen energy is restricted, making the development of hydrogen storage technology and hydrogen storage materials essential. Among the many hydrogen storage materials, liquid low-molecular-weight materials have attracted attention as hydrogen energy carriers. Ammonia molecules (NH 3 ) has a hydrogen content of 17.6 wt%, demonstrating its obvious advantages as a hydrogen energy carrier. However, its development and utilization have been consistently slow, mainly due to limitations in the oxidation half-reaction of ammonia. Small molecule metal complexes, as homogeneous catalysts, offer a solution for the catalysis of the oxidation of ammonia molecules under mild conditions.

[0003] Diazane (N 2 H 4 Hydrazine, also known as N, is a highly reducing and energetic chemical reagent that is widely used in the fields of chemical industry, aerospace, and energy. 2 H 4 After more than 100 years of development since the realization of industrial production, 2 H 4 The industrial production of is still based on the traditional or modified Raschig process, which converts NH 3 Chemically oxidize to N 2 H 4However, it still faces many bottleneck problems.

[0004] [ka]

[0005] 1) The conversion rate is low, and the product concentration in the reaction system is low. NH 3 Dehydrogenation to N 2 H 4 Because it is thermodynamically very unfavorable to convert JPEG0007629655000002.jpg14108 (as shown in (A)). In the conventional process, NH 3 From N 2 H 4 The conversion efficiency to NH is low (<10%). 3 / N 2 H 4 It is common to increase the molar ratio of N (>40 / 1) to improve conversion, resulting in 2 H 4 This results in low product concentrations (<8%). This also reduces the subsequent formation of hydrazine monohydrate (N 2 H 4 H 2 O) extraction and concentration industrial processes are lengthy and energy intensive.

[0006] 2) Environmental pollution, large amount of by-products. The conventional Raschig process requires the use of a large amount of strong oxidizing agent containing chlorine, which causes environmental pollution problems. In addition, the improved Raschig process also generates a large amount of organic by-products.

[0007] 3) Anhydrous N 2 H 4 The cost of producing anhydrous N is high. 2 H 4 The added value of hydrazine monohydrate (N 2 H 4 H 2 O), and anhydrous N 2 H 4 450,000 RMB / ton, while 80% of N2 H 4 H 2 The Raschig process is carried out in aqueous solution, usually with hydrazine monohydrate (N 2 H 4 H 2 O), so anhydrous N 2 H 4 To obtain this, it must undergo a costly dehydration process.

[0008] In short, N.H. 3 Dehydrogenation to N 2 H 4 The conversion of N to N is a thermodynamically very unfavorable scientific challenge that has been overcome very slowly. 2 H 4 However, a series of problems, such as the complicated operation, low yield, and high energy consumption, have not been resolved in the production process of N 2 H 4 The price of anhydrous N remains high. 2 H 4 Developing a new method for producing β-acetylglucosamine with high efficiency is not only a formidable scientific challenge, but also has important application value.

[0009] NH in organic solvent 3 By applying electrocatalysis to the oxidation of 2 H 4 and H 2 This process has an atom economy of 100%, low cost, and a short industrial process, making it suitable for the production of anhydrous N 2 H 4 Therefore, the development of a catalyst that can produce hydrazine by electrocatalysis of ammonia oxidation is of great theoretical significance and application value. Summary of the Invention [Problem to be solved by the invention]

[0010] In order to solve the problems existing in the prior art, the first object of the present invention is to provide a pyridine-pyrrole-metal ruthenium complex having high catalytic activity for electrocatalysis towards ammonia oxidation.

[0011] A second object of the present invention is to provide a method for producing pyridine-pyrrole-metal ruthenium complexes, which has simple operations and steps and is low cost.

[0012] The third object of the present invention is to provide an application of the pyridine-pyrrole-ruthenium complex as a catalyst that exerts an electrocatalytic action on ammonia oxidation. The pyridine-pyrrole-ruthenium complex has high catalytic activity for the electrocatalytic oxidation of ammonia, and can convert ammonia to H with high efficiency and high selectivity. 2 , N 2 and N 2 H 4 It can be converted into. [Means for solving the problem]

[0013] In order to achieve the above technical object, the present invention provides a pyridine-pyrrole-ruthenium complex having any one of the structures of formulas 1 to 5.

