Hybrid catalyst as well as preparation method and application thereof

Abstract

The invention discloses a hybrid catalyst as well as a preparation method and application thereof. The hybrid catalyst comprises a metal complex and a nano carbon material, the metal complex comprises a metal element and an X ligand; the metal element is selected from at least one of Co, Ni, Fe, Cu and Mn; the X ligand is selected from a phthalocyanine ligand and / or a porphyrin ligand. The catalytic system disclosed by the invention is suitable for water phase reaction at normal temperature and pressure, the reaction condition is mild and non-toxic, and the operation method is simple. In the reaction for synthesizing the alpha-amino acid through electro-catalysis of co-reduction of nitrate and alpha-keto acid, the Faraday efficiency of the alpha-amino acid generated by the optimized CoPc / CNT catalyst can reach 61.2%, and the partial current density reaches 42 mA cm <-2 >, which is the highest value reported at present.

Description

Technical Field

[0001] The present application relates to a hybrid catalyst, a preparation method and an application thereof, and belongs to the technical field of amino acid synthesis. Background Art

[0002] α-amino acids are the basic structural units of organisms and play a very important role in organic chemistry, protein synthesis, and pharmaceuticals. The traditional process of synthesizing α-amino acids has disadvantages such as the use of highly toxic cyanide and its derivatives, the use of strong oxidizing / reducing agents, and the use of precious metal catalysts. Therefore, the development of new and efficient electrocatalysts to achieve the synthesis of α-amino acids through environmentally friendly and sustainable methods has important research value and application prospects.

[0003] At present, the synthesis of α-amino acids is mainly based on biosynthesis and chemical synthesis. Patent CN 108675937B uses sunlight as an energy source, an external electron donor, and imine compounds and CO2 as raw materials to synthesize α-amino acids. In the literature (Angew. Chem. Int. Ed. 2023, e202304007), J. Xian et al. reported that the Faraday efficiency of the co-reduction of NO and α-keto acid to generate α-amino acids using Fe single-atom catalysts was less than 10%, and the partial current density of the generated amino acids was less than 2 mA cm -2 The literature (Angew.Chem.Int.Ed.2023, e202306726) shows that the Faradaic efficiency of one-step co-reduction of NO and α-keto acid to amino acids using CoFe alloy is less than 42%, and the current density of amino acid generation is less than 7 mA cm -2 Recently, the literature (Angew.Chem.Int.Ed.2023,e202311196) reported the electrocatalytic activity of NO3 - The Faradaic efficiency of co-reduction with pyruvate to alanine is 51%, but its violent hydrogen production side reaction makes the partial current density very low.

[0004] In summary, NO x In the one-step electrochemical synthesis of amino acids, due to serious side reactions such as hydrogen evolution in aqueous solutions (especially acidic solutions), the Faradaic efficiency and activity of the generated amino acids are low. Therefore, the development of more efficient electrocatalyst materials to achieve green synthesis of α-amino acids under mild conditions remains to be developed. Summary of the invention

[0005] In nature, organisms can use nitrate as a nitrogen source and α-keto acids as a carbon source to produce various complex amino acids and proteins. At the same time, some metal complexes have high performance in the electrocatalytic reduction of nitrogen oxides.

[0006] Based on this, the present application uses a simple and feasible method to electrochemically synthesize α-amino acids from nitrate and α-keto acids in one step through a class of hybrid electrocatalysts of metal complexes and nanocarbon materials. By reasonably designing the catalyst and adjusting conditions such as the components of the reaction solution in the electrocatalytic reaction, a variety of α-amino acids are synthesized efficiently and with high selectivity. The preparation method described in the present application can obtain highly active catalysts by modulating the types and loadings of metal complexes, the types of carbon materials, and their hydrophilicity and hydrophobicity, thereby achieving different catalytic effects. α-Amino acids are efficiently synthesized by controlling parameters such as the acidity of the solution, the ratio of nitrate to α-keto acid, the electrode potential, and the reaction time during the catalytic reaction process. At the same time, the hybridization between the metal complex and the nanocarbon material ensures uniform dispersion of the active components, an efficient charge transfer process, and good stability.

[0007] The object of the present application is to provide a simple and feasible one-step synthesis method for the electrocatalytic co-reduction of nitrate and α-keto acid to synthesize α-amino acids. This method has a simple preparation process and the obtained catalyst has a stable structure, and can efficiently convert nitrate and α-keto acid into α-amino acids in one step under non-toxic and mild conditions.

[0008] According to one aspect of the present application, a hybrid catalyst is provided, and the hybrid catalyst includes a metal complex and a nanocarbon material;

[0009] The metal complex includes a metal element and an X ligand;

[0010] The metal element is selected from at least one of Co, Ni, Fe, Cu, and Mn;

[0011] The X ligand is selected from a phthalocyanine ligand and / or a porphyrin ligand.

