杂原子介孔MCM-41分子筛的制备及其对含喹啉模拟柴油的吸附脱氮性能

制备了介孔MCM-41分子筛和三种杂原子(Zn、Ba和Ce)介孔MCM-41分子筛,通过X射线衍射(XRD)、红外光谱(FT-IR)、低温N_2吸附-脱附等手段对其进行表征,研究了几种介孔分子筛对氮含量为1732μg/g含喹啉模拟柴油的吸附脱氮性能。结果表明,所制备的几种分子筛均具有典型的介孔结构,且杂原子已进入到分子筛骨架中。利用Materials Studio软件构建介孔分子筛模型,模拟的XRD谱图与实验结果基本相符;进一步模拟了喹啉分子在杂原子介孔分子筛团簇上的吸附,计算了吸附能及被吸附分子和吸附中心的距离(d_((N-M)))。几种分子筛的吸附脱氮性能顺序依次为Zn-MCM-41 Ce-MCM-41 Ba-MCM-41 MCM-41;Zn-MCM-41的吸附性能最好,吸附能最大,吸附分子和吸附中心的距离d_((N-M))最小。吸附时间对杂原子介孔分子筛的吸附脱氮性能具有较大影响,而吸附温度的影响相对较小;Zn-MCM-41、Ba-MCM-41和Ce-MCM-41分子筛的最佳吸附时间分别为40、10和30 min,最佳吸附温度分别为40、30和40℃。

Preparation of heteroatom-containing mesoporous MCM-41 molecular sieves and their performance in the adsorption denitrification of quinoline in model diesel oil

The mesoporous MCM-41 molecular sieve and heteroatom (Zn, Ba, and Ce) containing mesoporous MCM-41 molecular sieves were synthesized and characterized by X-ray diffraction (XRD), FT-infrared spectroscopy (FT-IR) and N₂ sorption; their performance in the adsorption denitrification of quinoline in model diesel oil was investigated. The results indicate that all the synthesized molecular sieves take typical mesoporous structure and heteroatoms are successfully incorporated into the molecular sieves framework. An 8T cluster model for the MCM-41 molecular sieves was built by using the Materials Studio software; the simulated XRD spectrum is basically consistent with the experimental spectrum, proving the accuracy of cluster model. The adsorption of quinoline on the heteroatom-containing mesoporous MCM-41 molecular sieves were then simulated and the adsorption energy and the distance between the adsorbed molecule and the adsorption center (d_(N-M)) were calculated. The results suggest that the adsorption denitrification performance of various molecular sieves follows the order of Zn-MCM-41 > Ce-MCM-41 > Ba-MCM-41 > MCM-41; that is, Zn-MCM-41 exhibits the best adsorption denitrification performance, with the highest adsorption energy and shortest distance between the adsorption molecule and the adsorption center. Moreover, the adsorption time has a significant influence on the denitrification efficiency, whereas the effect of adsorption temperature is relatively minor; the optimal adsorption times for Zn-MCM-41, Ba-MCM-41 and Ce-MCM-41 are 40, 10 and 30 min, respectively, whereas the optimal adsorption temperatures for three molecular sieves are 40, 30 and 40℃, respectively.