Ammonium metatungstate is the main raw material of tungsten-based catalyst, which can greatly improve the catalytic performance of the prepared product. In recent years, with the development of petroleum refining and petrochemical industries, the amount of tungsten compounds has also increased.
Ammonium metatungstate is an inorganic compound with a chemical formula of H28N6O41W12, a molecular weight of 2974.32, with white or light yellow color, the purity is up to 99.95%, and main content of WO3 is up to 83.0%. It is soluble in water and can be used as a petroleum catalyst and raw materials for tungsten products. At present, the common production methods are: neutralization method, tungstic acid method, thermal decomposition method, solvent extraction method and ion exchange method.
The neutralization method uses ammonium paratungstate and nitric acid as raw materials to prepare AMT. The tungstic acid method dissolves tungstic acid in ammonia water, and then prepares the product through a series of steps. The thermal decomposition method uses ammonium paratungstate as raw material to obtain the product. The solvent extraction method uses tributyl phosphate and kerosene solvent to form the organic phase of the ammonium tungstate solution, and extracts the ammonium ions in the ammonium tungstate to obtain the product. The ion exchange method also uses ammonium paratungstate for the raw material to make the product.
Preparation of petroleum catalyst containing AMT: It is a product that uses activated clay treated with hydrochloric acid vapor as a carrier and heteropolyacid ammonium metatungstate as an active component. Under the polymerization process conditions of temperature 130°C, pressure 4.0MPa and space velocity 0.5h-1, the generation temperature of hydrochloric acid vapor is 50°C, the treatment temperature of activated clay is 500°C, and when the active component ammonium metatungstate loading mass fraction is 8%, the catalyst has good catalytic activity, excellent selectivity, large specific surface area, good water solubility, long service life and other characteristics, and the kinematic viscosity of lubricating oil (40°C) 38.98mm²•s-1 , bromine value 8.23g•(100g)-1, freezing point -45.2°C.
