Reaction characteristics and lattice oxygen transformation mechanism of semi-coke chemical looping gasification with Fe2O3/CaSO4–Al2O3 oxygen carrier

Guan, Yu; Liu, Yinhe; Wang, Bo; Feng, Ying; Lyu, Qiang

doi:10.1016/j.jclepro.2022.133291

Cited by 22 publications

(7 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is a good research direction to modify CaSO 4 by using other materials to weaken the adsorption of Hg 0 over oxygen carriers during the reduction process. By modifying CaSO 4 with metals such as Fe, , not only the oxygen release can be enhanced but the Fe atoms wrapped around Ca and S atoms in the outer layer can reduce the direct contact between Hg 0 and CaS surface and decrease the adsorption of CaS on mercury.…”

Section: Resultsmentioning

confidence: 99%

Understanding the Impacts of Different Impurities on Elemental Mercury Removal by CaS in Chemical Looping Combustion of Coal: A First Principle Study

Fan,

Jin,

Liu

et al. 2023

ACS Omega

View full text Add to dashboard Cite

CaSO 4 has the advantages of abundant yield, high oxygen-carrying capacity, low cost, and no heavy metal pollution, making it promising as an oxygen carrier for chemical looping combustion (CLC). In comparison with other oxygen carriers, CaS as the reduced product of CaSO 4 exhibits superior adsorption efficiency for Hg 0 in the flue gas. In this paper, density functional theory (DFT) was used to investigate the adsorption mechanism of Hg 0 on the adsorbent surface of CaS(001). The adsorption energies of different oxidized mercury species such as HgS, HgCl, and HgBr over the CaS surface were summarized. Furthermore, the effects of various flue gas components including SO 2 , H 2 S, S, HCl, Cl 2 , CO, H 2 , H 2 O, and C on Hg 0 adsorption over the CaS(001) surface were evaluated. The results show that Hg 0 can be adsorbed on the CaS(001) surface in a chemisorption manner with a reaction energy of −65.1 kJ/mol. The adsorption energy of different forms of mercury on the CaS(001) surface varies greatly, and mercury in the oxidized state is more easily captured by CaS. SO 2 inhibits while other flue gas components promote Hg 0 adsorption over the CaS surface. Overall, CaS tends to adsorb mercury in the reduction reactor and release mercury when CaS is re-oxidized to CaSO 4 in the oxidation reactor. This is detrimental to mercury removal in the CLC of coal. This study sheds light on the migration and transformation of mercury in the CLC of coal with CaSO 4 as the oxygen carrier.

show abstract

Section: Resultsmentioning

confidence: 99%

Understanding the Impacts of Different Impurities on Elemental Mercury Removal by CaS in Chemical Looping Combustion of Coal: A First Principle Study

Fan,

Jin,

Liu

et al. 2023

ACS Omega

View full text Add to dashboard Cite

show abstract

“…The tools for exploring the bulk ion diffusion and surface reactions of oxygen carriers mainly include theory calculations, characterization tests, and a few designed experiments. Notably, there is an emerging trend to complement experimental findings with theory calculations. − Thus, the knowledge obtained is crucial for investigating the structure–activity relationships and the underlying redox mechanisms, which are critical for the rational design of OCs with effective activity, stability, and selectivity. In situ techniques (combined with theoretical calculations) can provide real reaction pathways.…”

Section: Advanced Technology For Exploring the Chemical Looping React...mentioning

confidence: 99%

“…For single-metal OCs, the mechanism of lattice oxygen migration and transformation is relatively simple. The generally recognized reaction mechanism is that the surface oxygen species (lattice oxygen and adsorbed oxygen) react with fuel to generate oxygen vacancies and gaseous products. , As a result, a concentration gradient of oxygen between the oxygen carrier’s surface and bulk is formed, causing bulk lattice oxygen to migrate to the surface. When the reduced OC particles are exposed to air, generating O 2– to refill the oxygen vacancies formed during the reduction process, they undergo renewed oxidation.…”

Section: Migration and Transformation Of Oc’s Lattice Oxygenmentioning

confidence: 99%

Review on Migration and Transformation of Lattice Oxygen during Chemical Looping Conversion: Advances and Perspectives

