CN-118142583-B - Method for catalyzing nitro compound hydrogenation by porous polymer-based metal catalyst

CN118142583BCN 118142583 BCN118142583 BCN 118142583BCN-118142583-B

Abstract

The invention relates to a catalyst preparation technology, and aims to provide a method for catalyzing hydrogenation of nitro compounds by using a porous polymer-based metal catalyst. The method comprises the steps of adding nitro compounds and a catalyst into a reactor, uniformly mixing, filling hydrogen for hydrogenation reaction, and obtaining amine compounds after the reaction is finished, wherein the catalyst consists of metal elements serving as active centers and porous polymers serving as carriers, and the porous polymers are obtained by a polymer monomer through a solvothermal method. The catalyst used in the invention has very excellent hydrogenation activity, can realize solvent-free hydrogenation of nitro compounds to amine compounds at normal temperature and normal pressure, is favorable for realizing large-scale production, and has low potential safety hazard. The invention provides a more efficient method for preparing amine compounds, which has low reaction temperature, does not need to additionally add reaction auxiliary agents in the synthesis process, does not generate toxic and harmful byproducts after reaction, and is environment-friendly in the whole synthesis process.

Inventors

WANG HAI
LUO QINGSONG
WANG LIANG
XIAO FENGSHOU

Assignees

浙江大学

Dates

Publication Date: 20260512
Application Date: 20240306

Claims (4)

1. A method for catalyzing the hydrogenation of nitro compounds by a porous polymer-based metal catalyst, comprising the steps of: adding a nitro compound and a catalyst into a reactor, wherein the mass fraction of the catalyst in the mixture is 0.1-10%, uniformly mixing, then charging hydrogen to the pressure of 0.1-3 MPa, and carrying out hydrogenation reaction at 15-180 ℃, wherein the reaction is completed after 12-48 hours to obtain an amine compound; The catalyst consists of a metal element serving as an active center and a porous polymer serving as a carrier, wherein the metal loading amount is 0.01-5% m/m, the metal element is any one or more of Pd, pt, rh, ru, ir, au, the porous polymer is prepared from a polymer monomer by a solvothermal method, the polymer monomer is vinyl pyrrolidone and ethylene imine, or the polymer monomer is vinyl pyrrolidone and divinylbenzene, or the polymer monomer is vinyl pyrrolidone, caprolactam and ethylene imine; The catalyst is prepared by the following steps: Uniformly dispersing the porous polymer in an organic solvent containing metal elements, vigorously stirring for more than 8 hours, adding a reducing agent, uniformly stirring, carrying out reduction reaction at-20-50 ℃, filtering, washing and drying a solid product after the reaction is finished to obtain a catalyst, controlling the dosage of the porous polymer and the metal elements to ensure that the metal loading capacity in the final catalyst product is 0.01-5% m/m, wherein the reducing agent is NaBH 4 or KBH 4 , and the molar ratio of the metal elements to the reducing agent is 0.2-20; or the catalyst is prepared by the following method: uniformly dispersing the porous polymer in an organic solvent containing metal elements, vigorously stirring for more than 8 hours, filtering, washing and drying the mixture to obtain a solid product, reducing the solid product by hydrogen at 50-450 ℃ to obtain a catalyst, and controlling the dosage of the porous polymer and the metal elements to ensure that the metal loading capacity in the final catalyst product is 0.01-5% m/m; The preparation method of the porous polymer comprises the steps of dissolving a polymer monomer in a proper amount of organic solvent, adding an initiator, performing hydrothermal reaction for 12 hours at 60-200 ℃, and washing and drying a reaction product to obtain the porous polymer.
2. The method according to claim 1, wherein the nitro compound is any one or more of nitrobenzene, p-chloronitrobenzene, p-vinylnitrobenzene, p-cyanonitrobenzene, p-methylnitrobenzene, 1, 4-dinitrobenzene, p-aminonitrobenzene, 1-nitrobutane.
3. The method according to claim 1, wherein the organic solvent is any one or more of ethanol, methanol, dimethylformamide, ethyl acetate, and tetrahydrofuran, and the solvent mass is 0 to 100 times the monomer mass.
4. The method according to claim 1, wherein the initiator is any one of tert-butyl hydroperoxide, dicyclohexyl peroxydicarbonate, potassium persulfate, cyclohexanone peroxide, azobisisobutyronitrile or azobisisoheptonitrile, and the mass of the initiator is 0.01-1 wt% of the total mass of the reaction system.

