杂原子介孔Ce-MCM-41分子筛的制备及其吸附脱除甲硫醚性能

以十六烷基三甲基溴化铵为模板剂,正硅酸乙酯(TEOS)为硅源,硝酸铈为铈源,采用水热法合成了杂原子介孔分子筛Ce-MCM-41。XRD和FT-IR表征结果表明,当加入的Ce/Si物质的量比小于0.04时合成了规整有序的介孔结构,并将Ce原子引入到MCM-41骨架中。N₂吸附-脱附测试获得MCM-41和Ce-MCM-41(Ce/Si物质的量比为0.04)的平均孔径分别为2.82和2.46 nm,孔容分别为0.762 1和 0.689 4 m³/g,BET比表面积分别为986.42和756.8 m²/g。NH₃-TPD表征结果表明,Ce-MCM-41的酸性要明显强于MCM-41,但两种分子筛的酸性均较弱。利用合成的MCM-41和Ce-MCM-41吸附脱除甲硫醚浓度为58 μg(甲硫醚)/g的甲硫醚/氮气混合气中的甲硫醚。甲硫醚分子尺寸的模拟结果为0.464 8 nm,可以很容易地进入分子筛的介孔孔道中。由于Ce-MCM-41分子筛具有较多的酸量,其硫吸附容量7.52 mg(S)/g明显高于MCM-41的4.57 mg(S)/g。MCM-41和Ce-MCM-41都具有较好的再生性能,再生3次后硫吸附容量仍可恢复到初始容量的80%,分别为3.52和 5.86 mg(S)/g。

Preparation of heteroatomic mesoporous Ce-MCM-41 molecular sieve and its performance in the adsorptive removal of dimethyl sulfide

Heteroatomic mesoporous Ce-MCM-41 molecular sieve was synthesized by using hydrothermal synthesis method with cetyltrimethy ammonium bromide (CTMABr) as template, cerium chloride as cerium source and sodium silicate as silica source. X-ray diffraction (XRD) and infrared spectrum (FT-IR) results indicate that the well-ordered meso-porous structure was obtained when the Ce/Si molar ratio is less than 0.04; Ce was incorporated into the framework of MCM-41. Nitrogen physisorption measurements indicate that the average pore diameters of MCM-41 and Ce-MCM-41 are 2.82 and 2.46 nm, with pore volumes of 0.762 1 and 0.689 4 m³/g and BET surface areas of 986.42 and 756.8 m²/g, respectively. Dimethyl sulfide with a molecular size of 0.464 8 nm can easily enter the meso-scale pores of MCM-41 and Ce-MCM-41. NH₃-TPD results illustrate that the acidity of Ce-MCM-41 is stronger than that of MCM-41. As a result, for the adsorptive removal of dimethyl sulfide from nitrogen with a dimethyl sulfide content of 58 μg/g, the desulfurization capacity of Ce-MCM-41 is 7.52 mg(S)/g, higher than that of MCM-41 (4.57 mg(S)/g). Furthermore, both MCM-41 and Ce-MCM-41 molecular sieves could be easily regenerated after adsorption of dimethyl sulfide; the desulfurization capacity can be recovered up to 80% of the original capacity after regenerated for three times.