Solid-phase synthesis method for magnesium borohydride ammoniates

Abstract

The invention discloses a solid-phase synthesis method for magnesium borohydride ammoniates. The solid-phase synthesis method comprises the following step of: performing ball milling on magnesium borohydride and an ammonia source under the atmosphere of protective gas to obtain the magnesium borohydride ammoniate. According to the solid-phase synthesis method for the magnesium borohydride ammoniates, the complicated operation processes of filtration, distillation and solvent removal in traditional methods are avoided, and the problem that organic waste liquid needs to be specially treated is solved; the product yield is increased; a series of magnesium borohydride ammoniates with different ammonia complexing numbers can be prepared; the operation is simple; the product purity is high; the yields of the magnesium borohydride ammoniates are respectively higher than 95 percent; the dehydriding temperature of the obtained product is about 130 DEG C; and the hydrogen discharge amount is higher than 13 weight percent (wt%).

Description

technical field [0001] The invention relates to the preparation of hydrogen storage materials, in particular to a solid-phase synthesis method of magnesium borohydride ammonium hydrogen storage materials. Background technique [0002] Magnesium borohydride ammonium compound has the advantages of large hydrogen storage capacity (>13wt%), low hydrogen release temperature, and insensitivity to oxygen. It is widely used in hydrogen energy utilization and is one of the research hotspots of hydrogen storage materials at present. [0003] At present, for the synthesis method of magnesium borohydride ammonium compound in the world, there are mainly used ammonia gas and magnesium borohydride ether solution to prepare hexaammine magnesium borohydride, hexaammine magnesium borohydride decomposition to prepare diammine magnesium borohydride, and benzene, respectively. React with magnesium borohydride and ammonia gas in a near-stoichiometric ratio in ether to generate diammine magnesi...

AI Technical Summary

Problems solved by technology

However, the benzene and ether used in this reaction route have certain toxicity, and benzene is a carcinogen

In addition, the synthetic route also needs to undergo subsequent treatments such as filtration, solvent washing and vacuum drying, which is not conducive to large-scale promotion

At the same time, the method needs to accurately control the amount of liquid magnesium borohydride ether complex and gaseous ammonia, which is difficult to achieve in industrial production and will lead to increased production costs.

[0010] In addition, the existing methods for synthesizing magnesium borohydride ammonium compounds can only synthesize diammine magnesium borohydride, triammine magnesium borohydride and hexaammine magnesium borohydride, and the ammonia complex number is not equal to two, three or six The synthesis method of magnesium borohydride ammonia compound has not yet been reported, which restricts the application of magnesium borohydride ammonia compound as hydrogen storage material in hydrogen storage system

[0011] In summary, the existing methods for the preparation of ammonium borohydride ammonium compounds are difficult to control the number of ammonium complexes, and there are problems in the preparation process, such as low yield and low purity, difficult operation, and unfavorable for large-scale production. However, it cannot satisfy its application as a hydrogen storage material. Therefore, it is necessary to develop a method for preparing magnesium borohydride ammonium compound that is simple and feasible, with controllable ammonia complexation number, high purity and yield.

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