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The catalytic oxidation of formaldehyde to CO2 and H2O under low temperature is of great significance and insistent demand for indoor air purification. In this work, through alkali metal doping, we significantly improved the formaldehyde oxidation activity of Mn-based catalysts. At a temperature as low as 97 °C, 300 ppm of formaldehyde can be completely eliminated over 5%Cs/MnOx. The results showed that the presence of alkali metals markedly increased the redox ability of MnOx catalyst and the proportion of reactive oxygen species. The adsorption and reaction path of formaldehyde on the surface of the catalysts were studied by in-situ infrared spectroscopy. It was found that the adsorption form of formaldehyde on the surface of alkali metals doped MnOx catalyst was different from that of MnOx, except for monodentate formate detected over MnOx, more easily decomposed bridged adsorbed formate was another prominent adsorbed species over 5%Na/MnOx and 5%Cs/MnOx catalysts. The difference in reaction paths may be the key to the higher activities of alkali doped MnOx catalysts. This finding may provide some new ideas for the design of low temperature formaldehyde oxidation catalysts. The intermediate species during formaldehyde oxidation on MnOx and Na+/Cs+-doped MnOx are different, which may be the key reason why the latter exhibit higher activities than MnOx. [ABSTRACT FROM AUTHOR]

The catalytic production of aromatic azo compounds by aniline's oxidative coupling process is significant in organic synthesis. However, the catalysts used in this method generally exhibit low selectivity for the desired products and need costly preparation methods. In this study, for the first time, we proposed a species regulation strategy to synthesize the Rb-doped Cu/CeO2 nanorod catalyst, which showed high conversion (98%) and selectivity (95%) toward oxidative coupling of aniline to azoxybenzene using H2O2 as the oxidant. Aniline radical ion trapping experiments demonstrated that the oxidative coupling of aniline to azoxybenzene follows a nitrosobenzene intermediate mechanism. Characterization studies revealed that the addition of Rb not only enhances the interaction between Cu species and CeO2 but also increases oxygen vacancy content. DFT calculations indicate that the Cu–Ce and Rb–Ce interfaces are the main active sites, offering excellent catalytic performance. The reusability test for five cycles shows good stability of a Rb–Cu/CeO2 nanorod catalyst. The study provides a promising species regulation strategy for Rb-promoted nanocatalysts with ultrahigh selectivity, expanding their applicability in oxidative coupling and related reactions. [ABSTRACT FROM AUTHOR]

It is known that the insulator-metal transition occurs upon loading guest Na atoms into cages of the zeolite low silica X (LSX). In this study, the metallic and insulating phases of this material were investigated by the muon spin rotation (μ SR) method. We succeeded in detecting the muon frequency shift K μ for the insulating and metallic phases in low temperatures, which was not observed in the previous 23 Na-NMR measurements. Contribution to K μ , which is proportional to the density of state at the Fermi energy, is deduced to be 18±2% of that in the bulk metallic Na. [ABSTRACT FROM AUTHOR]

Solid state structural studies of three supramolecular coordination complexes establish the formation of hetero‐bimetallic two‐ and three‐dimensional ensembles involving sulfonated calix[4]arene, and sodium ions and low nuclearity lanthanide(III) ions. The interplay of components is altered in response to the addition of different auxiliary molecules during crystallisation which is associated with significant changes in the metal coordination environments and overall molecular packing, as established in comparing the structures of complexes of similar cell dimensions with those available in the literature. The sulfonated calixarene form a common self‐assembly array despite different lanthanides being incorporated, as an isostructural series of complexes. Crystallographic analysis shows a continually decreasing trend in the lanthanide–oxygen bond length as the lanthanide atomic number increases. As smaller molecules are incorporated to the hetero‐bimetallic calixarene system, the self‐assembly and the metal coordination environment are perturbed. [ABSTRACT FROM AUTHOR]

Ammonia decomposition to H2 (ADH) is one of the key reactions in the ammonia‐based energy system. Recent research has been focused on developing more active and affordable catalysts, however, few can operate below 500 °C and typically require the expensive metal ruthenium. Herein, a fundamentally different thermal ADH via a chemical looping process (CLADH) mediated by alkali metal and its amide pairs, which can work under lower temperatures than the catalytic process, is reported. This CLADH consists of two steps: 1) Ammoniation step ̶ NH3 reacts with Na or K to generate NaNH2 or KNH2, respectively, accompanied by releasing one‐third of H2 in NH3 at room temperature; 2) Decomposition step ̶ NaNH2 or KNH2 decomposes to N2 and H2 with the regeneration of Na or K which can be performed above 275 °C. Additionally, due to the significant enthalpy change in the two‐step reactions of this CLADH, −78.0 kJ mol−1 for the first step and 123.9 kJ mol−1 for the second, using the Na and NaNH2 pair—suggest potential for thermal energy storage. This work not only reports an alternative route to produce H2 from NH3, but also unravels the potential of chemical looping process for thermal energy storage. [ABSTRACT FROM AUTHOR]

An efficient and facile water dissociation process plays a crucial role in enhancing the activity of alkaline hydrogen evolution reaction (HER). Considering the intricate influence between interfacial water and intermediates in typical catalytic systems, meticulously engineered catalysts should be developed by modulating electron configurations and optimizing surface chemical bonds. Here, a high‐entropy double perovskite (HEDP) electrocatalyst La2(Co1/6Ni1/6Mg1/6Zn1/6Na1/6Li1/6)RuO6, achieving a reduced overpotential of 40.7 mV at 10 mA cm−2 and maintaining exemplary stability over 82 h in a 1 m KOH electrolyte is reported. Advanced spectral characterization and first‐principles calculations elucidate the electron transfer from Ru to Co and Ni positions, facilitated by alkali metal‐induced super‐exchange interaction in high‐entropy crystals. This significantly optimizes hydrogen adsorption energy and lowers the water decomposition barrier. Concurrently, the super‐exchange interaction enhances orbital hybridization and narrows the bandgap, thus improving catalytic efficiency and adsorption capacity while mitigating hysteresis‐driven proton transfer. The high‐entropy framework also ensures structural stability and longevity in alkaline environments. The work provides further insights into the formation mechanisms of HEDP and offers guidelines for discovering advanced, efficient hydrogen evolution catalysts through super‐exchange interaction. [ABSTRACT FROM AUTHOR]