Song

Lin

et al. 2023

Energy Fuels

View full text Add to dashboard Cite

Chemical looping technology is one of the most promising approaches in the fields of fuel conversion, pollution removal, energy conservation, and carbon dioxide capture and utilization and has been extensively investigated for more than two decades. A majority of the chemical looping process is achieved through the migration and transformation of lattice oxygen. Thus, exploring the migration and transformation of lattice oxygen is critical to clarify chemical looping’s reaction rules to allow for further control of reaction selectivity and yield. Herein, recent advances in the exploration of lattice oxygen’s migration mechanism are systematically reviewed, with a focus on structure–activity relationships. The great roles that characterization techniques perform to address the challenges in exploring the migration mechanism of lattice oxygen activities are discussed first. We then outline the categories of oxygen carrier materials and the migration mechanism of lattice oxygen. Lastly, the most promising research directions that design high-performance oxygen carriers with well-regulated lattice oxygen activity through the redox reaction mechanism are overviewed. We infer that the research on the relationship between lattice oxygen activity and target products is challenging but essentialit is a direction worthy of our efforts in the future.

show abstract

“…It is reasonable to anticipate that natural ores and industrial wastes should be possible OC candidates for industrial implementation in the CLC process . Fe-based OCs, such as hematite or red mud, are widely used in the CLC process due to their vast resources and low price . However, the reduction of Fe 2 O 3 to FeO or Fe is limited by thermodynamics when the steam is used as the gasification agent, resulting in low reactivity and weak oxygen transfer ability.…”

Section: Introductionmentioning

confidence: 99%

Reduction Kinetics of Low-Cost Cu/Fe-Based Oxygen Carriers in Chemical Looping Mode

Li,

Wang,

Liu

et al. 2023

Energy Fuels

View full text Add to dashboard Cite

Cu–Fe bimetallic oxides have been proposed as promising OC candidates in chemical looping combustion (CLC) due to their high reactivity and resistance to sintering, and the reduction kinetics of the Cu–Fe composite OCs is significantly essential. In this article, several low-cost Cu/Fe-based OCs are prepared using fine natural ores or red mud as raw materials. Among these OCs, the composite OC with thermal neutrality is determined by reduction investigation within the typical CLC temperature range. The heat flow curves indicate that the autothermal balance could be achieved when the mixing ratio of copper ore to hematite is 20:80 (i.e., Cu20Fe80@C), which further guides the design of the copper ore/red mud composite OC (i.e., Cu10.9Red89.1@C). Subsequently, 50 cyclic redox tests are performed to evaluate the reaction stability of these OCs, and the results show that the composite OCs (i.e., Cu20Fe80@C and Cu10.9Red89.1@C) exhibit a better cyclic stability as well as a higher oxygen transfer rate than those of pure Fe-based materials (i.e., red mud and Fe100@C). Moreover, the reduction kinetics of these OCs is studied in detail at both high- and low-temperature conditions. It is found that the OC reduction data obtained from high temperatures (750–950 °C) are inappropriate for analyzing the kinetic parameters, whose process is likely to be dominated by gas diffusion in the particle boundary layer. At low temperatures (400–610 °C), the reduction of all targeted OCs can be described by the shrinking core model, and the pure Fe-based OCs correspond to the mechanism function of G(X) = 1 – (1 – X)1/3, while that is G(X) = 1 – (1 – X)1/2 for the composite OCs. Additionally, it should be noted that the composite OCs present lower activation energy than their corresponding pure Fe-based OCs. In summary, this study shows the superiority of composite OCs in terms of cyclic reactivity and kinetic parameters, which will further guide and optimize the design of low-cost OCs.

show abstract

Reaction characteristics and lattice oxygen transformation mechanism of semi-coke chemical looping gasification with Fe2O3/CaSO4–Al2O3 oxygen carrier

Cited by 22 publications

References 64 publications

Understanding the Impacts of Different Impurities on Elemental Mercury Removal by CaS in Chemical Looping Combustion of Coal: A First Principle Study

Understanding the Impacts of Different Impurities on Elemental Mercury Removal by CaS in Chemical Looping Combustion of Coal: A First Principle Study

Review on Migration and Transformation of Lattice Oxygen during Chemical Looping Conversion: Advances and Perspectives

Reduction Kinetics of Low-Cost Cu/Fe-Based Oxygen Carriers in Chemical Looping Mode

Contact Info

Product

Resources

About