Key Takeaways & Executive Findings
- •• • The Ce-Co0.025/TiO2-SG catalyst, prepared via sol-gel with Co/Ti mass ratio 0.025, achieved >95% NO conversion in the 225–350 °C range, outperforming impregnation and co-precipitation methods, which is critical for meeting ultra-low emission standards in cement plants. • • The catalyst exhibited high N2 selectivity, minimizing undesirable N2O byproduct formation, which is essential for environmental compliance and ammonia slip reduction. • • Characterization revealed abundant surface oxygen vacancies and a high Ce3+ proportion, which enhance redox properties and oxygen mobility, leading to improved low-temperature activity. • • The catalyst displayed the lowest reduction peak temperature in H2-TPR, indicating excellent reducibility, and a mesoporous structure that increased acidic site exposure, both contributing to its superior performance.
Abstract
This study systematically optimized the preparation of Co-modified Ce/TiO2 catalysts and investigated the effects of preparation method and Co loading on their low-temperature denitrification activity. The sol-gel method with a Co/Ti mass ratio of 0.025 (Ce-Co0.025/TiO2-SG) yielded superior performance compared to impregnation and co-precipitation methods. The catalyst maintained NO conversion above 95% in the 225–350 °C range and exhibited high N2 selectivity. Characterization via BET, XRD, XPS, H2-TPR, and in situ DRIFTS revealed that the enhanced activity was attributed to abundant surface oxygen vacancies, a high proportion of Ce3+ species, and prominent acidic sites. The catalyst followed the Eley-Rideal mechanism, effectively inhibiting nitrate intermediate formation and promoting NO-to-NO2 oxidation. This work provides a reference for developing efficient low-temperature denitrification catalysts for industrial applications such as cement production, which emitted 722,000 tons of NOx in 2020, accounting for 17.3% of industrial emissions.
1. Introduction
The cement industry, a cornerstone of infrastructure development, is also a major source of nitrogen oxides (NOx) emissions. In 2023, China produced over 2 billion tons of cement, accounting for more than 50% of global output, and emitted 722,000 tons of NOx in 2020, representing 17.3% of total industrial emissions. Conventional NOx control technologies, such as low-nitrogen burners and staged combustion, achieve only 25–40% efficiency, falling short of ultra-low emission requirements. End-of-pipe solutions like selective non-catalytic reduction (SNCR) reach ~60% efficiency but suffer from high ammonia slip, while selective catalytic reduction (SCR) can exceed 90% efficiency with minimal ammonia slip, making it the preferred technology for stringent regulations.
However, commercial SCR catalysts often exhibit inadequate low-temperature activity, limiting their application in cement flue gas streams where temperatures are typically below 300 °C. This study addresses this bottleneck by developing Co-modified Ce/TiO2 catalysts via different preparation methods. The sol-gel method, with an optimized Co/Ti ratio of 0.025, produced a catalyst with superior low-temperature denitrification performance, maintaining >95% NO conversion at 225–350 °C. The enhanced activity is attributed to abundant oxygen vacancies, high Ce3+ content, and increased acidic sites, which collectively improve redox properties and promote the Eley-Rideal mechanism. These findings offer a promising pathway for efficient low-temperature SCR catalysts tailored to the cement industry.
Loading authentic research manuscript (Pages 1–5)...
YU Chao, ZHANG Boya, SHEN Kai, HAN Yuxuan, ZHANG Yaping (2026). Influence of Preparation Method on the Denitration Performance of Co-Modified Ce/TiO2 Catalysts. Journal of Fuel Chemistry and Technology. https://doi.org/10.1016/S1872-5813(25)60613-X
Research & Educational Purpose Only: The translations, structured abstracts, analytical annotations, and data reports provided by SinoGreenTechare intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoGreenTech claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the optimal Co loading and preparation method for maximizing low-temperature denitration activity?
The optimal catalyst is Ce-Co0.025/TiO2-SG, prepared via sol-gel with a Co/Ti mass ratio of 0.025. It achieves >95% NO conversion in the 225–350 °C range, outperforming catalysts made by impregnation and co-precipitation.
How does the sol-gel method enhance the catalyst's redox properties compared to other methods?
The sol-gel method yields a catalyst with the lowest reduction peak temperature in H2-TPR, indicating superior reducibility. This is attributed to abundant oxygen vacancies and a high Ce3+ proportion, which facilitate electron transfer and oxygen mobility.
