ACTIVATION OF COALS MODIFIED BY NITRATION

摘要

The authors estimated the contribution of the nitration of coal polyarenes to the general process of formation of structurally modified coals (SMCs) in the coal/HNO_3/Ac_2O system (18+-2 ℃) upon variation of the degree of metamorphism (DM) in the carbon content range of C~(daf) = 70.4-95.2%. The degree of nitration is at a maximum for coals of medium and high degree of metamorphism (C~(daf) = 88-92%). A side reaction―the oxidation of methylene and methyl groups―leads to the formation of oxygen (phenolic, carboxyl, quinoid) groups in molecules of nitroarenes and also of ester bridge bonds between them. No oxidative degradation of aromatic rings occurs. The thermolysis of NO_2 groups determines the differences between the structure of SMC carbonizates and the carbonization products of ROM coals and also exerts an effect on activation (an activator is 1 g KON/1 g SMC; 500-800℃; time up to 2 h). Using a coal of grade OS (C~(daf) = 90.0%), it has been shown that SMC is readily activated and forms carbonaceous adsorbents with a specific surface of S < 1200 m~2/g as compared to S ≤ 400m~2/g of activated ROM coal.