Electrolysis of coal slurries to produce hydrogen gas: Effects of different factors on hydrogen yield

The study was aimed to investigate the effects of different factors (such as acid concentration, cell potential, temperature, coal types, and geometric area of the membrane) on the coal slurry electrolysis and hydrogen evolution. It was observed that all of the above factors affected hydrogen production upon completion of the electrolysis. The results revealed that an increase in the initial acid concentration up to 5.0 M brought about an increase in the current density and hydrogen evolution. However, the higher the acid concentration was taken (>7.0 M) then the lower the current density and hydrogen evolution were, which resulted in significant change due to the agglomeration of coal samples and stuck on the electrode surface.Furthermore, the CO2 evolution (14 ml) was observed only at high temperature (100 °C) and high (2.0 V) cell potential when the H2 amount was 776 ml. The coal type was observed to have influenced the electrolysis.

► At high acid concentrations (>7.0 M) the H2 evolution and current density decreased.
► Electrolysis was observed to be depended on coal types.
► In the absence of iron ions no significant changes were observed in the current density and H2 evolution.
► The CO2 evolution was observed only at high temperature and high cell potential.
► The significant increase in hydrogen evolution was observed at 100 °C and 2.0 V cell potential.