Coal gasification is an effective use of coal for power generation and syngas production. In addition, it has advantages in emission control and CCS. In recent years, the study of catalytic gasification has received attention because it requires less thermal energy input but products higher carbon conversion. However, use of catalyst in coal gasification suffers from serious economic constraints because of the high costs of catalyst, as well as environmental impact of gasified char if it disposed by conventional landfill. Therefore, due to both economic and environmental reasons, catalyst recovery is necessary.
In the present study, extraction schemes were investigated including water washing, limewater (CaO, KOH) washing and water-limewater-combined washing, respectively, in order to evaluate their efficiency of extraction. In this research, catalyst recovery process from gasified residue from steam gasification with Lanna raw coal catalyzed with 20 wt.% Potassium carbonate (K2CO3) on a laboratory fixed-bed reactor. Effects of process variables, such as reaction time, temperature and residue/solution weight ratio, on the extraction efficiency were evaluated. The optimal experiment condition for catalyst recovery were 150 ℃, 20/1, 2 h. In conclusion, water-limewater-combined washing was found to be the most desirable because of it costs was lower than limewater washing and its efficiency was high enough to accept. In addition, it was proven that the recovered potassium has the same catalytic activity as potassium carbonate.