Benzoate substituted with a cationic quaternary ammonium group at the para‐position, [4‐(CH3)3N(C6H4)CO2], forms mononuclear alkali metal ion complexes, [4‐(CH3)3N(C6H4)CO2M]+ (M=Li, Na, K, Rb and Cs), which are observed by electrospray‐ionisation mass spectrometry. When mass selected and subjected to collision‐induced dissociation each of these complexes undergoes decarboxylation to produce the mononuclear arylalkali complex cations, [4‐(CH3)3N(C6H4)M]+, which subsequently react with water via hydrolysis to yield the quaternary ammonium cation, (CH3)3NC6H5+. The unexpected product ions, [M((CH3)2NC6H5)]+, [M(CH3OH)]+, and M+, which are associated with the hydrolysis pathway, suggest an unusual reaction occurring within the exit channel ion‐molecule complex, [(CH3)3NC6H5+MOH]+. DFT calculations were used to examine the: decarboxylation reaction of [4‐(CH3)3N(C6H4)CO2M]+, which readily proceeds via a four‐centred transition state; the hydrolysis and SN2 reactions accounting for formation of products in the exit channel, which are connected via a roaming mechanism in which the metal hydroxide moiety migrates from the para‐hydrogen of (CH3)3NC6H5+ to one of the methyl groups. [ABSTRACT FROM AUTHOR]

The application of non-noble metal catalysts in the catalytic direct gas-phase epoxidation of propylene with H2 and O2 to produce propylene oxide is valuable and challenging. The introduction of alkali metal promoters is one of the effective methods to improve the catalytic activity of catalysts. Herein, a series of alkali metal (Li, Na, K, Rb, and Cs)-promoted Ni/TS-1 catalysts were prepared to deeply understand the effect of alkali metals on the structure-activity relationship for gas-phase epoxidation of propylene. Among them, the Na-Ni/TS-1 catalyst exhibits the highest catalytic activity (propylene conversion of 7.35% and PO formation rate of 157.9 g h−1 kgcat−1) and the best stability (long-term stability exceeding 140 h at 200 °C). X-ray absorption and photoelectron spectroscopy revealed that the electronic structure of Ni can be tuned by the addition of alkali metal promoters. NH3-TPD-MS, CO2-TPD-MS, and C3H6-TPD-MS results indicate that the acidity of the catalyst can also be adjusted by the introduction of alkali metal, whereas the Na-Ni/TS-1 catalyst exhibits the strongest C3H6 adsorption capacity. Thus, the suitable acid-base properties, unique electronic properties of Ni species, and the strongest propylene adsorption capacity resulted in improved propylene gas-phase epoxidation activity of Na-Ni/TS-1 catalyst. This study not only provides a new strategy for the practical application of nickel-based catalysts in the gas-phase epoxidation of propylene but also provides insights into the promoting effect of alkali metals. [ABSTRACT FROM AUTHOR]

BACKGROUND: Magnesium oxide (MgO) is favored for solid‐state carbon dioxide (CO2) capture due to its high theoretical adsorption capacity, abundant reserves, low cost, and environmental friendliness. However, its practical application in industry is hindered by low CO2 adsorption capacity under moderate operating conditions. In this work, MgO was modified by a deposition method using LiNO3, NaNO3, KNO3, Na2CO3 and K2CO3 as additives. RESULTS: The study determines optimal ratios within the [(Li, Na, K)x − (Na, K)]y/MgO system, specifically identifying x = 0.5 and y = 0.15 as most effective. At 275 °C under pure CO2 conditions, the adsorption capacity peaks at 0.631 g CO2 g−1 adsorbent. Effective regeneration of the adsorbent occurs at 400 °C under 100% N2 for 15 min. Under Integrated Gasification Combined Cycle (IGCC) conditions, the adsorption capacity stabilizes at 0.462 g g−1 after 20 cycles, representing a 25% decrease from initial capacity. CONCLUSION: Experimental findings demonstrate that the inclusion of alkali metal salts in MgO precursors enhances the adsorbent's microstructure, thereby improving its CO2 capture efficiency and bolstering cycling stability. This research enhances our understanding of the factors influencing CO2 adsorption and cyclic stability in alkali metal salt‐promoted MgO, providing valuable insights for further refinement in the formulation and synthesis protocols of MgO‐based CO2 adsorbents. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

In order to alleviate the influence of greenhouse effect on global climate change, the effective utilization of CO2 to prepare fine chemicals should be paid more attention to, however, which is greatly blocked by the catalyst with low efficiency. Here, alkali metal (Li, Na, or K) are employed as a modification aid to prepare CuO/ZrO2 catalyst for CO2 hydrogenation to methanol. The effects of alkali metal on physicochemical properties and catalytic activities of CuO/ZrO2 catalyst were studied in detail by the XRD, N2‐physisorption, ICP‐OES, SEM/EDS, H2/N2O/CO2/NH3‐chemisorption, and evaluation test. The results verified that the use of complex combustion method enabled the uniform combination of all components in precursor. High‐temperature calcination (700 °C) further enhanced the strong interaction and synergistic effect between Cu and ZrO2. Most importantly, the introduction of alkali metal effectively altered the structure and catalytic activity of CuO/ZrO2 catalysts. However, the selectivity to methanol increased while the CO2 conversion decreased regardless of different kinds of alkali metal being introduced to the CuO/ZrO2 catalysts. For example, CuO/ZrO2 catalyst modified by K exhibited excellent performance for methanol production that 98.9% selectivity of methanol based on 8.8% conversion of CO2 after 48 h online reaction. [ABSTRACT FROM AUTHOR]