[0014] [ka]

[0015] [ka]

[0016] [ka]

[0017] [ka]

[0018] [ka]

[0019] The pyridine-pyrrole-ruthenium complex of the present invention has metallic ruthenium as the central metal ion and a pyridine-pyrrole compound as the ligand. Metallic ruthenium belongs to the high-period transition metals. Metallic ruthenium has multiple oxidation numbers (valence range from -2 to +8) and exhibits high reaction activity. On the other hand, the pyridine-pyrrole ligand has electron donating / withdrawing properties and can effectively reduce the potential of ammonia oxidation. In addition, the intramolecular hydrogen bond formed between the pyridine group of the pyridine-pyrrole ligand and the ammonia molecule can accelerate the deprotonation process in ammonia oxidation. This gives the pyridine-pyrrole-ruthenium complex as a whole high activity and high selectivity when catalyzing ammonia oxidation.

[0020] The present invention further provides a method for synthesizing a pyridine-pyrrole-ruthenium complex, comprising the steps of:

[0021] 1) 2,5-dipyridylpyrrole, 2,5-dipyridyl-3-methyl-4-acetylpyrrole, or 4-Methyl-2,5-di(pyridin-2-yl)-1H-pyrrole-3-carboxylate methyl Cis-dichlorotetra(dimethylsulfoxide)ruthenium, bipyridine and an alkali compound are dissolved in an organic solvent, and a pyridine-pyrrole-ruthenium complex having the structure of Formula 1, Formula 4 or Formula 5 is obtained by heating and refluxing.

[0022] 2) The pyridine-pyrrole-ruthenium complex having the structure of formula 1 is dissolved in a solvent. Then, the mixture is heated under reflux, and saturated ammonium hexafluorophosphate is added to carry out an ion exchange reaction, thereby obtaining a pyridine-pyrrole-ruthenium complex having the structure of formula 2.

[0023] 3) The pyridine-pyrrole-ruthenium complex having the structure of formula 2 is dissolved in a solvent, and an ammonia-containing gas is introduced to react with the resulting solution to obtain a pyridine-pyrrole-ruthenium complex having the structure of formula 3.

[0024] As a preferred embodiment, 2,5-dipyridylpyrrole, 2,5-dipyridyl-3-methyl-4-acetylpyrrole, or 4-Methyl-2,5-di(pyridin-2-yl)-1H-pyrrole-3-carboxylate methyl and cis-dichlorotetra(dimethylsulfoxide)ruthenium in a molar ratio of 1:2 to 2:1.

[0025] As a preferred method, the molar ratio of cis-dichlorotetra(dimethylsulfoxide)ruthenium to bipyridine is 1:3 to 3:1.

[0026] In a preferred embodiment, the alkaline compound is at least one of calcium hydride, sodium hydride, and triethylamine. These alkaline compounds are mainly 2,5-dipyridylpyrrole, 4-Methyl-2,5-di(pyridin-2-yl)-1H-pyrrole-3-carboxylate methyl It is used to promote the deprotonation reaction of the following. The amount of the alkali compound used relative to the pyridine-pyrrole ligand is 1 to 8:1.

[0027] As a preferred method, any alkaline compound capable of promoting the deprotonation reaction, such as sodium, sodium bicarbonate, sodium carbonate, sodium methoxide, or sodium hydroxide, can be used.

[0028] As a preferred method, in step 1), the reaction temperature is 50-115°C and the reaction time is 8-12 hours.

[0029] In the preferred method, in step 1), the organic solvent is dichloromethane, trichloromethane, acetonitrile, methanol, tetrahydrofuran, benzene, or toluene.

[0030] As a preferred method, in step 2), the reflux reaction temperature is 50-115° C. and the reaction time is 2-6 d.

[0031] Preferably, the ammonia gas concentration in the ammonia-containing gas is greater than 1%. The ammonia-containing gas may be pure ammonia gas, or a combination of ammonia gas and nitrogen gas or rare gas.

