Effect of SO2 on Na2ZrO3 sorbent for CO2 capture: An experimental and density functional theory study.

The development of exceptionally stable porous solid physisorbents is vital for deep flue gas desulfurization (FGD) and SO2 recovery, as the corrosive and reactive nature of SO2 restricts the applicability of most porous materials in this demanding scenario. Herein, we report the synthesis of microporous SSZ-13 zeolite to obtain the exceedingly stable Na-SSZ-13 with low-Si/Al-ratio (5:1), and systematically evaluate its dynamic SO2 adsorption performance. Na-SSZ-13 exhibits excellent water, thermal, and chemical stability, high SO2 affinity and adsorption kinetics with extraordinary SO2/CO2 separation selectivity (2673 at zero coverage, 298 K), and exceptional low-concentration SO2 adsorption capacity (4.6/2.7mmol g-1 at 0.1/0.002bar) with the highest surface-specific SO2 uptake among reported zeolites. Column breakthrough experiments demonstrate efficient SO2 capture capability from a quaternary flue-gas mixture at high temperature (323 - 423 K). Moreover, it achieves 96.5% purity of the recovered SO2 during the regeneration process, and shows fully reversible SO2 uptake and excellent cycling stability. GCMC simulations, DFT calculations, and in situ DRIFT analyses reveal a selective SO2 adsorption mechanism with the counter-cations (Na+) serving as primary SO2 adsorption sites, elucidating the role of cation···SO2 interactions that underpin the application of zeolite-based materials for deep FGD under high-temperature and low-concentration working conditions.

The existence of O2 in flue gas, which can induce oxidative degradation and cause adsorption capacity losses, has been an obstacle for solid amine adsorbents in practical applications. Herein, a simple and scalable synthesis of PEI-impregnated silica modified with low-dose inhibitors is reported. Compared to previous studies, the novelty of this work lied in its simplicity and its ability to maintain high adsorption capacity (over 170 mg/g) when achieving excellent antioxidation and antiurea effects. The strategy can slow down the oxidation kinetics as well as relieve oxidative degradation of the adsorbents under conditions of high oxidation temperature, high O2 concentration, and long oxidation time. The cyclic stability can be increased by 43.8%, and the O2 resistance can be improved by 66.8%. Using a multitechnique approach, we have unraveled the effects of the separate and coexisting presence of CO2 and O2 in long-term applications and provided important guidance for the selection of certain inhibitors (NaH2PO4, Na3PO4, or HCOONa) based on actual application situations. This study demonstrated that the adsorbent modified with NaH2PO4 can avoid the weakening of antiurea effects when CO2 and O2 coexist, while Na3PO4 can still exhibit the overall effect of high cyclic stability even with the weakened antiurea effects; thus, NaH2PO4 and Na3PO4 have the potential for long-term carbon capture from O2-containing flue gas.

Growing efforts to reduce air pollution have accelerated the development of advanced flue gas treatment technologies for coal-fired power plants. This study presents the design, development, and industrial-scale implementation of a microwave-assisted non-thermal plasma reactor, powered by a 75 kW, 915 MHz magnetron, for simultaneous sulfur dioxide (SO2) removal and fly ash agglomeration. The reactor was installed on the outlet line of the selective catalytic reduction (SCR) system of a 22 MWe pulverized-coal-fired boiler and evaluated under real flue gas conditions. The flue gas stream, extracted by an induced-draft fan, was supplied to the reactor through two configurations—radial and axial injection—to investigate the influence of gas flow rate and microwave power on SO2 abatement performance. Under radial injection, the system achieved a maximum SO2 removal efficiency of 99.0% at 5194 Nm3/h and 75 kW, corresponding to a specific energy consumption of 14.4 Wh/Nm3. Axial injection resulted in a removal efficiency of 97.5% at 4100 Nm3/h. Beyond SO2 mitigation, exposure of flue gas to the microwave-assisted plasma environment significantly enhanced particle agglomeration, as confirmed by means of SEM imaging and particle size distribution analyses. Notably, the proportion of fine particles smaller than 2.5 µm (PM2.5) decreased from 70.25% to 18.63% after plasma treatment, indicating improved capture potential in the downstream electrostatic precipitator (ESP). Overall, microwave-assisted plasma provides efficient SO2 removal and enhanced particulate capture, offering a compact and potentially waste-free alternative to conventional systems.

