Effects of hydrogen transport on the kinetic regimes of 4-nitrophenol reduction by sodium borohydride

Nizkaia T, Groppe P, Müller V, Harting J, Wintzheimer S, Malgaretti P (2026)

Publication Type: Journal article

Publication year: 2026

Journal

Catalysis: Science and Technology Royal Society of Chemistry

DOI: 10.1039/d5cy01411e

Abstract

The reduction of 4-nitrophenol (4-NiP) by sodium borohydride is widely used to benchmark heterogeneous catalysts and is commonly simplified as a pseudo-first-order reaction, characterized by a single reaction rate constant. In reality, this reaction is more complex, as it is accompanied by hydrolysis of borohydride and concurrent hydrogenation of 4-NiP by produced hydrogen. This makes the local hydrogen concentration at catalytic sites an important, and so far overlooked, factor in shaping the apparent catalytic activity of heterogeneous catalysts. Re-examining benchmarking experiments on Pt–SiO2 supraparticles with different pore structures, we attribute contrasting kinetic behavior to distinct regimes of hydrogen transport: diffusive transport sustains high local concentrations of hydrogen and pseudo-first-order kinetics of 4-NiP hydrogenation, while bubble-mediated escape causes hydrogen loss, deviations from pseudo-first-order regime and incomplete conversion of 4-NiP. We propose a kinetic model that captures this transition and enables consistent interpretation of experimental data. More broadly, our analysis shows that apparent differences in activity observed in benchmarking experiments that use 4-NiP reduction by borohydride as a test reaction, can arise from hydrogen transport rather than intrinsic properties of the catalyst. This highlights the need to account for the hydrogen transport regime (bubbling/non-bubbling), when comparing catalyst performance across different experiments.

Authors with CRIS profile

Philipp Groppe Professur für Anorganische Chemie Valentin Müller Lehrstuhl für Partikelbasierte Materialchemie Susanne Wintzheimer Professur für Anorganische Chemie

Involved external institutions

Forschungszentrum Jülich / Research Centre Jülich (FZJ) DE Germany (DE)

How to cite

APA:

Nizkaia, T., Groppe, P., Müller, V., Harting, J., Wintzheimer, S., & Malgaretti, P. (2026). Effects of hydrogen transport on the kinetic regimes of 4-nitrophenol reduction by sodium borohydride. Catalysis: Science and Technology. https://doi.org/10.1039/d5cy01411e

MLA:

Nizkaia, Tatiana, et al. "Effects of hydrogen transport on the kinetic regimes of 4-nitrophenol reduction by sodium borohydride." Catalysis: Science and Technology (2026).

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