A kind of framework nickel catalyst precursor, a kind of framework nickel catalyst and its preparation method and use

Abstract

The invention discloses a framework nickel catalyst precursor, a framework nickel catalyst and a preparation method and application thereof. Three kinds of alloy particles with different particle sizes and compositions are added into a uniform slurry by adding dispersant and water, and then activated and post-treated to prepare a catalyst. The particle size distribution of the catalyst is wide, and there is a magnetic synergy between the particles of different particle sizes. The catalyst with small particle size has high hydrogenation activity, the catalyst with medium particle size has good activity stability, and the catalyst with large particle size has magnetic properties, which can adsorb medium and small particle size catalysts and reduce the loss rate thereof. The catalyst is applied to an industrial plant for the hydrogenation of dinitrotoluene (DNT) to prepare toluenediamine (TDA).

Description

technical field [0001] The invention relates to a hydrogenation catalyst and a preparation method and application thereof, in particular to a framework Ni catalyst with high activity, low unit consumption and good fluidity, a preparation method thereof, and a hydrogenation process for dinitrotoluene (DNT) Application of toluenediamine (TDA) in tank-type hydrogenation reactor of industrial equipment. Background technique [0002] Toluene diamine (TDA) is an intermediate in the preparation of toluene diisocyanate (TDI), and TDI is an important primary product for the preparation of polyurethane (PU), which is widely used in elastomers, foams, coatings, adhesives and fibers, etc. It is one of the most promising synthetic materials at present. TDA synthesis process mainly includes: iron powder reduction method, alkali sulfide reduction method, electrolytic reduction method, catalytic hydrogenation method, etc. Catalytic hydrogenation has broad prospects for development due to ...

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Problems solved by technology

[0003] The catalysts used in the preparation of TDA by liquid-phase hydrogenation technology are mainly divided into two categories, one is supported Pd / C or Pt / C noble metal catalysts, which have high hydrogenation activity, low reaction pressure (1MPa) and no need for reaction. Additional solvents and other advantages, but noble metal catalysts are expensive, easily deactivated by carbon deposition or poisoning, and difficult to separate; the second type is Raney nickel catalysts, which have the advantages of low price and simple separation, but conventional Raney nickel The settling speed of the base catalyst is fast, and it is mainly suitable for batch reactors, not suitable for continuous reactors with continuous and stable addition and discharge of catalysts. At the same time, the activity of conventional Raney nickel catalysts is low, and the reaction process requires additional solvents (methanol , ethanol, etc.), and the reaction pressure is high (>2MPa), and the equipment investment is large

[0004] CN102580748A discloses a kind of loaded on SiO 2 The method of the amorphous Ni-B catalyst on the above, specifically, the soluble metal salt solution is mixed with the water-soluble silicon source to prepare NiO / SiO 2 precursor, followed by KBH 4 Solution reduction, the hydrogenation activity of the catalyst prepared by this method is better, but in the process of preparing the catalyst precursor, the gel formed needs to be broken and screened, and the silica gel below 300 mesh cannot be used, resulting in high catalyst cost; Ni / SiO 2 The supported catalyst has a slow settling rate and poor catalyst strength, so it is not suitable for industrial tank reactors

[0005] CN102744071A discloses a lacquer original nickel catalyst used for hydrogenation of aromatic nitro compounds to prepare aromatic amino compounds. The catalyst preparation process is complicated, and Fe needs to be extracted with hydrochloric acid from the catalyst precursor after loading. The extraction process is easy. Lead to the loss of Ni active centers. At the same time, the hydrochloric acid and soluble salts used in the preparation of catalysts in this scheme contain chloride ions, which are difficult to completely remove in the later stage of washing. Chloride ions are very easy to cause corrosion of the device during use, limiting its Industrial application

The catalyst has good activity, but the preparation of alloy powder by gas atomization method needs to make Ni-Al metal into regular rod or wire shape. The atomization powder making equipment is expensive and the production capacity is low, and the prepared alloy powder is positive The particle size of alloy powder needs to be controlled by screening. Compared with air crushing and air classification, vibratory screening is less efficient and has poor separation effect, which limits the large-scale production and application of catalysts.

[0007] CN101439285A discloses a catalyst preparation method for catalytic hydrogenation of nitro compounds to prepare corresponding amino compounds. The catalyst is prepared by an impregnation method. The loading of metal nickel in the catalyst is about 55%, which is far lower than that of the skeleton Ni Ni content in the catalyst, so the activity of the prepared catalyst is lower than that of the skeleton Ni catalyst, the hydrogenation reaction process requires the addition of solvent ethanol, and the catalyst preparation process is complicated

[0008] CN102274724A discloses a preparation method of a highly active aromatic compound hydrogenation catalyst. The catalyst uses graphene as a carrier and Pt as an active component. The production cost of the catalyst is very high, and industrial application cannot be realized

[0010] Based on the defects in the above-mentioned prior art, combined with the requirements for the use of dinitrotoluene hydrogenation industrialized continuous tank reactors, it is necessary to seek a new preparation method for a new catalyst suitable for dinitrotoluene hydrogenation industrialization units, Avoid the use of precious metals or other expensive carriers, reduce the cost of catalysts, and solve the problems of adding organic solvents and high reaction pressures in DNT hydrogenation reactions, and realize continuous addition and recycling of catalysts in industrialized devices

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