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1.
Proc Natl Acad Sci U S A ; 121(17): e2318853121, 2024 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-38630722

RESUMO

Recently, there has been a notable surge in interest regarding reclaiming valuable chemicals from waste plastics. However, the energy-intensive conventional thermal catalysis does not align with the concept of sustainable development. Herein, we report a sustainable electrocatalytic approach allowing the selective synthesis of glycolic acid (GA) from waste polyethylene terephthalate (PET) over a Pd67Ag33 alloy catalyst under ambient conditions. Notably, Pd67Ag33 delivers a high mass activity of 9.7 A mgPd-1 for ethylene glycol oxidation reaction (EGOR) and GA Faradaic efficiency of 92.7 %, representing the most active catalyst for selective GA synthesis. In situ experiments and computational simulations uncover that ligand effect induced by Ag incorporation enhances the GA selectivity by facilitating carbonyl intermediates desorption, while the lattice mismatch-triggered tensile strain optimizes the adsorption of *OH species to boost reaction kinetics. This work unveils the synergistic of strain and ligand effect in alloy catalyst and provides guidance for the design of future catalysts for PET upcycling. We further investigate the versatility of Pd67Ag33 catalyst on CO2 reduction reaction (CO2RR) and assemble EGOR//CO2RR integrated electrolyzer, presenting a pioneering demonstration for reforming waste carbon resource (i.e., PET and CO2) into high-value chemicals.

2.
Cell Mol Life Sci ; 81(1): 273, 2024 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-38900294

RESUMO

Long-term memory formation requires de novo RNA and protein synthesis. Using differential display PCR, we found that the NCoR1 cDNA fragment is differentially expressed between fast learners and slow learners, with fast learners showing a lower expression level than slow learners in the water maze learning task. Fast learners also show lower NCoR1 mRNA and protein expression levels. In addition, spatial training decreases both NCoR1 mRNA and protein expression, whereas NCoR1 conditional knockout (cKO) mice show enhanced spatial memory. In studying the molecular mechanism, we found that spatial training decreases the association between NCoR1 and DEC2. Both NCoR1 and DEC2 suppress the expression of BDNF, integrin α3 and SGK1 through C/EBPα binding to their DNA promoters, but overexpression of DEC2 in NCoR1 cKO mice rescues the decreased expression of these proteins compared with NCoR1 loxP mice overexpressing DEC2. Further, spatial training decreases DEC2 expression. Spatial training also enhances C/EBPα binding to Bdnf, Itga3 and Sgk1 promoters, an effect also observed in fast learners, and both NCoR1 and DEC2 control C/EBPα activity. Whereas knockdown of BDNF, integrin α3 or SGK1 expression impairs spatial learning and memory, it does not affect Y-maze performance, suggesting that BDNF, integrin α3 and SGK1 are involved in long-term memory formation, but not short-term memory formation. Moreover, NCoR1 expression is regulated by the JNK/c-Jun signaling pathway. Collectively, our findings identify DEC2 as a novel interacting protein of NCoR1 and elucidate the novel roles and mechanisms of NCoR1 and DEC2 in negative regulation of spatial memory formation.


Assuntos
Aprendizagem em Labirinto , Camundongos Knockout , Correpressor 1 de Receptor Nuclear , Memória Espacial , Animais , Memória Espacial/fisiologia , Camundongos , Correpressor 1 de Receptor Nuclear/metabolismo , Correpressor 1 de Receptor Nuclear/genética , Aprendizagem em Labirinto/fisiologia , Masculino , Camundongos Endogâmicos C57BL , Regiões Promotoras Genéticas , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Proteínas Serina-Treonina Quinases , Proteínas Imediatamente Precoces
3.
Small ; 20(15): e2308004, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37992242

RESUMO

In the electrochemical CO2 reduction reaction (CO2RR), the coverages of *CO and *H intermediates on a catalyst surface are critical for the selective generation of C1 or C2 products. In this work, we have synthesized several CuxZnyMnz ternary alloy electrocatalysts, including Cu8ZnMn, Cu8Zn6Mn, and Cu8ZnMn2, by varying the doping compositions of Zn and Mn, which are efficient in binding *CO and *H adsorbates in the CO2 electroreduction process, respectively. The increase of *H coverage allows to promotion of the CH4 and H2 formation, while the increase of the *CO coverage facilitates the production of C2H4 and CO. As a result, the Cu8ZnMn catalyst presented a high CO2-to-CH4 partial current density (-418 ± 22 mA cm-2) with a Faradaic efficiency of 55 ± 2.8%, while the Cu8Zn6Mn catalyst exhibited a CO2-to-C2H4 partial current density (-440 ± 41 mA cm-2) with a Faradaic efficiency of 58 ± 4.5%. The study suggests a useful strategy for rational design and fabrication of Cu electrocatalysts with different doping for tailoring the reduction products.