Lithium (Li) is the lightest metal in existence. Its effects on higher plants are still under discussion because both positive and toxic results have been reported in different species. In the last decade, the use of Li has increased considerably, and it is projected that Li waste will be an environmental problem in the near future, such that various organisms, including plants, may be altered by its presence. Interestingly, Li can trigger hormesis, with beneficial effects at low doses and inhibitory or harmful effects at high doses. Currently, numerous research groups are focusing their studies on agriculture to obtain crops fortified with Li, which represents a nutritional advantage in food if adequate concentrations are used. However, more studies are still needed in order to understand the biochemical mechanisms of the effects of Li on plants. This review describes the natural and anthropogenic sources of Li, as well as the concentrations of this element in different environments. Regarding the uses of Li in different areas, topics related to doses that cause toxicity and lethality in humans are addressed. Given its impact on crop production, mechanisms of Li uptake and transport in higher plants are reviewed, as well as the effects on plant metabolism and physiology. Likewise, the perspective on the controlled use of Li in biostimulation and biofortification of crops is addressed. [ABSTRACT FROM AUTHOR]

A series of titanium μ2‐nitrido complexes supported by the triamidoamine ligand Xy‐N3N (Xy‐N3N={(3,5‐Me2C6H3)NCH2CH2}3N3−) is reported. The titanium azido complex [(Xy‐N3N)TiN3] (1‐N3), prepared by salt metathesis of the chloride complex [(Xy‐N3N)TiCl] (1‐Cl) with NaN3, reacted with lithium metal or with alkali metal naphthalenides (alkali metal M=Na, K, and Rb) in THF to give the corresponding dinuclear μ2‐nitrido complexes M[(Xy‐N3N)Ti=N‐Ti(Xy‐N3N)] (2‐M; M=Li, Na, K, Rb). Single crystal X‐ray diffraction studies of 2‐Li, 2‐Na, and 2‐K revealed alkali metal dependent structures in the solid state. While 2‐Li and 2‐K contain a μ2‐nitrido ligand with a linear Ti−N−Ti core, 2‐Na includes a μ3‐nitrido ligand as part of a T‐shape Ti2NaN fragment with the sodium cation weekly coordinated to the nitrido nitrogen atom. When the synthesis of the nitrido complexes was carried out in the presence of excess alkali metals, decomposition of the nitrido complexes was observed affording some intractable titanium species along with the trialkali metal salts [M3(Xy‐N3N)] (3‐M) (M=Li, Na, K, and Rb). These salts were also prepared by deprotonation of (Xy‐N3N)H3 with the corresponding alkali metal hexamethyldisilazide and characterized by multinuclear NMR spectroscopy as well as single crystal X‐ray diffraction. [ABSTRACT FROM AUTHOR]

During the operation of the waste liquid incinerator, the alkali metal slag might adhere to the surface of the refractory material to form an inhomogeneous solid slag layer, causing the furnace lining to be simultaneously corroded by three phases of alkali metals: vapor, molten salt, and slag. This phenomenon intensifies the damage to the refractory material. Therefore, this paper investigates the mass transfer and permeation process, phase change process and corrosion rate of Na 2 CO 3 inside corundum refractory materials in three phases: Na vapor, molten Na 2 CO 3 and Na-slag. The results showed that alkali vapor penetrated the interior through the pores, and the NaAlO 2 and β-Al 2 O 3 generated by the reaction led to the volume expansion and microcracks. Na vapor continued to penetrate the interior along the cracks and eroded the sample, and the higher the temperature the greater Na vapor penetration. In vapor phase corrosion, the effect of corrosion time on the erosion resistance of corundum refractories is less than that of temperature, and the increase in corrosion time does not lead to the formation of additional new phases. In the molten salt corrosion experiments, it was found that the molten salt corrosion was accompanied by vapor phase corrosion at 1100 °C, and the amount of Na 2 CO 3 has a greater effect on the corroded mass than the temperature. Comparing the corrosion of refractory materials by the three phases of Na 2 CO 3 , the molten salt corrosion rate was the highest, followed by the vapor phase corrosion, and finally the slag corrosion. It is concluded that the slag layer can effectively prevent the corrosion of the refractory material by alkali metal molten salts and vapors, thus prolonging the service life of refractories. [ABSTRACT FROM AUTHOR]

The combination of biomass and oxy-fuel combustion technology integrates the advantages of biomass combustion and carbon capture and storage (CCS) technology. Because of its ability to achieve "negative carbon emissions," it is widely considered one of the key technologies for eliminating atmospheric emissions and helping to achieve long-term decarbonization. However, problems such as ash deposition, slagging, and corrosion in combustion caused by a large amount of alkali metals in the biomass have limited the development of the technology. In this paper, an air-cooled steel probe in a drop tube furnace (DTF) was used as the simulation of heat transfer surface of biomass boilers to collect the deposits during biomass oxy-fuel combustion for analysis. Microscopic morphology and elements content of inner and outer layer of deposits were analyzed separately. K content and composition of the deposits were also analyzed. The effects of fuel particle size, combustion temperature, combustion atmosphere, and probe surface temperature on ash deposition were investigated. The results showed that the use of coarse-grained fuels produced a more complete inner layer of KCl, while fine-grained fuels significantly increased the mass of deposits. Combustion temperatures below 800 °C could reduce K content and ash deposition rate. Oxy-fuel combustion promoted sulphuration reactions compared to air combustion. Higher oxygen fraction increased the weight of deposits but reduced the K content. Probe surface temperature had a signification effect on the distribution of ash on the probe surface. [ABSTRACT FROM AUTHOR]

