Production of Aluminium Hydride by Plasma Chemical Catalytic Reaction

Abstract

In the plasma chemical reaction between aluminium chloride and hydrogen, it is on the reactor substrate that aluminium chloride compounds form, which, under the right conditions, can help obtain AlH3 in stoichiometric composition. A rising partial pressure of Н2 in the reaction zone serves as the main stimulant for the AlH3 formation. The rate of this plasma chemical reaction tends to rise in the presence of palladium catalyst. Highly dispersed particles of palladium on charcoal blend with aluminium chloride particles, and this mechanical mixture gets processed in a lowtemperature plasma reactor in a hydrogen flow at the temperature of up to 2·104 К. A higher dispersion degree of the catalyst particles is associated with a higher yield of aluminium hydride. The concentration of palladium on charcoal mixed with aluminium chloride aimed at enhancing the formation of aluminium hydride should not exceed 2%, as any further increase in the catalyst concentration does not benefit the AlH3 yield but rather affect it. This can be attributed to the fact that once a certain catalyst concentration has been reached, the slow stage of the heterogeneous catalytic reaction between hydrogen and aluminium chloride particles involves Н2 absorption on their surface, where the presence of catalyst has no effect on the reaction rate. The plasma chemical reaction between hydrogen and aluminium chloride particles in the presence of palladium catalyst results in the formation of aluminium hydrides with an orthorhombic structure. It was found that the rate of the catalytic reaction tends to rise as the aluminium hydride layer forms. This can be attributed to the fact that the AlH3 formed acts as a catalyst. The catalytic effect of aluminium hydride was proved by plasma chemical reduction of cobalt from its oxides in the presence of elemental sulphur. An aluminium-cobalt mixture gets formed as a result.