Work

NOx decomposition through seaweed biocarbon as biosourced catalyst: Experimental and density functional theory approaches

Year: 2026

Type: article

Abstract: Understanding the NOx abatement and deactivation mechanisms is essential to improve the performance and regeneration of bio-based catalysts. In this study, biocarbon obtained from marine algae (SW), rich in nitrogen and minerals, was used as a biosourced catalyst for the decomposition of a flux of 1021 ppm of NO in argon (deNOx). Several parameters were studied, including pyrolysis temperature (650 and 800 °C) and deNOx operating temperature (200, 350, and 500 °C). Additionally, a theoretical study using density functional theory (DFT) calculations investigated the role of nitrogen and catalytic (Fe) or promoter (K) elements and functional groups (O-groups) in NO adsorption. The results indicated that the bio-based catalyst produced at 800 °C (SW800) achieved the highest conversion rate of 22.5 ± 1% at 350 °C compared to the catalyst produced at 650 °C (SW650), which achieved a conversion rate of 15.6 ± 1%. This result is attributed to the higher mineral content (52.99 wt%, db) of the SW800 catalyst rather than its specific surface area, which was not identified as a discriminating parameter under the studied conditions. Regarding the reaction mechanism, nitrogen and oxygen atomic balances confirm the multistep decomposition hypothesis. Furthermore, the slight increase in lactone and carbonyl groups after the deNOx process suggests that oxygen remains on the biocarbon. This contributes to reduce active sites and to deactivate the biocarbon catalyst, as observed. Coke deposition on active sites and metal sintering can also contribute to deactivation. Based on the calculations on representative nitrogen-rich biocarbon structures, the adsorption energies (E ads ) on pyridinic N (−71.10 kJ mol −1 ) and pyrrolic N (−69.30 kJ mol −1 ) sites are high, demonstrating their roles in NO abatement. However, the presence of an oxygen group close to a nitrogen site inhibits NO adsorption due to its high electronegativity. This information is in agreement with the deactivation of nitrogen sites by residual oxygen from NO decomposition, as observed experimentally. • Seaweed biocarbon catalysts rich in nitrogen and minerals are used for NOx abatement. • The non-N 2 and O 2 stoichiometric ratio in gas products suggests catalytic decomposition. • Partial biocarbon decomposition is assumed due to CO emission during deNOx at 500 °C. • N-adsorption sites are more favorable to NO adsorption than the graphitic carbon ones. • The presence of an oxygen group close to a nitrogen site inhibits NO adsorption.

Source: Journal of Environmental Management

DOI: 10.1016/j.jenvman.2026.128992

Authors: Ronan Pelé, María González Martínez, Ange Nzihou

Institutions: Centre National de la Recherche Scientifique, IMT Mines Albi, Centre de Recherche d'Albi en génie des Procédés, des SOlides Divisés, de l'Énergie et de l'Environnement, Université de Toulouse, Princeton University

Language: English

Topic: Industrial Gas Emission Control

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

SDGs: Responsible consumption and production, Affordable and clean energy, Climate action

Open Access status: hybrid

Estimated APC paid: $3,750