4.
Small ; : e2401872, 2024 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-38639027

RESUMO

Electrochemical glycerol oxidation features an attractive approach of converting bulk chemicals into high-value products such as glyceric acid. Nonetheless, to date, the major product selectivity has mostly been limited as low-value C1 products such as formate, CO, and CO2, due to the fast cleavage of carbon-carbon (C-C) bonds during electro-oxidation. Herein, the study develops an atomically ordered Ni3Sn intermetallic compound catalyst, in which Sn atoms with low carbon-binding and high oxygen-binding capability allow to tune the adsorption of glycerol oxidation intermediates from multi-valent carbon binding to mono-valent carbon binding, as well as enhance *OH binding and subsequent nucleophilic attack. The Ni3Sn electrocatalyst exhibits one of the highest glycerol-to-glyceric acid performances, including a high glycerol conversion rate (1199 µmol h-1) and glyceric acid selectivity (62 ± 3%), a long electrochemical stability of > 150 h, and the capability of direct conversion of crude glycerol (85% purity) into glyceric acid. The work features the rational design of highly ordered catalytic sites for tailoring intermediate binding and reaction pathways, thereby facilitating the efficient production of high-value chemical products.

5.
Angew Chem Int Ed Engl ; : e202411194, 2024 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-38995549

RESUMO

The electrochemical reduction of CO or CO2 into C2+ products has mostly been focused on Cu-based catalysts. Although Ag has also been predicted as a possible catalyst for the CO-to-C2+ conversion from the thermodynamic point of view, however, due to its weak CO binding strength, CO rapidly desorbs from the Ag surface rather than participates in deep reduction. In this work, we demonstrate that single-atomic Pd sites doped in Ag lattice can tune the CO adsorption behavior and promote the deep reduction of CO toward C2 products. The monodispersed Pd-Agn sites enable the CO adsorption with both Pd-atop (PdL) and Pd-Ag bridge (PdAgB) configurations, which can increase the CO coverage and reduce the C-C coupling energy barrier. Under room temperature and ambient pressure, the Pd1Ag10 alloy catalyst exhibited a total CO-to-C2 Faradaic efficiency of ~37% at ‒0.83 V, with appreciable current densities and electrochemical stability, thus featuring unconventional non-Cu electrocatalytic CO-to-C2 conversion capability.

6.
Angew Chem Int Ed Engl ; 63(17): e202316907, 2024 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-38436539

RESUMO

The efficient ethanol electrosynthesis from CO2 is challenging with low selectivity at high CO2 electrolysis rates, due to the competition with H2 and other reduction products. Copper-based bimetallic electrocatalysts are potential candidates for the CO2-to-ethanol conversion, but the secondary metal has mainly been focused on active components (such as Ag, Sn) for CO2 electroreduction, which also promote selectivity of ethylene or other reduction products rather than ethanol. Limited attention has been given to alkali-earth metals due to their inherently active chemical property. Herein, we rationally synthesized a (111) facet-oriented nano Cu2Mg (designated as Cu2Mg(111)) intermetallic compound with high-density ordered Cu3-Mg sites. The in situ Raman spectroscopy and density function theory calculations revealed that the Cu3 - δ $_{^{\rm{{\rm \delta} }} }$ --Mg- δ $_{^{\rm{{\rm \delta} }} }$ + active sites allowed to increase *CO surface coverage, decrease reaction energy for *CO-CO coupling, and stabilize *CHCHOH intermediates, thus promoting the ethanol formation pathway. The Cu2Mg(111) catalyst exhibited a high FEC2H5OH of 76.2±4.8 % at 600 mA⋅cm-2, and a peak value of |jC2H5OH| of 720±34 mA⋅cm-2, almost 4 times of that using conventional Cu2Mg with (311) facets, comparable to the best reported values for the CO2-to-ethanol electroreduction.

