Hydrogenation of sodium metaborate using low-pressure hydrogen mixed gas plasma

Abstract The regeneration of NaBH 4 from NaBO 2 using low-temperature microwave plasma was investigated. The effect of adding C 2 H 2 to hydrogen plasma were also examined, and the results indicated enhanced reduction due to reactive carbon species. NaBO 2 powder was treated with either hydrogen gas plasma or C 2 H 2 /H 2 mixture plasma, and the amount of hydrogen released from the regenerated NaBH 4 was measured. The maximum hydrogen release was obtained when the sample was placed in the downstream region with 1% C 2 H 2 in H 2 mixture. A high ion flux caused significant Na etching and volatilization from NaBO 2 surface, which suppressed NaBH 4 formation. Successful plasma-based regeneration of NaBH 4 depends on treating NaBO 2 at an appropriate ion density and adding a small fraction of hydrocarbon gas (e.g. 1% C 2 H 2 ) to the hydrogen plasma.