Three Major Applications of Tungsten Heteropoly Acid

Tungsten heteropoly acid is a kind of nano scale inorganic cluster which is determined by structure. Especially the tungsten heteropoly acid with Keggin structure is stable and has both acid and redox property. It can be used to design different functional catalysts and is very popular. Its superior catalytic performance is mainly embodied in petrochemical industry, sewage treatment and light industry.

In the field of petrochemical industry, tungstic heteropoly acid can be used as an acid catalyst. Its catalytic activity is 100-1000 times higher than that of inorganic acid. It can react under mild conditions, and it is not easty to produce side reactions. Tungstic heteropoly acid has higher catalytic activity than molybdenum heteropoly acid because the acid containing tungsten heteropoly acid is stronger. Tungstic heteropoly acid can catalyze the reaction as an acid catalyst: The reaction of esterification and vinegar exchange, nitrification, dilute alkyne hydrate, dealkylation, sintering and etherification of epoxides, etc. In almost the petrochemical industry, most of the chemical products that need the catalyst can be catalyzed by tungstic acid, and they are innocuous, clean and environmentally friendly.

In the field of sewage treatment, the absorption peak of tungstoxic acid is in the ultraviolet region, while the tail band can extend to the visible light area. The spectral properties of heteropoly acids can be regulated by the selection of different substituted atoms. Therefore, tungstic heteropoly acid also has tungstic acid photocatalyst. At present, phosphotungstic acid [PW₁₂O₄₀]^3- and silicon tungstic heteropoly acid [SiW₁₂O₄₀]^4- can be applied to photocatalytic degradation of organic pollutants.

In the light industry, heteropoly acid can effectively catalyze the selective oxidation of alcohol to produce corresponding aldehydes or cavern. In the light industry, heteropoly acid can effectively catalyze the selective oxidation of alcohol to produce corresponding aldehydes or cavern. Many chemical agents such as adipic acid, octyl acetate, cinnamic acid isoamyl acetate, butyric acid vinegar, soybean oil base polyol and so on can be prepared by tungstic heteropoly acid. In the oxidation reaction of alcohols, the activity of supported phosphor based tungstic acid catalyst is the best, which indicates that the conversion rate of alcohol oxidation is over 93% when H₂O₂ is used as oxidant, and the catalytic activity is higher than that of the heteropoly acid modified by the ionic liquid. After completion of the reaction, the catalyst can be recovered by simple treatment and reused, and the activity of the catalyst is not significantly reduced after repeated use for seven times. The structure of the catalyst was characterized by IR spectroscopy. Compared with the initial catalyst, the structure was not changed.

Tungstic heteropoly acid as a catalyst has been widely studied because of its following characteristics: first, it is soluble in water, ethanol and acetone and other strong small molecule solvents, but not soluble in glycerol and other weak polar macromolecules or non-polar solvents. As a result, it can be used as homogeneous or solid catalyst. Second, the structure of tungsten heteropoly acid anions is relatively stable, while different components of atoms will form heteropolyacids of different properties. Some of their properties can be achieved at the molecular level of heteropoly anions. Third, heteropoly acid has both acid and redox properties. According to these properties, different functional catalysts can be designed to maintain the structure of heteropoly anions and change the composition group.

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