[0012] Optionally, the metal complex accounts for 0.5-10 wt.% of the hybrid catalyst.

[0013] Optionally, the metal complex accounts for the hybrid catalyst independently selected from any value of 0.5 wt.%, 1 wt.%, 2 wt.%, 3 wt.%, 3.8 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, 10 wt.% or the range value between any two of the above.

[0014] Optionally, the nanocarbon material is selected from at least one of carbon nanotubes, nitrogen-doped carbon nanotubes, carbon nanofibers, graphene, and conductive carbon black.

[0015] Optionally, the nanocarbon material is selected from at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes, double-walled carbon nanotubes, nitrogen-doped carbon nanotubes, carbon nanofibers, graphene, and conductive carbon black.

[0016] According to another aspect of the present application, there is provided a method for preparing the hybrid catalyst described above, and the preparation method includes the following steps:

[0017] (1) Treat the nanocarbon material with an acid solution to obtain a pretreated nanocarbon material;

[0018] (2) Stir and dry the mixture containing the metal complex and the pretreated nanocarbon material to obtain the hybrid catalyst.

[0019] Optionally, in the step (1), the acid solution is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid, and perchloric acid.

[0020] Optionally, in the step (1), the acid solution is selected from at least one of hydrochloric acid and nitric acid.

[0021] Optionally, the concentration of the acid solution is 0.1 - 8 mol / L.

[0022] Optionally, the concentration of the acid solution is independently selected from any value of 0.1 mol / L, 0.2 mol / L, 0.5 mol / L, 0.7 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L or the range value between any two of the above.

[0023] Optionally, the concentration of the acid solution is 0.2 - 2 mol / L.

[0024] Optionally, in the step (2), the mass ratio of the metal complex to the pretreated nanocarbon material is 1:5 - 1:40.

[0025] Optionally, in the step (2), the mass ratio of the metal complex to the pretreated nanocarbon material is independently selected from any value of 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40 or the range value between any two of the above.

[0026] Optionally, in the step (2), the mass ratio of the metal complex to the pretreated nanocarbon material is 1:10 - 1:25.

[0027] Optionally, in the step (2), in the mixture, the concentration of the metal complex is 0.01 - 0.3 g / L.

[0028] Optionally, in the step (2), in the mixture, the concentration of the metal complex is independently selected from any value of 0.01 g / L, 0.03 g / L, 0.04 g / L, 0.07 g / L, 0.1 g / L, 0.15 g / L, 0.2 g / L, 0.25 g / L, 0.3 g / L or the range value between any two of the above.

[0029] Optionally, in the step (2), in the mixture, the concentration of the metal complex is 0.03 - 0.2 g / L.

[0030] Optionally, in the step (2), the temperature of the stirring is 5 - 40 °C, and the time of the stirring is 5 - 40 h.

[0031] Optionally, in the step (2), the temperature of the drying is -50 - 0 °C, and the time of the drying is 1 - 10 h.

[0032] According to another aspect of the present application, a method for an electrocatalytic reaction for synthesizing α-amino acids is provided, and the method includes:

[0033] Reacting a raw material containing a reaction solution and a catalyst to obtain the α-amino acid;

[0034] The reaction solution includes an inorganic acid solution, a nitrate, and an α-keto acid;

[0035] The α-amino acid is selected from at least one of glycine, pyruvic acid, glutamic acid, aspartic acid, and leucine;

[0036] The catalyst includes a conductive substrate and a hybrid catalyst loaded on the surface of the conductive substrate;

[0037] The hybrid catalyst is selected from the above-mentioned hybrid catalysts;

[0038] In the catalyst, the loading amount of the hybrid catalyst is 0.1 - 1.5 g / m 2 ;

[0039] The conductive substrate is selected from at least one of a gas diffusion electrode, carbon paper, carbon sheet, and carbon felt.

[0040] Optionally, in the catalyst, the loading amount of the hybrid catalyst is independently selected from any value of 0.5 g / m 2 , 0.6 g / m 2 , 0.8 g / m 2 , 1.0 g / m 2 , 1.2 g / m 2 , 1.5 g / m 2 or the range value between any two of the above.

[0041] Optionally, the conductive substrate is selected from at least one of a gas diffusion electrode and carbon paper.

[0042] Optionally, the inorganic acid solution is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid.

[0043] Optionally, the inorganic acid solution is selected from at least one of sulfuric acid and nitric acid.

[0044] Optionally, the nitrate is selected from at least one of sodium nitrate, potassium nitrate, ammonium nitrate, and calcium nitrate.

[0045] Optionally, the nitrate is selected from at least one of sodium nitrate and potassium nitrate.

