NO_x在氢氧化钠溶液中吸收速率的研究

NOx Absorption Rate Studies in Sodium Hydroxide Solution

通过实验对氮稀释气体中的NO_2/N_2O_4和NO/NO_2/N_2O_3在25℃时、在0.5M和1.0M氢氧化钠溶液中的吸收进行了动力学研究。当NO_2的浓度>2×10^(-7)mol/cm^8时,从排出的气流中观察到氧化氮的存在。故液体中的表面可能有酸膜存在。在此浓度下,NO_2的吸收速率与NO_2气体浓度的平方成正比。由此可以证实N_2O_4是主要的吸收和反应成份。生成的NO的三倍量与被吸收的NO_2的线性关系图表明,由N_2O_4水解生成的亚硝酸(HNO_2)实际上被分解成一氧化氮和硝酸。这是吸收器中存在酸性液膜表面层的有力证据。实验发现,N_2O_4一次不可逆水解的吸收速率常数H(KD)^(1/2)在25℃时为0.136m/s。这一数值远大于研究人员过去观察到的数值。在25℃的温度下,N_2O_3的一次不可逆溶解和水解的吸收速率常数H(KD)^(1/2)为2.71m/s,而Komiyama在1982年报告中给出的在15℃时的数值为2.55m/s。

The kinetics of absorption of NO_2/N_2O_4 and of NO/NO_2/N_2O_3 from nitrogen diluent gas into 0.5 and 1.0 sodium hydroxide solutions at 25℃ have been studied experimentally. In those trials with NO_2 concentrations greater than 2×10^(-7)mol/cm^3 (0.45M), nitric oxide was observed to appear in the exit gas stream which suggests there may be an acidic layer present at the liquid surface. The absorption rate of NO_2 at these concentrations is proportional to the square of the NO_2 gas concentration confirming that N_2O_4 is the main dissolving and reacting species. A linear plot of 3NO formed against NO_2 absorbed indicates that virtually all the nitrous acid HNO_2 by N_2O_4 hydrolysis decomposes to nitric oxide and nitric acid which is strong evidence for the presence of an acidie liquid surface layer in the absorber. The absorption rate constant H KD^(1/2) for first order irreversible hydrolysis of N_2O_4 was found to be 0.136 m/s at 25℃ which is significantly larger than values observed by previous researchers. The absorption rate constant assuming first order irreversible dissolution and hydrolysis of N_2O_3 at 25℃ was found to be 2.71m/s for (H KD^(1/2)) N_2O_3, Komiyama (1982) reported a value of 2.55m/s at 15℃.