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The structure of aqueous ammonia solutions is investigated through classical molecular dynamics (MD) and ab initio molecular dynamics (AIMD) simulations. We have preliminarily compared three well-known classical force fields for liquid water (SPC, SPC/E, and TIP4P) in order to identify the most accurate one in reproducing AIMD results obtained at the Generalized Gradient Approximation (GGA) and meta-GGA levels of theory. Liquid ammonia has been simulated by implementing an optimized force field recently developed by Chettiyankandy et al. [Fluid Phase Equilib. 511, 112507 (2020)]. Analysis of the radial distribution functions for different ammonia concentrations reveals that the three water force fields provide comparable estimates of the mixture structure, with the SPC/E performing slightly better. Although a fairly good agreement between MD and AIMD is observed for conditions close to the equimolarity, at lower ammonia concentrations, important discrepancies arise, with classical force fields underestimating the number and strength of H-bonds between water molecules and between water and ammonia moieties. Here, we prove that these drawbacks are rooted in a poor sampling of the configurational space spanned by the hydrogen atoms lying in the H-bonds of H2O⋯H2O and, more critically, H2O⋯NH3 neighbors due to the lack of polarization and charge transfer terms. This way, non-polarizable classical force fields underestimate the proton affinity of the nitrogen atom of ammonia in aqueous solutions, which plays a key role under realistic dilute ammonia conditions. Our results witness the need for developing more suited polarizable models that are able to take into account these effects properly. [ABSTRACT FROM AUTHOR]

Ammonia, as a zero-carbon fuel, has the potential to serve as a medium for the production, transportation, and utilization of clean energy. The scaling up of green ammonia production also necessitates broader utilization channels for ammonia. Applying ammonia as a fuel in engines is an effective way to reduce carbon emissions. This paper employs dual direct injection technology of ammonia and diesel in a novel ammonia-fueled engine to implement various control strategies and investigates their effects on combustion and emission performance. The results indicate that when the ammonia injection timing is advanced from −40°CA ATDC to −60°CA ATDC, the flash boiling of liquid ammonia decreases the indicated thermal efficiency (ITE) below 39% and increases unburned gas emissions. Globally, injecting ammonia during the intake stroke could receive better performance. Split injection strategies of diesel significantly improve the ITE, especially under a higher pilot-injection ratio of 75%. Additionally, increasing the load benefits the ammonia combustion process. Raising the IMEP to 12 bar improves ammonia combustion efficiency to over 95%, with an ITE reaching 49%. [Display omitted] • Lifecycle zero carbon emission is achieved through green ammonia combustion. • Zero-carbon fuel ammonia is directly injected into a heavy-duty engine. • The influence of flashing boiling of ammonia in the cylinder is talked about. • Flexible control strategies are tested for lower unburned emissions and higher ITE. [ABSTRACT FROM AUTHOR]

The extraction of the solid state materials "MSnBix" (M/x=Cs/1, Na/3) in liquid ammonia in the presence of different chelating agents yielded the novel Zintl anion [Sn5Bi3]3−. The anion could be crystallized and characterized via single crystal X‐ray diffraction in [Cs@[18]crown‐6]3[Sn5Bi3] ⋅ 7NH3, [K@[18]crown‐6]1.5[Cs@[18]crown‐6][Cs@([18]crown‐6)2]0.5[Sn5Bi3] ⋅ 3.98NH3, [Na@DB[18]crown‐6]2[Na(NH3)6][Sn5Bi3] ⋅ 14NH3 and [Cs@[2.2.2]crypt]6[Sn5Bi3]2 ⋅ 9.53NH3. The [Sn5Bi3]3− anion is further investigated by mass spectrometry and DFT calculations to confirm its composition and elucidate its electronic structure. [ABSTRACT FROM AUTHOR]

