Phosphomolybdenum Tungsten Heteropoly Acid

In recent years, metal rhenium compounds have attracted much scientists' attention and research in the field of catalytic application. There are two main reasons: first, the multiple valence states of rhenium provide a precondition for the formation of various stable rhenium compounds. Second, most rhenium compounds are inert to water and oxygen, so they are easily controlled in the organic catalytic reaction.

The catalytic application of rhenium is in the field of petrochemical industry. However, rhenium is expensive and scarce resources, looking for alternatives is imperative. Transition metal molybdenum and tungsten is a kind of high performance material, with high hardness, high melting point, high strength, wear resistance and good electrical conductivity, has been widely used in petrochemical, aerospace, defense, machinery, electronics, metallurgy, nuclear industry and other fields. Molybdenum, tungsten and rhenium have similar physical and chemical properties, and have unique catalytic properties and price advantages. Therefore, molybdenum and tungsten catalysts are the most promising catalysts instead of rhenium.

In the study, scholars have found that using phosphomotungstic acid or phosphomo heteropoly acid to catalyze the epoxidation of olefin is far less effective than rhenium. Thus, the complex of tungsten and molybdenum into a new heteropoly-molybdophosphoric acid [PMoW₃O₂₄] ^3-, which has a collection of tungsten and molybdenum elements in a composite catalyst, not only the performance of high efficiency, but also in the catalytic experiment process can be recycled.

Tungsten molybdenum heteropoly acid test catalytic cyclooctene epoxidation, using UHP as oxidant, the amount of oxidant UHP was 1.5mol, the amount of catalyst was 20 mg, the reaction temperature was 70 ℃ and the reaction time was 50 min. The reaction was carried out in this condition with a yield of 99.35% and a selectivity of > 99%.

Tungsten molybdenum heteropoly acid test catalytic cyclooctene epoxidation, using UHP as oxidant, the amount of oxidant UHP was 1.5mol, the amount of catalyst was 35 mg, the reaction temperature was 60 ℃ and the reaction time was 50 min. The reaction was carried out in this condition with a yield of 91.91% and a selectivity of > 99%.

The catalytic results show that phosphomolybdenum tungsten heteropoly acid reaction system can not only catalyze the epoxidation of cyclooctene, moreover, it has good catalytic effect on cyclohexene epoxidation. The reaction has the advantages of high conversion rate, good selectivity, simple operation, mild reaction conditions and low cost. It has great catalytic potential for rhenium catalyst.

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