[0046] Optionally, the α-keto acid is selected from at least one of glyoxylic acid, pyruvic acid, α-ketoglutaric acid, oxaloacetic acid, oxovaleric acid, and 4-hydroxyphenylpyruvic acid.

[0047] Optionally, the molar ratio of the nitrate to the α-keto acid is 1:1 to 20:1.

[0048] Optionally, the molar ratio of the nitrate to the α-keto acid is independently selected from any value among 1:1, 2:1, 2.3:1, 3:1, 3.5:1, 5:1, 7:1, 8:1, 10:1, 12:1, 15:1, 18:1, 20:1 or the range value between any two of them.

[0049] Optionally, the molar ratio of the nitrate to the α-keto acid is 2:1 to 8:1.

[0050] Optionally, the concentration of the inorganic acid solution is 0.05 to 4 mol / L.

[0051] Optionally, the concentration of the inorganic acid solution is independently selected from any value among 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L or the range value between any two of the above.

[0052] Optionally, the concentration of the inorganic acid solution is 0.2 to 2 mol / L.

[0053] Optionally, the concentration of the nitrate is 0.05 to 4 mol / L.

[0054] Optionally, the concentration of the nitrate is independently selected from any value of 0.05 mol / L, 0.2 mol / L, 0.5 mol / L, 0.7 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L or a range value between any two of them.

[0055] Optionally, the concentration of the nitrate is 0.2 - 2 mol / L.

[0056] Optionally, the concentration of the α-keto acid is 0.01 - 3 mol / L.

[0057] Optionally, the concentration of the α-keto acid is independently selected from any value of 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L or a range value between any two of them.

[0058] Optionally, the concentration of the α-keto acid is 0.05 - 1 mol / L.

[0059] Optionally, the reaction time is 0.2 - 4 h.

[0060] Optionally, the reaction time is independently selected from any value of 0.2 h, 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h or a range value between any two of the above.

[0061] As an optional implementation manner, the present application is achieved through the following technical solutions:

[0062] The preparation method of the catalyst B for electrocatalytic co-reduction of nitrate and α-keto acid to synthesize α-amino acid includes the following steps:

[0063] (1) Immerse the nanocarbon material in an acidic solution for ultrasonic pretreatment, and then wash and dry to obtain material A;

[0064] (2) Mix and ultrasonically stir material A and the metal complex in an organic solvent to obtain a uniformly dispersed hybrid catalyst precursor solution, and wash and dry the catalyst precursor solution to obtain a hybrid catalyst B of the metal complex and the nanocarbon material.

[0065] The beneficial effects that the present application can produce include:

[0066] 1) The preparation process of the hybrid catalyst of the metal complex and the nanocarbon material provided by this application is simple, the active components are evenly dispersed, it has good electrical conductivity, and the hydrophobicity can be adjusted. When electrocatalytically co-reducing nitrate and α-keto acid to synthesize α-amino acid by a one-step method, it shows excellent selectivity and activity. Among them, the most active CoPc / CNT catalyst has a maximum Faraday efficiency of 61.2% for generating α-amino acid and a partial current density of 42 mA cm -2 in the reaction solution of 0.4 mol / L H2SO4, 1 mol / L KNO3 and 0.2 mol / L α-keto acid at room temperature, far higher than the work of using NO x to electrochemically synthesize amino acid in one step (Faraday efficiency is lower than 51%, partial current density is less than 7 mA cm -2 ).

[0067] 2) The method for electrocatalytically synthesizing α-amino acid from nitrate by a one-step method provided by this application is applicable to aqueous-phase reactions at normal temperature and pressure, the reaction conditions are mild and non-toxic, and the operation method is simple. Specific embodiments

[0068] The following describes this application in detail with reference to the embodiments, but this application is not limited to these embodiments.

[0069] Unless otherwise specified, the raw materials in the embodiments of this application are all purchased through commercial channels.

[0070] This application uses a Shanghai Chenhua CHI660E electrochemical workstation to perform performance tests under a constant potential condition of -0.4 to -0.8 V RHE .

[0071] Example 1

[0072] Step 1, ultrasonically treat the multi-walled carbon nanotube support in 0.6 mol / L dilute hydrochloric acid for 2 hours, and then wash and dry to obtain the multi-walled carbon nanotube (CNT) support.