The extraction of the solid state materials "MSnBix" (M/x=Cs/1, Na/3) in liquid ammonia in the presence of different chelating agents yielded the novel Zintl anion [Sn5Bi3]3−. The anion could be crystallized and characterized via single crystal X‐ray diffraction in [Cs@[18]crown‐6]3[Sn5Bi3] ⋅ 7NH3, [K@[18]crown‐6]1.5[Cs@[18]crown‐6][Cs@([18]crown‐6)2]0.5[Sn5Bi3] ⋅ 3.98NH3, [Na@DB[18]crown‐6]2[Na(NH3)6][Sn5Bi3] ⋅ 14NH3 and [Cs@[2.2.2]crypt]6[Sn5Bi3]2 ⋅ 9.53NH3. The [Sn5Bi3]3− anion is further investigated by mass spectrometry and DFT calculations to confirm its composition and elucidate its electronic structure. [ABSTRACT FROM AUTHOR]

Birch reactions employing alkali metals in ammonia have been a well‐established method for the reduction and functionalisation of aromatic compounds for nearly 100 years. Speculations regarding intermediates in the reaction pathway have been discussed since the beginning. We hereby report the isolation of NMe4(HNaph) (1), a kinetically trapped intermediate of the Birch reaction of naphthalene and sodium in liquid ammonia. 1 has been fully characterised and has been shown to continue to react to 1,2/1,4‐dihydronaphthalene – the Birch product of the reduction of naphthalene. The reactivity of 1 was investigated towards activity as an electron and hydride transfer agent with both, elements and small organic molecules. 1 demonstrates a tamed reduction potential which allows for controlled reactions such as the selective formation of hexasulphide and hexaselenide anions. [ABSTRACT FROM AUTHOR]

Ammonia, as a carbon-free fuel, can serve as an alternative fuel for future engines, which is consistent with the requirements of national carbon reduction policies. However, the higher concentrations of NOx, unburned ammonia and hydrogen emissions of ammonia-fueled engines need to be controlled seriously to meet the increasingly stringent emission regulations. In this study, a pre-chamber jet ignition single-cylinder engine with port pure ammonia injection was carried. The formation process of gaseous pollutants during engine operation was investigated using CFD simulations in the equivalence ratio range of 0.8–1.3. And, the study also discusses different methods for reducing gaseous pollutant emissions. The results reveal that under lean burn conditions, the ITE can exceed 49%, and unburned ammonia and hydrogen emissions are extremely low. However, the NO emission concentration is relatively high, reaching above 1500 × 10−6, and primarily dominated by thermal NO. N 2 O is primarily distributed near the flame front, The low temperature at the cylinder walls decelerates the pyrolysis of N 2 O, coupled with the influence of secondary combustion, both leading to higher N 2 O emission concentrations, with maximum value reaching 78.6 × 10−6. NO 2 emissions are primarily generated in the burned regions. Under rich burn conditions, the ITE significantly decreases, with an ITE of only 34.6% at an equivalence ratio of 1.3. The unburned ammonia emissions rise with an increase in the equivalence ratio, and hydrogen emissions are mainly generated through the pyrolysis of residual ammonia in the burned region, so that the elevated unburned ammonia emissions could lead to an increase in hydrogen emissions. Fuel NO is dominant in NO emissions, and the reduction reaction of unburned ammonia results in extremely low emission concentrations, and also leading to the low levels of N 2 O and NO 2 emissions. According to a comprehensive evaluation of pollutant emissions and engine thermal efficiency, stoichiometric condition is deemed optimal for engine operation, as it can achieve a balance between ITE and gaseous pollutant emissions. Moreover, the adoption of water injection technology can further reduce NOx emissions. Furthermore, the EGR technology and direct liquid ammonia injection will also achieve lower NOx emissions. However, it is insufficient to meet the national emission regulations that only controlling gaseous pollutant emissions during the combustion, and development of the special aftertreatment systems for ammonia fueled engines should not be neglected. • The higher hydrogen emissions primarily originat from the pyrolysis of residual ammonia in burned area under rich burn conditions. • Thermal NO dominates the NO emissions under lean burn conditions, and fuel NO is dominant under rich burn conditions. • N 2 O emissions is primarily impacted by reformation of N 2 O near the cylinder wall, which is promoted by secondary combustion. • The condition of equivalence ratio of 1.0 is preferable to trade off between the gaseous pollutant emissions and ITE. [ABSTRACT FROM AUTHOR]

