Adsorption of acetic acid and methanol on H-Beta zeolite: An experimental and theoretical study

The adsorption of acetic acid and methanol on H-Beta zeolite as a model of reaction of first step of the esterification reaction has been investigated with TGA-IR coupled, ATR-FTIR spectroscopy together with Density Functional Theory (DFT) calculations at M06–2X/6-31G(D) level. From the theoretical...

Full description

Saved in:
Bibliographic Details
Published in:Microporous and mesoporous materials 2017-11, Vol.252, p.17-28
Main Authors: Gomes, Glaucio J., Zalazar, M. Fernanda, Lindino, Cleber A., Scremin, Fernando R., Bittencourt, Paulo R.S., Costa, Michelle Budke, Peruchena, Nélida M.
Format: Article
Language:English
Subjects:
ATR-FTIR
Brønsted acid site
Combined TGA-IR
DFT
Green chemistry
Heterogeneous catalysis
Vibrational spectroscopy
Zeolites
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The adsorption of acetic acid and methanol on H-Beta zeolite as a model of reaction of first step of the esterification reaction has been investigated with TGA-IR coupled, ATR-FTIR spectroscopy together with Density Functional Theory (DFT) calculations at M06–2X/6-31G(D) level. From the theoretical viewpoint, different models of adsorption of acetic acid and methanol on the surface of H-Beta zeolite are studied. TGA-IR experiments show that both reactants are molecularly adsorbed on H-Beta, beyond 200 °C for methanol and 250 °C for acetic acid other species are also formed due to the surface reactivity being strongly adsorbed on the catalyst. Results from ATR-FTIR spectroscopy and theoretical calculations reveal that the predominant adsorption mode of acetic acid involves the ads_AA(CO) complex where the acetic acid is molecularly adsorbed by the carbonyl group on the Brønsted acid site of catalyst, and the OH group is oriented to the Al-O-Si bridge. The mechanism of adsorption of both acetic acid and methanol is also discussed at molecular level. The complexes where the acetic acid is adsorbed by the carbonyl group are clearly the most stable one. [Display omitted] •TGA-IR measurements show molecular adsorption of methanol and acetic acid on H-Beta.•Results from ATR-FTIR spectroscopy are supported by DFT calculations.•Adsorption of acetic acid on H-Beta occurs by carbonyl group on BAS.•DFT was applied to identify key elementary surface adsorption steps.
ISSN:1387-1811
1873-3093
DOI:10.1016/j.micromeso.2017.06.008