稻壳活性炭对噻吩类硫化物的吸附

Adsorption of thiophenic sulfur compounds on rice husk-based activated carbon

以稻壳为原料、采用KOH浸渍和高温活化法制备稻壳活性炭,研究其对模拟油中噻吩类硫化物的吸附脱除性能,利用环己烯、甲苯为竞争组分,研究燃油中烯烃、芳烃对稻壳活性炭吸附脱硫性能的影响。通过静态吸附实验分别考察炭化温度、KOH浸渍质量分数及活化温度对稻壳活性炭吸附脱硫性能的影响,从而确定最佳制备条件。采用Langmuir和Freundlich吸附模型对稻壳活性炭的吸附噻吩进行拟合,用准n阶和修正准n阶动力学模型进行分析。采用热重(TG)、N_2吸附/脱附(BET)、扫描电镜(SEM)对样品表征,考察其受热分解状况、孔隙结构、表面形貌等特性。结果表明:在最佳制备条件下,制备的稻壳活性炭比表面积和平均孔径分别为1 207.649 m^2·g^(-1)和2.24 nm。用固定床进行动态吸附实验,得到稻壳活性炭对噻吩类硫化物的总穿透硫容为7.092 4 mg·g^(-1)。在模拟油中加入环己烯、甲苯后,稻壳活性炭对噻吩类硫化物的穿透硫容分别下降了36.4%和63.5%,由等温吸附和动力学模拟分析得实验数据很好的符合Langmuir和修正的准n阶动力学吸附模型。

Rice husk-based activated carbon was prepared by KOH impregnation and high temperature activation. The adsorption of thiophenic sulfur compounds from gasoline（ used as a model） was investigated. Cyclohexene and methylbenzene were used as competing components,and the effect of alkene and arene on the adsorption properties were studied on the rice husk-based activated carbon. Various factors influencing adsorption capacity,such as carbonization temperature,soaked mass fraction of KOH,and activation temperature were investigated through static adsorption,and then the optimum preparation conditions ascertained. Langmuir and Freundlich adsorption models and adsorption kinetic models were used to fit the test results. The rice husk-based activated carbon was characterized by thermal analysis（ TG）,nitrogen sorption（ BET） and scanning electron microscopy（ SEM）,and its thermal decomposition conditions,pore structure,and surface area were discussed. The results indicated that the specific surface area and average pore diameter of rice husk-based activated carbon were1 207. 649 m2·g-1and 2. 24 nm,respectively. The total breakthrough capacity of sulfur through fixed bed dynamic adsorption was 7. 092 4 mg·g-1. The adsorption breakthrough capacity of sulfur decreased by 36. 4% and63. 5%,for cyclohexene and toluene,respectively. The experimental results agreed well with a Langmuir and pseudo-n-order modified adsorption kinetics model.