Catalysed and uncatalysed steam gasification of eucalyptus char: influenceof variables and kinetic study

A study of the steam gasification of Eucalyptus chars has been carried out, using Li, Na and K chlorides as catalysts, in order to characterise the ga s phase with a view to its energy use, analysing the influence of steam flo w rates, initial mass of char, particle size and temperature. The main gase s generated were H-2, CO and CO2, with a higher heating value between 9 and 10 MJ/N m(3). The presence of alkaline metals as catalysts resulted in a h igh process rate. The catalyst concentration had a positive effect up to a given level (1% for LiCl and 3% for NaCl and KCl), above which there was sa turation due to the blocking of the carbon pores. A kinetic model based on gas generation gave the activation energy and the reaction order with respe ct to each catalyst. These activation energies were in all cases lower than that of the uncatalysed process. This, together with a decrease in the Arr henius pre-exponential factor, leads to isokinetic points, i.e. temperature s at which the catalysed and uncatalysed processes take place at the same r ate. These isokinetic points were 903, 1356 and 998 degreesC for Li, Na and K chlorides, respectively. (C) 2001 Elsevier Science Ltd. All rights reser ved.