Immobilized Phosphotungsten Heteropoly Acid Preparation by Extraction

In the conventional preparation of phosphotungstic acid, a large amount of ether is used to extract the reaction liquid of phosphotungstic heteropoly acid, and a yellowish transparent oily ether-phosphotungstic heteropoly acid is obtained. The solid product of yellowish phosphotungstic heteropoly acid is obtained by blowing ether with air. Moreover, the ether used in the whole extraction process is difficult to recycle, resulting in waste of resources and environmental pollution.

In order to solve these problems, tungsten heteropoly acids are often immobilized on appropriate supports as catalysts, thus increasing the specific surface area of the catalysts, realizing heterogeneous catalysis, and enhancing the mechanical strength and thermal stability of the catalysts. For example, some scholars used ether/polyaniline extraction to prepare immobilized Phosphotungsten heteropoly acids.

1. Preparation of ether/polyaniline extractant
The carrier polyaniline was prepared by chemical oxidation method, and then the ether/polyaniline extractant was prepared by impregnation or adsorption method.

2. Preparation of immobilized Phosphotungsten heteropoly acid
Hydrochloric acid was added to sodium tungstate and disodium hydrogen phosphate solution at a certain temperature. The reaction temperature was controlled and the amount of acid was added to ensure that no crystals were formed after the reaction.

Then, the reaction liquid was cooled to room temperature, and a proper amount of hydrochloric acid and ether/polyaniline extractant were added in turn, stirring, stationary, filtration, drying and drying were used to obtain the Supported Phosphotungstic heteropoly acid.

Using ether-polyaniline extractant to extract heteropoly acid in reaction solution can not only simplify the preparation process of immobilized phosphotungstic heteropoly acid, but also avoid the waste and difficult recycling of ether in the extraction process of conventional preparation of phosphotungstic heteropoly acid, which is also of environmental protection significance.

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