[0032] The present invention further provides an application of the pyridine-pyrrole-ruthenium complex, which is capable of electrocatalyzing the oxidation of ammonia to form N 2 H 4 While generating H 2 This is an application as a catalyst for the simultaneous production of

[0033] A specific method for producing the pyridine-pyrrole-ruthenium complex provided by the present invention is as follows.

[0034] (1) Under a nitrogen gas atmosphere, 2,5-dipyridylpyrrole, 2,5-dipyridyl-3-methyl-4-acetylpyrrole, or 4-Methyl-2,5-di(pyridin-2-yl)-1H-pyrrole-3-carboxylate methyl Any one of the ligands, dichlorotetra(dimethylsulfoxide)ruthenium, bipyridine, and an alkali compound are dissolved in a solvent such as toluene, methanol, or tetrahydrofuran, and the solution is stirred by magnetic force and heated under reflux for 8 to 12 hours.

[0035] (2) After the reaction is completed, the reaction mixture is washed three times under a nitrogen gas atmosphere with a solvent such as toluene, ethyl ether or water. The solid thus obtained is dissolved in dichloromethane, and anhydrous sodium sulfate is added to remove water from the solution. At the same time, the solvent in the filtrate is removed to obtain a red solid, which is a ruthenium complex having the structure of Formula 1, Formula 4 or Formula 5.

[0036] (3) Under a nitrogen gas atmosphere, the pyridine-pyrrole-ruthenium complex having the structure of formula 1 is dissolved in a solvent such as toluene, methanol, or tetrahydrofuran, and the solution is stirred and heated under reflux for 2 to 6 days.

[0037] (4) A saturated aqueous solution of ammonium hexafluorophosphate is added dropwise to the above solution, and after stirring for 2 hours, the reaction solution is filtered and centrifuged to obtain a yellow solid, which is a pyridine-pyrrole-ruthenium complex having the structure of Formula 2.

[0038] (5) The pyridine-pyrrole-ruthenium complex having the structure of formula 2 is dissolved in a solvent such as trichloromethane, dichloromethane or tetrahydrofuran, acetonitrile, etc. Then, ammonia gas having a concentration of 1 to 99.9% is introduced for 30 minutes or more, and the mixture is allowed to stand and allowed to stand for at least 2 days to obtain a red solid, which is the pyridine-pyrrole-ruthenium complex having the structure of formula 3.

[0039] The pyridine-pyrrole-ruthenium complexes of the present invention having the structures of Formulae 1 to 5 all exhibit an electrocatalytic action in the oxidation of ammonia, and 2 , N 2 and N 2 H 4 For example, under an argon gas atmosphere, 0.5V vs.Cp 2 Fe + / 0 When electrolysis was performed for 0 to 72 hours at the above potential, 0 to 2500 μmol of H 2 , 0 to 25 μmol N 2 and 0 to 2500 μmol N 2 H 4 is generated. NH 3 From N 2 H 4 The conversion rate to N can reach 45%, and the N 2 H 4 The solubility of is 0.032 mol / L. In addition, a high faradaic efficiency FE of 50 to 92% can be obtained. Effect of the Invention

[0040] Compared with the prior art, the technical solutions of the present invention have the following beneficial technical effects:

[0041] 1) The pyridine-pyrrole-ruthenium complex of the present invention has highly active metallic ruthenium as the central metal ion and a pyridine-pyrrole compound having electron withdrawing / donating properties as the ligand. This gives the pyridine-pyrrole-ruthenium complex as a whole high catalytic activity for ammonia oxidation. The operation and steps of the method for producing the pyridine-pyrrole-ruthenium complex of the present invention are simple and low cost, making it advantageous for large-scale production.

[0042] 2) The pyridine-pyrrole-ruthenium complex of the present invention has high selectivity (n N2H4 / n N2max 200), high catalytic efficiency (TOF N2H4max 400h -1 ), high Faraday efficiency (FE max 92%) in NH 3 By realizing electrocatalysis for the oxidation of anhydrous N 2 H 4 While generating H 2 It is possible to simultaneously generate

[0043] 3) The pyridine-pyrrole-ruthenium complex of the present invention is N 2 H 4 Since it is possible to realize one-step production, it is convenient for separation and purification.