[0073] Step 2: Ultrasonically stir 0.002 g of different cobalt complexes and 0.03 g of multi-walled carbon nanotube supports in N,N-dimethylformamide and stir at 25 °C for 20 h. Among them, the cobalt complexes are cobalt phthalocyanine (CoPc), fluorine-substituted cobalt phthalocyanine (CoPc-F), amino-substituted cobalt phthalocyanine (CoPc-NH2), sulfonated cobalt phthalocyanine (CoPc-SO3H), chlorine-substituted cobalt phthalocyanine (CoPc-Cl), Co-N-C, tetraphenyl cobalt porphyrin (CoTPP), and cobalt porphyrin (CoPP) in sequence. After sufficient stirring, wash the catalyst and dry it at -30 °C for 6 h to obtain hybrid catalysts containing different cobalt complexes respectively, where the loading of the metal complex in the hybrid catalyst is 3.8 wt%. Subsequently, drop-coat the hybrid catalysts containing different cobalt complexes / CNT on the gas diffusion electrode respectively, and the loading of the catalyst is 0.1 g / m 2 .

[0074] Step 3: Place the electrode prepared in Step 2 in an H-type reactor for electrochemical testing. The electrochemical reaction adopts a three-electrode system, where the conductive substrate loaded with the hybrid catalyst is the working electrode, the platinum sheet is the counter electrode, and the Ag / AgCl electrode is the reference electrode; the composition of the reaction solution is 0.1 mol / L H2SO4, 0.7 mol / L KNO3, and 0.2 mol / L pyruvic acid, and the reaction time is 4000 s. The specific reaction results are shown in Table 1.

[0075] Table 1 shows the specific values of the Faraday efficiency and partial current density of alanine generated after 4000 s of electrochemical reaction in a reaction solution composed of 0.1 mol / L H2SO4, 0.7 mol / L KNO3, and 0.2 mol / L pyruvic acid by different cobalt complex / CNT hybrid catalysts prepared in Example 1 through electrocatalytic one-step synthesis method. The electrochemical testing adopts a three-electrode system: the conductive substrate loaded with the hybrid catalyst is the working electrode, the platinum sheet is the counter electrode, and the Ag / AgCl electrode is the reference electrode.

[0076] Table 1: Performance of Electrochemical Synthesis of Alanine by Different Cobalt Complex / CNT

[0077]

[0078] Note: The reaction solution corresponding to the data in Table 1 is 0.1 mol / L H2SO4 + 0.7 mol / L KNO3 + 0.2 mol / L pyruvic acid, and the reaction duration is 4000 s.

[0079] Table 1 shows the specific values of the Faraday efficiency and partial current density of electrochemically synthesizing alanine in one step by different cobalt complex / CNT prepared in Example 1. Compared with other cobalt complexes, the performance of electrocatalytic synthesis of alanine using CoPc / CNT is the highest.

[0080] Example 2

[0081] A one-step electrochemical synthesis method is adopted. The preparation of the catalyst and the process of the electrochemical reaction are basically the same as those in Example 1, except that in step 2: the metal complexes are cobalt phthalocyanine dimer and sulfonated cobalt phthalocyanine dimer respectively.

[0082] Table 2 shows the specific values of the Faraday efficiency and partial current density of alanine generated after 4000 s of electrochemical reaction in a reaction solution composed of 0.1 mol / L H2SO4, 0.7 mol / L KNO3 and 0.2 mol / L pyruvic acid by the electrocatalytic one-step synthesis method for the cobalt phthalocyanine dimer / CNT and sulfonated cobalt phthalocyanine dimer / CNT catalysts prepared in Example 2. The electrochemical test uses a three-electrode system.

[0083] Table 2: Performance of Electrochemical Synthesis of Alanine by Cobalt Phthalocyanine Dimer / CNT and Sulfonated Cobalt Phthalocyanine Dimer / CNT

[0084]

[0085] Note: The reaction solution corresponding to the data in Table 2 is 0.1 mol / L H2SO4 + 0.7 mol / L KNO3 + 0.2 mol / L pyruvic acid, and the reaction duration is 4000 s.

[0086] Table 2 shows the specific values of the Faraday efficiency and partial current density of the electrochemical one-step synthesis of alanine by the cobalt phthalocyanine dimer / CNT and sulfonated cobalt phthalocyanine dimer / CNT catalysts prepared in Example 2. The selectivity and activity of alanine generation are both less than the results obtained when CoPc / CNT is used as the catalyst.

[0087] Example 3

[0088] A one-step electrochemical synthesis method is adopted. The preparation of the catalyst and the process of the electrochemical reaction are basically the same as those in Example 1, except that in step 2: the metal complex is only cobalt phthalocyanine (CoPc); in step 3, the concentration of H2SO4 in the reaction solution of the electrochemical reaction is one of 0.1 mol / L, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L and 0.8 mol / L.

[0089] Table 3 shows the specific values of the Faraday efficiency and partial current density of alanine produced after 4000 s of electrochemical reaction in a reaction solution composed of different concentrations of H2SO4, 0.7 mol / L KNO3, and 0.2 mol / L pyruvic acid by the electrocatalytic one-step synthesis method using the CoPc / CNT catalyst prepared in Example 3. The concentration of H2SO4 is one of 0.1 mol / L, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, and 0.8 mol / L, and the electrochemical test uses a three-electrode system.

