# Carbon Nanotube‐Supported Mo, Ni, and Co Nitrides as Stable Catalysts for Levulinic Acid Conversion: Influence of Metal–Nitrogen Interactions and Confinement Effects

## TL;DR

Researchers developed stable, non-precious metal catalysts using carbon nanotubes to convert levulinic acid, with nickel nitride showing the best performance.

## Contribution

The study introduces metal nitride catalysts supported on carbon nanotubes, emphasizing the role of metal-nitrogen interactions and confinement effects in catalytic performance.

## Key findings

- Ni3N/CNT catalyst shows highest activity due to hydrogenation-active sites on CNT surface.
- CNT support enhances Ni3N phase stability and maintains activity over multiple cycles.
- Metal-nitrogen bond strength influences particle size and acid site density.

## Abstract

Transition metal nitrides (MxNy, where M = Mo, Ni, or Co) supported on carbon nanotubes (CNTs) are synthesized and evaluated as catalysts for the conversion of levulinic acid at 250 °C and 50 bar H2. The catalysts are extensively characterized by N2 physisorption, XRD, TEM, FT–IR, H2‐TPR, NH3–TPD, 2‐propanol conversion, and XPS. Among the series, the Mo2N/CNT catalyst exhibits stronger metal–support interaction, smaller particle size, and more pronounced confinement within the CNT structure. This is attributed to the higher Mo–N bond strength compared to Ni–N and Co–N, which also influence the density and strength of surface acid sites. In contrast, the Ni3N/CNT catalyst displays the highest catalytic activity and is associated with smaller nitride particles located on the external CNT surface. The Co4N/CNT catalyst shows intermediate behavior. Product selectivity is primarily governed by the presence of surface nitride and oxynitride species, rather than the specific nature of the transition metal. These findings highlight the role of metal–support interactions and active phase dispersion in the design of stable, nonnoble metal catalysts for biomass‐derived platform molecule conversions.

Nitride‐phase catalysts (MxNy/CNT) are active in levulinic acid conversions. Ni3N/CNT shows the best performance due to hydrogenation‐active sites within and on the surface of CNT graphene layers. The CNT support also enhances the Ni3N phase stability, maintaining catalytic activity over multiple recycling tests.© 2025 WILEY‐VCH GmbH