[0044] 4) Until now, N 2 H 4 The synthesis of these compounds was carried out by the conventional Raschig method and non-catalytic oxidation route, but these routes had problems such as complicated process routes, low yields, high energy consumption, and serious pollution. In contrast, the pyridine-pyrrole-ruthenium complex of the present invention uses only electrocatalytic oxidation at room temperature and pressure as the reaction stage, and synthesizes two extremely valuable products in one step. In addition, the separation step is extremely simple, so that the subsequent separation can be carried out with anhydrous N 2 H 4 It is fully capable of providing revolutionary innovation technology for industrialized production. [Brief description of the drawings]

[0045] [Figure 1] Figure 1 shows the single crystal diffraction pattern of complex 1 [Ru(K2-N,N'-dpp)(bpy)(S-dmso)(Cl)]. [Diagram 2] Figure 2 shows the single crystal diffraction pattern of complex 2 [Ru(K3-N,N'N''-dpp)(bpy)(S-dmso)]·PF6. [Diagram 3] Figure 3 shows the single crystal diffraction pattern of complex 3 [Ru(K2-N,N'-dpp)(bpy)(S-dmso)(NH3)]·PF6. [Figure 4] FIG. 4 is the single crystal diffraction pattern of complex 4 [Ru(K2-N,N'-mdpc)(bpy)(S-dmso)(Cl)]. [Diagram 5] FIG. 5 is the single crystal diffraction pattern of complex 5 [Ru(K3-N,N'N''-mdpe)(bpy)(Cl)]. [Figure 6] FIG. 6 is a gas chromatography standard curve for hydrogen gas and nitrogen gas. [Figure 7] FIG. 7 shows the gas composition diagram during the reaction process of electrocatalysis for ammonia oxidation by 0.01 mM complexes 1, 2 and 3. [Figure 8] FIG. 8 is a diagram of gas composition during the reaction process of electrocatalysis for ammonia oxidation by 0.01 mM complex 3 according to reaction time. [Figure 9] FIG. 9 is a diagram of gas composition during the reaction process of electrocatalysis for ammonia oxidation by 0.01 mM complex 5 according to reaction time. [Figure 10] FIG. 10 is a standard curve of UV-Visible spectral absorption intensity versus hydrazine concentration. [Figure 11] Figure 11 shows the UV-visible absorption spectra of complexes 1, 2, and 3 after reacting the electrolyte with p-C9H11NO for 1 h. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] In order to facilitate understanding of the present invention, the present invention will be described more fully and in detail in the following in combination with preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0047] The substrate raw materials and solvents referred to in the following examples are all commercially available products (AR grade reagents). All reagents used have been purified, dried and deoxygenated prior to use, and standard anhydrous and oxygen-free processing techniques are used in the relevant synthesis and processing steps. 1 H NMR, 31 P NMR, 19 F NMR was performed in CDCl. 3 is used as the solvent and TMS is used as the internal standard.

[0048] The multiplicity is defined as s (singlet), d (doublet), t (triplet), q (quartet), and m (multiplet), and the absorption strength is defined as s (strong absorption), m (moderate absorption), and w (weak absorption).

[0049] Unless otherwise defined, all technical terms used below have the same meaning as commonly understood by those skilled in the art. In addition, the technical terms used in the present specification are only for the purpose of describing specific examples, and do not all fall within the scope of protection of the present invention. EXAMPLES

[0050] 1. Complex 1 [Ru(K 2 -N,N'-dpp)(bpy)(S-dmso)(Cl)]

[0051] [ka]

[0052] (1) Under a nitrogen gas atmosphere, cis-dichlorotetra(dimethylsulfoxide)ruthenium (1.088 g, 2.248 mmol), 2,5-dipyridylpyrrole (0.566 g, 2.248 mmol), bipyridine (0.351 g, 2.247 mmol), and triethylamine were dissolved in an organic solvent (50 mL), stirred magnetically, and heated to 105°C for 10 hours.