7.
J Am Chem Soc ; 145(48): 26374-26382, 2023 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-37992232

RESUMO

The electrochemical conversion of CO2 into multicarbon (C2) products on Cu-based catalysts is strongly affected by the surface coverage of adsorbed CO (*CO) intermediates and the subsequent C-C coupling. However, the increased *CO coverage inevitably leads to strong *CO repulsion and a reduced C-C coupling efficiency, thus resulting in suboptimal CO2-to-C2 activity and selectivity, especially at ampere-level electrolysis current densities. Herein, we developed an atomically ordered Cu9Ga4 intermetallic compound consisting of Cu square-like binding sites interspaced by catalytically inert Ga atoms. Compared to Cu(100) previously known with a high C2 selectivity, the Ga-spaced, square-like Cu sites presented an elongated Cu-Cu distance that allowed to reduce *CO repulsion and increased *CO coverage simultaneously, thus endowing more efficient C-C coupling to C2 products than Cu(100) and Cu(111). The Cu9Ga4 catalyst exhibited an outstanding CO2-to-C2 electroreduction, with a peak C2 partial current density of 1207 mA cm-2 and a corresponding Faradaic efficiency of 71%. Moreover, the Cu9Ga4 catalyst demonstrated a high-power (∼200 W) electrolysis capability with excellent electrochemical stability.

8.
Phys Rev Lett ; 131(2): 026701, 2023 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-37505968

RESUMO

In kagome metal CsV_{3}Sb_{5}, multiple intertwined orders are accompanied by both electronic and structural instabilities. These exotic orders have attracted much recent attention, but their origins remain elusive. The newly discovered CsTi_{3}Bi_{5} is a Ti-based kagome metal to parallel CsV_{3}Sb_{5}. Here, we report angle-resolved photoemission experiments and first-principles calculations on pristine and Cs-doped CsTi_{3}Bi_{5} samples. Our results reveal that the van Hove singularity (vHS) in CsTi_{3}Bi_{5} can be tuned in a large energy range without structural instability, different from that in CsV_{3}Sb_{5}. As such, CsTi_{3}Bi_{5} provides a complementary platform to disentangle and investigate the electronic instability with a tunable vHS in kagome metals.

9.
Phys Chem Chem Phys ; 25(15): 10561-10566, 2023 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-36988073

RESUMO

Based on first-principles calculations and symmetry analysis, we propose that trigonal CaI2 with the space group P3̄m1 possesses straight and twisted open nodal-line phonon states with linear dispersion. The symmetry analysis indicates that joint symmetry PT and rotational symmetry C3z protect the straight nodal lines along Γ-A and K-H while PT and mirror symmetry M010 (M110) maintain the twisted nodal lines that traverse Γ-M (Γ-K) and A-L (A-H). The calculated π Berry phase suggests that all the nodal lines are nontrivial and the corresponding drumhead-like surface states are clearly visible in the observation window, which is less than 6 THz, suggesting a significant chance for them to be measured using meV-resolution inelastic X-ray scattering. The distribution of the nodal lines in the Brillouin zone is also confirmed by the phononic tight-binding model. Furthermore, the isostructural compounds MgBr2 and MgI2 show similar phonon spectra and topological nontrivial surface states. This work provides promising candidates for investigating straight and twisted open nodal-line phonon states in a single material, which will facilitate future experimental observation.

10.
Int J Mol Sci ; 24(23)2023 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-38068902

RESUMO

Food-based carbon dots (CDs) hold significant importance across various fields, ranging from biomedical applications to environmental and food industries. These CDs offer unique advantages over traditional carbon nanomaterials, including affordability, biodegradability, ease of operation, and multiple bioactivities. This work aims to provide a comprehensive overview of recent developments in food-based CDs, focusing on their characteristics, properties, therapeutic applications in biomedicine, and safety assessment methods. The review highlights the potential of food-based CDs in biomedical applications, including antibacterial, antifungal, antivirus, anticancer, and anti-immune hyperactivity. Furthermore, current strategies employed for evaluating the safety of food-based CDs have also been reported. In conclusion, this review offers valuable insights into their potential across diverse sectors and underscores the significance of safety assessment measures to facilitate their continued advancement and application.


