Low-temperature NH3-SCR performance of a novel Chlorella@Mn composite denitrification catalyst

Hengheng Liu; Fengyu Gao; Songjin Ko; Ning Luo; Xiaolong Tang; Erhong Duan; Honghong Yi; Yuansong Zhou

doi:10.1016/j.jes.2022.12.010

Low-temperature NH₃-SCR performance of a novel Chlorella@Mn composite denitrification catalyst

J Environ Sci (China). 2024 Mar:137:271-286. doi: 10.1016/j.jes.2022.12.010. Epub 2022 Dec 20.

Authors

Hengheng Liu¹, Fengyu Gao², Songjin Ko³, Ning Luo¹, Xiaolong Tang⁴, Erhong Duan⁵, Honghong Yi², Yuansong Zhou²

Affiliations

¹ School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China.
² School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China.
³ School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China; Department of Chemistry, Pyongyang University of Architecture, Pyongyang, Democratic People's Republic of Korea.
⁴ School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China. Electronic address: txiaolong@126.com.
⁵ School of Environmental Science and Engineering, University of Science and Technology Hebei, Hebei 050018, China.

PMID: 37980014
DOI: 10.1016/j.jes.2022.12.010

Abstract

The synthesis process of conventional Mn-based denitrification catalysts is relatively complex and expensive. In this paper, a resource application of chlorella was proposed, and a Chlorella@Mn composite denitrification catalyst was innovatively synthesized by electrostatic interaction. The Chlorella@Mn composite denitrification catalyst prepared under the optimal conditions (0.54 g/L Mn²⁺ concentration, 20 million chlorellas/mL concentration, 450°C calcination temperature) exhibited a well-developed pore structure and large specific surface area (122 m²/g). Compared with MnOx alone, the Chlorella@Mn composite catalyst achieved superior performance, with ∼100% NH₃ selective catalytic reduction (NH₃-SCR) denitrification activity at 100-225°C. The results of NH₃ temperature-programmed desorption (NH₃-TPD) and H₂ temperature-programmed reduction (H₂-TPR) showed that the catalyst had strong acid sites and good redox properties. Zeta potential testing showed that the electronegativity of the chlorella cell surface could be used to enrich with Mn²⁺. X-ray photoelectron spectroscopy (XPS) confirmed that Chlorella@Mn had a high content of Mn³⁺ and surface chemisorbed oxygen. In-situ diffuse reflectance infrared Fourier transform spectroscopy (in-situ DRIFTS) experimental results showed that both Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) mechanisms play a role in the denitrification process on the surface of the Chlorella@Mn catalyst, where the main intermediate nitrate species is monodentate nitrite. The presence of SO₂ promoted the generation and strengthening of Brønsted acid sites, but also generated more sulfate species on the surface, thereby reducing the denitrification activity of the Chlorella@Mn catalyst. The Chlorella@Mn composite catalyst had the characteristics of short preparation time, simple process and low cost, making it promising for industrial application.

Keywords: Chlorella@Mn catalyst; Influence of SO(2); NH(3)-SCR; Poisoning resistance; Reaction mechanism.

MeSH terms

Ammonia / chemistry
Catalysis
Chlorella*
Cold Temperature
Denitrification
Oxidation-Reduction
Temperature

Substances

Ammonia
Manganese-54