Method for preparing palladium/carbon catalyst for hydrogenation

Abstract

This invention relates to a method for preparing a hydrogenation palladium or carbon catalyst. The catalyst uses the particles or shaping active carbon as the carrier, loading active component metal Pd, wherein the Pd content is 0.2-5wt%. The preparing method comprises the following steps: a) acid cleaning the carrier active carbon; then flushing with water until neutral; drying; b) preparing Pd solution with water-soluble Pd compound and a complex builder; using Pd solution to immerse or spray the carrier active carbon, loading the Pd compound on the active carbon and then getting the catalyst prosoma, wherein the Pd compound content is 15-20wt% computed by Pd, the molecular ratio of complex builder and Pd is (0.01-1):1, the complex builder is any one from 8-bioquin, 2,3,4-trihydroxy-4-sulfonic acid azobenzene, ortho phenanthroline, o-aminophenol, o-hydroxybenzoic acid sodium or salicylaldehyde benzaldoxime; c) aging the catalyst prosoma, then deacidizing and getting the catalyst.

Description

technical field [0001] The invention relates to a preparation method of a supported palladium / carbon catalyst for hydrogenation reaction, in particular to a preparation method of a supported palladium / carbon catalyst for refining crude terephthalic acid through selective hydrogenation reaction. Background technique [0002] The supported palladium / carbon catalyst is mainly used for the selective hydrogenation of unsaturated organic matter, especially for the purification of crude terephthalic acid. Impurities such as p-carboxybenzaldehyde (4-CBA) in crude terephthalic acid are After the hydrogen is transformed into other compounds, it can be separated and purified by crystallization. Because the palladium / carbon catalyst usually adopts a single active component, its improvement research has always focused on the structure of the support and the distribution of metal Pd on the support in the prior art, and this will indeed have a great impact on the performance of the catalys...

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Problems solved by technology

However, because hydrogen peroxide itself is also oxidizing, it can oxidize the surface groups of activated carbon, which will change the surface physical and chemical properties of the support, that is, change the surface group structure of the support, which has a strong uncertain negative impact and will damage the catalyst. Other properties, such as palladium loading strength, catalyst life, selectivity, etc.

U.S. Patent No. 4,476,242 proposes to use organic solvents such as methanol or pyridine to prepare impregnation solutions containing Pd compounds. It is said that this is also very effective in preventing the migration of Pd and grain growth, but the production process uses methanol or pyridine, which is harmful to the human body. Harmful organic compounds are unfavorable in terms of environmental protection or labor protection

In addition, there is a patent report to convert the chloropalladium acid solution into a palladium colloid by adjusting the pH value, which is said to prevent the reducing groups on the surface of the activated carbon from directly reducing Pd ions to zero-valent metal Pd, but the colloid is not stable. , it is difficult to distribute evenly on the carrier activated carbon, which will also affect the dispersion of Pd

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