Copyright of Integrated Intelligent Energy is the property of Editorial Department of Integrated Intelligent Energy and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Alkali contents with low melting points in the ash of woody biomass vaporize during the biomass gasification process, damaging various downstream energy conversion devices, such as the solid oxide fuel cells (SOFCs). In this study, the degradation of SOFC anodes by the deposition of potassium compounds (KCl, K2CO3, and KOH) was investigated. An aqueous solution of potassium compounds was dripped onto the anode surface of the SOFC button cell at room temperature. After drying at 343 K, 6.964 × 10-6 mol KCl, 6.964 × 10-6 mol KOH, and 3.482 × 10-6 mol K2CO3 was deposited on the anode. Button cells with the deposition of K compounds were employed for power generation experiments at 1023 K with the supply of artificial syngas from biomass gasification. After the power generation experiments, the surface structures of the anodes were microscopically analyzed using the SEM and EDS. As a result, K compounds hardly affected the OCV of SOFC. With the addition of KCl, no apparent change in the anode structure was observed, and only a slight KCl deposit was detected. However, chloride tends to be chemisorbed on Ni, increasing the ohmic resistance as well as the adsorption/desorption resistance. However, KOH transformed to K2CO3 and then remained massively on the anode, which was clearly observed in the SEM images. K2CO3 significantly decreased the cell voltage under a current density of 100 mA·cm−2. Through impedance analyses, this voltage drop was mainly attributed to the ohmic resistance and gas diffusion resistance. However, there is no evidence that this deposit degrades Ni particles.

We herein report that the highly hydrophobic ether 4‐MeTHP constitutes a promising resource for the development of sustainable synthetic methodologies grounded on the use of organometallic reagents. The beneficial effects of 4‐MeTHP as reaction medium are illustrated in the organolithium‐promoted anionic ortho‐Fries rearrangement of 1,1'‐bi‐2‐naphthol (BINOL)‐based carbamates under bench‐type conditions. The use of 4‐MeTHP induces a remarkable and unexpected stability of the organolithiums species, enabling the efficient preparation of chiral (bis)carboxamide catalysts. Furthermore, superior performances of 4‐MeTHP than other environmentally responsible solvents are observed using the synthesized BINOL catalysts in the asymmetric addition of organozinc reagents to aldehydes. Spectroscopic studies in solution suggest that 4‐MeTHP plays a key role in these reactions by inducing the preferential formation of a reactive monomeric dinuclear complex. This methodology allows for the asymmetric assembly of enantioenriched secondary alcohols in good yields and high stereoselectivity, working at 0 °C and under air. [ABSTRACT FROM AUTHOR]

This work highlights the novel approach of incorporating potassium iodide (KI) doping during the synthesis of In0.53P0.47 core quantum dots (QDs) to significantly reduce the concentration of vacancies (i.e., In vacancies; VIn−) within the bulk of the core QD and inhibit the formation of InPOx at the core QD–Zn0.6Se0.4 shell interfaces. The photoluminescence quantum yield (PLQY) of ~97% and full width at half maximum (FWHM) of ~40 nm were achieved for In0.53P0.47/Zn0.6Se0.4/Zn0.6Se0.1S0.3/Zn0.5S0.5 core/multi-shell QDs emitting red light, which is essential for a quantum-dot organic light-emitting diode (QD-OLED) without red, green, and blue crosstalk. KI doping eliminated VIn− in the core QD bulk by forming K+-VIn− substitutes and effectively inhibited the formation of InPO4(H2O)2 at the core QD–Zn0.6Se0.4 shell interface through the passivation of phosphorus (P)-dangling bonds by P-I bonds. The elimination of vacancies in the core QD bulk was evidenced by the decreased relative intensity of non-radiative unpaired electrons, measured by electron spin resonance (ESR). Additionally, the inhibition of InPO4(H2O)2 formation at the core QD and shell interface was confirmed by the absence of the {210} X-ray diffraction (XRD) peak intensity for the core/multi-shell QDs. By finely tuning the doping concentration, the optimal level was achieved, ensuring maximum K-VIn− substitution, minimal K+ and I− interstitials, and maximum P-dangling bond passivation. This resulted in the smallest core QD diameter distribution and maximized optical properties. Consequently, the maximum PLQY (~97%) and minimum FWHM (~40 nm) were observed at 3% KI doping. Furthermore, the color gamut of a QD-OLED display using R-, G-, and B-QD functional color filters (i.e., ~131.1%@NTSC and ~98.2@Rec.2020) provided a nearly perfect color representation, where red-light-emitting KI-doped QDs were applied. [ABSTRACT FROM AUTHOR]

Alkaline earth metal (Mg2+, Ca2+, Sr2+, Ba2+) complexes of guanine (Gu), a purine-based nucleobase were synthesized. The characterization of these complexes involved elemental analysis (CHN), determination of metal and chloride contents, FTIR, UV–Visible, 1H-NMR spectroscopy, thermal analysis (TGA, DSC), molar conductance, and PXRD measurements. Based on the elemental analysis, the molecular formulae of the complexes were proposed as [Mg(Gu)2Cl2]·4H2O, [Ca(Gu)2Cl2]·3H2O, [Sr(Gu)3Cl2]·5H2O and [Ba(Gu)3Cl2](Gu)·5H2O. The molar conductance measurement showed that the complexes were non-electrolytic. The mode of chelation of guanine through N(7) and O(6) sites was explained using FTIR and 1H-NMR spectral analysis. Thermal analysis in a nitrogen atmosphere showed that the complexes were fairly stable up to 100 °C, with decomposition starting above this temperature and indicating the presence of hydrated water. The crystallite size, microstrain, and dislocation density of the complexes were determined using XRD data. The antibacterial and antifungal activities of guanine and its complexes were screened against five gram-positive, eight gram-negative bacteria, and three fungi. Guanine did not exhibit any antibacterial activity, while the metal complexes showed significant antibacterial and antifungal activities. In vitro cytotoxicity testing revealed that the alkaline earth metal complexes exhibited potential cytotoxic activity, with LC50 values ranging from 18.55 to 40.61 µg mL−1. HeLa cervical cancer cell lines were used to investigate the anticancer activity of metal complexes, and each complex demonstrated cytotoxicity toward HeLa cell lines. [ABSTRACT FROM AUTHOR]

Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Combining biomass co-firing with oxy-fuel combustion is a promising Bioenergy with Carbon Capture and Storage (BECCS) technology. It has the potential to achieve a large-scale reduction in carbon emissions from traditional power plants, making it a powerful tool for addressing global climate change. However, mercury in the fuel can be released into the flue gas during combustion, posing a significant threat to the environment and human health. More importantly, mercury can also cause the fracture of metal equipment via amalgamation, which is a major risk for the system. Therefore, compared to conventional coal-fired power plants, the requirements for the mercury concentration in BECCS systems are much stricter. This article reviews the latest progress in mercury control under oxy-fuel biomass co-firing conditions, clarifies the impact of biomass co-firing on mercury species transformation, reveals the influence mechanisms of various flue gas components on elemental mercury oxidation under oxy-fuel combustion conditions, evaluates the advantages and disadvantages of various mercury removal methods, and finally provides an outlook for mercury control in BECCS systems. Research shows that after biomass co-firing, the concentrations of chlorine and alkali metals in the flue gas increase, which is beneficial for homogeneous and heterogeneous mercury oxidation. The changes in the particulate matter content could affect the transformation of gaseous mercury to particulate mercury. The high concentrations of CO2 and H2O in oxy-fuel flue gas inhibit mercury oxidation, while the effects of NOx and SO2 are dual-sided. Higher concentrations of fly ash in oxy-fuel flue gas are conducive to the removal of Hg0. Additionally, under oxy-fuel conditions, CO2 and metal ions such as Fe2+ can inhibit the re-emission of mercury in WFGD systems. The development of efficient adsorbents and catalysts is the key to achieving deep mercury removal. Fully utilizing the advantages of chlorine, alkali metals, and CO2 in oxy-fuel biomass co-firing flue gas will be the future focus of deep mercury removal from BECCS systems. [ABSTRACT FROM AUTHOR]

In recent years, climate change has increasingly become one of the major challenges facing mankind today, seriously threatening the survival and sustainable development of mankind. Dramatically increasing carbon dioxide concentrations are thought to cause a severe greenhouse effect, leading to severe and sustained global warming, associated climate instability and unwelcome natural disasters, melting glaciers and extreme weather patterns. The treatment of flue gas from thermal power plants uses carbon capture, utilization, and storage (CCUS) technology, one of the most promising current methods to accomplish significant CO2 emission reduction. In order to implement the technological and financial system of CO2 capture, which is the key technology of CCUS technology and accounts for 70–80% of the overall cost of CCUS technology, it is crucial to create more effective adsorbents. Nowadays, with the development and application of various carbon dioxide capture materials, it is necessary to review and summarize carbon dioxide capture materials in time. In this paper, the main technologies of CO2 capture are reviewed, with emphasis on the latest research status of CO2 capture materials, such as amines, zeolites, alkali metals, as well as emerging MOFs and carbon nanomaterials. More and more research on CO2 capture materials has used a variety of improved methods, which have achieved high CO2 capture performance. For example, doping of layered double hydroxides (LDH) with metal atoms significantly increases the active site on the surface of the material, which has a significant impact on improving the CO2 capture capacity and performance stability of LDH. Although many carbon capture materials have been developed, high cost and low technology scale remain major obstacles to CO2 capture. Future research should focus on designing low-cost, high-availability carbon capture materials. [ABSTRACT FROM AUTHOR]

Copyright of Chemical Engineering (China) / Huaxue Gongcheng is the property of Hualu Engineering Science & Technology Co Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Lead‐free metal halide double perovskites have emerged as promising scintillators owing to their superior optoelectronic properties, low‐cost and solution processability. However, it is still challenging to develop high‐performance flexible X‐ray scintillators based on the B(I)‐site alkali metal modulation in lead‐free double perovskite nanocrystals (NCs). Herein, a series of novel Cs2B(I)GdCl6 (B: Li, Na, K) of double perovskite A2B(I)M(III)X6 NCs structures are successfully synthesized, the optical and scintillator properties of which are significantly sensitive to the B(I)‐site alkali metals with the doping of Sb3+. They showed efficient self‐trapped exciton (STE) emission with high photoluminescence quantum yield (PLQY) and exhibited the highest X‐ray detection limit (86 nGyair s−1) and excellent spatial resolutions (>15 lp mm−1). The femtosecond transient absorption measurement and theoretical analysis further revealed that the B(I)‐site alkali metal fundamentally balanced the exciton–phonon coupling with appropriate STEs formation energy barrier and the electron localization and thus improved the optical and scintillator properties. This B(I)‐site alkali metal engineering offers a strategy to develop bright luminescent double perovskite NCs for X‐ray detection and imaging devices. [ABSTRACT FROM AUTHOR]

Inorganic metal halide perovskite CsPbX3 (X = I, Br, and Cl) nanocrystals (NCs) are rapidly developed due to their excellent photophysical properties and potential applications in lighting, lasers, and scintillators. However, the materials for growing perovskite NCs are insoluble or hydrolyzed in most green solvents, limiting their further development. Based on rational chemical analysis, an alkali‐metal–assisted green‐solvent synthesis method for in situ growth of CsPbBr3 NCs within SAPO‐34 zeolite with bright luminescence is developed. Water is the only solvent used in the whole process. Surprisingly, by the synergistic effect of the channel structure of SAPO‐34 and alkali‐metal ions crystallization regulation, the CsPbBr3 NCs embedded in SAPO‐34 assisted by Na+ emit bright blue light under ultraviolet illumination, with a 30 nm blue shift comparing to the CsPbBr3 NCs assisted by K+. Moreover, CsPbBr3 NCs can also be grown in mesoporous SiO2 SBA‐15 and zeolites including ZSM‐5, AlPO‐5, and SOD, indicating that the method is universal for in situ growth of luminescent perovskite NCs in porous materials. This alkali‐metal–assisted green‐solvent synthesis provides a new strategy for developing high‐quantum–yield, tunable‐emission, and stable perovskite luminescent materials. [ABSTRACT FROM AUTHOR]