[0053] (2) After the reaction was completed, the reaction mixture was washed three times with toluene, ethyl ether, and water under a nitrogen gas atmosphere. The resulting solid was dissolved in dichloromethane, and anhydrous sodium sulfate was added to remove water from the solution. The solvent in the filtrate was also removed to obtain a red solid.

[0054] (3) The obtained red solid was dissolved in dichloromethane by liquid phase diffusion, and then ethyl ether and n-hexane were added in that order. After leaving it for two weeks, red needle-like crystal complex 1 was obtained.

[0055] Yield: 32%.

[0056] 1 H NMR (400 MHz, CDCl 3 ):δ10.171-10.186(d,1H),δ9.399-9.413(d,1H),δ8.125-8.137(d,1H),δ7.9 14-7.934(d,1H),δ7.644-7.731(m,3H),δ7.573-7.607(t,2H),δ7.472-7.510 (m,1H),δ7.099-7.169(m,4H),δ6.963-6.995(m,1H),δ6.829-6.838(d,1H),δ 6.676-6.710(m,1H),δ6.299-6.309(d,1H),δ3.165(s,3H),δ2.401(s,3H)ppm.

[0057] IR (KBr, cm -1):1589(s),1522(s),1433(s),1323(s),1279(w),1152(w),1074(s),1014(s),961(w),919(w),789(m),766(s),724(m),686(m),435(m).

[0058] 2. Complex 2 [Ru(K 3 -N,N'N''-dpp)(bpy)(S-dmso)]·PF 6 Generation of

[0059] target product

[0060] [ka]

[0061] (4) Under a nitrogen gas atmosphere, complex 1 was dissolved in an organic solvent, and the solution was stirred and heated to 60°C. After reacting for 4 days, the solution was evaporated to 3 mL with rotation.

[0062] (5) A saturated aqueous solution of ammonium hexafluorophosphate was added dropwise to the above solution, and after stirring for 2 hours, the reaction solution was filtered and centrifuged to obtain a yellow solid.

[0063] (6) The obtained red solid was dissolved in dichloromethane by liquid phase diffusion, and then ethyl ether and n-hexane were added in that order. After leaving it for 2 weeks, red needle-like crystal complex 2 was obtained.

[0064] Yield: 93%.

[0065] 1 H NMR (400 MHz, CDCl 3): δ 10.315 - 10.301 (d, 1H), δ 8.583 - 8.563 (d, 1H), δ 8.442 - 8.422 (d, 1H), δ 8.177 - 8.138 (t, 1H), δ 7.924 - 7.884 (t, 1H), δ 7.763 - 7.730 (t, 1H), δ 7.550 - 7.511 (m, 2H), δ 7.418 - 7.399 (d, 2H), δ 7.328 - 7.315 (d, 2H), δ 7.231 - 7.197 (t, 1H), δ 6.909 (s, 2H), δ 6.823 - 6.809 (d, 1H), δ 6.748 - 6.715 (m, 2H), δ 2.582 (s, 6H) ppm.

[0066] 31 P NMR (162 MHz, CDCl 3 ): δ - 135.60, δ - 140.01, δ - 144.40, δ - 148.80, δ - 153.20 ppm.

[0067] 19 F NMR (380 MHz, CDCl 3 ): δ - 72.36, δ - 74.25 ppm.

[0068] IR (KBr, cm -1 ): 1598 (s), 1486 (s), 1396 (m), 1298 (s), 1263 (w), 1156 (w), 1087 (m), 1042 (w), 1008 (m), 840 (s), 760 (s), 557 (s), 431 (m).

[0069]

Table 1

[0070] [Table 2]

[0071] 3. Complex 3 [Ru(K 2 -N,N'-dpp)(bpy)(S-dmso)(NH 3 )]·PF 6 Generation of

[0072] target product

[0073] [ka]

[0074] (1) Complex 2 (35 mg, 0.050 mmol) was dissolved in trichloromethane, and then 2% ammonia gas (carrier gas was nitrogen gas) was introduced for 30 minutes and the solution was left to stand for 1 hour. This was repeated three times and the solution was left to stand for two weeks. Finally, the solution was concentrated at room temperature, and ethyl ether and n-hexane were added in that order to obtain red plate-like crystal complex 3 by liquid phase diffusion.