Assuntos
Nanoestruturas , Pontos Quânticos , Pontos Quânticos/uso terapêutico , Carbono , Nanoestruturas/uso terapêutico , Antifúngicos , Antibacterianos
11.
Angew Chem Int Ed Engl ; 62(5): e202217071, 2023 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-36468671

RESUMO

The electrochemical nitrate reduction reaction (NO3 RR) is an appealing technology for regulating the nitrogen cycle. Metallic iron is one of the well-known electrocatalysts for NO3 RR, but it suffers from poor durability due to leaching and oxidation of iron during the electrocatalytic process. In this work, a graphene-nanochainmail-protected iron nanoparticle (Fe@Gnc) electrocatalyst is reported. It displays superior nitrate removal efficiency and high nitrogen selectivity. Notably, the catalyst delivers exceptional stability and durability, with the nitrate removal rate and nitrogen selectivity remained ≈96 % of that of the first time after up to 40 cycles (24 h for one cycle). As expected, the conductive graphene nanochainmail provides robust protection for the internal iron active sites, allowing Fe@Gnc to maintain its long-lasting electrochemical nitrate catalytic activity. This research proposes a workable solution for the scientific challenge of poor lasting ability of iron-based electrocatalysts in large-scale industrialization.

12.
Molecules ; 26(20)2021 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-34684677

RESUMO

Two new phthalide derivatives, rhytidhylides A (1) and B (2), together with ten known compounds (3-12) were isolated from cultures of Rhytidhysteron sp. BZM-9, an endophyte isolated from the leaves of Leptospermum brachyandrum. Their structures were identified by an extensive analysis of NMR, HRESIMS, ECD, and through comparison with data reported in the literature. In addition, the cytotoxic activities against two human hepatoma cell lines (HepG2 and SMMC7721) and antibacterial activities against MRSA and E. coli were evaluated.


Assuntos
Ascomicetos/química , Benzofuranos/isolamento & purificação , Benzofuranos/efeitos adversos , Benzofuranos/farmacologia , Linhagem Celular Tumoral/efeitos dos fármacos , Endófitos/química , Escherichia coli/efeitos dos fármacos , Humanos , Leptospermum/microbiologia , Estrutura Molecular
13.
Molecules ; 26(17)2021 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-34500834

RESUMO

Four new biflavonoids (1-4) were isolated from Selaginella doederleinii together with a known biflavonoid derivative (5). Their structures contained a rare linker of individual flavones to each other by direct C-3-O-C-4''' bonds, and were elucidated by extensive spectroscopic data, including HRESIMS, NMR and ECD data. All isolates significantly inhibited the proliferation of NSCLC cells (IC50 = 2.3-8.4 µM) with low toxicity to non-cancer MRC-5 cells, superior to the clinically used drug DDP. Furthermore, the most active compound 3 suppressed XIAP and survivin expression, promoted upregulation of caspase-3/cleaved-caspase-3, as well as induced cell apoptosis and cycle arrest in A549 cells. Together, our findings suggest that 3 may be worth studying further for intervention of NSCLC.


Assuntos
Biflavonoides/química , Selaginellaceae/química , Células A549 , Antineoplásicos/química , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Biflavonoides/farmacologia , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Ciclo Celular/efeitos dos fármacos , Humanos , Neoplasias Pulmonares/metabolismo
14.
Environ Sci Technol ; 53(19): 11597-11612, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31448908

RESUMO

A cascade-arch-firing low-NOx and high-burnout configuration (CLHC) was proposed as a solution for the W-shaped flame furnace's incompatibility problem of strengthened low-NOx combustion and high burnout. Numerical simulations verified by industrial-size measurements of a 600 MWe W-shaped flame furnace were used to confirm the CLHC's low-NOx and high-burnout characteristics and evaluate its cascade-arch configuration effect on the gas/particle flow, coal combustion, and NOx formation. The furnace with the existing low-NOx combustion art showed NOx emissions of about 900 mg/m3 at 6% O2 and carbon in fly ash of about 5%. In applying CLHC as a replacement for the prior art, numerical simulations at typical cascade-arch configurations of CL = 1/5, 1/4, and 1/3 (CL signifying the ratio of the lower arch depth to the total arch depth) showed that as CL increased, both the flow field and combustion symmetry initially improved but then deteriorated. In conjunction with the improvement in both NOx emissions and burnout, the CL = 1/4 setting achieved the best furnace performance with NOx emissions 707 mg/m3 at 6% O2 and carbon in fly ash of 5.5%. In comparison with the prior low-NOx art, CLHC reduced further NOx emissions by 22% and almost maintains the burnout rate.