Description

Method for catalyzing nitro compound hydrogenation by porous polymer-based metal catalyst Technical Field The invention relates to a catalyst preparation technology, in particular to a method for catalyzing hydrogenation of nitro compounds by using a porous polymer-based metal catalyst. Background Amine compounds are widely used as important intermediates and raw materials in pharmaceuticals, dyes, polyurethanes, explosives and agrochemicals. In the 20 s of the 19 th century, aniline was first separated. In the 50 s, aniline has been widely used in the dye field, and has made a great contribution to the development of the dye industry in China. In the 20 th century, the preparation of aromatic amines by hydrogenation of aromatic nitro compounds has been industrially produced. The hydrogenation of nitro compounds to amine compounds has become a recent research focus. At present, the traditional commercial production usually uses iron, zinc, tin or metal sulfide as a reducing agent for preparing aromatic amine, but the method breaks against the basic standards of green chemistry and sustainable development, and has serious problems of difficult separation of products, corrosion of a reactor, generation of waste acid/alkali byproducts and the like. The method for preparing the amine compound is an efficient and environment-friendly method for preparing the amine compound by using hydrogen as a reducing agent and adopting a recyclable multiphase transition metal catalyst to carry out catalytic hydrogenation on the nitro compound. However, the secondary pollution is caused by adding additives (alkali and metal salts) into the liquid phase reaction system to assist the reaction. Therefore, by preparing a high-activity heterogeneous catalyst, the catalytic hydrogenation of the nitro-compound to the amine compound agent under the mild condition without an additive is of great importance. Disclosure of Invention The invention aims to solve the technical problem of overcoming the defects in the prior art and providing a method for catalyzing hydrogenation of nitro compounds by using a porous polymer-based metal catalyst. In order to solve the technical problems, the invention adopts the following solutions: there is provided a method for catalyzing the hydrogenation of nitro compounds by a porous polymer-based metal catalyst comprising the steps of: Adding a nitro compound and a catalyst into a reactor, wherein the mass fraction of the catalyst in the mixture is 0.1-10%, uniformly mixing, then charging hydrogen to the pressure of 0.1-3 MPa, and carrying out hydrogenation reaction at 15-180 ℃, wherein the reaction is finished after 0.5-48 hours to obtain an amine compound; the catalyst consists of a metal element serving as an active center and a porous polymer serving as a carrier, wherein the metal loading amount is 0.01-5% (m/m), the porous polymer is prepared from a polymer monomer by a solvothermal method, and is one of polyvinylpyrrolidone (PVP), polyamide (PA), polyethyleneimine (PEI) or Polydivinylbenzene (PDVB), or a composite material of two or more of polyvinylpyrrolidone (PVP), polyamide (PA), polyethyleneimine (PEI) or Polydivinylbenzene (PDVB). As a preferable scheme of the invention, the nitro compound is one or more of nitrobenzene, p-chloronitrobenzene, p-vinylnitrobenzene, p-cyanonitrobenzene, p-methylnitrobenzene, 1, 4-dinitrobenzene, p-aminonitrobenzene and 1-nitrobutane. In a preferred embodiment of the present invention, the metal element in the catalyst is any one or more of Pd, pt, rh, ru, ir, au, fe, co, ni. As a preferred embodiment of the present invention, the catalyst is prepared by the following method: Uniformly dispersing the porous polymer in an organic solvent containing metal elements, vigorously stirring for more than 8 hours, adding a reducing agent, uniformly stirring, carrying out reduction reaction at-20-50 ℃, filtering, washing and drying a solid product after the reaction is finished to obtain a catalyst, controlling the dosage of the porous polymer and the metal elements to ensure that the metal loading amount in the final catalyst product is 0.01-5% (m/m), wherein the reducing agent is NaBH 4 or KBH 4, and the molar ratio of the metal elements to the reducing agent is 0.2-20. As a preferred embodiment of the present invention, the catalyst is prepared by the following method: Uniformly dispersing the porous polymer in an organic solvent containing metal elements, vigorously stirring for more than 8 hours, filtering, washing and drying the mixture to obtain a solid product, reducing the solid product by hydrogen at 50-450 ℃ to obtain a catalyst, and controlling the dosage of the porous polymer and the metal elements to ensure that the metal loading capacity in the final catalyst product is 0.01-5% (m/m). The preparation method of the porous polymer comprises the steps of dissolving polymer monomers in a proper amount of organic solvent, adding an initiator, carrying out hydro