Characteristics of CaS–CaO Oxidation for Chemical Looping Combustion with a CaSO<sub>4</sub>-Based Oxygen Carrier

Zheng, Mianping; Zhong, Simei; Li, Kongzhai; Wang, Hua; Liu, Huili; Wei, Yonggang; Zhu, Xing

doi:10.1021/acs.energyfuels.7b01771

Cited by 17 publications

(11 citation statements)

References 25 publications

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“…What is worse is that increasing the operating temperature would singly exacerbate the emission of sulfur from CaSO 4 via the side reactions of eqs 1−5 below. 13,14 Sulfur released not only led to atmospheric pollution but also tarnished the purity of outlet CO 2 and declined the reactivity of CaSO 4 .…”

Section: Introductionmentioning

confidence: 99%

Chemical Looping Combustion Characteristics of Coal with a Novel CaSO₄–Ca₂CuO₃ Mixed Oxygen Carrier

Wang

Liang

et al. 2020

Energy Fuels

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Resource utilization of the disposed CaSO 4 waste as an oxygen carrier (OC) in chemical looping combustion (CLC) is of great meaning as a result of its attractive strengths, such as easy availability, low cost, large oxygen capacity, and avoidance of potential environmental harm. In this research, a novel mixed OC of CaSO 4 doped with Ca 2 CuO 3 was first reported and produced using a combined template preparation method. Its reaction behavior with a typical lignite designated as YN was studied, which indicated that doped Ca 2 CuO 3 well enhanced the reactivity of CaSO 4 with YN coal. The CO 2 yield as formed was greatly accelerated, while SO 2 evolved from the CaSO 4 side reactions could be effectively controlled, as expected. Furthermore, the potential oxygen transfer mechanism during the CaSO 4 −Ca 2 CuO 3 mixed OC reaction with YN coal was revealed, wherein elemental Cu derived from reduced Ca 2 CuO 3 could regain lattice oxygen inherent in unreacted CaSO 4 via its melting interface. In situ reoxidized CuO would decompose and emit O 2 for direct combustion of residual char of YN. Then, migration and redistribution of the sulfur species were completely investigated. Added Ca 2 CuO 3 was found to be reduced to CaO and elemental Cu during its reaction with YN, both of which were able to directionally fix gaseous sulfur evolved from CaSO 4 to form CaS and Cu 2 S, respectively. Thus, the gaseous sulfur retention capacity of this mixed OC was much improved. In addition, the prepared CaSO 4 −Ca 2 CuO 3 mixed OC demonstrated good regeneration capacity and strong sintering resistance as well. Overall, the novel CaSO 4 −Ca 2 CuO 3 mixed OC as reported possessed good reactivity and directional fixation of gaseous sulfur, which benefited from simultaneous carbon capture and in situ desulfurization in CLC, and as such is quite attractive for future application.

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Section: Introductionmentioning

confidence: 99%

Chemical Looping Combustion Characteristics of Coal with a Novel CaSO₄–Ca₂CuO₃ Mixed Oxygen Carrier

Wang

Liang

et al. 2020

Energy Fuels

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“…The preparation of oxygen carriers is similar to our previous studies [23]. The analytical CaSO4 (Tianjin Fuchen Chemical Factory) and the analytical CuO (Guangdong Guanghua Science and Technology CO., Ltd.) particles were used in this work.…”

Section: Preparation Of Oxygen Carriersmentioning

confidence: 89%

“…In our previous studies, the addition of https://doi.org/10.37358/RC. 21.3.8443 CaO not only achieved high CO2 production efficiency, but also inhibited the side reaction of CaSO4 and prevented the emission of gaseous sulfur [23]. Wang et al [24] reported to use the CaSO4-CuO as an mixed OC for the coal-fueled CLC and confirmed its feasibility.…”

Section: Introductionmentioning

confidence: 98%

Reduction Characteristic of CaSO4-CuO Combined Oxygen Carrier Under CO Atmosphere

Li¹,

Zheng²,

Wang³

et al. 2021

Rev. Chim.

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CaSO4 oxygen carrier is considered to be a potential oxygen carrier (OC) for Chemical Looping Combustion because of its high oxygen capacity and low price. But its reactivity is lower than the main metal oxide oxygen carriers, and it deactivates due to sulfur loss as well as sintering at high reaction temperatures above 920 ℃. To improve the performance of CaSO4-based oxygen carrier, small amounts of CuO particles were mixed mechanistically with CaSO4 particles to use as combined oxygen carrier in this work. The reduction reactions of CaSO4 oxygen carrier, CuO oxygen carrier and CaSO4-CuO combined oxygen carrier under CO atmosphere were investigated. The effects of reaction factors including reaction temperature, the oxygen-carrying ratio of CuO to CaSO4 and mass of oxygen carrier, on the reductions have been investigated in this study. XRD, SEM-EDS, BET and gas analyses were performed to investigate the variations of solid phase, element compositions in solid residual and sulfur release with reaction time. The results show that the addition of CuO increases the reactivity of the CaSO4-based oxygen carrier while also suppressing the release of the gas sulfur. For the individual reduction of CaSO4 by CO, with the increase of CaSO4 mass (500 - 1200 mg), CO2 yield also increases until 1000 mg stops and SO2 released rises remarkably; An increase in the reaction temperature aggravated the SO2 emission. The carbon dioxide generation efficiency also increases with an increase in temperature, but decreases when the temperature exceeds 950 ℃ due to sintering of the oxygen carrier particles; With respect to the reaction of CuO with CO, CO2 yield does not change significantly with increasing temperature, due to the sintering of the CuO oxygen carrier in a high temperature reaction environment;For the combined oxygen carrier: a.As the reduction reaction temperature increases, the reduction reaction performance of the combined oxygen carrier is enhanced within the reaction temperature range of 750~900℃. b. CaO the use of CuO additives not only improves the CO conversion rate, but also inhibits the release of gas sulfide. As the oxygen carrying fraction of CuO increases, SO2 released is reduced and the SO2 release time is delayed. What� more, the solid products after reduction reaction mainly contain CaS, CaO, CuO, Cu2O and CaSO4, and no copper sulfide is detected. c. When the oxygen-carrying ratio of CuO to CaSO4 is increasing from 15% to 20%, CO2 yield increases greatly.

