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PRINCIPAL PUBLICATION AND AUTHORS

From Lab to Technical CO2 Hydrogenation Catalysts: Understanding PdZn Decomposition, P. Ticali (a), D Salusso (a), A. Airi (a), S. Morandi (a), E. Borfecchia (a), A. Ramirez (b), T. Cordero-Lanzac (c), J. Gascon (b), U. Olsbye (c). F. Joensen (d), S. Bordiga (a), ACS Appl. Mater. Interfaces 15, 5218-5228 (2023); https:/doi.org/10.1021/acsami.2c19357 (a) Department of Chemistry, NIS Center and INSTM Reference Center, University of Turin (Italy) (b) King Abdullah University of Science and Technology, Thuwal (Saudi Arabia) (c) SMN Centre for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, Oslo (Norway) (d) Haldor Topsøe, A/S Kongens Lyngby (Denmark)

REFERENCES

[1] A. Ramirez et al., JACS Au 1, 1719-1732 (2021).

X-rays reveal challenges in scaling up a catalyst for CO2 hydrogenation to propane

The valorisation of CO2 to produce high-value chemicals such as methanol and hydrocarbons represents key technology for a future net-zero society. X-ray absorption spectroscopy was used to investigate a scaled-up PdZn/ZrO2 + SAPO-34 catalyst for conversion of CO2 and H2 into propane.

The catalyst PdZn/ZrO2 + SAPO-34 has been previously studied for the conversion of CO2 into propane [1]. The focus of this work was to investigate if scaled-up versions of this catalyst were able to maintain the same performances as the lab-scale catalyst, considering the different preparation, which included an alumina phase as a binder to obtain tablets and extrudates.

Using X-ray absorption spectroscopy at beamline BM31, with the support of Fourier transform-infrared characterisation (Figure 131), the catalyst was shown

to exhibit inferior performances to the lab-scale and physical mixture used as references. The physical mixture featured the presence of a PdZn alloy that was missing in both tablets and extrudates. Instead, tablets and extrudates showed the formation of Zn islands upon reduction and partial migration of Zn from the oxidic phase to the alumina binder, highlighted by the formation of Zn aluminates. The extruded catalyst showed a higher amount of Zn aluminates and showed the presence of metallic Pd, potentially leading to catalyst deactivation.

The findings were consistent with catalytic results, highlighting the impact of Zn aluminate formation and metallic Pd separation from the alloy on catalytic activity, with tablets showing reduced methanol conversion, due to partial deactivation of the SAPO-34, and extrudates exhibiting high methane selectivity and unconverted methanol, related to the presence of metallic Pd, maybe anchored on Zn islands. These insights shed light on critical points that could emerge during the development of catalysts for net-zero industrial applications.

Fig. 131: X-ray absorption spectroscopy and Fourier transform-infrared characterisation was used to investigate a PdZn/ZrO2 + SAPO-34 catalyst for conversion of CO2 and H2 into propane.