Method for preparing palladium/carbon catalyzer by hydrogenising and refining crude terephthalic acid

Abstract

A method for preparing Pd / C catalyst for selective hydrogenation is provided. The content of Pd in catalyst is 0.2 to 5% by weight. The preparing process includes the following steps: active carbon carrier is washed by 0.1 to 5N concentration of acid washing liquid selected from hydrochloric acid, nitric acid or phosphoric acid; active carbon carrier is washed to neutrality by water and dried; the active carbon carrier is soaked in nitrite ion containing solution for 2 to 24 hours and dried; the Pd compound is sprayed on the active carbon carrier to form catalyst precursor, after aging and reduction process, the catalyst product is obtained. Metal Pd in catalyst has higher dispersion degree and the content of crystallite is very high.

Description

technical field [0001] The invention relates to a preparation method of a supported palladium / carbon catalyst for selective 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 refining process of crude terephthalic acid, where impurities such as p-carboxybenzaldehyde (4-CBA) in crude terephthalic acid are passed through After hydrogenation, it can be transformed into other compounds, which can be separated and purified by crystallization. Since palladium / carbon catalysts usually use a single active component, the research on its improvement has been focused on the structure of the support and the distribution of metal Pd on the support, which will indeed have a great impact on the ...

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Problems solved by technology

However, the stability of the impregnation solution containing Pd compounds is very poor, which relatively increases the requirements of the catalyst preparation process.

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. Harmful organic compounds to the human body are unfavorable in terms of environmental protection or labor protection

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