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“…In addition, the overall reaction process can be described with the shrinking core model. Furthermore, the high Ca/S ratio can inhibit the sulfur release. , When coal is used as the fuel, the gasification influences the whole reaction and the ability of the oxygen-transmitting capacity is about 4 times as much as other cheap OCs, such as ilmenite . Although the reaction rate of the char–OC reaction is slower than the gas–OC reaction, it still affects the overall reaction.…”

Section: Introductionmentioning

confidence: 99%

Understanding the Interaction Mechanism of Char and CaSO₄ Oxygen Carrier in Chemical Looping Combustion: Semi-empirical Tight-Binding Method Calculation and Grand Canonical Monte Carlo Simulation

et al. 2020

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Controlling carbon emissions is an effective way to mitigate the greenhouse effect. According to the primary energy consumption of China, chemical looping combustion (CLC) using coal as the fuel has great development prospects. In the solid-fuel CLC process, the interaction of char and oxygen carrier cannot be ignored. The CaSO4 oxygen carrier is cheap and oxygen-rich. Thus, the interaction of char and CaSO4 was investigated in this paper to reveal the reason for the low reaction rate for the char–CaSO4 reaction from the perspective of the binding process. It could offer the guide for improving the binding ability of the CaSO4 oxygen carrier. The binding process of the char model composed of five benzene rings and the CaSO4 cluster was calculated by the semi-empirical tight-binding quantum chemistry method, and the influence of the temperature and pressure was simulated by the grand canonical Monte Carlo (GCMC) method. The interaction of char and CaSO4 is the exothermic reaction, and the dispersion contributes the most energy to attractive interaction. The binding system is the typical weak interaction system. From the property analysis, the H1–H2–O ring causes the system to stay stable, and there are hydrogen bonds that appear in the interaction area between the two fragments. The results of the independent gradient model verify the position of the hydrogen bond interaction, and the atom contributions of char and CaSO4 to the interaction are 0.1564–0.5958 and 0.2347–0.4854, respectively. The results of the electron density difference demonstrate that most atoms in the interaction area (z = 5.5–9.5 Å) get electrons to cause the positive electrostatic energy. According to the GCMC simulation, the binding process changes from type 2 binding to type 3 binding with the temperature increasing and the binding energy decreases. Meanwhile, the fitted energy curves change from the polynomial function to the exponentiation. To improve the interaction ability of the two fragments, it would be a choice to increase the electron transfer ability between char and the CaSO4 surface.

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Characteristics of CaS–CaO Oxidation for Chemical Looping Combustion with a CaSO₄-Based Oxygen Carrier

Cited by 17 publications

References 25 publications

Chemical Looping Combustion Characteristics of Coal with a Novel CaSO₄–Ca₂CuO₃ Mixed Oxygen Carrier

Chemical Looping Combustion Characteristics of Coal with a Novel CaSO₄–Ca₂CuO₃ Mixed Oxygen Carrier

Reduction Characteristic of CaSO4-CuO Combined Oxygen Carrier Under CO Atmosphere

Understanding the Interaction Mechanism of Char and CaSO₄ Oxygen Carrier in Chemical Looping Combustion: Semi-empirical Tight-Binding Method Calculation and Grand Canonical Monte Carlo Simulation

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Characteristics of CaS–CaO Oxidation for Chemical Looping Combustion with a CaSO4-Based Oxygen Carrier

Cited by 17 publications

References 25 publications

Chemical Looping Combustion Characteristics of Coal with a Novel CaSO4–Ca2CuO3 Mixed Oxygen Carrier

Chemical Looping Combustion Characteristics of Coal with a Novel CaSO4–Ca2CuO3 Mixed Oxygen Carrier

Reduction Characteristic of CaSO4-CuO Combined Oxygen Carrier Under CO Atmosphere

Understanding the Interaction Mechanism of Char and CaSO4 Oxygen Carrier in Chemical Looping Combustion: Semi-empirical Tight-Binding Method Calculation and Grand Canonical Monte Carlo Simulation

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Characteristics of CaS–CaO Oxidation for Chemical Looping Combustion with a CaSO₄-Based Oxygen Carrier

Chemical Looping Combustion Characteristics of Coal with a Novel CaSO₄–Ca₂CuO₃ Mixed Oxygen Carrier

Chemical Looping Combustion Characteristics of Coal with a Novel CaSO₄–Ca₂CuO₃ Mixed Oxygen Carrier

Understanding the Interaction Mechanism of Char and CaSO₄ Oxygen Carrier in Chemical Looping Combustion: Semi-empirical Tight-Binding Method Calculation and Grand Canonical Monte Carlo Simulation