What reaction mechanism does the Ce-Co0.025/TiO2-SG catalyst follow, and how does it affect performance?
In situ DRIFTS studies show the catalyst follows the Eley-Rideal (E-R) mechanism, where gaseous NO reacts with adsorbed NH3 species. This pathway effectively inhibits nitrate intermediate formation and enhances NO-to-NO2 oxidation, contributing to high N2 selectivity and low-temperature activity.
What are the key surface characteristics that contribute to the catalyst's high activity?
The catalyst possesses abundant surface oxygen vacancies, a high proportion of Ce3+ species, and prominent acidic sites. These features increase chemisorbed oxygen and enhance NH3 adsorption, promoting the SCR reaction at lower temperatures.
How does the catalyst's performance compare to commercial SCR catalysts in terms of temperature window and selectivity?
The Ce-Co0.025/TiO2-SG catalyst maintains >95% NO conversion from 225 to 350 °C, which is a broader and lower temperature window than many commercial catalysts that typically operate above 300 °C. It also exhibits high N2 selectivity, minimizing N2O byproduct formation.
Related Chinese Research & Cross-Citations
Recent Advances in Carbon-Based Materials for CO2 Capture and Utilization
CO2 capture and utilization (CCU) technologies are critical for mitigating global warming and promoting resource circularity. Carbon-based materials, with tunable pore structures, abundant active sites, high specific surface area, and excellent chemical stability, show significant potential for CO2 capture and conversion. This review systematically analyzes the adsorption behaviors and performance variations of activated carbon, porous carbon, graphene, and carbon nanotubes in CO2 capture. For utilization, recent advances in catalytic applications for methanation, reverse water-gas shift (RWGS), dry reforming of methane (DRM), and alcohol synthesis are emphasized. The benefits and drawbacks of carbon materials regarding adsorption capacity, catalytic activity, and stability are evaluated, and their potential in integrated CCU technologies is discussed. Key strategies for enhancing performance through structural modulation and surface modification are elucidated. This review provides theoretical guidance for future development and large-scale implementation of carbon-based materials in CCU.
Fabrication and Microwave Absorption Performance of FexOy/TiO2/C Composites Derived from Red Mud
Red mud, an industrial solid waste from alumina production, poses severe environmental challenges. This study presents a resource-efficient strategy to convert red mud into high-performance microwave absorbing materials. FexOy/TiO2/C composites were synthesized via a sol-gel method using starch as carbon source, followed by carbothermal reduction. The phase composition and microstructure were optimized by adjusting calcination temperature and raw material ratio. The optimal sample, RmCT-5.4-700, exhibited a minimum reflection loss (RLmin) of -30.2 dB at 14.0 GHz with an effective absorption bandwidth (EAB) of 5.3 GHz at a coating thickness of 2.0 mm. The superior absorption performance is attributed to the synergistic effects of dielectric components (TiO2, graphitized carbon) and magnetic components (Fe3O4/Fe). Carbothermal reduction introduces defects that induce dipole polarization, while the conductive network formed by graphitized carbon and Fe3O4/Fe particles enhances conductive loss. Heterogeneous interfaces between Fe3O4, Fe, TiO2, and the red mud matrix promote interfacial polarization. The magnetic loss of Fe3O4/Fe improves impedance matching, facilitating electromagnetic wave penetration and absorption. This work not only provides a novel route for red mud valorization but also contributes to the high-value utilization of solid wastes.
Damage Mechanism of High Chromia Refractory in the Slag Tapping Hole of Commercial Entrained-Flow Gasifiers
The service life of refractory bricks in the slag tapping hole of entrained-flow gasifiers is a critical bottleneck for long-term stable operation. This study investigated the damage mechanism of high chromia refractories in four commercial coal-water slurry gasifiers by analyzing gasification coal samples and corroded refractory bricks. Slag characteristics, including crystallization and viscosity-temperature behavior, were evaluated. Results revealed that low-viscosity slag induces more severe refractory damage. To mitigate slag crystallization risk, a safe slag tapping temperature range is recommended as tICT−t2.5 when tICT exceeds t25. Interior morphology of corroded bricks exhibited cracks, primarily attributed to molten slag penetration and subsequent reactions with refractory material. SEM-EDS analysis of slag-aggregate and slag-matrix interfaces identified reduction in Cr2O3 content as the earliest damage characteristic. XRD detected no zirconium-containing spinel in cracks, indicating that thermal expansion mismatch between newly formed phases and the refractory matrix drives crack propagation. A damage mechanism is proposed: initial Cr2O3 depletion compromises both matrix and aggregate, facilitating slag ingress and new phase formation, ultimately leading to structural failure. Early detection or prevention of Cr2O3 reduction is essential to prolong refractory service life.
