Mechanism of Mercury Adsorption and Oxidation by Oxygen over the CeO2 (111) Surface: A DFT Study

Zhao, Li; Wu, Yang‐wen; Han, Jian; Lü, Qiang; Yang, Yongping; Zhang, Laibao

doi:10.3390/ma11040485

Cited by 29 publications

(18 citation statements)

References 44 publications

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“…Hg 0 is physically adsorbed on the catalyst surface and then oxidized to HgO, and the consumed lattice oxygen is supplemented by gas-phase O 2 . The formation of HgO was shown to be an important factor affecting the rate of Hg 0 oxidation . Besides, the mutual conversion between Ce 3+ and Ce 4+ can promote NO and Hg 0 oxidation to NO 2 and HgO, respectively.…”

Section: Scr + Heavy Metal Controlmentioning

confidence: 98%

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Multipollutant Control (MPC) of Flue Gas from Stationary Sources Using SCR Technology: A Critical Review

Wang

Chen

Zhang

et al. 2021

Environ. Sci. Technol.

153

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The emission of gaseous pollutants from the combustion of fossil fuels is believed to be one of the most serious environmental challenges in the 21st century. Given the increasing demands of multipollutant control (MPC) via adsorption or catalysis technologies, such as NO x , volatile organic compounds (VOCs), heavy metals (Hg etc.), and ammonia, and considering investment costs and site space, the use of existing equipment, especially the selective catalytic reduction (SCR) system to convert pollutants into harmless or readily adsorbed substances, is one of the most practical approaches. Consequently, many efforts have been directed at achieving the simultaneous elimination of multipollutants in a SCR convertor, and this method has been widely used to mitigate the stationary emission of NO x . However, the development of active, selective, stable, and multifunctional catalysts/adsorbents suitable for large-scale commercialization remains challenging. Herein, we summarize recent works on the applications of SCR in MPC, describing the approaches of (i) SCR + VOCs oxidation, (ii) SCR + heavy metal control, and (iii) SCR + NH3 reduction to reveal that the efficiency of simultaneous elimination depends on catalyst composition and flue gas parameters. Furthermore, the synergistic promotional/inhibitory effects between SCR and VOCs/ammonia/heavy metal oxidations are shown to be the key to the feasibility of the reactions.

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Section: Scr + Heavy Metal Controlmentioning

confidence: 98%

“…The formation of HgO was shown to be an important factor affecting the rate of Hg 0 oxidation. 118 Besides, the mutual conversion between Ce 3+ and Ce 4+ can promote NO and Hg 0 oxidation to NO 2 and HgO, respectively. NO 2 can also react with Hg 0 as Hg 0 + NO 2 (ad) → HgO(ad) + NO.…”

Section: Hg Nomentioning

confidence: 99%

Multipollutant Control (MPC) of Flue Gas from Stationary Sources Using SCR Technology: A Critical Review

Wang

Chen

Zhang

et al. 2021

Environ. Sci. Technol.

153

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show abstract

“…As summarized in Table , both molecular simulation and computational studies have been conducted to investigate the interaction mechanism between different gaseous fuel molecules (i.e., CO and CH 4 ) and oxygen carriers (including Fe-based, , Ni-based, , Cu-based, Ce-based, , Mn-based, etc.). Recently, interests were also shown on the investigation of the potential adverse effects of gaseous impurities (such as sulfur and mercury) on oxygen carriers. − …”

Section: Microcosmic Reaction Mechanism and Redox Reaction Kineticsmentioning

confidence: 99%

Chemical Looping Combustion of Coal in China: Comprehensive Progress, Remaining Challenges, and Potential Opportunities