[0075] Yield: 98%.

[0076] 1 H NMR (400 MHz, CDCl 3): δ 9.871 - 9.858 (d, 1H), δ 8.412 - 8.401 (d, 1H), δ 8.313 - 8.293 (d, 1H), δ 8.251 - 8.231 (d, 1H), δ 7.714 - 7.675 (t, 1H), δ 7.646 - 7.612 (t, 1H), δ 7.517 - 7.503 (d, 1H), δ 7.463 - 7.402 (m, 2H), δ 7.328 - 7.315 (d, 2H), δ 7.189 - 7.175 (d, 1H), δ 7.095 - 7.175 (d, 1H), δ 7.095 - 7.064 (m, 1H), δ 7.029 - 7.019 (d, 1H), δ 6.981 - 6.952 (t, 1H), δ 6.617 - 6.586 (t, 1H), δ 3.160 (s, 3H), δ 3.110 (s, 3H), δ 2.534 (s, 3H) ppm.

[0077] 31 P NMR (162 MHz, CDCl 3 ): δ -135.92, δ -140.28, δ -144.64, δ -149.00, δ -153.36 ppm.

[0078] 19 F NMR (380 MHz, CDCl 3 ): δ -72.02, δ -73.89 ppm.

[0079] IR (KBr, cm -1 ): 3371 (w), 1604 (m), 1529 (m), 1454 (w), 1421 (m), 1325 (m), 1161 (w), 1080 (m), 1018 (m), 843 (s), 764 (m), 685 (w), 557 (m), 430 (m).

[0080] 4. Complex 4 [Ru(K 2 -N,N’-mdpc)(bpy)(S-dmso)(Cl)] formation

[0081] Target product

[0082]

Chemical Structure

[0083] (1) Under a nitrogen gas atmosphere, dichlorotetra(dimethylsulfoxide)ruthenium (1.088 g, 2.248 mmol), 4-Methyl-2,5-di(pyridin-2-yl)-1H-pyrrole-3-carboxylate methyl The ligand (0.659 g, 2.248 mmol), bipyridine (0.351 g, 2.247 mmol) and triethylamine were dissolved in an organic solvent (50 mL), stirred and heated to 105° C. for 9 hours to react.

[0084] (2) After the reaction was completed, the reaction mixture was washed three times with ethyl ether and water under a nitrogen gas atmosphere. The solid was dissolved in dichloromethane, and anhydrous sodium sulfate was added to remove water from the solution. The solvent in the filtrate was also removed to obtain a red solid.

[0085] (3) The red solid was separated by column chromatography using a silica column for chromatography to obtain a red solid product.

[0086] (4) The obtained red solid was dissolved in dichloromethane by liquid phase diffusion, and then ethyl ether and n-hexane were added in that order. After leaving it for 2 weeks, red needle-like crystal complex 4 was obtained.

[0087] Yield: 25%.

[0088] 1 H NMR (400 MHz, CDCl 3 ):δ9.677-9.689(d,1H),δ9.552-9.565(d,1H),δ8.045-8.091(t,2H),δ7.847-7.868 (d,2H),δ7.738-7.796(m,2H),δ7.485-7.528(m,1H),δ7.430-7.442(d,1H),δ7.132- 7.178(m,2H),δ7.026-7.062(m,1H),δ6.892-6.928(m,1H),δ6.779-6.813(m,1H),δ6 .724(s,1H),δ3.290(s,3H),δ3.019(s,3H)ppm,δ2.744(s,3H)ppm,δ2.460(s,3H)ppm.

[0089] IR (KBr, cm -1 ):3603(m),2916(s),2497(m),1682(s),1589(m),1521(w),1444(s),1414(w),1323( w),1261(w),1198(w),1153(w),1078(s),1012(w),766(s),729(w),679(w),430(m).