Research advances in the pyrolysis recycling of waste wind turbine blades
The global energy landscape is undergoing a profound transformation, with wind energy gaining increasing prominence due to its clean and renewable nature. However, as installed wind power capacity expands, disposal of waste wind turbine blades (WWTB) has emerged as a significant challenge. These blades are predominantly composed of epoxy resin (EP) polymers, carbon fibers (CFs), and glass fibers (GFs). Improper disposal exacerbates environmental concerns and leads to loss of valuable resources, particularly carbon-based materials. Pyrolysis technology, a versatile and environmentally sustainable method for resource recovery, has garnered considerable attention for WWTB disposal. This work presents a comprehensive review of pyrolytic recycling of WWTB, focusing on principles and classifications of pyrolysis technology, key factors influencing the pyrolysis process, as well as pyrolysis methods, equipment, products, and their applications. Through in-depth analysis of current research, this review identifies critical unresolved issues and provides a forward-looking perspective on emerging research trends. The review highlights that pyrolysis can effectively recover glass fibers and carbon fibers with mechanical property retention depending on process conditions, and that catalytic pyrolysis can enhance the quality of recovered products. Economic analysis indicates that collaborative disposal methods can improve cost-effectiveness. Future research should focus on optimizing process parameters for large-scale industrial application and developing more efficient catalysts to improve product selectivity and fiber quality.
Citric Acid-Modified HUSY Zeolite Catalyzes Alkylation of Phenol with Cyclohexanol for High-Density Aviation Fuel Precursors
Lignin-derived oxygenated aromatics, particularly phenols and aromatic ethers, are promising feedstocks for synthesizing high-density, high-heat-sink aviation fuels via alkylation-hydrogenation processes. This study systematically evaluates the catalytic performance of various zeolites (Hβ, HZSM-5, MCM-41, and HUSY) in the alkylation of phenol with cyclohexanol. Characterization demonstrates that HUSY zeolite exhibits superior catalytic activity due to its favorable pore architecture and well-balanced acid site distribution, which synergistically facilitate molecular diffusion and catalytic transformations. To further enhance catalytic properties, HUSY was modified with citric acid at various concentrations and compared with NaOH and oxalic acid treatments. Results reveal that citric acid treatment preserves crystallinity while modulating acidity and pore structure. All modified zeolites enhance phenol alkylation activity. Notably, HUSY-0.5M, exhibiting the highest medium-strong acid to total acid ratio, achieves superior performance: 80.4% phenol conversion and 99.6% selectivity for alkylation products. The catalyst also shows high activity for various lignin-derived compounds (p-cresol, anisole, guaiacol), demonstrating broad applicability. This work provides a new strategy for valorizing lignin-derived phenols into high-value fuel precursors through alkylation.
Hydrogen Production and Structure Evolution Mechanism during Thermochemical Conversion of Microalgae Pellet in Molten Hydroxide Salts
This study investigates the thermochemical conversion behavior of microalgae pellets in a molten hydroxide salt (80% NaOH-20% Na2CO3) system and its influence on hydrogen production. By comparing temperature evolution, gas release characteristics, and structural evolution of pellets with and without molten salt, and integrating char alkalization experiments, the regulatory mechanism of molten salt on reaction pathways and hydrogen production was systematically analyzed. Results indicate that molten salt significantly enhances internal heat transfer efficiency, achieving a central heating rate of 177 °C/s, effectively alleviating thermal hysteresis. Concurrently, molten salt promotes pore development through penetration, erosion, and catalytic effects, resulting in a porosity increase of 53.2%–104.3% after 10 s of reaction. Conversion efficiency is markedly improved, with the dominant reaction pathway shifting to char alkalization after only 70 s. Furthermore, when heating rate is increased above 600 °C, hydrogen yield from char alkalization improves more significantly, primarily attributed to the synergistic promotion of molten salt catalysis and rapid heating on volatiles reforming. This study provides a theoretical foundation for understanding efficient hydrogen production from biomass in molten hydroxide salts.