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.