Influences of alkali in borates on recovery of sodium borohydride

In this work, influences of Na2O in compounds lying within the Na2O–NaBO2 composition domain on NaBH4 recovery have been investigated. It is found that Na2O plays different roles in NaBH4 formation. Na2O is beneficial in terms of NaBH4 formation and reaction kinetics when Al is used for NaBH4 recovery, but harmful to NaBH4 formation when Mg is used for NaBH4 recovery from compounds lying within the Na2O–NaBO2 composition domain. High borate conversion rates can be obtained when Mg reacts with compounds lying within the Na2O–NaBO2 composition domain with less Na2O or Al reacts with the compounds containing more Na2O. NaBH4 formation temperature depends upon the used metals.