Assuntos
Poluentes Atmosféricos , Esgotamento Psicológico , Carbono , Carvão Mineral , Cinza de Carvão
15.
Small ; 12(41): 5656-5675, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27717177

RESUMO

Electrocatalysts are playing a prominent role in the design of renewable energy devices. Benefiting from a long and prosperous history of synthesizing individual hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) electrocatalysts, the development of bifunctional ORR/OER or HER/OER electrocatalysts has recently emerged as a new research hotspot. In this review, a brief account of recent developments of bifunctional electrocatalysts for ORR/OER and HER/OER are introduced, aiming to provide insights into theoretical understanding of these reactions through analysis and comparison of various bifunctional electrocatalysts. The related reaction mechanisms and the associated activity descriptors for aforementioned reactions in the recent literatures are also presented. Different series of bifunctional electrocatalysts with much improved performances are discussed in detail and their design principles are outlined. Finally, the existing challenges and the future effort directions for enhancing the performance of bifunctional electrocatalysts are proposed.

16.
Environ Sci Technol ; 50(3): 1604-10, 2016 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-26752460

RESUMO

To solve the water wall overheating in lower furnace, and further reduce NOx emissions and carbon in fly ash, continuous improvement of the previously proposed multiple injection and multiple staging combustion (MIMSC) technology lies on three aspects: (1) along the furnace arch breadth, changing the previously centralized 12 burner groups into a more uniform pattern with 24 burners; (2) increasing the mass ratio of pulverized coal in fuel-rich flow to that in fuel-lean flow from 6:4 to 9:1; (3) reducing the arch-air momentum by 23% and increasing the tertiary-air momentum by 24%. Industrial-size measurements (i.e., adjusting overfire air (OFA) damper opening of 20-70%) uncovered that, compared with the prior MIMSC technology, the ignition distance of fuel-rich coal/air flow shortened by around 1 m. The gas temperature in the lower furnace was symmetric and higher, the flame kernel moved upward and therefore made the temperature in near-wall region of furnace hopper decrease by about 400 °C, the water wall overheating disappeared completely. Under the optimal OFA damper opening (i.e, 55%), NOx emissions and carbon in fly ash attained levels of 589 mg/m(3) at 6% O2 and 6.18%, respectively, achieving NOx and carbon in fly ash significant reduction by 33% and 37%, respectively.


Assuntos
Poluição do Ar/prevenção & controle , Centrais Elétricas/instrumentação , Carbono/análise , Carvão Mineral , Cinza de Carvão , Indústrias , Tecnologia , Temperatura
17.
Nanotechnology ; 26(30): 304002, 2015 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-26150371

RESUMO

We prepared hierarchical Cu2O/CuO/Co3O4 core-shell nanowires (NWs) via a facile chemical deposition method followed by calcination for use as the electrode of supercapacitors. The Cu2O/CuO/Co3O4 electrode showed a specific capacitance of 318 F g(-1) at a current density of 0.5 A g(-1). 80% of the original specific capacitance was retained after 3000 cycles at a current density of 5 A g(-1). An asymmetric supercapacitor cell using Cu2O/CuO/Co3O4 NWs as the positive electrode and activated graphene as the negative electrode exhibited a maximum energy density of 12 Wh kg(-1). The electrochemical properties of the electrode were strongly related to the hierarchical nanostructure, which not only provided rich active sites but also shortened ion transport pathways.