Zhao

Tian

et al. 2020

Energy Fuels

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Chemical looping combustion (CLC) has emerged as an efficient and promising combustion technique for fossil fuels during the past few decades. The main advantages of CLC lie in its inherent CO 2 sequestration and cascade energy utilization, being primarily benefited from the in situ reactive separation facilitated by the circulation of a solid intermediate. Up to date, the research on the CLC-related oxygen carrier, reactor, and system has made extensive and in-depth development worldwide. CLC units with thermal power ranging from the kW th to MW th scale were demonstrated with fuels of different types (gaseous, liquid, and solid fuels). Over the past 20 years, Chinese researchers have made significant progress in chemical looping technologies, extending from fundamental oxygen carrier studies to the implementation of pilot-scale CLC units. For the use of solid fuels, such as coal, in CLC, it is a rather challenging task but a lot of opportunities also remain. As a result of the particular "rich coal, meager oil, and deficient gas" energy reserve characteristics, China has become the main research battlefield on CLC of coal these years. In this paper, the main advances and research status on CLC of coal in China are reviewed and appraised. The contents in this paper cover most of, if not all, the research hotspots on CLC of coal, i.e., oxygen carrier screening, reactor design/construction/operation, pollutant emission, reaction kinetics, and numerical simulation. Chinese researchers have made substantial contributions to two bottleneck issues faced by the coal-derived CLC technique, i.e., developing and preparing a low-cost while well-performing oxygen carrier and promoting the slow char gasification process in the fuel reactor. In addition, remaining challenges that constrain the development of large-scale CLC units and indeed deserve in-depth investigation are analyzed. Particular attention is paid to the following three key challenges: severe mismatch of reaction rates in CLC of coal, difficulty in attaining a good balance between the oxygen carrier performance and cost, and challenge in controlling solid circulation to manage heat and mass transfer. Accordingly, potential opportunities for future research and scaling-up of the coal-derived CLC technique are discussed. The academic thoughts that are highlighted here include (1) achieving a good compromise between the oxygen carrier cost and performance through the rational design of a multifunctional and composite oxygen carrier and its scalable preparation using cheap raw materials, (2) coordination among reactor modeling− reactor design−reactor operation to attain effective management of heat and mass transfer in the CLC reactor, and (3) a complex while effective matching matrix among coal type, oxygen carrier particle, and reactor configuration to acquire the optimal performance of the whole CLC system. Overall, this review summarizes the contributions of Chinese scholars to CLC of coal and presents how these research achievements benefit the commercial-sca...

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“…The first-principles calculations based on DFT were performed using the Cambridge Sequential Total Energy Package (CASTEP) and the Perdew-Wang-91 (PW91) functional within the generalized gradient approximation (GGA) [20]. The energy cutoff was set to 400 eV, and a 2 × 2 × 1 k-point grid sampling was used for Brillouin-zone integration throughout the study [21][22][23][24]. The dynamics were calculated using the NTV ensemble, and the time step for the solution of dynamic KS equation was configured at 1.0 fs.…”

Section: Computational Detailsmentioning

confidence: 99%

Adsorption Characteristics of Gas Molecules (H2O, CO2, CO, CH4, and H2) on CaO-Based Catalysts during Biomass Thermal Conversion with in Situ CO2 Capture

et al. 2019

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Biomass thermochemical conversion with in situ CO2 capture is a promising technology in the production of high-quality gas. The adsorption competition mechanism of gas molecules (H2O, CO2, CO, CH4, and H2) on CaO-based catalyst surfaces was studied using density functional theory (DFT) and experimental methods. The adsorption characteristics of CO2 on CaO and 10 wt % Ni/CaO (100) surfaces were investigated in a temperature range of 550–700 °C. The adsorption energies were increased and then weakened, reaching their maximum at 650 °C. The simulation results were verified by CO2 temperature-programmed desorption (CO2-TPD) experiments. By the density of states and Mulliken population analysis, CaO doped with Ni caused a change in the electronic structure of the Osurf atom and decreased the C–O bond stability. The molecular competition mechanism on the CaO-based catalyst surface was identified by DFT simulation. As a result, the adsorption energies decreased in the following order: H2O > CO2 > CO > CH4 > H2. The increase of CO2 adsorption energy on the 10 wt % Ni/CaO surface, compared with the CaO surface, was the largest among those of the studied molecules, and its value increased from 1.45 eV to 1.81 eV. Therefore, the 10 wt % Ni/CaO catalyst is conducive to in situ CO2 capture in biomass pyrolysis.

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Mechanism of Mercury Adsorption and Oxidation by Oxygen over the CeO2 (111) Surface: A DFT Study

Cited by 29 publications

References 44 publications

Multipollutant Control (MPC) of Flue Gas from Stationary Sources Using SCR Technology: A Critical Review

Multipollutant Control (MPC) of Flue Gas from Stationary Sources Using SCR Technology: A Critical Review

Chemical Looping Combustion of Coal in China: Comprehensive Progress, Remaining Challenges, and Potential Opportunities

Adsorption Characteristics of Gas Molecules (H2O, CO2, CO, CH4, and H2) on CaO-Based Catalysts during Biomass Thermal Conversion with in Situ CO2 Capture

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