载溴石油焦脱除烟气痕量Hg^0的动力学机理

Kinetic mechanism of brominated petroleum coke for trace Hg^0 removal from flue gas

采用化学-机械溴化法对废弃物石油焦进行改性,制得的载溴石油焦吸附剂用来脱除燃煤烟气中的痕量Hg^0.通过比表面积及孔径分析(BET)、X射线衍射(XRD)和X-射线光电子能谱(XPS)对石油焦载溴前后进行表征和分析,发现石油焦中的有机硫促进了溴的负载,且负载方式为化学吸附.通过固定床脱汞试验,并应用4种动力学模型对初始汞浓度梯度和反应温度梯度下的实验数据进行拟合分析,结果表明:温度在150℃时,载溴石油焦的汞吸附效果最优;增加烟气中痕量Hg^0浓度能提高载溴石油焦的汞吸附速率和单位累积汞吸附量;描述化学吸附的Elovich动力学模型的拟合相关系数达到0.9999以上,说明化学吸附在载溴石油焦脱汞过程中起主导作用.

Petroleum coke,a waste by-product of petroleum refining,brominated by chemical-mechanical bromination process,was used to remove trace Hg0 from flue gas.Specific surface area and pore size analyzer(BET),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS)analysis indicated that the inherent organic sulfur enhanced bromine chemisorption on petroleum coke surface.Four kinetic models were conducted to study the brominated petroleum coke for elemental mercury capture in a fixed bed system simulation test.The results show that the adsorption rate and mercury accumulating quantity are increasing when the temperature set at 150℃and the inlet mercury concentration increased;The model fitting correlation coefficient of Elovich model which based on chemisorption reaches above 0.9999,indicating the mercury adsorption process of brominated petroleum coke is controlled dominantly by chemisorption.