[0090] Table 3: Performance of CoPc / CNT Electrochemical Synthesis of Alanine at Different Acid Concentrations

[0091]

[0092]

[0093] Note: The reaction solution corresponding to the data in Table 3 is x mol / L H2SO4 + 0.7 mol / L KNO3 + 0.2 mol / L pyruvic acid, the reaction duration is 4000 s, and x refers to the concentration of H2SO4.

[0094] Table 3 shows the specific values of the Faraday efficiency and partial current density of alanine electrochemically synthesized in one step by the CoPc / CNT hybrid catalyst prepared in Example 3 in different concentrations of H2SO4. When the concentration of H2SO4 is less than 0.4 mol / L, the performance of CoPc / CNT in producing alanine decreases, that is, a higher acid concentration is beneficial to this catalytic reaction.

[0095] Example 4

[0096] Using the one-step electrochemical synthesis method, the catalyst preparation and the electrochemical reaction process are basically the same as those in Example 1, and the differences are as follows: in step 2, the metal complex is only cobalt phthalocyanine (CoPc); in step 3, the reaction solution for the electrochemical reaction contains 0.4 mol / L H2SO4, and the molar ratio of KNO3 to pyruvic acid is one of 2.3:1, 3.5:1, 5:1, and 7:1.

[0097] Table 4 shows the specific values of the Faraday efficiency and partial current density of alanine produced after 4000 s of electrochemical reaction in a reaction solution composed of 0.4 mol / L H2SO4 and different ratios of KNO3 and pyruvic acid by the electrocatalytic one-step synthesis method using the CoPc / CNT catalyst prepared in Example 4. The molar ratio of KNO3 to pyruvic acid is one of 2.3:1, 3.5:1, 5:1, and 7:1, and the electrochemical test uses a three-electrode system.

[0098] Table 4: Performance of CoPc / CNT Electrochemical Synthesis of Alanine at Different Substrate Ratios

[0099]

[0100] Note: The reaction solution corresponding to the data in Table 4 is 0.4 mol / L H2SO4 + x mol / L KNO3 + y mol / L pyruvic acid, the reaction time is 4000 s, x refers to the concentration of KNO3, and y refers to the concentration of pyruvic acid.

[0101] Table 4 shows the specific values of the Faraday efficiency and partial current density for the electrochemical one-step synthesis of alanine by the CoPc / CNT hybrid catalyst prepared in Example 4 in a reaction solution of 0.4 mol / L H2SO4 and containing different ratios of KNO3 and pyruvic acid. When the molar ratio of KNO3 to pyruvic acid in the reaction solution is 5:1, the Faraday efficiency and activity of CoPc / CNT for generating alanine are the highest.

[0102] Example 5

[0103] A one-step electrochemical synthesis method is adopted. The preparation of the catalyst and the electro-chemical reaction process are basically the same as those in Example 1, except that in step 2: the metal complex is only cobalt phthalocyanine (CoPc); in step 3, the composition of the reaction solution during the electro-chemical reaction is 0.4 mol / L H2SO4, 1 mol / L KNO3 and 0.2 mol / L pyruvic acid; the reaction time is one of 1000 s, 2000 s, 3000 s, 4000 s and 5000 s.

[0104] Table 5 shows the specific values of the Faraday efficiency and partial current density for the formation of alanine by the CoPc / CNT catalyst prepared in Example 5 through electrocatalytic one-step synthesis in a reaction solution composed of 0.4 mol / L H2SO4, 1 mol / L KNO3 and 0.2 mol / L pyruvic acid after different electro-chemical reaction times, where the electro-chemical reaction time is one of 1000 s, 2000 s, 3000 s, 4000 s and 5000 s, and the electro-chemical test adopts a three-electrode system.

[0105] Table 5: Performance of CoPc / CNT in Electrochemical Synthesis of Alanine at Different Reaction Times

[0106]

[0107] Note: The reaction solution corresponding to the data in Table 5 is 0.4 mol / L H2SO4 + 1 mol / L KNO3 + 0.2 mol / L pyruvic acid.

[0108] Table 5 shows the specific values of the Faraday efficiency and partial current density for the electrochemical one-step synthesis of alanine by the CoPc / CNT hybrid catalyst prepared in Example 5 after different reaction times in 0.4 mol / L H2SO4, 1 mol / L KNO3, and 0.2 mol / L pyruvic acid. When the reaction time is less than 4000 s, the electrocatalytic reaction cannot proceed sufficiently, and the performance of producing alanine is low.

