Adsorption of unsaturated hydrocarbons on zeolites: the effects of the zeolite framework on adsorption properties of ethylene

Density functional theory study of the ethylene epoxidation over Ti-substituted silicalite (TS-1)

“…Furthermore, all of these studies used the cluster models to represent the reactive center and thus did not include the effects of the zeolite framework. In our previous study, we found that the Madelung potential from the zeolite framework can increase the adsorption energy of ethylene in H-ZSM-5 zeolite by about 50% and bring the predicted results in much closer agreement with experimental observations [22]. This indicates that the Madelung potential could be an important factor in stabilizing the adsorption complexes and transition states for the ethylene epoxidation over TS-1 catalyst.…”

“…SCREEP embedded cluster model for studying adsorption or reaction in zeolites. several previous studies [22,[26][27][28][29][30][31]. These models consist of three layers.…”

“…The surface charge representation of the external embedded potential (SCREEP) embedded cluster methodology was used. This method has been found to be rather accurate in representing the Madelung potential for studying adsorptions and reactions in zeolites [22,[26][27][28][29][30][31].…”

Alkylation of benzene with ethylene over faujasite zeolite investigated by the ONIOM method

“…Neglecting the extended framework effect has been shown to lead to discrepancies between the cluster results and the actual zeolite behaviors [21,22]. The recent development of hybrid methods, such as embedded cluster or combined quantum mechanics/molecular mechanics (QM/MM) [14,15,[21][22][23][24][25] methods, as well as the more general ONIOM (Our-own-N-layer Integrated molecular Orbital + molecular Mechanics) method [26,27] has brought a larger system within reach of obtaining accurate results.…”

Adsorptive removal of halo-olefinic impurities from 1,1,1,3,3-pentafluoropropane over ion-exchanged Y zeolites

“…It has been reported that the double bond of the olefin can form p-complexes with some transition metal cations such as Cu + and Ag + , and a difference in adsorption affinity between olefin and alkane can be achieved [17,18]. HCFC-1233zd can also [13,15,16,19,20]. It is well known that Brønsted acid sites are generated via the hydrolysis of water molecules associated to the multivalent metal cations in the zeolite [12,21].…”