Planar hypercoordination has sparkled interest among the researchers from last few decades. Most of the elements in the Periodic Table have shown this remarkable structural feature. However, the smallest element, hydrogen, is missing in the list. No evidence is there in the literature. Herein, we introduce the first planar pentacoordinate hydrogen atom (ppH) in the global minimum geometry of Li5H6− cluster. Bonding analysis indicates that the central hydrogen atom is stabilized by multicentre bonding with five surrounding Li atoms. Natural charge analysis reveals that the central hydrogen is acting like a hydride which is strongly attracted by the positively charged surrounding lithium centres. The ppH structure is stabilized by strong electrostatic attraction as well as extensive multicentre bonding. Aromaticity has no role to play here. The cluster is dynamically stable and is expected to be detected in gas phase. [ABSTRACT FROM AUTHOR]

The structures of five ammonium salt forms of monosulfonated azo dyes, derivatives of 4‐(2‐phenyldiazen‐1‐yl)benzenesulfonate, with the general formula [NH4][O3S(C6H4)NN(C6H3)RR′]·XH2O [R = OH, NH2 or N(C2H4OH)2; R′ = H or OH] are presented. All form simple layered structures with alternating hydrophobic (organic) and hydrophilic (cation, solvent and polar groups) layers. To assess for isostructural behaviour of the ammonium cation with M+ ions, the packing of these structures is compared with literature examples. To aid this comparison, the corresponding structures of four potassium salt forms of the monosulfonated azo dyes are also presented herein. Of the five ammonium salts it is found that three have isostructural equivalents. In two cases this equivalent is a potassium salt form and in one case it is a rubidium salt form. The isostructurality of ion packing and of unit‐cell symmetry and dimensions tolerates cases where the ammonium ions form somewhat different interaction types with coformer species than do the potassium or rubidium ions. No sodium salt forms are found to be isostructural with any ammonium equivalent. However, similarities in the anion packing within a single hydrophobic layer are found for a group that consists of the ammonium and rubidium salt forms of one azo anion species and the sodium and silver salt forms of a different azo species. [ABSTRACT FROM AUTHOR]

The high content of water-soluble sodium, chlorine and sulfate ions in Xinjiang’s high-alkali coal seriously affects the clean and efficient utilization of Xinjiang’s coal. The combination mode of water-soluble elements in high-alkali coal and the influence on coal quality has become a basic problem to be solved in the scientific understanding and evaluation of Xinjiang’s coal. We collected coal seam and commercial coal samples from Dajing, Xiheishan, Santanghu, Naomaohu and Shaerhu mining areas in eastern Xinjiang, as well as surface soil overlying on the coal seams, roof and gangue samples in different mining areas, including surface salt rock samples from some mining areas. The content of water-soluble ions in relevant samples was determined by the leaching experiment. Based on the method of coal ash composition, proportion of water-soluble ions, water-soluble ions ratio parameter and Piper trilinear diagram, the difference of the combined characteristics of water-soluble elements in coal in different mining areas were analyzed. The possible causes and influencing factors of water-soluble elements in coal were discussed by comparing the variations of water-soluble ions in coal seams, other rock layers of coal-bearing strata and surface soil. The result shows that there are significant differences in the content and combination modes of water-soluble elements in coal from different mining areas in eastern Xinjiang, and the degree of difference in content can be about 3 times. In terms of combination modes, there are Cl-Na type and Cl·HCO3-Na type, as well as other types of combinations such as SO4-Na·Ca type and SO4·HCO3-Na type. The ratio parameters of various water-soluble ions show that there have been ion-exchange between water-soluble ions in the coal. The formation of high-alkali coal in Xinjiang is a modern geological processes currently still in development. There has been a distinct possibility that water-soluble ions in the salt rock and soil on the surface were carried gradually into the coal seams along with the groundwater infiltration, which leads to the formation of high-alkali coal, and the process is relatively complex. Affected by ion-exchange and precipitation, the combination forms and occurrence states of alkali metals, alkali earth metals, chlorine, sulfur and other elements in coal become more complex, but the water-soluble state is still the main form.

Lithium (Li) is the lightest metal in existence. Its effects on higher plants are still under discussion because both positive and toxic results have been reported in different species. In the last decade, the use of Li has increased considerably, and it is projected that Li waste will be an environmental problem in the near future, such that various organisms, including plants, may be altered by its presence. Interestingly, Li can trigger hormesis, with beneficial effects at low doses and inhibitory or harmful effects at high doses. Currently, numerous research groups are focusing their studies on agriculture to obtain crops fortified with Li, which represents a nutritional advantage in food if adequate concentrations are used. However, more studies are still needed in order to understand the biochemical mechanisms of the effects of Li on plants. This review describes the natural and anthropogenic sources of Li, as well as the concentrations of this element in different environments. Regarding the uses of Li in different areas, topics related to doses that cause toxicity and lethality in humans are addressed. Given its impact on crop production, mechanisms of Li uptake and transport in higher plants are reviewed, as well as the effects on plant metabolism and physiology. Likewise, the perspective on the controlled use of Li in biostimulation and biofortification of crops is addressed.

Lignin utilization is a potential approach for replacing fossil energy and releasing the environment pressure. Herein, we synthesized a series of novel Cu-based catalysts, Cu@NS-SiO2 (NS = nano sphere) and alkali metals (Na, K, Rb, and Cs) doped Cu@NS-SiO2, and applied them in hydrodeoxygenation reaction of anisole. High Cu dispersion was presented on all catalysts. The modification of alkali metals on Cu@NS-SiO2 significantly enhanced the electron density of Cu sites in the following order: Cs > Rb > K > Na, among which Cs decreased the Cu 2p3/2 binding energy most (by 0.7 eV). Moreover, the modification did not substantially affect the geometric structure of Cu species. This regulable electronic environment of Cu sites was crucial for selective deoxygenation and inhibiting the hydrogenation of aromatic rings in anisole, and thus promoted the selectivity of benzene. Compared with Cu@NS-SiO2 (∼59%), the highest benzene selectivity was obtained on Cs/10Cu@NS-SiO2 at ∼83%.