Catalysis-free green synthesis of thiophenes and thioketones by one-pot method based on the resource utilization of SO2 in flue gas

ABSTRACTThe cofiring of biomass and coal has garnered significant attention in reducing pollutant emissions in power plants recently. In this study, the cofiring of eucalyptus bark (EB) and coal in a wall‐fired boiler is investigated through numerical simulation. The influence of the EB blending ratio, which is 0%–20%, and different EB cofiring positions on the combustion characteristics and pollutant emission of the boiler is analyzed. The cofiring characteristics and pollutant emission under different cofiring positions blended with 20% EB are further analyzed. The results indicate that the cofiring of EB and coal in the furnace reduces the flue gas temperature and pollutant emissions. Under a 20% EB blending ratio, the flue gas temperature, NO emission, and SO2 content at the furnace outlet are 1433 K, 178.18 ppm, and 0.16%, respectively. The simulation results indicate that blending with EB at the first, second, and third burner positions reduces 4%, 2%, and 8% of the furnace's heat flux density compared with pure coal combustion. The lowest burnout rate of 93.46% for the blend with EB occurs in the first‐layer burner, while the lowest NO emission of 178.18 ppm is obtained in the third burner. This study will provide theoretical guidance and a foundation for the feasibility of cofiring EB and coal in the boiler.

Removal of SO2 and NO in flue gas using a vacuum ultraviolet light/Oxone/H2O2 oxidation system

The transition from fossil fuels to renewable energy sources often requires shifting toward biomass fuels such as agriculture residues and waste, which tend to emit higher emission rates during combustion, and one of them is sulfur compounds. The main objective of this study is to clarify the regularities of the formation of sulfur compounds depending on the technological factors when burning sulfur-containing biomass. The experiments were conducted on two experimental stands—models of 20 kW and 25 kW capacities of industrial boilers equipped with reciprocating grates—by burning sunflower husk pellets and meat bone meal. The influence of incomplete combustion (indicator CO concentration), flue gas recirculation, and combined effects of both factors on concentrations of SO2, SO3, and H2S were investigated during experiments. In addition, 20–90% of the sulfur in the fuel is converted to SO2, contingent upon the combustion conditions. These findings have practical implications for the design and operation of biomass combustion systems. The highest SO2 emissions were observed when primary air was mixed with flue gas recirculation and at the highest content of CO. The correlation of SO2 and SO3 and SO2 and H2S concentrations in flue gases of boilers was investigated. The conversion ratio of SO2 to SO3 was determined under different combustion modes and showed that this ratio can reach up to 5%. The sulfur content in ash deposits in different areas of the actual industrial boiler was analyzed. The highest percent of sulfur (S = 20%) in ash was found on the first boiler pass.

The removal of SO2 from flue gas remains a challenge. Adsorption-based separation of SO2 using porous materials has been proposed as a more energy-efficient and cost-effective alternative to more traditional methods such as cryogenic distillations. Here we report a flexible hydrogen-bonded organic framework (HOF-NKU-1) that enables the sieving of SO2 through the guest-adaptive response and shape-memory effect of the material. HOF-NKU-1 exhibits a high selectivity of 7,331 for the separation of SO2/CO2 and a high SO2 storage density of 3.27 g cm-3 within the pore space at ambient conditions. The hydrophobic nature of HOF-NKU-1 enables high dynamic SO2 uptake and SO2 recovery, even in conditions of 95% humidity. The SO2/CO2 separation mechanism is studied through combinatorial gas sorption isotherms, breakthrough experiments and single-crystal diffraction studies, paving the way for the development of multifunctional shape-memory porous materials in the future.

Research on effective mercury removal from flue gas over Cl/Br/I/O modified adsorbents at ultra-low temperature

Influence of flue gas components on SO2 adsorption by activated carbon at low temperature

Detection of ultra-low concentration NH3, SO2, and NO using UV-DOAS combined with multidimensional spectral fusion

In the present work, CCl4-adsorbed activated carbon pretreated by the mechanochemical method (CCl4-AC) was produced for gas-phase mercury capture. The physicochemical properties of the CCl4-AC sorbent were analyzed via N2 adsorption, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The mercury capture performance of the CCl4-AC sorbent under different flue gas components was investigated in a fixed-bed experimental device. The programmed temperature desorption of mercury was used to determine the mercury capture product of the spent CCl4-AC. Finally, the mass transfer factor model proposed by Fulazzaky was used to analyze mercury capture on the CCl4-AC for clarifying its characteristics. The results showed that the prepared CCl4-AC can be used as a mercury sorbent because of its high mercury capture performance. Mercury capture by the CCl4-AC was interfered by SO2 and promoted by O2 and H2O. Hg-temperature programmed desorption (Hg-TPD) analysis indicated that the main mercury capture products of the CCl4-AC were HgCl2 and HgO. Because of the presence of SO2 in flue gas, there was a little Hg2SO4 formation on the sorbent. XPS analysis showed that the functional group of C-Cl played the dominant role in Hg0 capture, and part of the C-Cl groups were converted into Cl- after mercury capture. The mercury desorption energy of the spent CCl4-AC was 50.49 kJ/mol and stronger compared with that of raw activated carbon. Mass transfer analysis displayed that surface adsorption was the main form at the beginning of mercury adsorption, and the external mass transfer was the mercury adsorption rate-controlling step. Then, mercury adsorption entered the second stage; internal diffusion adsorption stage with internal mass transfer became the adsorption rate control step.