[0090] 5. Complex 5 [Ru(K 3 -N,N'N''-mdpe)(bpy)(Cl)]

[0091] target product

[0092] [ka]

[0093] (1) Under a nitrogen gas atmosphere, cis-[Ru(dmso) 4 (Cl) 2 ] (1.088 g, 2.248 mmol), 2,5-dipyridyl-3-methyl-4-acetylpyrrole (0.623 g, 2.248 mmol), bipyridine (0.351 g, 2.247 mmol) and a base were dissolved in an organic solvent (50 mL), stirred and heated to 100° C. for 12 h.

[0094] (2) After the reaction was completed, the reaction mixture was washed three times with toluene, ethyl ether, and water under a nitrogen gas atmosphere. The resulting solid was dissolved in dichloromethane, and anhydrous sodium sulfate was added to remove water from the solution. The solvent in the filtrate was also removed to obtain a red solid.

[0095] (3) The obtained red solid was dissolved in dichloromethane by liquid phase diffusion, and then ethyl ether and n-hexane were added in that order. After standing for 2 weeks, red needle-like crystal complex 5 was obtained.

[0096] Yield: 30%.

[0097] 1 H NMR (400 MHz, CDCl 3 ):δ10.443-10.457(d,1H),δ8.906-8.927(d,1H),δ8.159-8.179(d,1H),δ7. 913-7.932(d,1H),δ7.787-7.826(t,1H),δ7.709-7.722(d,1H),δ7.612-7.64 5(t,1H),δ7.454-7.505(t,1H),δ7.249-7.351(m,2H),δ7.087-7.110(t,2H) ,δ6.847-6.886(m,2H),δ6.406-6.475(m,2H),δ2.794(s,3H),δ2.603(s,3H).

[0098] IR (KBr, cm -1 ):3095(w),3059(m),1631(m),1589(s),1460(s),1417(m),1354(w),1340(w),1242(w),1136(s),1020(w),982(w),945(w),754(m),619(w).

[0099] 6. Gas Chromatography Experiment:

[0100] (1) The gas composition during the reaction was measured by gas chromatography. Experimental conditions: potential was 0.5 V vs Cp 2 Fe + / 0 The electrolyte was 0 to 0.1 mM of complex 1, 2, 3, 4 or 5 and 0.1 M of [NBu 4 ][PF 6 ] and NH of 0 to 2.5M 3 The organic solution contained:

[0101] (2) At each time point of electrolysis, 100 μL of the upper layer gas was collected using an airtight syringe and injected into a gas chromatograph to obtain the composition and content of the gas in the electrolytic cell.

[0102] Measurement results: After 24 h of electrolysis, complex 1 had 375.4 μmol of H 2and 7.4 μmol N 2 Complex 2 is produced with 459.5 μmol of H 2 and 6.32 μmol N 2 Complex 3 was produced with 1458.35 μmol of H 2 and 10.55 μmol N 2 After 48 h of electrolysis, complex 5 produced 86.08 μmol of H 2 and 5.85 μmol N 2 The gas chromatography experiment showed that H 2 and N in the system 2 The ratio of hydrogen to nitrogen in the ammonia molecule (3:1) was found to be in the range of 10:1 to 200:1. This was much higher than the ratio of hydrogen to nitrogen in the ammonia molecule (3:1). 2 The remaining anodic products are all NH 2 NH 2 And NO 2 - No 3 - No such products were produced.

[0103] 7. UV-Visible Spectrum Experiment:

[0104] (1) In a 10 mL cuvette, add 0.4 mL of electrolyte, 0.5 mL of HCl (0.6 mol / L) solution, and 0.5 mL of pH 9 H 11 An ethanol solution of NO was added, and then the mixture was diluted to 10 mL with water and reacted for 1 h.

[0105] (2) 0.5 mL of the reaction solution was taken in a 10 mL cuvette and diluted to 10 mL. Then, the absorption intensity at 455 nm was collected using a UV-Vis spectrometer, and NH 2 NH 2 The NH in the electrolyte was measured by comparing with a standard curve of concentration and absorbance at 455 nm. 2 NH 2 The content of was obtained.

