STUDY ON THE PREPARATION OF MOLYBDENUM(IV)CHLORIDE WITH HIGH PURITY

Molybdenum tetrachloride is a black, non-volatile solid compound. It is insoluble in non-polar solvents and reacts slowly with most highly polar solvents. In addition to being used as a raw material for preparing other molybdenum compounds, molybdenum tetrachloride is also widely used as a catalyst for preparing an organic polymerization reaction. Since molybdenum tetrachloride is highly susceptible to deuteration and has high oxidation instability, the preparation of pure molybdenum tetrachloride is very complicated. There have been some reports on the preparation methods at home and abroad, mainly including the following preparation routes:
(1) Molybdenum pentachloride with hydrogen metal. The raw materials of the method are easy to obtain, but the purity of the product is not high;
(2) The reaction is completed by a reaction of molybdenum trichloride and molybdenum pentachloride. The method has high yield, but the operating conditions are harsh;
(3) Reactively reacting molybdenum trioxide with hexachloropropene. The method has high yield and short reaction time, but the raw material price is high;
(4) The molybdenum pentachloride is refluxed in tetrachloroethylene. The raw material of the method is easy to obtain, and the purity of the product is extremely high, and the yield is nearly 100%. However, the reaction time is longer.
Although there are many preparation methods for molybdenum tetrachloride, the research on the optimal process conditions for its preparation has not been reported. Based on the reference literature, this paper selects the fourth route from the aspects of raw material cost, difficulty in preparation method, product purity and safe production, and improves the original reaction device to make the operation more convenient and safe. Through experimental research, the optimal process conditions were determined, which provided a basis for achieving large-scale production. The reaction device was fixed on a electromagnetic stirring heater in a fume hood, and the reactor was evacuated to a vacuum line, and after replacing with high-purity nitrogen, the reactor was nitrogen-filled. A certain amount of freshly sublimed molybdenum pentachloride was added to the reactor A chamber each time through the side tube B, and then a certain amount of tetrachloroethylene was added to the chamber A by vacuum distillation. The reaction was heated to the desired temperature by an oil bath while the reactants were irradiated with two 100w bulbs about 30 cm from the device. After completion of the reaction, it was cooled, suction-filtered through a glass core crucible (constant weight), and the product was washed with carbon tetrachloride, vacuum dried for several hours, weighed, and the yield was calculated based on molybdenum pentachloride.

STUDY ON THE PREPARATION OF MOLYBDENUM(IV)CHLORIDE WITH HIGH PURITY