18.
Environ Sci Technol ; 48(20): 12419-26, 2014 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-25256210

RESUMO

A 600 MW(e) down-fired pulverized-coal supercritical boiler, which was equipped with a deep-air-staging combustion system for reducing the particularly high NOx emissions, suffered from the well-accepted contradiction between low NOx emissions and high carbon in fly ash, in addition to excessively high gas temperatures in the hopper that jeopardized the boiler's safe operations. Previous results uncovered that under low-NOx conditions, strengthening the staged-air effect by decreasing the staged-air angle and simultaneously increasing the staged-air damper opening alleviated the aforementioned problems to some extent. To establish low-NOx and high-burnout circumstances and control the aforementioned hopper temperatures, a further staged-air retrofit with horizontally redirecting staged air through an enlarged staged-air slot area was performed to greatly strengthen the staged-air effect. Full-load industrial-size measurements were performed to confirm the availability of this retrofit. The present data were compared with those published results before the retrofit. High NOx emissions, low carbon in fly ah, and high hopper temperatures (i.e., levels of 1036 mg/m(3) at 6% O2, 3.72%, and about 1300 °C, respectively) appeared under the original conditions with the staged-air angle of 45° and without overfire air (OFA) application. Applying OFA and reducing the angle to 20° achieved an apparent NOx reduction and a moderate hopper temperature decrease while a sharp increase in carbon in fly ash (i.e., levels of 878 mg/m(3) at 6% O2, about 1200 °C, and 9.81%, respectively). Fortunately, the present staged-air retrofit was confirmed to be applicable in regulating low-NOx, high-burnout, and low hopper temperature circumstances (i.e., levels of 867 mg/m(3) at 6% O2, 5.40%, and about 1100 °C, respectively).


Assuntos
Poluentes Atmosféricos/análise , Carbono/análise , Cinza de Carvão/análise , Óxidos de Nitrogênio/análise , Centrais Elétricas , Carvão Mineral , Temperatura Alta
19.
Environ Sci Technol ; 48(1): 837-44, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24274316

RESUMO

Deep-air-staging combustion conditions, widely used in tangential-fired and wall-arranged furnaces to significantly reduce NOx emissions, are premature up to now in down-fired furnaces that are designed especially for industry firing low-volatile coals such as anthracite and lean coal. To uncover combustion and NOx emission characteristics under deep-air-staging conditions within a newly operated 600 MWe down-fired furnace and simultaneously understand the staged-air effect on the furnace performance, full-load industrial-size measurements taken of gas temperatures and species concentrations in the furnace, CO and NOx emissions in flue gas, and carbon in fly ash were performed at various staged-air damper openings of 10%, 20%, 30%, and 50%. Increasing the staged-air damper opening, gas temperatures along the flame travel (before the flame penetrating the staged-air zone) increased initially but then decreased, while those in the staged-air zone and the upper part of the hopper continuously decreased and increased, respectively. On opening the staged-air damper to further deepen the air-staging conditions, O2 content initially decreased but then increased in both two near-wall regions affected by secondary air and staged air, respectively, whereas CO content in both two regions initially increased but then decreased. In contrast to the conventional understanding about the effects of deep-air-staging conditions, here increasing the staged-air damper opening to deepen the air-staging conditions essentially decreased the exhaust gas temperature and carbon in fly ash and simultaneously increased both NOx emissions and boiler efficiency. In light of apparently low NOx emissions and high carbon in fly ash (i.e., 696-878 mg/m(3) at 6% O2 and 9.81-13.05%, respectively) developing in the down-fired furnace under the present deep-air-staging conditions, further adjustments such as enlarging the staged-air declination angle to prolong pulverized-coal residence times in the furnace should be considered to improve the deep-air-staging combustion configuration.


Assuntos
Poluentes Atmosféricos/análise , Ar , Carvão Mineral/análise , Temperatura Alta , Nitratos/análise , Nitritos/análise , Centrais Elétricas/instrumentação , Gases/análise
20.
Nat Commun ; 15(1): 2110, 2024 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-38454003

RESUMO

Pilot-diesel-ignition ammonia combustion engines have attracted widespread attentions from the maritime sector, but there are still bottleneck problems such as high unburned NH3 and N2O emissions as well as low thermal efficiency that need to be solved before further applications. In this study, a concept termed as in-cylinder reforming gas recirculation is initiated to simultaneously improve the thermal efficiency and reduce the unburned NH3, NOx, N2O and greenhouse gas emissions of pilot-diesel-ignition ammonia combustion engine. For this concept, one cylinder of the multi-cylinder engine operates rich of stoichiometric and the excess ammonia in the cylinder is partially decomposed into hydrogen, then the exhaust of this dedicated reforming cylinder is recirculated into the other cylinders and therefore the advantages of hydrogen-enriched combustion and exhaust gas recirculation can be combined. The results show that at 3% diesel energetic ratio and 1000 rpm, the engine can increase the indicated thermal efficiency by 15.8% and reduce the unburned NH3 by 89.3%, N2O by 91.2% compared to the base/traditional ammonia engine without the proposed method. At the same time, it is able to reduce carbon footprint by 97.0% and greenhouse gases by 94.0% compared to the traditional pure diesel mode.

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