[0109] Example 6

[0110] Using the method of one-step electrochemical synthesis, the catalyst preparation and the electrochemistry reaction process are basically the same as those in Example 1, and the differences are as follows: in Step 2, the metal complexes are cobalt phthalocyanine (CoPc), nickel phthalocyanine (NiPc), iron phthalocyanine (FePc), copper phthalocyanine (CuPc), and manganese phthalocyanine (MnPc) respectively; in Step 3, the composition of the reaction solution during the electrochemistry reaction is 0.4 mol / L H2SO4, 1 mol / L KNO3, and 0.2 mol / L pyruvic acid.

[0111] Table 6 shows the specific values of the Faraday efficiency and partial current density for the production of alanine by electrocatalytic one-step synthesis by the hybrid catalysts with different metal centers (one of CoPc / CNT, NiPc / CNT, FePc / CNT, CuPc / CNT, and MnPc / CNT) prepared in Example 6 in the reaction solution composed of 0.4 mol / L H2SO4, 1 mol / L KNO3, and 0.2 mol / L pyruvic acid after 4000 s of electrochemistry reaction. The three-electrode system is used for the electrochemical test.

[0112] Table 6: Performance of Electrochemical Synthesis of Alanine by MPc / CNT with Different Metal Centers

[0113]

[0114] Note: The reaction solution corresponding to the data in Table 6 is 0.4 mol / L H2SO4 + 1 mol / L KNO3 + 0.2 mol / L pyruvic acid, and the reaction duration is 4000 s.

[0115] Table 6 shows the specific values of the Faraday efficiency and partial current density for the electrochemical one-step synthesis of alanine by the CoPc / CNT, NiPc / CNT, FePc / CNT, CuPc / CNT, and MnPc / CNT hybrid catalysts prepared in Example 6 after 4000 s in 0.4 mol / L H2SO4, 1 mol / L KNO3, and 0.2 mol / L pyruvic acid. Compared with other metal phthalocyanines, the CoPc / CNT catalyst has the highest selectivity and activity for producing alanine.

[0116] Example 7

[0117] Using a one-step electrochemical synthesis method, the preparation of the catalyst and the electro-chemical reaction process are basically the same as in Example 1, except that in Step 1: the nano-carbon carriers are multi-walled carbon nanotubes (CNT), single-walled carbon nanotubes (SWCNT), partially oxidized multi-walled carbon nanotubes (CNT(O)), graphene, and conductive carbon black; in Step 2: the metal complex is only cobalt phthalocyanine (CoPc); in Step 3, the composition of the reaction solution during the electro-chemical reaction is 0.4 mol / L H2SO4, 1 mol / L KNO3, and 0.2 mol / L pyruvic acid.

[0118] Table 7 shows the specific values of the Faraday efficiency and partial current density of alanine generated after 4000 s of electro-chemical reaction in a reaction solution composed of 0.4 mol / L H2SO4, 1 mol / L KNO3, and 0.2 mol / L pyruvic acid by the electro-catalytic one-step synthesis method using the catalysts (one of CoPc / CNT, CoPc / SWCNT, CoPc / CNT(O), CoPc / graphene, and CoPc / carbon black) obtained in Example 7. The electro-chemical test uses a three-electrode system.

[0119] Table 7: Performance of CoPc / carbon material hybrid catalysts for electro-chemical synthesis of alanine on different carbon carriers

[0120]

[0121] Note: The reaction solution corresponding to the data in Table 7 is 0.4 mol / L H2SO4 + 1 mol / L KNO3 + 0.2 mol / L pyruvic acid, and the reaction duration is 4000 s.

[0122] Table 7 shows the specific values of the Faraday efficiency and partial current density of alanine generated by the electro-chemical one-step synthesis after 4000 s in 0.4 mol / L H2SO4, 1 mol / L KNO3, and 0.2 mol / L pyruvic acid using the CoPc / CNT, CoPc / SWCNT, CoPc / CNT(O), CoPc / graphene, and CoPc / carbon black hybrid catalysts prepared in Example 7. Compared with other nano-carbon material carriers, the hybrid catalyst CoPc / CNT prepared using CNT has the highest selectivity and activity for generating alanine.

[0123] Example 8

[0124] Using a one-step electrochemical synthesis method, the preparation of the catalyst and the electro-chemical reaction process are basically the same as those in Example 1, except that in Step 2: the metal complex is only cobalt phthalocyanine (CoPc), and the loading of the metal complex in the hybrid catalyst is one of 1.6 wt%, 3.8 wt%, 4.1 wt%, and 4.8 wt%; in Step 3, the composition of the reaction solution during the electro-chemical reaction is 0.4 mol / L H2SO4, 1 mol / L KNO3, and 0.2 mol / L pyruvic acid.

