Abstract: The role and effect of simulated flue gas on adsorption of elemental mercury (Hg⁰)on coconut shell activated carbon (CS-AC)were studied by adsorption experiment carried out at 130℃ in a bench-scale fixed bed to reveal the characteristics of homogeneous/heterogeneous oxidation reaction between components of simulated flue gas，Hg⁰ and CS-AS surface.The experiments were divided into three parts：first，adsorption of Hg⁰ on surface of CS-AC in nitrogen (N₂)gas and simulated flue gas; second，homogeneous oxidation reaction between the components of simulated flue gas and Hg⁰; and third，adsorption of Hg⁰ in N₂ gas on surface of CS-AC pre-adsorbed by simulated flue gas.The results showed that CS-AC can not adsorb Hg⁰ in N₂ gas，however，it became easy in simulated flue gas and the initial adsorption efficiency was up to 80%.According to the result of homogeneous reaction between the simulated flue gas and Hg⁰ at the temperature of 130℃，only about 14% of Hg⁰ can be oxidized to divalent mercury (Hg²⁺)which is easily adsorbed by CS-AC，which was much lower than 80% of initial Hg⁰ adsorption efficiency in the simulated flue gas.This result could indicate that homogeneous reaction between simulated flue gas and Hg⁰ was not the main reason of high Hg⁰ adsorption efficiency.It was very interesting that in N₂ gas Hg⁰ could be adsorbed by CS-AC if it was pre-treated with simulated flue gas without Hg⁰.The pre-adsorption process of simulated flue gas could fix some components in flue gas，such as NO_x，etc.，on surface of CS-AC，and these components would help adsorption of Hg⁰ in N₂ gas，and the initial adsorption efficiency was about 67%.During the oxidation adsorption process，surface of CS-AC played important role.Therefore，it could be thought that the adsorption process of Hg⁰ by CS-AC is a heterogeneous chemical oxidation reaction and adsorption process between oxidizing components in flue gas，element mercury Hg⁰ and the CS-AC’s surface，whatever in N₂ gas or in simulated flue gas.

Key words: activated carbon；elemental mercury；chemical adsorption, heterogeneous reaction

摘要： 通过固定床吸附实验，在130℃温度下模拟研究燃煤烟气组分在椰壳活性炭(CS-AC)表面吸附气态元素汞(Hg⁰)过程中的作用与影响，揭示模拟烟气组分、Hg⁰以及活性炭表面三者间的均相、异相氧化反应特性。实验研究了CS-AC在N₂和模拟烟气气氛下对Hg⁰的吸附，模拟烟气组分与Hg⁰间的均相氧化反应，以及吸附模拟烟气组分后CS-AC在N₂气氛下对Hg⁰的吸附。研究表明在N₂气氛下CS-AC对Hg⁰不具备物理吸附的能力，而在模拟烟气组分下CS-AC对Hg⁰具有较强的吸附能力，初始吸附效率达80%。仅在模拟烟气均相反应作用下，大约只有14%的Hg⁰被氧化为Hg²⁺。经过预先跟常规模拟烟气吸附反应，CS-AC表面具备一定氧化性化学元素基团（如NO_x）后，能够在N₂气氛下对Hg⁰进行化学吸附，初始吸附效率达67%左右。可以认为模拟烟气和Hg⁰两者间的均相作用不是促进CS-AC在模拟烟气组分下对Hg⁰具有较强的吸附能力的主因。活性炭吸附Hg⁰的过程中，活性炭表面在烟气组分氧化Hg⁰的过程中起到了积极的促进作用。无论在N₂气氛下，还是在模拟烟气下，CS-AC吸附Hg⁰是气氛中氧化性组分、Hg⁰和活性炭表面三者间的异相化学氧化吸附反应过程。

关键词: 活性炭, 元素汞, 化学吸附, 异相反应