Superfine wool fiber has a soft and luxurious texture, excellent moisture absorption and is warmer and more comfortable than ordinary wool. Liquid ammonia, which has exceptional permeability, exerts a certain modification effect on the surface scales of wool in the finishing and processing of wool fabric, thereby enhancing its wear performance. However, limited research has been conducted on the impact of liquid ammonia on valuable wool fibers such as superfine wool and cashmere. In this article, superfine wool tops were treated with continuous liquid ammonia finishing equipment and the effects of liquid ammonia on the microstructure and surface morphology of superfine wool fiber were investigated. In addition, the changes in length, fineness, anti-felting, and dyeing properties of superfine wool fiber after liquid ammonia treatment were examined. The results demonstrated that the interstitial integrity of intercellular substance of superfine wool was compromised following treatment with liquid ammonia, which had a greater tendency to infiltrate cortical cells and induce alterations in wool structure and performance. Furthermore, the surface scales of superfine wool were damaged after treatment with liquid ammonia, leading to improved anti-felting and dyeing properties. [ABSTRACT FROM AUTHOR]

Hydrogen is commonly perceived as the key player in the transition towards a low-carbon future. Nevertheless, H 2 low energy density hinders its easy storage and transportation. To address this issue, different alternatives (liquefied hydrogen, ammonia and liquid organic hydrogen carriers) are explored as hydrogen vectors. The techno-economic assessment of H 2 transport through these carriers is strongly dependent on the basis of design adopted, such that it is difficult to draw general conclusions. In this respect, this work is aimed at performing a sensitivity analysis on the hypotheses introduced in the layout of H 2 value chains. Different scenarios are discussed, depending on harbour-to-harbour distances, cost of utilities and raw materials and H 2 application to the industrial or mobility sector. The most cost-effective carrier is selected for each case-study: NH 3 is the most advantageous for industrial sector, while LH 2 holds promises for mobility. Critical issues are pointed out for future large-scale applications. [Display omitted] • NH 3, liquefied H 2 , toluene and dibenzyltoluene assessment as H 2 carrier. • H 2 application to both the industrial and mobility sectors. • Sensitivity study on harbour-to-harbour distance, utilities and raw materials cost. • NH 3 is the most cost-effective H 2 carrier for industrial applications. • LH 2 is the most cost-effective H 2 carrier for mobility applications. [ABSTRACT FROM AUTHOR]

Many countries, especially those with a high energy demand but insufficient renewable resources are currently investigating the role that imported low carbon hydrogen may play in meeting future energy requirements and emission reduction targets. A future hydrogen economy is uncertain and predicated on reduced price of hydrogen delivered to customers. Current hydrogen production, steam reforming of natural gas or coal gasification, is co-located to its end-use as a chemical feedstock. Large-scale multi-source value chains of hydrogen needed to support its use for energy are still at concept phase. This research investigates the combination of technical and economic factors which will determine the viability and competitiveness of two competing large scale renewable hydrogen value chains via ammonia and liquid hydrogen. Using a techno-economic model, an evaluation of whether green hydrogen exports to Germany from countries with low-cost renewable electricity production, but high-costs of storage, distribution and transport will be economically competitive with domestic renewable hydrogen production is conducted. The model, developed in Python, calculates costs and energy losses for each step in the value chain. This includes production from an optimised combination of solar and/or wind generation capacity, optimised storage requirements, conversion to ammonia or liquid hydrogen, distribution, shipping, and reconversion. The model can easily be applied to any scenario by changing the inputs and was used to compare export from Chile, Namibia, and Morocco with production in Germany using a 1 GW electrolyser and 2030 cost scenario in each case. • Electrolyser utilisation is more important than renewable energy storage when determining the LCOH. • The lowest cost LCOE for green hydrogen production does not always result in the LCOH. • The reconversion of ammonia back to hydrogen significantly increases the cost of energy to the end user. [ABSTRACT FROM AUTHOR]