[0125] Table 8 shows the specific values of the Faraday efficiency and partial current density of alanine formed after 4000 s of electro-chemical reaction in a reaction solution composed of 0.4 mol / L H2SO4, 1 mol / L KNO3, and 0.2 mol / L pyruvic acid by the electro-catalytic one-step synthesis method using CoPc / CNT hybrid catalysts with different CoPc loadings prepared in Example 8. Among them, the loading of CoPc on CoPc / CNT is one of 1.6 wt%, 3.8 wt%, 4.1 wt%, and 4.8 wt%, and the electro-chemical test uses a three-electrode system.

[0126] Table 8: Influence of CoPc Loading in CoPc / CNT on the Performance of Electro-chemical Synthesis of Alanine

[0127]

[0128] Note: The reaction solution corresponding to the data in Table 8 is 0.4 mol / L H2SO4 + 1 mol / L KNO3 + 0.2 mol / L pyruvic acid, and the reaction duration is 4000 s.

[0129] Table 8 shows the specific values of the Faraday efficiency and partial current density of electro-chemical one-step synthesis of alanine after 4000 s in 0.4 mol / L H2SO4, 1 mol / L KNO3, and 0.2 mol / L pyruvic acid using hybrid catalysts with different cobalt phthalocyanine loadings prepared in Example 8. When the cobalt phthalocyanine loading is too low, the selectivity and activity of the hybrid catalyst for forming alanine are significantly reduced.

[0130] Example 9

[0131] Using a one-step electrochemical synthesis method, the preparation of the catalyst and the electro-chemical reaction process are basically the same as those in Example 1, except that in Step 2: the metal complex is only cobalt phthalocyanine (CoPc); in Step 3, the composition of the reaction solution during the electro-chemical reaction is 0.4 mol / L H2SO4, 1 mol / L KNO3, and 0.2 mol / L α-keto acid, where the α-keto acids are glyoxylic acid, pyruvic acid, α-ketoglutaric acid, oxaloacetic acid, and oxovaleric acid respectively.

[0132] Table 9 shows the specific values of the Faraday efficiency and partial current density of alanine produced after 4000 s of electrochemical reaction in a reaction solution composed of 0.4 mol / L H2SO4, 1 mol / L KNO3, and 0.2 mol / L α-keto acid by the CoPc / CNT hybrid catalyst prepared in Example 9 through an electrocatalytic one-step synthesis method. Among them, the α-keto acids in the electrochemical reaction solution are glyoxylic acid, pyruvic acid, α-ketoglutaric acid, oxaloacetic acid, and oxovaleric acid, and a three-electrode system is used for the electrochemical test.

[0133] Table 9: Different α-keto acids and NO3 - Performance of electrochemically synthesizing amino acids on CoPc / CNT

[0134]

[0135] Note: The reaction solution corresponding to the data in Table 9 is 0.4 mol / L H2SO4 + 1 mol / L KNO3 + 0.2 mol / L α-keto acid, and the reaction duration is 4000 s.

[0136] Table 9 shows the specific values of the Faraday efficiency and partial current density of electrochemically synthesizing alanine in one step after 4000 s by the CoPc / CNT hybrid catalyst prepared in Example 9 in 0.4 mol / L H2SO4, 1 mol / L KNO3, and different types of 0.2 mol / L α-keto acids. The maximum Faraday efficiency of electrochemically converting nitrate to α-amino acid in one step using CoPc / CNT is 61.2%, and the maximum partial current density of generating amino acid is 42 mA cm -2 。

[0137] The Faraday efficiency and partial current density of electrochemically reducing nitrate and α-keto acid in one step to synthesize α-amino acid by the metal complex and nanocarbon material hybrid catalyst system described in Examples 1-9 above under different reaction conditions (reaction solution composition, reaction time) are shown in Tables 1-9. It can be seen from Tables 1-9 that CoPc / CNT has advantages in the one-step electrocatalytic synthesis of α-amino acid.

[0138] According to the specific implementation schemes (Examples 1-9) of the present application, the CoPc / CNT electrode of the present application shows excellent catalytic performance in the one-step electrocatalytic co-reduction of nitrate and α-keto acid to synthesize α-amino acid system, indicating that factors such as the structure of the metal complex, the type and hydrophilic-hydrophobicity of the nanocarbon carrier, the acidity of the reaction solution, the ratio of substrates, and the reaction time in this system can significantly affect the performance of generating amino acids. Reasonable design of the catalyst and regulation of the electrochemical reaction conditions can greatly improve the selectivity and activity of the target product.

