Effect of Methane on the Rate of Hydrogen Absorption by LaNi sub 5 H/sub X/ in Liquid Suspension

摘要

The effect of CH sub 4 upon the kinetics of the absorption of H sub 2 by LaNi sub 5 H/sub x/ suspended in n-undecane was determined at two different gas compositions; 5 and 25 mol % CH sub 4 in H sub 2 . The systems behave similiarly to those studied in the absence of CH sub 4 and the same rate equation holds. The rate limiting process is dissolution of H sub 2 in the liquid phase. The activation energy for this process, E/sub s/, varied with CH sub 4 pressure; at 40 kPa, E/sub s/ = 9.3+/-.5 kJ/mol H sub 2 , at 253 kPa, E/sub s/ = 5.5+/-.9 kJ/mol H sub 2 . The pre-exponential in the rate equation is reduced by the presence of CH sub 4 , however the absorption rate is very little changed relative to pure H sub 2 in the gas phase because of the lower E/sub s/. The reduction of E/sub s/ is attributed to the dissolution of CH sub 4 in the liquid phase and a consequent lowering of its surface tension. 6 refs., 4 figs., 2 tabs. (ERA citation 11:040077)