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CN-121974955-A - CO2Ruthenium catalyst for preparing formic acid and dehydrogenation of formic acid, and preparation method and application thereof

CN121974955ACN 121974955 ACN121974955 ACN 121974955ACN-121974955-A

Abstract

The invention relates to the technical field of carbon dioxide hydrogenation homogeneous catalysis, and discloses a catalyst for preparing formic acid and dehydrogenating ruthenium formate from CO 2 , wherein the catalyst comprises ruthenium metal and a2, 5-di (1H-pyrazol-3-yl) pyrazine ligand compound. The invention also discloses a preparation method of the catalyst, which comprises the following steps of S1, synthesizing 2, 5-di (1H-pyrazol-3-yl) pyrazine ligand compound and ruthenium metal complex precursor, S3, controlling the complex synthesis condition, and S4, preparing formic acid by CO 2 and purifying the formic acid dehydrogenation ruthenium catalyst. The invention also discloses application of the CO 2 formic acid preparation and formic acid dehydrogenation ruthenium catalyst in CO 2 formic acid preparation and formic acid dehydrogenation reactions. The ruthenium catalyst disclosed by the invention has the advantages that the ligand is not easy to dissociate in the reaction period due to the rigidity of the multidentate chelate ligand structure of pyrazole-pyrazine-pyrazole, so that the stability of the ruthenium catalyst can be effectively improved.

Inventors

  • CUI TIANHUA
  • HUANG YE
  • ZHENG HUAAN
  • SHI TONGQIANG
  • CHEN JINGRUN
  • ZHANG XU
  • WEI TAO
  • ZHANG LEI
  • YANG CHENLU

Assignees

  • 陕西氢能研究院有限公司

Dates

Publication Date
20260505
Application Date
20260128

Claims (10)

