Key Takeaways & Executive Findings
- •• • Mn-45/F-0.2 composite adsorbent extended SO2 breakthrough time from 50.9 to 54.5 min, a 7.1% increase, directly improving operational runtime for dry desulfurization systems. • • Sulfur breakthrough capacity increased from 190.2 to 205.4 mg/g (8.0% improvement), enabling higher contaminant loading per adsorbent mass and reducing material replacement frequency. • • Hg0 co-removal efficiency improved from 10.4% to 14.9% (43.3% relative increase), demonstrating enhanced multi-pollutant control capability in a single unit. • • Mn doping and F127 modification increased specific surface area and pore volume, mitigating pore blockage by CaSO3/CaSO4 and preserving active sites for sustained SO2/Hg0 removal.
Abstract
Under the carbon neutrality strategy, biomass boilers have emerged as key facilities for renewable energy utilization, yet are characterized by low-concentration SO2 emissions. Ca-based dry desulfurization presents a promising technology for biomass boiler flue gas purification due to its compact structure, low capital investment and simple operation and maintenance. However, it is generally limited by the low adsorbent utilization and insufficient desulfurization efficiency. Herein, this study developed a novel Ca-Mn composite adsorbent through a synergistic strategy integrating F127 surfactant to optimize dispersion and Mn loading to enhance oxidation efficiency. The resulting adsorbent not only significantly increased the breakthrough sulfur capacity of the Ca-based material but also markedly improved the synergistic removal of Hg0. It was demonstrated that the introduction of Mn elements and F127 effectively suppressed the agglomeration of Ca(OH)2 crystallites and induced an oxygen vacancy-rich structure, while simultaneously optimizing the pore structure of the adsorbent. The modified adsorbent exhibited the enlarged specific surface area and pore volume, which favored to enhance the reaction mass transfer and effectively prevent the pore blockage and coverage of active sites by desulfurization products. The Mn sites and oxygen vacancies formed catalytic centers, which not only accelerated the desulfurization reaction by promoting SO2 oxidation but also enabled the adsorbent to couple with Hg0 catalytic oxidation functionality. Consequently, the simultaneous removal of SO2 and Hg0 was significantly enhanced on the Ca-Mn composite adsorbent.
1. Introduction
Biomass boilers, integral to renewable energy utilization, emit low-concentration SO2 (<300 mg/m3), yet conventional Ca-based dry desulfurization suffers from low adsorbent utilization and insufficient efficiency due to intrinsic Ca(OH)2 reactivity limits and pore blockage by dense CaSO3/CaSO4 layers. These bottlenecks escalate operational costs and hinder compliance with stringent environmental standards, necessitating advanced adsorbent designs that enhance mass transfer and active site availability.
This study addresses these limitations by developing a Ca-Mn composite adsorbent via synergistic F127 surfactant dispersion and Mn doping. The approach suppresses Ca(OH)2 crystallite agglomeration, induces oxygen vacancies, and optimizes pore architecture, thereby increasing specific surface area and pore volume. Mn sites and oxygen vacancies act as catalytic centers, accelerating SO2 oxidation to SO3 and enabling Hg0 catalytic oxidation, thus achieving simultaneous removal of SO2 and Hg0 with improved breakthrough capacity and efficiency.
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LIU Shuaipeng, LI Dalai, REN Zihan, LIU Jie, WANG Lidong (2026). Construction of Calcium-Manganese Composite Desulfurizer for Synergistic Removal of SO2/Hg0. Journal of Fuel Chemistry and Technology. https://doi.org/10.1016/S1872-5813(26)60656-1
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Frequently Asked Questions
What is the specific role of F127 surfactant in enhancing the performance of the Ca-Mn composite adsorbent?
F127 surfactant facilitates uniform distribution of Mn within the Ca(OH)2 matrix, increasing surface concentration of Mn active sites. This prevents Mn agglomeration and ensures optimal dispersion, which is critical for maximizing catalytic oxidation of SO2 and Hg0.
How does Mn doping influence the structural properties of Ca(OH)2 and what are the implications for desulfurization?
Mn doping suppresses rapid crystallization and agglomeration of Ca(OH)2 particles, leading to an oxygen vacancy-rich structure and enlarged specific surface area and pore volume. These changes enhance mass transfer and prevent pore blockage by desulfurization products, extending breakthrough time and increasing sulfur capacity.
What are the synergistic mechanisms for simultaneous removal of SO2 and Hg0 on the Mn-45/F-0.2 adsorbent?
Mn sites and adjacent oxygen vacancies form catalytic centers that promote oxidation of SO2 to SO3 and Hg0 to Hg2+. The SO3 is then captured by Ca(OH)2, while the enhanced pore structure facilitates mass transfer and prevents active site coverage, leading to improved removal efficiencies for both pollutants.
What is the industrial significance of the observed increase in Hg0 co-removal efficiency from 10.4% to 14.9%?
The 43.3% relative improvement in Hg0 removal efficiency is significant for meeting mercury emission regulations without additional equipment. This synergistic removal capability reduces capital and operational costs for biomass boiler flue gas treatment, making the technology more economically viable.
How does the Mn-45/F-0.2 adsorbent compare to unmodified Ca(OH)2 in terms of breakthrough sulfur capacity and what does this mean for adsorbent lifetime?
The breakthrough sulfur capacity increased from 190.2 to 205.4 mg/g, an 8.0% improvement. This translates to a longer adsorbent lifetime, reducing the frequency of adsorbent replacement and downtime, thereby lowering operational costs and improving process reliability.
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