The implementation of renewable energy sources to electrify ammonia (NH3) production is identified as a critical approach for achieving successful decarburization in the pursuit of a more sustainable future. A liquid metal‐based method is presented for synthesizing bismuth (Bi) nano‐electrocatalysts, enabling efficient and sustainable ammonia production via nitrate electroreduction. Bi‐metal precipitated from a gallium liquid metal alloy yields solution‐processable Bi and oxide with controllable nanostructures such as nanosheets, nanotubes, and nanoparticles. Combining Bi nano‐electrocatalysts and graphene liquid crystals creates self‐assembling layered electrocatalytic systems. Integrating 3D printing technology allows for precise control over the geometry, microporosity, and number of deposited layers of the electrocatalytic scaffold electrode, resulting in improved mass transport properties, durability, and the prevention of catalyst detachment. Consequently, the ammonia production rate reaches 400 nmol s−1 cm−2, with a Faradaic efficiency of over 90% and current densities exceeding 350 mA cm−2. These numbers indicate the excellent scalability potential of the proposed electrocatalytic system. [ABSTRACT FROM AUTHOR]

The investigation of experimental pKa values in liquid ammonia at room temperature for a series of 30 organic compounds containing eight distinct chemical groups enabled an accurate assessment of the proton ammoniation free energy. The deprotonation free energies, as well as the solvation free energies of acids and conjugate bases, were computed using a combination of quantum chemical and electrostatic approaches. Two thermodynamic schemes were employed to reproduce experimental pKa values while scanning a large interval of probable values of proton ammoniation free energy. The desired quantity corresponded to the lowest mean absolute deviation of the overall reproduced pKa values of the series. As a result, the proton ammoniation free energy was evaluated to be −275.0 Kcal/mol. Test results show that this proposed value is well suited for pKa calculation in liquid ammonia at room temperature. [ABSTRACT FROM AUTHOR]

This study synthesizes nano composite (Ea-AgNPs-Si) using Euphorbia antisyphilitica(Ea), employing it as a poultry reformer, sorptive material, pathogen suppressor and sprouting catalyst. Characterization involved XRD, SEM, TEM, Zetasizer, UV-Visible and FT-IR techniques. Ea-AgNPs-Si adopted a face centered cubic arrangement with average crystalline size of 20.34 nm. Zeta potential assessed stability. PDI value of Ea-AgNPs-Si nanocomposite is 1 indicating the polydisperse distribution. SEM revealed flower shape (Ea-AgNPs-Si), ranging 70-100 nm in diameter. The disc diffusion method reveals that Ea-AgNPs-Si exhibits potent antimicrobial activity at 60 μl against Staphylococcus aureus, Actinomycetes, Escherichia coli, Klebsiella pneumonia and Pseudomonas aeruginosa, attributed to its deep diffusion and release of silver ions and silica. It is unequivocally evident from the data that Langmuir isotherm and Pseudo II order model provides a superior fit approaching R² value as 0.9972, 0.9461, 0.916, 0.9827, 0.9455 and 0.9534 for LA(I), LA(II), LA(III) describing monolayer chemisorption onto surfaces with uniform adsorption energies than Freundlich, Tempkin and BET models, which is synonymous with the results obtained from R2011a Matlab neuro solution. Through final germination (FG) we concluded that among 130 corriandrum seeds sown,109 sprouted in 20 days. Higher germination index (GI) T2>T4>T1>T3> expedited that Ea-AgNPs-Si shall be used as a nutrient to boost the growth of crops. Ordinarily, it necessitates a span of 45 days for a single batch to attain harvest readiness; however, through our efforts, we have accomplished this feat in a mere 20 days. Henceforth, Ea-AgNPs-Si shall be employed as a Poultry Reformer, Pathogen Suppressor, Sprouting Catalyst and Adsorbent. [ABSTRACT FROM AUTHOR]

