溴素改性活性炭汞吸附特性研究

Studies on Mercury Adsorption on Bromine Modified Activated Carbon

在固定床实验台上进行了1%NH_4Br改性活性炭汞吸附实验。利用吸附动力学模型从动力学角度探讨了汞吸附速率控制步,汞吸附活化能与初始汞吸附速率。结果表明:150℃时,1%NH_4Br改性活性炭脱汞能力显著增强,其原因是改性后活性炭表面活性位点(Br)明显增加,强化了化学吸附作用。但低温时,化学吸附增强作用不明显。汞在改性活性炭表面的吸附活化能为29.69 kJ/mol,说明吸附以物理吸附为主,化学吸附为辅。改性活性炭的初始汞吸附速率随温度增加而增加。活性位吸附是汞吸附速率控制步,外部传质控制也影响整个汞吸附过程,吸附遵循Langmuir吸附等温方程。

An experimental study on mercury adsorption of 1%NH_4Br modified activated carbon was carried out in a fixed-bed reactor.Adsorption kinetic models were used to investigate mercury adsorption rate controlling step,adsorption activation energy and initial mercury adsorption rate from the kinetic point of view.The results show that mercury adsorption capacity of modified activated carbon increases significantly at 150℃ due to addition of active site(Br) on activated carbon surface,which improves chemisorption.However,performance of chemisorption at low flue gas temperature is not dominant.The activation energy of mercury adsorption on modified activated carbon surface is 29.69 kJ/mol,which illustrates that mercury adsorption is mainly physisorption but enhanced by chemisorption.The initial mercury adsorption rate of modified activated carbon increases with temperature elevation.Mercury adsorption on active sites is the adsorption rate controlling step and external mass transfer also plays an important role.Mercury adsorption on modified activated carbon follows the Langmuir isotherm equation.