Tungsten Oxide

Heteropoly acid is one of the most active catalysts in acid catalytic reaction and redox reaction. Phosphotungstic acid H 3 PW 12 O 40 •nH 2 O is the most widely used in heteropoly acid. The purity of phosphotungstic acid directly affects the conversion rate of the catalytic system. Therefore, the preparation of high purity phosphotungstic acid is especially important. Some scholars have proposed a purification method for phosphotungstic acid crystals. (1) The crystal of industrial phosphotungstic acid is dissolved in water and the inorganic acid is added to the solution of phosphotungstic acid containing inorganic acid. The concentration of tungsten trioxide is 50-150g/L, and the volume molar concentration of the inorganic acid is 0.5 ~ 6mol/L. (2) In the solution of phosphotungstic acid containing inorganic acids, the oil phase organic alcohol extractant was extracted with the volume concentration of 5-50%, and the volume ratio of the two phase was oil phase = 1:1-10:1, and the organ...

Biodiesel is usually synthesized from vegetable oils and fats and waste edible oils by simple transesterification. In the synthesis of biodiesel, the key technology is the selection of the catalyst, the traditional inorganic acid and alkali catalyst, facing strong corrosive and non renewable, easy to cause problems such as saponification reaction against the original intention of the environmental protection of bio diesel.  Phosphotungstic acid is an environmentally friendly catalyst widely used in catalysis in recent years. It has strong acidity, and many industrial processes that need to be catalyzed by inorganic acids can be replaced by phosphotungstic acid. But in the biodiesel production process, found itself acid soluble in water, for many catalytic processes of catalytic esterification, the esterification rate is generally not high, in addition, the activity of the heteropoly salt group easily lost, so that it can not be used repeatedly, which leads to high cost. Even so, t...

Four hydrogen sulfide is a chemical intermediate of nitro spray paint, rubber and other solvents, so is often used in the protection of hydroxyl groups. The catalysts, Lewis acid and ion exchange resin used in the preparation of the four - hydrogen catalyst, all of which have good catalytic effect. However, there are some shortcomings in these methods, such as longer reaction time, reflux, solvent, complex catalyst preparation procedure and unsatisfactory yield. Phosphotungstates have copper phosphotungstic acid , zinc phosphotungstate and aluminum phosphotungstate. As a kind of heteropoly acid salts, phosphotungstates are widely used as catalysts. It has been proved by experiments that the catalytic activity of phosphotungstic acid for the catalytic hydrogenation of four hydrogen peroxide is better than that of the four hydrogenation of alcohol, thus, a green environmental reaction route is provided for the four hydrogen alkylation reaction better than other methods. The results show ...

At present, environmental pollution has become one of the most important concerns of mankind, especially organic pollutants. Their damage to the environment such as water, atmosphere and soil will be damaged if they are not dealt with in time, and cause an irreversible loss. In recent years, photocatalytic degradation has become one of the most important methods for organic pollutants because of its high efficiency, environmental protection and easy operation.  As far as photocatalytic reaction is concerned, titanium dioxide TiO 2  is one of the most studied semiconductors. This is due to its early application, cheapness, ease of handling, large specific surface area, and stability. Photocatalysis has attracted the most attention in the field of wastewater purification and treatment. But what can not be evaded is that TiO 2  band gap is wider (about 3.2 e V), it can only be excited by ultraviolet light, the use of solar energy is limited, photoinduced electron re...

Levulinic acid, also known as fructose, is the basic raw material for the synthesis of various light chemical products, and has high activity. High value-added products can be produced by chemical reactions such as esterification, halogenation, hydrogenation, oxidative dehydrogenation and condensation. They are widely used in organic synthesis, industry, agriculture and pharmaceutical industry. Although levulinic acid is good, the preparation method is relatively troublesome. There are many problems in the preparation of traditional acid process, such as corrosion of equipment, serious pollution, complex treatment process and difficult separation of products. To solve these problems, scientists are trying to find the appropriate solid acid catalyst to replace the traditional acid catalyst. However, a variety of solid acid catalysts have been tried with little success until the appearance of phosphotungstic acid . Phosphotungstic acid is a kind of heteropoly acid. Becau...