Development of Removal Method of Fuel Nitrogen as N_2

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1.About 50 - 60 % of fuel nitrogen in coal can successfully be removed as N_2 when coal with the finely dispersed iron catalyst is simply pyrolyzed in an inert atmosphere. The amounts of NH_3 and HCN evolved are decreased by catalyst addition, and the residual nitrogen in the char is also decreased remarkably. Expensive H_2 is unnecessary for the present nitrogen removal. Heat treatment of a nitrogen enriched carbon shows that fine iron particles promote solid phase removal reactions of fuel nitrogen.2.The chlorine-free, highly-dispersed iron can be prepared from inexpensive FeCl_3 by the precipitation method using Ca(OH)_2. The iron on coal exists as fine FeOOH particles, which are reduced to iron metal and carbide with the size of 20 - 50 nm during coal pyrolysis. Such fine particles and/or the clusters promote the nitrogen removal of coal.3.The yields of oil and tar evolved are unchanged by iron addition, but the nitrogen contents are decreased. The presence of the iron leads to a lower amount of volatile nitrogen and a higher amount of N_2, showing the conversion to N_2 by secondary decomposition reactions of volatile nitrogen over the catalyst. The experiments using pure N-containing compounds verify that the finely-dispersed iron can promote the decomposition of pyrrol considerably.4.The atomic ratio of H/C is lower in the iron-bearing char than in the original char, and the degree of carbon crytallinity is higher in the former. The carbon crystallization and decreased catalyst dispersion by pyrolysis lower not only the reactivity of char in steam but the rate enhancement by the iron. The functionality analysis of char nitrogen shows that pyrrolic nitrogen is converted to N_2 more selectively with the catalyst. Fuel nitrogen can be removed mostly as N_2 during the iron-catalyzed CO_2 gasification of coal.