The problem is modeled using correlations representing a binary chemical reaction, activation energy with multiple diffusions, and a nanofluid. The fundamental objective of this study is to characterize the time, activation energy, and diffusions of liquid hydrogen and ammonia in a nonlinear mixed convective flow around a sphere. First, the nonsimilar transformations are applied to convert the dimensional governing equations to dimensionless form. The obtained equations are then discretized using the implicit finite difference method after being linearized using the quasilinearization method. By increasing the temperature difference ratio and the Brownian diffusion parameter and decreasing the combined convection, Brinkman number, and thermophoresis, it is possible to reduce the entropy generation. The activation energies improve while chemical reaction parameters reduce the width of liquid hydrogen and ammonia's concentration boundary layer. The results reveal that the mass transport strength of liquid ammonia is big enough to dwarf liquid hydrogen. The mass transport strength of liquid ammonia R e − 1 / 2 S h 2 is greater than that of the liquid hydrogen's mass transport strength R e − 1 / 2 S h 1 . Specifically, at τ = 1 , the R e − 1 / 2 S h 2 is 25% greater than the R e − 1 / 2 S h 1 at Nt = 0.5 when α > 0. Further, at τ = 1 , the nanoparticle's mass transportation strength enhances approximately 28% if Lewis number Le rises from 10 to 20 at Nr = 1 for α > 0. [ABSTRACT FROM AUTHOR]

One of the biggest challenges to the sustainable manufacture of liquid ammonia and the prevention of worldwide water contamination is the development of effective electrocatalysts for the electrochemical reduction of nitrate (NO 3 −) to NH 3 with high stability. Herein, a highly active and serviceable electrocatalyst is synthesized by pyrolysis, composed of nanostructure nickel phosphide (Ni 2 P) embedded in nitrogen phosphide doped carbon (NPC) followed by deposition on carbon paper (CP) to improve the electrocatalytic nitrate reduction. Various characterization techniques investigate the crystallinity, morphology, and chemical components of the Ni 2 P-NPC/CP nanoparticles. The results support the formation of nanostructure Ni 2 P and strong synergistic interactions between Ni 2 P and NPC, which resulted in substantial active sites and high electrical conductivity. Excellent performance of Ni 2 P-NPC/CP nanoparticles is achieved for electrocatalytic NO 3 − reduction with an NH 4 + yield rate of 2.468 mg h−1 mg cat. −1 and Faradaic efficiency (FE) of 84.6% at −1.2 V vs. RHE. Additionally, Ni 2 P-NPC/CP nanoparticles exhibit exceptional robustness and endurance. Studies using isotope labeling have been carried out, and the results show that nitrate reduction produces ammonia. Ni 2 P-based electrocatalysts can effectively treat nitrate wastewater to recover ammonia and facilitate its use in diverse industrial applications. • Ni 2 P-NPC/CP offers a highly active and durable electrocatalyst for the conversion of nitrate to ammonia. • Ni 2 P-NPC/CP achieved NH 4 + yield rate of 2.468 mmol h−1 mgcat−1 and Faradaic efficiency of 84.6% at −1.2 V. • The unique Ni 2 P-NPC/CP ensures robustness and practical options for continuous nitrate reduction processes. • Ni 2 P-NPC/CP offers a carbon-free energy solution through the selective conversion of nitrate to NH 3. [ABSTRACT FROM AUTHOR]

