37.石炭の高温熱分解時におけるガス状窒素化合物の生成機構

抄録

Low rank coals have been pyrolyzed with fixed bed and free fall type reactors to examine factors controlling the reactivity of char-N after devolatilization. At 400℃/min, Ca^<2+> ions added at 3wt% to the demineralized coals enhance more efficiently formation of N_2 and NH_3 from char-N at 1000-1350℃. The Ca is also active even in rapid pyrolysis (10^4〜10^5℃/s). The increase in N_2 yield at residence time of 30sec by Ca addition is 10%. The Ca can thus catalyze N_2 formation from char-N after complete release of volatile matters. The XRD measurements of the chars reveal that the Ca exists as CaO with the average size of 25-40nm. It is lilely that the highly dispersed CaO catalyzes conversion reactions of char-N to N_2 and NH_3 at solid phase and formation of crystallized carbon. The reaction mechanism is discussed in term of interactions between CaO particles and char-N.