In the present work, the influence of alkali ions (Li, Na, K) on the structural and spectroscopic properties of silica glasses doped with Sm3+ was investigated. Infrared and Raman spectroscopy techniques were used to investigate the structural properties of the alkali silicate glasses. The optical absorption showed bands characteristic of Sm3+ ions in alkali silicate glasses, and this was investigated. The Judd–Ofelt theory was applied to evaluate the phenomenological intensity parameters (Ω2, Ω4, and Ω6) of the optical absorption measurements. The multi-channel visible and near infrared emission transitions originating from the 4G5/2-emitting state of the Sm3+ in alkali silicate glasses with a maximum phonon energy of ~1050 cm−1 were investigated. From the evaluated Judd–Ofelt parameters, radiative parameters such as spontaneous emission probabilities, radiative lifetimes, branching ratios, and stimulated emission cross-sections were calculated. The recorded luminescence spectra regions revealed intense green, orange, red, and near-infrared emission bands, providing new traces for developing tunable laser and optoelectronic devices.

Alkali-Metal-Thermal-Electric-Converter systems (AMTEC-systems) pose a promising approach for energy conversion, e.g. from waste heat. Central components are a gas-tight ion-conductive solid membrane and an enclosed porous electrode. The presented study covers an adapted synthesis routine for single-phase sodium-tritanate (Na2Ti3O7) and its assessment as an alternative AMTEC-membrane-material. In contrast to the conventional stoichiometric solid state reaction between sodium carbonate and titania, the adapted synthesis reaction was performed with sodium excess. Up to 900 °C, the as-synthesised material evinced both, a constant thermal expansion behaviour over various thermal cycles and an expected electric conductivity. More important, phase stability either in pure state as well as in contact with a potential electrode material (La0.8Sr0.2)0.98MnO3 was demonstrated by long term exposure at 900 °C over 240 h. According to those findings the synthesised Na2Ti3O7 is considered to be an alternative membrane-material for AMTEC-application.

The thermal polymerization controlled the thickness and composition of graphic carbon nitride (g-C 3 N 4) to affect the photocatalytic performance. In this paper, potassium and sodium ions were firstly incorporated in bulk g-C 3 N 4 prepared using melamine through a mechano-chemical pre-reaction. After a two-step thermal polymerization treatment at 500 and 550 °C, respectively, superior thin g-C 3 N 4 nanosheets were created because K or Na ions implanted between g-C 3 N 4 layers, in which activated cites were remained in the nanosheets. The results revealed that potassium or sodium ion doping revealed an important impact on the photocatalytic activity of g-C 3 N 4. With an optimized K loading of 3%, the hydrogen evolution rate of potassium doped g-C 3 N 4 superior thin nanosheets was 18.1 times of that of bulk g-C 3 N 4. For the degradation of the degradation rate of Rhodamine B (Rh B), K-doped g-C 3 N 4 sample revealed 3.8 times increase compared with pure g-C 3 N 4. To indicate the role of alkaline metal ions, Na-doped samples were also used for H 2 generation and Rh B degradation. Meanwhile, the hydrogen generation and Rh B degradation rate of sodium doped g-C 3 N 4 nanosheets improved to 3.6 and 1.75 times higher than those of pure g-C 3 N 4 , respectively. The result suggested a mechano-chemical pre-treatment helped K and Na ions to improve the microstructure of g-C 3 N 4 nanosheets and increase activated cites for photocatalysis. [Display omitted] • K and Na were firstly incorporated in precursors through a mechano-chemical pre-reaction. • The precursors were treated by a two-step thermal polymerization to get g-C 3 N 4 nanosheets. • The superior thin g-C 3 N 4 nanosheets revealed enhanced H 2 generation and RhB degradation. • Increased activated cites from volume and surface defects play important role during photocatalysis. [ABSTRACT FROM AUTHOR]

Alkali metal‐doped boron clusters have captured much attention because of their novel electronic properties and structural evolution. In the study of RbBn0/− (n = 2–12) clusters, the minimum global search of the potential energy surface and structure optimization at the level of PBE1PBE by using the CALYPSO method and Gaussian package coupled with DFT calculation; the geometrical structures and electronic properties are systematically investigated. At n = 8, the ground‐state structures are composed of an Rb atom above B atoms, forming a structurally stable pagoda cone. By stability analysis and charge transfer calculation, the RbB8− cluster shows more stability. It found that s‐p hybridization between Rb atom and B atoms as well as s‐p hybridization between B atoms is one of the reasons for the outstanding stability exhibited in the RbB80/− clusters by using DOS and HOMO–LUMO orbital contour maps. The chemical bonding of the RbB80/− groups was analyzed by using the AdNDP method, and B atoms with larger numbers readily form multi‐center chemical bonds with the Rb atom. From the results of the bonding analysis, the interaction between the Rb atom and B atoms strengthens the stability of the RbB80/− clusters. It is hoped that this work provides a direction for experimental manipulation. [ABSTRACT FROM AUTHOR]

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Heat pipe cooled reactors (HPCRs) have broad application prospects due to their advantages, such as high power density, compact structure, lower cost, and easy modular assembly. Numerous countries have engaged in extensive research and development of HPCR conceptual designs. The heat from the reactor is removed by high temperature heat pipes (HTHPs), which generally employ alkali metals as the working fluid, such as potassium, sodium, and lithium. Understanding the thermal-hydraulic performance of HTHPs is essential for the safe and efficient operation of a reactor. Therefore, the objective of this paper is to provide a comprehensive review of HPCR conceptual designs developed by various countries in recent years. The research progress of HTHPs on flow and heat transfer performance is reviewed, with an emphasis on both transient and steady-state characteristics. Research progress, as well as the issues that need to be focused on in future research, are discussed in detail. [ABSTRACT FROM AUTHOR]

