Catalytic activity of alkali and iron salt mixtures for steam-char gasification

Abstract

The catalytic activity of five different binary mixtures of alkali (K 2CO 3, K 2SO 4, Na 2CO 3) and iron salts (FeSO 4, Fe(NO 3) 3) on steam-char gasification at 700–800 °C was measured in a thermobalance reactor. Under the same experimental conditions with 3 wt% catalyst loading, the catalytic activity of the pure salts is in the order K 2 CO 3 Na 2 CO 3 ≈ FeSO 4 K 2 SO 4 Fe( NO 3) 3. For K 2SO 4 and Na 2CO 3 the gasification rate could be enhanced by addition of iron salt. A synergistic effect of alkali and iron salts on the gasification rate was observed and the mixtures K 2 SO 4 + FeSO 4 and K 2 SO 4 + Fe( NO 3) 3 exhibited better catalytic activity than K 2CO 3 at 800 °C. A kinetic parameter is proposed as a simple measure of activity of various catalysts based on the grain model. On the basis of the kinetic parameters and melting behaviour, K 2 SO 4 + FeSO 4 in the temperature range 700–800 °C is an effective catalyst for steam-char gasification.