A combined DFT and FT-IR study on the surface interactions in alumina supported ionic liquid [H-Pyr]+[HSO4]

Ivaylo Tankov; Rumyana Yankova

doi:10.1016/j.saa.2019.117545

A combined DFT and FT-IR study on the surface interactions in alumina supported ionic liquid [H-Pyr]⁺[HSO₄]

Spectrochim Acta A Mol Biomol Spectrosc. 2020 Feb 5:226:117545. doi: 10.1016/j.saa.2019.117545. Epub 2019 Oct 14.

Authors

Ivaylo Tankov¹, Rumyana Yankova²

Affiliations

¹ University "Prof. Dr. Assen Zlatarov" Burgas, 8010, Bulgaria.
² University "Prof. Dr. Assen Zlatarov" Burgas, 8010, Bulgaria. Electronic address: r_iankova@yahoo.com.

PMID: 31710889
DOI: 10.1016/j.saa.2019.117545

Abstract

The surface interactions in [H-Pyr]⁺[HSO₄]^-/γ-Al₂O₃ system (prepared by wetness impregnation method) are investigated theoretically and experimentally. For that purpose, atoms in molecules theory, natural bond orbital and natural charge population analyses in a combination with a vibrational spectroscopy (FT-IR) are used. It is established that a bond formation between the hydrogen sulfate anion and the alumina influences the IL-support interaction in a great extent. However, a support-cation and a cation-anion interaction in the immobilized [H-Pyr]⁺[HSO₄]^- present as well. A comparative analysis between the experimental and the calculated vibrational modes is carried out and a significant number of infrared bands are assigned. The results indicate a good correlation between the experimental and the theoretical IR frequencies. It is found that the aforementioned interactions affected the vibrational frequencies in the supported IL.

Keywords: Alumina carrier; DFT analysis; Infrared spectroscopy; Ionic liquids.