Work

Characterization of Unmodified and Zinc-modified ZSM-5 Zeolites with Temperature-programmed Desorption of Ammonia and Isopropylamine

Year: 2025

Type: article

Abstract: While the temperature-programmed desorption of ammonia (NH 3 -TPD) is widely used to analyze the combined Lewis and Brønsted acidity of heterogeneous catalysts, the temperature-programmed desorption of isopropylamine (IPAm-TPD) can be used for the selective analysis of Brønsted acidity. This work compared NH 3 -TPD and IPAm-TPD as analysis methods for the acidity of zeolitic samples, including H-ZSM-5-23, H-ZSM-5-50, H-ZSM-5-280, a Zn-modified H-ZSM-5-50 sample, and a γ-Al 2 O 3 reference sample. For the unmodified H-ZSM-5-23, H-ZSM-5-50, and H-ZSM-5-280, the total acidity determined with NH 3 -TPD remained higher and the Brønsted acidity determined with IPAm-TPD lower than the theoretical acidity estimated with the Al content of the materials. When the NH 3 -TPD saturation temperature was varied for H-ZSM-5-50 to examine the trends observed in the analyses, the temperature change affected primarily the low temperature peak of the TPD traces. The Zn-modified Zn/H-ZSM-5-50 sample yielded a multi-peak IPAm-TPD trace, though only a single peak trace was expected. Additionally, the value of Brønsted acidity showed no change from the unmodified zeolite.

Source: Topics in Catalysis

DOI: 10.1007/s11244-025-02112-0

Authors: Ellen Järvinen, Jorge A. Velasco, Reetta Karinen, Riikka L. Puurunen

Institution: Aalto University

Language: English

Topic: Zeolite Catalysis and Synthesis

Subfield: Inorganic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,590

Funders: Aalto-Yliopisto, Business Finland