[0106] Measurement results: After 24 h of electrolysis, complexes 1, 2, and 3 gave 341.2 μmol, 423.0 μmol, and 1380.04 μmol of NH 2 NH 2 was generated.

[0107] Above, the main preparation methods of complexes 1, 2, 3, 4, and 5 in the present invention and their electrocatalytic properties for ammonia oxidation have been presented and described.

[0108] Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and the description of the specification are merely a process for explaining the principles and methods of the present invention, and the present invention may have various modifications and improvements without departing from the spirit and scope of the present invention. In addition, all of these modifications and improvements are included in the scope of the present invention that is claimed for protection. The scope of the present invention that is claimed for protection is defined by the appended claims and their equivalents.

Claims

1. A pyridine-pyrrole-ruthenium complex having any one of the structures of formulas 1 to 5. 【Chemistry 1】 【Chemistry 2】 【Chemistry 3】 【Chemistry 4】 【Chemistry 5】

2. 1) 2,5-dipyridylpyrrole, 2,5-dipyridyl-3-methyl-4-acetylpyrrole, or 4-methyl-2,5-di(pyridin-2-yl)-1H-pyrrole-3-methyl carboxylate, cis-dichlorotetra(dimethylsulfoxide)ruthenium, bipyridine, and an alkali compound are dissolved in a solvent, and a pyridine-pyrrole-ruthenium complex having the structure of Formula 1, Formula 4, or Formula 5 is obtained by heating and refluxing the mixture; 2) The pyridine-pyrrole-ruthenium complex having the structure of formula 1 is dissolved in a solvent, heated under reflux, and then a saturated ammonium hexafluorophosphate solution is added to carry out an ion exchange reaction, thereby obtaining a pyridine-pyrrole-ruthenium complex having the structure of formula 2; 3) The pyridine-pyrrole-ruthenium complex having the structure of formula 2 is dissolved in a solvent, and an ammonia-containing gas is introduced to react with the resulting compound to obtain a pyridine-pyrrole-ruthenium complex having the structure of formula 3.

2. The method for synthesizing a pyridine-pyrrole-ruthenium complex according to claim 1, comprising the steps of:

3. The method for synthesizing a pyridine-pyrrole-ruthenium complex according to claim 2, characterized in that the molar ratio of 2,5-dipyridylpyrrole, 2,5-dipyridyl-3-methyl-4-acetylpyrrole, or 4-methyl-2,5-di(pyridin-2-yl)-1H-pyrrole-3-methyl carboxylate to cis-dichlorotetra(dimethylsulfoxide)ruthenium is 1:2 to 2:

1.

4. 3. The method for synthesizing a pyridine-pyrrole-ruthenium complex according to claim 2, wherein the molar ratio of cis-dichlorotetra(dimethylsulfoxide)ruthenium to bipyridine is 1:3 to 3:

1.

5. 3. The method for synthesizing a pyridine-pyrrole-ruthenium complex according to claim 2, wherein the alkaline compound is at least one of calcium hydride, sodium hydride, and triethylamine.

6. The method for synthesizing pyridine-pyrrole-ruthenium complex according to claim 2, characterized in that in step 1), the reaction temperature is 50-115° C. and the reaction time is 8-12 h.

7. The method for synthesizing pyridine-pyrrole-ruthenium complex according to claim 2, characterized in that in step 2), the temperature of the reflux reaction is 50-115° C. and the time is 2-6 days.

8. 3. The method for synthesizing a pyridine-pyrrole-ruthenium complex according to claim 2, wherein the ammonia gas concentration in the ammonia-containing gas is greater than 1%.

9. It acts as an electrode catalyst for ammonia oxidation and ２ H ４ While generating H ２ The pyridine-pyrrole-ruthenium complex as a catalyst according to claim 1, characterized in that

10. It acts as an electrode catalyst for ammonia oxidation and ２ H ４ While generating H ２ The pyridine-pyrrole-ruthenium complex as a catalyst according to claim 1, characterized in that the organic solvent selected is anhydrous tetrahydrofuran or anhydrous acetonitrile.

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