Alkali atom-doped hexalithioborazine (B3N3Li6-M) as a novel class of super-alkali complex has been investigated for their exceptionally high first-order and second-order electrical responsive properties. The stability of resulting complexes, B3N3Li6-M (M = Li, Na, and K), is confirmed by the ADMP simulation and the negative values of thermodynamic parameters such as binding energy (∆Eb) and Gibbs free energy (∆G). The relationship between aromaticity (NICS) and first hyperpolarizability of B3N3Li6-M follows linear relationship. Diffuse electron cloud around the central ring and doped alkali metal in the HOMO of B3N3Li6-M complexes has been attributed to the charge transfer from peripheral Li to the dopant metal (M) atom. The dipole moment of B3N3Li6-M varies between 0.507 D (M = Na) and 1.608 D (M = Li) due to charge transfer in these complexes. The mean polarizabilities (αav) of B3N3Li6-M ranging from 573.08 to 1598.86 a.u are observed. Exceptionally high value of second-order NLO parameter (βav = 5.133 × 105 a.u and βHRS = 2.166 × 106 a.u) are observed in case of Li-doped B3N3Li6 in this series. Thus, the first hyperpolarizability (βav and βHRS) values of the complexes produced by the interactions between alkali metal atoms (M) and B3N3Li6 are strong enough to demonstrate as potential second-order NLO materials. [ABSTRACT FROM AUTHOR]

Combining biomass co-firing with oxy-fuel combustion is a promising Bioenergy with Carbon Capture and Storage (BECCS) technology. It has the potential to achieve a large-scale reduction in carbon emissions from traditional power plants, making it a powerful tool for addressing global climate change. However, mercury in the fuel can be released into the flue gas during combustion, posing a significant threat to the environment and human health. More importantly, mercury can also cause the fracture of metal equipment via amalgamation, which is a major risk for the system. Therefore, compared to conventional coal-fired power plants, the requirements for the mercury concentration in BECCS systems are much stricter. This article reviews the latest progress in mercury control under oxy-fuel biomass co-firing conditions, clarifies the impact of biomass co-firing on mercury species transformation, reveals the influence mechanisms of various flue gas components on elemental mercury oxidation under oxy-fuel combustion conditions, evaluates the advantages and disadvantages of various mercury removal methods, and finally provides an outlook for mercury control in BECCS systems. Research shows that after biomass co-firing, the concentrations of chlorine and alkali metals in the flue gas increase, which is beneficial for homogeneous and heterogeneous mercury oxidation. The changes in the particulate matter content could affect the transformation of gaseous mercury to particulate mercury. The high concentrations of CO2 and H2O in oxy-fuel flue gas inhibit mercury oxidation, while the effects of NOx and SO2 are dual-sided. Higher concentrations of fly ash in oxy-fuel flue gas are conducive to the removal of Hg0. Additionally, under oxy-fuel conditions, CO2 and metal ions such as Fe2+ can inhibit the re-emission of mercury in WFGD systems. The development of efficient adsorbents and catalysts is the key to achieving deep mercury removal. Fully utilizing the advantages of chlorine, alkali metals, and CO2 in oxy-fuel biomass co-firing flue gas will be the future focus of deep mercury removal from BECCS systems.

Heat pipe cooled reactors (HPCRs) have broad application prospects due to their advantages, such as high power density, compact structure, lower cost, and easy modular assembly. Numerous countries have engaged in extensive research and development of HPCR conceptual designs. The heat from the reactor is removed by high temperature heat pipes (HTHPs), which generally employ alkali metals as the working fluid, such as potassium, sodium, and lithium. Understanding the thermal-hydraulic performance of HTHPs is essential for the safe and efficient operation of a reactor. Therefore, the objective of this paper is to provide a comprehensive review of HPCR conceptual designs developed by various countries in recent years. The research progress of HTHPs on flow and heat transfer performance is reviewed, with an emphasis on both transient and steady-state characteristics. Research progress, as well as the issues that need to be focused on in future research, are discussed in detail.

Because of the increasing demand for energy sources, searching for reversible and high-capacity hydrogen storage materials plays a vital role in the extensively utilizing of hydrogen as a clean energy source. In this study, dispersion-corrected density functional theory (DFT-D3) calculations are utilized to examine the possibility of storing H 2 molecules on Li, Na, and K alkali metals decorated C 6 O 6 Li 6 cluster. To evaluate H 2 adsorption capability, the adsorption energies, electron density difference iso-surfaces, and charge-transfers are calculated and discussed. The results indicate that a hydrogen molecule is physisorbed on the Li@C 6 O 6 Li 6 , Na@C 6 O 6 Li 6 , and K@C 6 O 6 Li 6 with average adsorption energies of −0.264, −0.150, and −0.109 eV, respectively. Double-sided alkali metal atoms decoration can lead to the maximum gravimetric density of 15.68, 14.49, and 13.79 wt% for 2Li@C 6 O 6 Li 6 –8H 2 , 2Na@C 6 O 6 Li 6 –10H 2 , and 2K@C 6 O 6 Li 6 –12H 2 complexes, respectively. Finally, desorption temperatures reveal that the systems can operate as reversible hydrogen storage materials. [Display omitted] • Alkali metal decorated C 6 O 6 Li 6 cluster for hydrogen storage using DFT-D3 calculations. • Double alkali metal decorated C 6 O 6 Li 6 cluster shows maximum gravimetric density above 10.00 wt%. • Adsorption capacities and desorption temperatures confirm H 2 storage reversibility. [ABSTRACT FROM AUTHOR]

Lignin utilization is a potential approach for replacing fossil energy and releasing the environment pressure. Herein, we synthesized a series of novel Cu-based catalysts, Cu@NS-SiO2 (NS ¼ nano sphere) and alkali metals (Na, K, Rb, and Cs) doped Cu@NS-SiO2, and applied them in hydrodeoxygenation reaction of anisole. High Cu dispersion was presented on all catalysts. The modification of alkali metals on Cu@NS-SiO2 significantly enhanced the electron density of Cu sites in the following order: Cs > Rb > K > Na, among which Cs decreased the Cu 2p3/2 binding energy most (by 0.7 eV). Moreover, the modification did not substantially affect the geometric structure of Cu species. This regulable electronic environment of Cu sites was crucial for selective deoxygenation and inhibiting the hydrogenation of aromatic rings in anisole, and thus promoted the selectivity of benzene. Compared with Cu@NS-SiO2 (~59%), the highest benzene selectivity was obtained on Cs/10Cu@NS-SiO2 at ~83%. [ABSTRACT FROM AUTHOR]