English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT
  Proton Mobility, Intrinsic Acid Strength, and Acid Site Location in Zeolites Revealed by Varying Temperature Infrared Spectroscopy and Density Functional Theory Studies

Losch, P., Joshi, H. R., Vozniuk, O., Grünert, A., Ochoa-Hernández, C., Jabraoui, H., et al. (2018). Proton Mobility, Intrinsic Acid Strength, and Acid Site Location in Zeolites Revealed by Varying Temperature Infrared Spectroscopy and Density Functional Theory Studies. Journal of the American Chemical Society, 140(50), 17790-17799. doi:10.1021/jacs.8b11588.

Item is

Basic

show hide
Genre: Journal Article

Files

show Files

Locators

show

Creators

show
hide
 Creators:
Losch, Pit1, Author           
Joshi, Hrishikesh R.2, Author           
Vozniuk, Olena2, Author           
Grünert, Anna2, Author           
Ochoa-Hernández, Cristina2, Author           
Jabraoui, Hicham3, Author
Badawi, Michael3, Author
Schmidt, Wolfgang1, Author           
Affiliations:
1Research Group Schmidt, Max-Planck-Institut für Kohlenforschung, Max Planck Society, ou_1445618              
2Research Department Schüth, Max-Planck-Institut für Kohlenforschung, Max Planck Society, ou_1445589              
3Laboratoire Physique et Chimie Théoriques, UMR 7019 CNRS-Université de Lorraine, Saint Avold 57500, France, ou_persistent22              

Content

show
hide
Free keywords: -
 Abstract: The intrinsic Brønsted acid strength in solid acids relates to the energy required to separate a proton from a conjugate base, for example a negatively charged zeolite framework. The reliable characterization of zeolites’ intrinsic acidity is fundamental to the understanding of acid catalysis and setting in relation solid Brønsted acids with their activity and selectivity. Here, we report an infrared spectroscopic study with partial isotopic deuterium exchange of a series of 15 different acidic aluminosilicate materials, including ZSM-5 zeolites with very few defects. Varying Temperature Infrared spectroscopy (VTIR) permitted estimating activation energies for proton diffusion. Two different proton transfer mechanisms have been distinguished for two different temperature ranges. Si-rich zeolites appeared to be promising proton-transfer materials (Eact. < 40 kJ mol–1) at temperatures above 150 °C (423 K). Further, a linear bathochromic shift of the Si–(OD)–Al stretching vibration as a function of temperature was observed. It can be assumed that this red-shift is related to the intrinsic O–(H/D) bond strength. This observation allowed the extrapolation and estimation of precise v(O–D)@0 K values, which could be attributed to distinct crystallographic locations through Density Functional Theory (DFT) calculations. The developed method was used to reliably determine the likelihood of the position of a proton in ZSM-5 zeolites under catalytically relevant conditions (T > 423 K), which has so far never been achieved by any other technique.

Details

show
hide
Language(s): eng - English
 Dates: 2018-11-062018-11-292018-12-19
 Publication Status: Published in print
 Pages: 10
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1021/jacs.8b11588
 Degree: -

Event

show

Legal Case

show

Project information

show

Source 1

show
hide
Title: Journal of the American Chemical Society
  Other : J. Am. Chem. Soc.
  Abbreviation : JACS
Source Genre: Journal
 Creator(s):
Affiliations:
Publ. Info: Washington, DC : American Chemical Society
Pages: - Volume / Issue: 140 (50) Sequence Number: - Start / End Page: 17790 - 17799 Identifier: ISSN: 0002-7863
CoNE: https://pure.mpg.de/cone/journals/resource/954925376870