Hydrofining catalyst for crude terephthalic acid as well as preparation method and application thereof

Abstract

The invention provides a hydrofining catalyst for crude terephthalic acid as well as a preparation method and application thereof. The preparation method comprises the following steps of adding activated carbon into a natural polysaccharide solution, stirring, filtering, washing, and carrying out vacuum drying, dipping the treated activated carbon in a palladium salt precursor solution for aging,reducing Pd ions in the palladium salt precursor solution into metal Pd nanoparticles by using a reducing agent to obtain a sample, and carrying out chemical liquid phase deposition modification on the sample by using an organosilicon compound solution to obtain the crude terephthalic acid hydrofining catalyst. The catalyst prepared by the method can be used for catalyzing the reaction of preparing purified terephthalic acid from crude terephthalic acid, and the selectivity of 4-CBA is high.

Description

technical field [0001] The invention relates to a catalyst, in particular to a catalyst for hydrorefining crude terephthalic acid, and belongs to the technical field of catalyst preparation. Background technique [0002] Purified terephthalic acid, commonly known as (PTA), is an important raw material for the synthesis of polyethylene terephthalate (PET). The presence of p-carboxybenzaldehyde (4-CBA) in crude terephthalic acid (CTA) will seriously affect the quality of PET. Therefore, at present, palladium-carbon catalyst is mainly used to hydrorefine CTA to obtain PTA. Since the active component of the palladium-carbon catalyst is only palladium, the distribution of palladium on the activated carbon has a great influence on the performance of the catalyst. [0003] Since the hydrogenation reaction is carried out on the surface of metal Pd, for the catalyst with the same loading of Pd, the higher the dispersion of metal Pd and the smaller the catalyst particle size, the hi...

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Problems solved by technology

The catalyst palladium particle size prepared by this method is between 3-8nm, but the oxidant (hydrogen peroxide) used in the preparation process is prone to danger

Chinese patent application CN103157464A has announced a kind of preparation method of palladium carbon catalyst, is used for the hydrogenation refining reaction of PTA, and the catalyst palladium particle size obtained is less than 2nm, but will use a large amount of oxidant (perchloric acid etc.) and Alkaline solution will cause greater harm to people and the environment

[0005] CN109569590A discloses a green and environment-friendly method for preparing palladium-carbon catalyst, which is used for PTA hydrorefining reaction. Firstly, chitin microspheres need to be calcined at 400-800° C. to obtain chitin carbon spheres, which are used as a carrier for catalyst preparation. Preparation, in the preparation process, it needs to be frozen at -30°C for 4-8h, the preparation process is more complicated, and the required cost is higher

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