Activated Carbon Supported Silver Phosphomolybdate-Tungsten Heteropoly Acid Catalyst

With the introduction of the concept of green chemistry, the enhancement of people's awareness of environmental protection and the emphasis on environmental protection, these inorganic acid catalysts are gradually being eliminated. Heteropoly acid and its salts catalysts are a new type of solid acid catalysts developed in recent years. Heteropoly acid is a kind of oxygen-containing polyacid formed by the bridging coordination of heteroatoms (such as P, Si, Fe, Co, etc.) and polyatoms (such as Mo, W, V) through oxygen atoms, such as phosphomolybdenum tungsten, phosphomolybdenum vanadium, silicotungstic acid and silicomolybdic acid.

Among the existing technologies, heteropoly acid catalysts supported on activated carbon have attracted much attention because of their strong acidity, high activity at low temperatures, acidity and oxidation properties. Some scholars have published papers on the preparation of silver heteropoly acid catalysts supported on activated carbon, such as phosphomolybdenum tungsten.

(1)The activated carbon particles with a diameter of 75-800 microns were added into 10%-20% HNO₃ aqueous solution until the HNO₃ solution was immersed in the activated carbon; the activated carbon particles were heated and refluxed, then washed in cooling water to be pH neutral; filtered; and then dried to constant weight at 80-150 ℃.

(2)H₃PW₆Mo₆O₄₀ solution with concentration of 10%-20% was prepared by mixing 95% ethanol and water in equal volume as solvent for reserve.

(3)The activated carbon particles treated in step (1) were added to the phosphomolybdenum tungsten heteropoly acid solution prepared in step (2) at the ratio of 1:0.1-0.8, stirred, and then dripped into 10%-20% AgNO₃ solution of 1-4 times the quality of phosphomolybdenum tungsten heteropoly acid. The silver salt of phosphomolybdenum tungsten heteropoly acid to be precipitated was loaded by activated carbon particles.

(4)The loaded activated carbon particles were placed in the drying chamber and dried at 90-100 ℃ for 1-10 hours (preferably 2-5 hours), then cooled in the dryer to obtain the activated carbon supported silver phosphomolybdenum tungsten heteropoly acid catalyst.

A series of catalysts with a wide range of loads can be synthesized by precipitation and adsorption, and the loads are synchronized with the formation of silver salts. This kind of silver heteropoly acid catalyst supported on activated carbon has high activity because of its granularity and easy treatment after reaction, which overcomes the shortcomings of low specific surface area of Heteropoly acid.

• < Prev
• Next >