[0139] The present application provides a method for electrocatalytic synthesis of α-amino acids from nitrate by a one-step method. The hybrid catalyst comprises a metal complex and a nanocarbon material support, and the catalyst system has a high dispersion degree and good conductivity. This electrocatalytic reaction is applicable to aqueous-phase reactions at normal temperature and pressure, with mild and non-toxic reaction conditions and a simple operation method. The acid concentration, substrate ratio, reaction time, etc. in the reaction solution can significantly affect the performance of the generated amino acids. Among them, the catalyst with the highest activity has a maximum Faraday efficiency of 61.2% for the generation of α-amino acids and a partial current density for the generation of α-amino acids of 42 mA cm -2 , which is much higher than other works on the one-step electrochemical synthesis of amino acids using NO x .

[0140] As described above, these are only several embodiments of the present application and do not impose any form of limitation on the present application. Although the present application is disclosed with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art, without departing from the scope of the technical solution of the present application, makes some changes or modifications using the technical content disclosed above, which are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A hybrid catalyst, characterized in that, The hybrid catalyst includes a metal complex and a nanocarbon material; The metal complex includes a metal element and an X ligand; The metal element is selected from at least one of Co, Ni, Fe, Cu, and Mn; The X ligand is selected from a phthalocyanine ligand and / or a porphyrin ligand.

2. The hybrid catalyst according to claim 1, characterized in that, The metal complex accounts for 0.5 to 10 wt.% of the hybrid catalyst; Preferably, the nanocarbon material is selected from at least one of carbon nanotubes, nitrogen-doped carbon nanotubes, carbon nanofibers, graphene, and conductive carbon black.

3. A method for preparing the hybrid catalyst according to any one of claims 1 to 2, characterized in that, The preparation method includes the following steps: (1) Treat the nanocarbon material with an acid solution to obtain a pretreated nanocarbon material; (2) Stir and dry the mixture containing the metal complex and the pretreated nanocarbon material to obtain the hybrid catalyst.

4. The preparation method according to claim 3, characterized in that, In the step (1), the acid solution is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid, and perchloric acid; Preferably, the concentration of the acid solution is 0.1 to 8 mol / L; Preferably, the concentration of the acid solution is 0.2 to 2 mol / L.

5. The preparation method according to claim 3, characterized in that, In the step (2), the mass ratio of the metal complex to the pretreated nanocarbon material is 1:5 to 1:40; Preferably, in the step (2), the mass ratio of the metal complex to the pretreated nanocarbon material is 1:10 to 1:25; Preferably, in the step (2), the concentration of the metal complex in the mixture is 0.01 to 0.3 g / L; Preferably, in the step (2), the concentration of the metal complex in the mixture is 0.03 to 0.2 g / L; Preferably, in the step (2), the stirring temperature is 5 to 40 °C, and the stirring time is 5 to 40 h; Preferably, in the step (2), the drying temperature is -50 to 0 °C, and the drying time is 1 to 10 h.

6. A method for an electrocatalytic reaction for synthesizing α - amino acids, characterized in that, The method includes: React the raw material containing the reaction solution and the catalyst to obtain the α-amino acid; The reaction solution includes an inorganic acid solution, a nitrate, and an α-keto acid; The α-amino acid is selected from at least one of glycine, pyruvic acid, glutamic acid, aspartic acid, and leucine; The catalyst includes a conductive substrate and a hybrid catalyst supported on the surface of the conductive substrate; In the catalyst, the loading amount of the hybrid catalyst is 0.1 to 1.5 g / m 2 ; The hybrid catalyst is selected from the hybrid catalysts described in any one of claims 1 to 2; The conductive substrate is selected from at least one of a gas diffusion electrode, carbon paper, carbon sheet, and carbon felt.

7. The method according to claim 6, characterized in that, The inorganic acid solution is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid; Preferably, the nitrate is selected from at least one of sodium nitrate, potassium nitrate, ammonium nitrate, and calcium nitrate; Preferably, the α-keto acid is selected from at least one of glyoxylic acid, pyruvic acid, α-ketoglutaric acid, oxaloacetic acid, oxovaleric acid, and 4-hydroxyphenylpyruvic acid.

8. The method according to claim 6, characterized in that, The molar ratio of the nitrate to the α-keto acid is 1:1 to 20:1; Preferably, the molar ratio of the nitrate to the α-keto acid is 2:1 to 8:

1.

9. The method according to claim 6, wherein, The concentration of the inorganic acid solution is 0.05 to 4 mol / L; Preferably, the concentration of the inorganic acid solution is 0.2 to 2 mol / L; Preferably, the concentration of the nitrate is 0.05 to 4 mol / L; Preferably, the concentration of the nitrate is 0.2 to 2 mol / L; Preferably, the concentration of the α-keto acid is 0.01 to 3 mol / L; Preferably, the concentration of the α-keto acid is 0.05 to 1 mol / L.

10. The method according to claim 6, wherein, The reaction time is 0.2 to 4 h.

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