Magnetic nano catalyst and preparation method thereof

Abstract

The invention relate to a magnetic nano catalyst and a preparation method thereof. The preparation method comprises the following steps of: sequentially adding a pure metal precursor, a long-chain organic polymer, a ferrite precursor and metal acetate to reducing ethanol and stirring to form a uniform suspension; transferring the uniform suspension into a reaction kettle for heating and then naturally cooling to room temperature to prepare a mixed catalysis body; settling and separating the mixed catalysis body under the action of an outer magnetic field, then scattering obtained solid substances into a mixed solvent for carrying out settlement, separation and a cleaning cycle respectively for 2-3 times; and finally, drying in vacuum at room temperature to obtain the magnetic nano catalyst. The preparation method is simple; the prepared catalyst has a reaction constant of 17.21-1.65 mmol-1s-1 in a p-nitrophenol hydrogenation reduction process; and the catalytic reaction rate constant has no obvious reduction during recycling the catalyst for many times.

Description

technical field [0001] The invention relates to a catalyst in the technical field of chemical catalysis and a preparation method thereof, in particular to a class of metal ferrite magnetic nanometer catalyst and a preparation method thereof. Background technique [0002] The heterogeneous catalytic process plays an important role in the fine chemical industry and even the development of the world economy. According to statistics, about 90% of the chemical products in current commodity transactions are obtained through the heterogeneous catalytic process. The development of heterogeneous catalysts with high catalytic activity and easy separation from the reaction system is in line with the development direction of "green chemistry" and "atom economy". Nanoscale catalysts have significantly better catalytic activity than corresponding bulk materials due to their small size, increased surface active sites, and increased contact area for chemical reactions. Due to its small siz...

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Problems solved by technology

[0004] p-Aminophenol (PAP for short) is an important organic fine chemical raw material and pharmaceutical intermediate, widely used in medicine, rubber, dyes and other fields. B, compound agent nicotinamide and 6-hydroxyquinoline, etc., wherein paracetamol is the most important antipyretic and analgesic drug in the world, and its sales account for 45% of the entire antipyretic and analgesic drug market; in the rubber industry, PAP is used for Synthesize p-phenylenediamine anti-aging agents H4010, 4020, 4030, etc. for radial tires. They are currently recognized as low-toxic, low-pollution, high-efficiency anti-aging agents in the world, and have good development prospects; PAP is also a dye industry Intermediates for the production of disperse dyes, acid dyes, direct dyes, sulfur dyes and fur dyes. In recent years, with the development of pharmaceutical and rubber industries and the continuous expansion of PAP application fields, the international consumption of PAP has been relatively high. With the rapid growth trend, it is necessary and urgent to develop a method that can prepare a large amount of PAP quickly. Reductive hydrogenation of p-nitrophenol is an important way to prepare p-aminophenol. The process of aminophenol: ① Iron powder reduction method (also known as Bochan method), that is, iron powder is used as the reducing agent to obtain p-aminophenol through reduction, neutralization, impregnation, filtration and drying. The process is cumbersome and The pollution is serious, and a large amount of iron sludge and waste water containing aromatic amines are produced during the preparation process, and the product has high iron content and low purity, so it cannot be directly used in the pharmaceutical industry. Due to serious environmental pollution, this process has been eliminated abroad, and China has also It is forbidden to build new production devices using this process. ② Catalytic hydrogenation reduction method of p-nitrophenol, that is, using fine particle precious metals (Pt / C, Pd / C) as catalysts, hydrogenation reduction, extraction and refining to obtain p-aminophenol .The main defect that this technology exists at present is that the catalyst used is difficult to recycle because the particle size is too small, and the manufacturing cost of the noble metal catalyst is expensive and the operation is complicated (Jiangsu Chemical Industry, 1999, 27, 13; Chinese patent: 200710040037.7). Therefore, at present It is still a challenge to design and synthesize cheap, efficient, convenient and recyclable catalysts for catalytic hydrogenation of p-nitrophenol.

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