Hydrogen generation from water and aluminum promoted by sodium stannate

Abstract

A new process to obtain H2 from H2O using Al corrosion in Na2SnO3 solutions is described. Results showed an enhancement of H2 production rates using Na2SnO3 instead of NaOH at the same pH. A side reaction of Al in Na2SnO3 solutions has been found, which consumes Al to produce metallic Sn. H2 yield depends chiefly on Al/Na2SnO3 molar ratio for experiments with Na2SnO3 concentrations above 0.025 M, reaching higher yields with higher Al/Na2SnO3 ratios. The maximum H2 production rates are proportional to the initially added Al mass. Two different shrinking core models for examining the kinetics of H2 generation are verified and the activation energy (Ea) is 73 ± 6 kJ mol-1, confirming a rate control by a chemical step. A mechanism of Al corrosion in Na2SnO3 solutions is proposed and compared with the mechanism in NaOH and NaAlO2 solutions.