  1. 1. A catalyst for preparing formic acid and dehydrogenating ruthenium from CO 2 is characterized by comprising ruthenium metal and a2, 5-di (1H-pyrazol-3-yl) pyrazine ligand compound, wherein the 2, 5-di (1H-pyrazol-3-yl) pyrazine ligand compound is a compound shown in the following general formula (I): Wherein R1 represents one of aryl, heteroaryl, alkyl, hydrogen, carboxyl, hydrocarbyloxycarbonyl, aminocarbonyl or substituted alkyl, and R2 represents aryl or alkyl.
  2. 2. The CO 2 process for preparing formic acid and the ruthenium dehydrogenation catalyst of formic acid as set forth in claim 1, wherein the substituted alkyl is one of aminomethyl, hydroxymethyl, mercaptomethyl, aminoethyl, hydroxyethyl and mercaptoethyl.
  3. 3. The catalyst for preparing formic acid and ruthenium dehydrogenation of formic acid from CO 2 as set forth in claim 1, wherein R1 represents 2-pyridyl and R2 represents methyl.
  4. 4. A preparation method of a catalyst for preparing formic acid and ruthenium dehydrogenation of formic acid from CO 2 , which is used for preparing the catalyst according to any one of claims 1 to 3, and is characterized by comprising the following steps: s1, oxidizing 2, 5-dimethyl pyrazine serving as a starting material into 2, 5-pyrazine dicarboxylic acid by using concentrated sulfuric acid, obtaining 2, 5-pyrazine dicarboxylic acid dimethyl ester through esterification, carrying out substitution reaction with acetone under a strong alkali condition, and reacting with 2-hydrazinopyridine to obtain 2, 5-bis [ 5-methyl-1 (pyridine-2-yl) -pyrazol-3-yl ] pyrazine; S2, adding 2, 5-bis [ 5-methyl-1 (pyridine-2-yl) -pyrazol-3-yl ] pyrazine and ruthenium metal complex precursors into a reaction vessel, and replacing the reaction vessel with gas for 3 times under the protection of nitrogen; S3, adding a solvent, stirring at normal temperature for 0.5-2 hours, reacting at 25-100 ℃ for 3-24 hours, and cooling to room temperature; And S4, adding diethyl ether after standing, performing ultrasonic dispersion, and performing suction filtration after standing, and washing a filter cake by diethyl ether to obtain the catalyst for preparing formic acid and ruthenium dehydrogenation formate from CO 2 .
  5. 5. The process for preparing a catalyst for the preparation of formic acid and ruthenium dehydrogenation from CO 2 as claimed in claim 4, wherein in the step S1 of the preparation method, 2, 5-dimethylpyrazine is used as a starting material, 1 equivalent of 2, 5-dimethylpyrazine is used to react with 10 equivalents of concentrated sulfuric acid at room temperature for 1 hour, then 2, 5-pyrazinedicarboxylic acid is obtained by concentration and filtration, 1 equivalent of 2, 5-pyrazinedicarboxylic acid is reacted with 2 equivalents of acetyl chloride in methanol for 6 hours at room temperature, dimethyl 2, 5-pyrazinedicarboxylate is obtained by extraction with diethyl ether, 1 equivalent of dimethyl 2, 5-pyrazinedicarboxylate, 6 equivalents of sodium ethoxide is obtained by extraction with diethyl ether, 2 equivalents of acetone is reacted in toluene solvent for 6 hours at room temperature, after substitution reaction occurs, and 2 equivalents of 2-hydrazinopyridine is reacted in ethanol solvent, then 2, 5-bis [ 5-methyl-2-yl) -pyrazol-3-yl ] pyrazine is obtained by concentration and filtration.
  6. 6. The method for preparing formic acid and ruthenium dehydrogenation formate catalyst from CO 2 as claimed in claim 4, wherein the ruthenium metal complex precursor in the step S2 of the preparation method is Ru(TPP)(C 10 H 14 )Cl 2 、HRu(CO)(TPP) 3 Cl、H 2 Ru(CO)(TPP) 3 、[Ru(C 10 H 14 )Cl 2 ] 2 、Ru(cod)Cl 2 、Ru(CO) 2 (TPP) 2 Cl 2 、Ru (TPP) 3 Cl 2 、Ru 3 (CO) 12 、Ru 2 (CO) 6 Cl 4 、H 2 Ru(TPP) 4 、[Ru(Cp*)Cl 2 ] 2 、[Ru(C 6 H 6 )Cl 2 ] 2 、RuCl 3 ·xH 2 O, wherein cod is 1, 4-cyclooctadiene, cp is pentamethyl cyclopentadiene anion, and TPP is triphenylphosphine.
  7. 7. The method for preparing formic acid and ruthenium dehydrogenation formate catalyst by CO 2 as set forth in claim 4, wherein the solvent added in the step S3 is one of methanol, ethanol, isopropanol, anisole, diethylene glycol dimethyl ether, toluene, xylene and trimethylbenzene.
  8. 8. An application of the catalyst for preparing formic acid and dehydrogenating ruthenium formate from CO 2 , which is characterized in that the catalyst for preparing formic acid and dehydrogenating ruthenium formate from CO 2 according to any one of claims 1-3 is applied to preparing formic acid and dehydrogenating formic acid by carbon dioxide hydrogenation, and the application comprises the following steps: Mixing water, naOH and CO 2 to prepare formic acid and a formic acid dehydrogenation ruthenium catalyst according to the mass ratio of 500:100:1, placing the mixed solution into a high-pressure reaction kettle with magnetic stirring, replacing air in the kettle by carbon dioxide, filling synthetic gas, reacting for 24 hours at 80-150 ℃, cooling to room temperature after the reaction is finished, and centrifugally filtering; Step two, taking the filter cake obtained in the step one as a new round of catalyst, mixing water, formic acid and the catalyst, placing the mixed solution in a high-pressure reaction kettle with magnetic stirring, replacing air in the kettle with nitrogen, reacting for 24 hours at 80-110 ℃, cooling to room temperature after the reaction is finished, and centrifugally filtering; And thirdly, taking the filter cake obtained in the second step as a new round of catalyst, and repeating the first and second steps.
  9. 9. The method for preparing formic acid and ruthenium dehydrogenation formate catalyst from CO 2 as set forth in claim 8, wherein the pressure of the synthesis gas charged in the first application step is 5MPa.
  10. 10. The use of the catalyst for preparing formic acid and ruthenium dehydrogenation of formic acid from CO 2 as set forth in claim 8, wherein the volume ratio of water to formic acid in the second step is 5:1, and the catalyst concentration is 1.67mg/ml.

