Study On Synthesis Of Aluminum Hydride

As one of the major new energy of the21st century, the technology of hydrogen storagebeen considered as a focused topic in the field of hydrogen energy. Aluminium hydride is acompound that is well known for its high gravimetric and volumetric hydrogen densities andfavorable hydrogen storage properties. Besides this, aluminum hydride compounds can alsobe widely used for reduction reactions of carboxyl, carbonyl, amide bond, ester etc. It can beused as a co-catalyst for olefin addition polymerization, precursor of the protective aluminumfilm that is crossing the surface of materials, reducing agent of power systems and so on.Many of these advantages lead aluminum hydride compounds make a difference in our lifeand production.In this paper, aluminum and hydrogen are used as raw material for the direct synthesis ofaluminum hydride, but aluminum is not reacted both at normal pressure and under certainpressure, so aluminum is need be activated. We use different activators for the activation ofaluminum, and the results are that aluminum chloride cannot activate aluminum, anhydrousaluminum chloride, iodide and iodoalkane with not good degree of activation, and mercurychloride or mixture of anhydrous aluminum chloride and iodide with very good activation.Use mercuric chloride as activator to initiate the reaction of aluminum and hydrogen underpressure, but only peaks of aluminum oxide are observed, so it it is unable to determinewhether the reaction is carried out or not. For further activation of aluminum, grignardreaction is carried out and organic aluminum compound is generated with high reactivity.Aluminum is dissolved in liquid phase. Direct hydrogenation under pressure obtain aluminumhydride, but it decomposes quickly.Aluminum dissolved in amine-complexing agent can lower its activation energy. Usealuminum to act with hydrogen under pressure but donot get aluminum hydride because oflack of reactivity. Activated aluminum with an organic aluminum compound preparesaluminum hydride in amine. The product prepared under normal pressure is unstable and iseasy to decompose, and aluminum hydride prepared under pressure failes to remove hydrogenbromide, and it has a certain influence on the reaction. In the direct synthesis of sodium aluminum hydride, aluminum, sodium and hydrogenare reacted in liquid paraffin at110℃and sodium aluminum hydride is prepared, but theproduct is unstable. We get sodium aluminium hydride by adding sodium or sodium hydrideto aluminum activated by organic aluminum compound which is obtained at normal pressureor under a certain pressure. We obtain pure sodium aluminum hydride by purifying crudeproduct. The molar ratio of aluminum ions and hydrogen atom analysized through drainageand gas collection and spectrophotometer is1:8, and proves that the product is sodiumtetrahydridoaluminate. Sodium aluminum hydride used as a raw material reacts with acids oracid salts in ethylene glycol dimethyl ether to get the aluminum hydride which is not easy totake off the complexing agent. Aluminum hydride with stable structure is prepared by reactionof anhydrous sodium aluminum hydride and aluminum chloride in ether and removing etherafter the reaction.