Asymmetric dual-chamber electrochemical reactor for reducing Fe(Ⅲ)EDTA to remove NOx by enhanced complexing absorption

PT. XYZ has an electric power capacity of 70 MW and began operating in 2014 during its operation there has been a decrease in power from 35 MW at the time of commissioning to 32 MW. This study investigates the impact of the air-fuel ratio (AFR) on the efficiency of a thermal system, focusing on the boiler, turbine, and overall thermal cycle efficiency. Variations in excess O2 in flue gas were examined at levels of 5.0%, 5.5%, and 6.0%. The results reveal that the boiler efficiency peaks at 5.0% excess O2 (73.50%), while an increase in excess O2 or AFR leads to a decrease in efficiency. Turbine efficiency remains relatively stable (74-76%) despite a slight decline with increased AFR. The thermal cycle efficiency reaches its maximum at an AFR of 13.61 (45.60%) but diminishes at higher AFR values.

The development of stable and selective electrocatalysts for converting CO2 to value-added chemicals or fuels has gained much interest in terms of their potential to mitigate anthropogenic carbon emissions. Most of the electrocatalysts are tested under pure CO2; however, industrial outlet flue gas contains numerous impurities, such as NO and SO2, which poison the electrocatalysts and alter the product selectivity. Developing electrocatalysts that are resistant to such impurities is essential for commercial implementation. Herein, we prepared bilayer porous electrocatalysts, namely, Sn, Bi, and In, on porous Cu foam mesh (Sn/Cu-f, Bi/Cu-f, and In/Cu-f) by a two-step electrodeposition process and employed these electrodes for the electrochemical reduction of CO2 to formate. It was observed that the bilayer porous electrocatalysts exhibited high CO2 reduction activity compared to catalysts coated on a Cu mesh. Among bilayer porous electrocatalysts, Sn/Cu-f and Bi/Cu-f electrocatalysts showed more than 80% faradaic efficiency (FE) toward formate production, with a formate partial current density of around -16 and -10.4 mA cm-2, respectively, at -1.02 V vs RHE. In/Cu-f electrocatalyst showed nearly 40% formate FE with formate partial current density of -15 mA cm-2 at -1.22 V vs RHE. We investigated the effect of NO and SO2 impurities (500 ppm of NO, 800 ppm of SO2, and 500 ppm of NO + 800 ppm of SO2) on these electrocatalysts' selectivity and stability toward formate. It was observed that the Bi/Cu-f electrocatalyst showed 50 h stability with 80 ± 5% formate FE, and Sn/Cu-f showed 18 h stability with above 80 ± 5% efficiency in the presence of NO and SO2 mixed with CO2. Furthermore, we studied the effect of CO2 concentration with Sn/Cu-f and Bi/Cu-f catalysts in the range of 15-100% CO2, for which formate FEs of 45-80% were observed.

Effect of the presence of trace sulfur dioxide on piperazine-based amine absorbents for carbon dioxide capture

Promotion of active H-assisted CaCO3 conversion for integrated CO2 capture and methanation

Highly efficient and low-energy SO2 capture technology is a key measure to control SO2 pollution and sulfur supply side and demand-side balancing. This paper reviews the current development of SO2 capture technology by chemical absorption from two aspects of absorbent and process enhancement. The SO2 absorption mechanism of various absorbents are first described, and it was divided into aqueous solvents and nonaqueous solvents. Four prediction models for the SO2 absorption capacity of different absorbents are proposed, providing an effective tool for the selection of efficient and low-energy absorbents. The advantages, bottlenecks, and development directions of each absorbent are analyzed. The diversity of organic amines provides a possibility for enhancing the market competitiveness of organic amine aqueous solutions in aqueous solvents, while the high energy consumption in the absorbent regeneration process is a disadvantage. The ionic amino acid aqueous solution reduces the volatilization of the effective components of the absorbent and has better SO2 absorption potential than the organic amine aqueous solution. The greatest advantage of the nonaqueous solvents is the avoidance of ineffective latent heat consumption. High-throughput screening has become a bridge for the application of aqueous and nonaqueous solvents to industrial SO2 capture processes. Finally, the application potential of a process intensification strategy in SO2 capture technology is discussed, in which solvent intensification can avoid latent heat consumption, equipment intensification can improve the efficiency of gas–liquid mass transfer and process matching can recover the available energy of SO2 capture system. The comprehensive evaluation of SO2 capture process based on various absorbents is the primary task to promote the development of promising absorbents. It is hoped that this paper can provide reference for the development of SO2 capture processes.

Effects of SO2 and H2O on the ash deposition and NO emission during oxy-fuel combustion of high-alkali coal