不同反应条件对煤中自由基的影响

Effects of different reaction conditions on the free radicals in coal

为了探讨不同反应条件对煤中自由基的影响,根据煤炭自燃的自由基反应机理,利用电子自旋共振(ESR)测谱仪,研究了煤在破碎、低温氧化和紫外光照射过程中自由基浓度的变化.结果表明,破碎、低温氧化和紫外光照射等不同反应条件均能诱发煤中自由基的形成,影响煤中自由基的浓度.煤破碎越小,煤中自由基浓度越大;氧化温度越高,煤中自由基浓度越大,当氧化温度超过125℃后,煤中自由基浓度显著增大;同一氧化温度下,氧化时间越长,煤中自由基浓度越大,但增加的速度较慢;煤中自由基对紫外光极其敏感,在开始光照的30 m in和撤除光照后的5 m in内,煤中自由基浓度变化最快.

In order to discuss the effects of different reaction conditions on the free radicals in coal, according to the mechanism of free radical reactions of in spontaneous combustion of coal, the variety of concentration of free radicals in coal was studied by electron spin resonance （ESR） spetroscopy during the process of fragmentizing, low-temperature oxidizing and ultraviolet radiating. The results show that different reaction conditions such as fragmentizing, low-temperature oxidizing and ultraviolet radiating are able to form new free radicals in coal, are able to influence the concentration of free radicals in coal. The smaller coal size, the higher the concentration of free radical in coal is. The concentration of free radicals in coal tends to increase with increasing oxidation temperature, the concentration of free radicals in coal increases rapidly after 125 ℃. Under the same oxidation temperature, the longer oxidation time, the concentration of free radicals in coal is higher, but the increasing speed is slower. The free radicals in coal are also very sensitive to the ultraviolet. The concentration of free radicals in coal increases sharply just in 30 minutes at the beginning and in 5 minutes at the finishing ultraviolet radiation.