Elucidation of hydrogen mobility in coal using a tritium pulse tracer method. Hydrogen exchange reaction of coal with tritiated gaseous hydrogen

Abstract

The hydrogen exchange of coal with gaseous hydrogen was carried out between 200 and 300°C using a pulse flow reaction system in the absence and presence of a Pt/Al2O3 catalyst to estimate the mobility of hydrogen in coals. In the absence of the catalyst, hydrogen exchange hardly occurred and hydrogen exchange ratio (HER) was fewer than 1% in most of coals used. Hydrogen exchange reaction between coal and gaseous hydrogen was enhanced remarkably in the presence of Pt/Al2O3 catalyst and HER was increased with temperature. The hydrogen mobility in coal was lower for higher rank of coals at each temperature. Further, the amount of hydrogen in functional groups of coal, which is contributed to the hydrogen exchange with tritiated gaseous hydrogen, could be estimated by the treatment of the tritiated coals with water. It was suggested that almost all hydrogen of functional group in coals were exchanged with gaseous hydrogen at high temperatures over 250°C in the presence of the catalyst.