Through this paper, the authors propose using the quantum cluster equilibrium (QCE) theory to reinvestigate ammonia clusters in the liquid phase. The ammonia clusters from size monomer to hexadecamer were considered to simulate the liquid ammonia in this approach. The clusterset used to model the liquid ammonia is an ensemble of different structures of ammonia clusters. After studious research of the representative configurations of ammonia clusters through the cluster research program ABCluster, the configurations have been optimized at the MN15/6‐31++G(d,p) level of theory. These optimizations lead to geometries and frequencies as inputs for the Peacemaker code. The QCE study of this molecular system permits us to get the liquid phase populations in a temperature range of 190–260 K, covering the temperatures from the melting point to the boiling point. The results show that the population of liquid ammonia comprises mainly the ammonia hexadecamer followed by pentadecamer, tetradecamer, and tridecamer. We noted that the small‐sized ammonia clusters do not contribute to the population of liquid ammonia. In addition, the thermodynamic properties, such as heat of vaporization, heat capacity, entropy, enthalpy, and free energies, obtained by the QCE theory have been compared to the experiment given some relatively good agreements in the gas phase and show considerable discrepancies in liquid phase except the density. Finally, based on the predicted population, we calculated the infrared spectrum of liquid ammonia at 215 K temperature. It comes out that the calculated infrared spectrum qualitatively agrees with the experiment. [ABSTRACT FROM AUTHOR]

Reactions of uranium tri‐ and tetrahalides, UBr3, UI3, UCl4, and UI4, with different cyanides MCN (M=K, Ag) in liquid anhydrous ammonia led to three novel uranium(IV) cyanide compounds. The reaction of UCl4 in the presence of KCN resulted in the compound [U(CN)(NH3)8]Cl3 ⋅ 3NH3, while UBr3 and UI3 were oxidized in the presence of AgCN to form the compounds ∞1[ ${{}_{\infty }{}^{1}[}$ (μ‐CN){(H3N)5U(μ‐NH2)3U(NH3)5}]Br4 ⋅ 2NH3, and ∞1[ ${{}_{\infty }{}^{1}[}$ (μ‐CN){(H3N)5U(μ‐NH2)3U(NH3)5}]I4 ⋅ 2NH3. The reaction of UI4 with KCN in aNH3 also yielded the compound ∞1[ ${{}_{\infty }{}^{1}[}$ (μ‐CN){(H3N)5U(μ‐NH2)3U(NH3)5}]I4 ⋅ 2NH3. The compounds ∞1[ ${{}_{\infty }{}^{1}[}$ (μ‐CN){(H3N)5U(μ‐NH2)3U(NH3)5}]X4 ⋅ 2NH3 (X=Br, I) crystallize in different space groups, Pmn21 (no. 31) and Imm2 (no. 44), respectively. In both cases, the ∞1[ ${{}_{\infty }{}^{1}[}$ (μ‐CN){(H3N)5U(μ‐NH2)3U(NH3)5}]4+ cation forms infinite strands. We conducted quantum‐chemical calculations and Intrinsic Bond Orbital analyses on the observed [U(CN)(NH3)8]3+ cation and the [(μ‐CN)2{(H3N)5U(μ‐NH2)3U(NH3)5}]3+ model cation to gain insight into the bonding situation. [ABSTRACT FROM AUTHOR]

Liquid ammonia is a promising clean fuel, but it has a greater tendency to flash-boil than conventional fuels. This study confirms the reliability of utilizing the Eulerian framework and homogeneous relaxation model for simulating flash-boiling liquid ammonia sprays by comparing the simulation results with experimental data. The characteristics of single-hole superheated liquid ammonia sprays are analyzed for different orifice aspect ratios and superheat degrees. The results indicate that superheat degree and orifice aspect ratio affect the external spray morphology by affecting the two-phase flow inside the orifice. The strong phase transition due to flash-boiling drives the spray expansion process and increases the velocity. Moreover, the extensive bubble breakup in flash-boiling sprays promotes faster atomization. However, flash-boiling also results in a more pronounced temperature drop in the spray zone. This research can provide valuable insights for future simulations and engineering practices involving flash-boiling ammonia sprays. [ABSTRACT FROM AUTHOR]