Description

Catalyst for preparing formic acid from CO 2 and dehydrogenating ruthenium formate, and preparation method and application thereof Technical Field The invention belongs to the technical field of carbon dioxide hydrogenation homogeneous catalysis, and particularly relates to a catalyst for preparing formic acid from CO 2 and dehydrogenating ruthenium formate, a preparation method and application thereof. Background The carbon dioxide resource utilization technology is an important way for achieving the aim of carbon neutralization, wherein the preparation of formic acid by hydrogenation of carbon dioxide and a reversible reaction system thereof are paid attention to because of the dual functions of energy storage and conversion. At present, a homogeneous ruthenium complex catalyst is generally adopted in the field, but two technical bottlenecks are still faced in practical application, namely, firstly, the organic ligand chelation effect of the traditional ruthenium catalyst is weak, ligand dissociation easily occurs in the catalytic cycle process, so that the metal center is deactivated due to the formation of inert nano particles by agglomeration, and secondly, the catalytic reaction needs to be carried out under severe high-temperature and high-pressure conditions, so that energy consumption is high, and the situation is caused by insufficient acting force between the existing catalyst molecules and gas small molecules, and the energy barrier required for activating reactant molecules is too high. The existing research shows that although the N-heterocyclic carbene ligand can improve the stability of the metal complex, the flexible molecular structure still has a dynamic dissociation risk in long-time reaction. The half-sandwich ruthenium complex improves the thermal stability through the steric hindrance effect, but has limited activation capability on carbon dioxide molecules, and cannot effectively reduce the reaction activation energy. While iridium-based catalysts perform well in the dehydrogenation of formic acid, precious metal replacement results in significant cost increases and their ligand design strategy cannot be directly applied to ruthenium catalytic systems. The stability of the catalyst is closely related to the structural characteristics of the ligand by its nature. Traditional bidentate or tridentate ligands are difficult to bear disturbance of coordination fields in the reaction process due to the flexible structure. While the existing rigid polydentate ligand can enhance structural stability, the electronic effect regulating capability of the existing rigid polydentate ligand is weak, and the dual requirements of stabilizing a metal center and activating a small molecular substrate cannot be met at the same time. Particularly for ruthenium catalytic systems, when the ligand has more variable conformations, coordination mode transformation easily occurs in the reaction process, and the deactivation process of the metal center is accelerated. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a catalyst for preparing formic acid and dehydrogenating ruthenium from CO 2, a preparation method and application thereof, and a ruthenium complex is further synthesized through a multidentate chelating ligand of pyrazole-pyrazine-pyrazole. Based on the ligand, two ruthenium metal centers can be chelated at the same time, so that the electron cloud density of the whole catalyst is higher, the hydrogenation of carbon dioxide to generate formic acid and the dehydrogenation of formic acid are facilitated, and the ligand is not easy to dissociate during the reaction due to the rigidity of the structure, so that the stability effect of the ruthenium catalyst can be effectively improved. In order to achieve the aim of effectively improving the stability of the ruthenium catalyst, the invention provides the following technical scheme: The catalyst is a bimetallic ruthenium catalyst and comprises ruthenium metal and a2, 5-di (1H-pyrazol-3-yl) pyrazine ligand compound, wherein the 2, 5-di (1H-pyrazol-3-yl) pyrazine ligand compound is a compound shown in the following general formula (I): Wherein R1 represents one of aryl, heteroaryl, alkyl, hydrogen, carboxyl, hydrocarbyloxycarbonyl, aminocarbonyl or substituted alkyl, and R2 represents aryl or alkyl. Further, the substituted alkyl is one of aminomethyl, hydroxymethyl, mercaptomethyl, aminoethyl, hydroxyethyl and mercaptoethyl. Further, R1 represents a 2-pyridyl group, and R2 represents a methyl group. A method for preparing a catalyst for preparing formic acid and ruthenium dehydrogenation of formic acid from CO 2, which is used for preparing the catalyst, comprising the following steps: s1, oxidizing 2, 5-dimethyl pyrazine serving as a starting material into 2, 5-pyrazine dicarboxylic acid by using concentrated sulfuric acid, obtaining 2, 5-pyrazine dicarboxylic acid dimethyl ester through esterification, carrying out