均相系统中汞的氧化实验与热力学平衡计算

EXPERIMENTS AND THERMODYNAMIC EQUILIBRIUM OF HOMOGENOUS OXIDATION OF MERCURY

本文采用水平管式电加热炉,使一定浓度的单质汞蒸气和各种反应气体的混合气在石英管反应器内发生氧化反应,研究了二价汞的生成比例。实验结果表明HCl对汞的氧化能力在473～873 K区间很低,而Cl_2对汞有很强的氧化能力。通过热力学计算对生成的二价汞的具体种类进行推断,还考查了气氛中H_2O的存在对汞氧化的影响,计算结果和实验结果基本相符。结果表明,Cl_2是汞氧化的重要因素,生成HgCl_2(g)。HCl对汞的氧化几乎不起作用。Cl_2和H_2O可能发生反应生成对汞氧化能力低的HCl,从而使汞氧化温度区域向低温转移。

Mercury vapor and some other gases were mixed and passed through a quartz tube reactor which was heated by a horizontal electrical tube furnace. In which mercury was oxidized by gas oxidizers, the fraction of oxidized mercury was sampled, measured and analyzed. It suggests that HCl is a very weak oxidizer of mercury in the temperature window of 473-873 K, while Cl2 is a very strong one. The thermodynamic equilibrium was used as a tool to determine what the oxidized mercury is and to evaluate how much the H2O in the reactants can affect the oxidation of mercury. The results of the equilibrium calculation shows nearly the same trend as the experimental results shows. Meanwhile, it is possible that Cl2 can react with H2O and some Cl2 is transformed into HCl which has much lower oxidation ability than Cl2, so the temperture window of mercury oxidation by Cl2 with H2O moves to lower temperure than that without H2O. Key words mercury; homogenous oxidation; thermodynamic equilibrium