Abstract
Coal, coa/CaO and coal/Ca(OH)_2 mixture were pyrolyzed under various pressure with heating rate 20K/min under various pressure. The total volume of gas product from pyrolysis was in the order of coal/Ca(OH)_2>coal/CaO >coal at high pressure. H_2 products in coal/CaO and coal/Ca(OH)_2 pyrolysis peaked in the temperature range of 923-973K. At this H_2 peak temperature, the H_2 content in product gas was approximately 80%, while there was little CO, CO_2, and CH_4. One reason for this is that the H_2O contained in coal can be brought to a higher temperature by the reactions of Ca(OH)_2 formation and decomposition. H_2O reacted with coal at high temperature, producing H_2 and CO. It was also found that CO can shift to CO_2, and that CO_2 can be fixed by CaO to CaCO_3 in the temperature range of the H_2 peak.
