An efficient approach to explore the adsorption of benzene and phenol on nanostructured catalysts: a DFT analysis

• Published in: RSC advances 2015-01, Vol.5 (122), p.100799-100808
• Main Authors: Javadian, Soheila, Ektefa, Fatemeh
• Format: Article
• Language: English
• Subjects: Adsorption; Benzene; Catalysts; Chemical bonds; Hydrogen bonding; Hydrogen bonds; Mathematical models; Phenol
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/C5RA20657J

Adsorption of benzene and phenol on the 8T cluster model of ZSM-5 and Al-ZSM-5 catalysts, defined as ((H) 3 SiO) 3 –Si–O–Si–(OSi(H) 3 ) 3 and ((H) 3 SiO) 3 –Si–O(H)–Al–(OSi(H) 3 ) 3 structures, respectively, has been investigated comparatively using B3LYP, M06-2X, and wB97XD functionals employing the 6-311++G** standard basis set. Geometric parameters predict one and two types of hydrogen bonding in the guest-ZSM-5 and guest-Al-ZSM-5 complexes, respectively. Variations of adsorption energy, isotropic chemical shifts, δ iso , of 1 H, 17 O, 27 Al, and 29 Si atoms contributing in the hydrogen bonding as well as quadrupole coupling constant, C Q , and asymmetry parameter, η Q , of 2 H, 17 O, and 27 Al atoms have been well correlated with the strength of the hydrogen bonds. Atom in molecules (AIM) calculations showed a covalent nature for the hydrogen bonds in the phenol⋯Al-ZSM-5 adsorption complex. Furthermore, based on AIM, NQR and NMR, the C–H⋯O and O–H⋯π hydrogen bonds have been confirmed in the benzene adsorbate zeolite, which may highlight a crucial feature of the adsorption of benzene molecules inside the pores of zeolites. The differences in the adsorption behavior between benzene and phenol on the ZSM-5 and Al-ZSM-5 are attributed to the differences in the strength of the hydrogen bonding interactions. Finally, Al-ZSM-5 appears to be an efficient adsorbent for phenol and benzene.