Interpretation of H2-TPR from Cu-CHA Using First-Principles Calculations
Artikel i vetenskaplig tidskrift, 2024

Temperature-programmed reduction and oxidation are used to obtain information on the presence and abundance of different species in complex catalytic materials. The interpretation of the temperature-programmed reaction profiles is, however, often challenging. One example is H2 temperature-programmed reduction (H2-TPR) of Cu-chabazite (Cu-CHA), which is a material used for ammonia assisted selective catalytic reduction of NOx (NH3-SCR). The TPR profiles of Cu-CHA consist generally of three main peaks. A peak at 220 °C is commonly assigned to ZCuOH, whereas peaks at 360 and 500 °C generally are assigned to Z2Cu, where Z represents an Al site. Here, we analyze H2-TPR over Cu-CHA by density functional theory calculations, microkinetic modeling, and TPR measurements of samples pretreated to have a dominant Cu species. We find that H2 can react with Cu ions in oxidation state +2, whereas adsorption on Cu ions in +1 is endothermic. Kinetic modeling of the TPR profiles suggests that the 220 °C peak can be assigned to Z2CuOCu and ZCuOH, whereas the peaks at higher temperatures can be assigned to paired Z2Cu and Z2CuHOOHCu species (360 °C) or paired Z2Cu and Z2CuOOCu (500 °C). The results are in good agreement with the experiments and facilitate the interpretation of future TPR experiments.

Författare

Joachim Bjerregaard

Chalmers, Fysik, Kemisk fysik

Joonsoo Han

Chalmers, Kemi och kemiteknik, Kemiteknik

Derek Claude Creaser

Chalmers, Kemi och kemiteknik, Kemiteknik

Louise Olsson

Chalmers, Kemi och kemiteknik, Kemiteknik

Henrik Grönbeck

Chalmers, Fysik, Kemisk fysik

Journal of Physical Chemistry C

1932-7447 (ISSN) 1932-7455 (eISSN)

Vol. 128 11 4525-4534

Cu-CHA zeolite-based catalysts for the selective catalytic reduction of NOx in exhaust diesel gas: addressing the issue of Sulfur Stability (CHASS)

Europeiska kommissionen (EU) (EC/H2020/955839), 2021-06-01 -- 2025-05-31.

Ämneskategorier

Oorganisk kemi

Fysikalisk kemi

Materialkemi

Organisk kemi

DOI

10.1021/acs.jpcc.3c07998

Mer information

Senast uppdaterat

2024-04-04