To decrease liquid ammonia leakage-induced casualties of ammonia chemical enterprises, a simulation comparison method of liquid ammonia toxicity leakage and crowd evacuation was proposed, a spatial model was constructed with Pyrosim software, using 8 liquid ammonia tanks as a layout example. The ammonia diffusion path under eight leakage scenes was analysed with FDS software by setting eight ammonia leakage points. The personnel evacuation model was built with the Pathfinder software, obtaining the crowd evacuation time under the eight scenes. Finally, the optimal site for liquid ammonia tanks in this case was determined through a comparison of ammonia diffusion path and evacuation time. Results show that among the eight candidate sites for ammonia tanks, the Leakage Scene 4 shows the longest time (78 s) for diffusion to the two evacuation exits, which is longer than the crowd emergency evacuation time (73 s) in the scene. Therefore, the Leakage Scene 4 can be used for the setting of liquid ammonia tanks. The obtained conclusions provide a safe suggestion for the scientific planning of the liquid ammonia storage sites of chemical enterprises. [ABSTRACT FROM AUTHOR]

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The spray characteristics of liquid ammonia under various ambient pressures and temperatures were analyzed in a constant volume chamber to cover a wide range of superheat degrees. The injection pressure was set as 70 and 80 MPa with ambient pressure ranging from 0.2 to 4 MPa. The ambient temperature was 500 K. The results showed that the higher the injection pressure, the greater the kinetic energy obtained. The droplet fragmentation was enhanced, and the phenomenon of gradual separation of the gas–liquid region occurred with increasing injection pressure. Under flash boiling spray conditions, the spray developed faster than non-flash boiling and transition flash boiling spray under the same injection pressure. In addition, the flash boiling spray tip penetration of the gas and liquid increased more than that of cold spray, and the fluctuation of the late stage of the injection was relatively large. Therefore, the injection pressure has a greater effect on the spray tip penetration of flash boiling spray. Moreover, ambient pressure greatly influences the flare flash boiling spray. The spray resistance phenomenon was found during the spray development in the flare flash boiling condition. With the increase in ambient pressure, the spray tip penetration of flash boiling spray decreases due to the reduction in the pressure difference inside and outside the spray hole and the restriction of ambient gas. Meanwhile, owing to the low ambient pressure and ambient density, the liquid penetration in the initial phase of the flare flash boiling spray will be abnormally shorter than that of the non-flash boiling spray. [ABSTRACT FROM AUTHOR]

This paper presents a quantitative risk assessment method to predict the potential risks of liquid ammonia tanks. The method combines probabilistic prediction and consequence assessment: the former is predicted by Bayesian networks derived from bow‐tie mapping, in which the conditional probabilities are determined by analytic hierarchy process, the latter is calculated based on numerical simulation of accident consequences and Probit probability model. The application results show that the method can be used for quantitative risk assessment of liquid ammonia storage tank, and the Bayesian network model is efficient and stable, which can realize risk prediction, accident causes analysis and risk mitigation analysis. Human errors during production or maintenance and corrosion are the main causes of liquid ammonia leakage. Toxicity has the greatest effect on the risk of liquid ammonia tanks. Risk mitigation measures can significantly reduce individual risk and societal risk. The obtained results provide meaningful guidance for the prevention and risk mitigation strategies of liquid ammonia leakage accidents, so as to improve the safety level of liquid ammonia during storage. [ABSTRACT FROM AUTHOR]

Anhydrous ammonia is transported via ship, rail, and road everyday in the United States as a refrigerated liquid at ambient pressure. As a result, unintential release of a large amount of anhydrous ammonia could result from an accident during transportation. The aim of this paper is to provide a better understanding of the evaporation of anhydrous ammonia from porous media. In our investigation, laboratory‐scale concrete coupons were used as a surrogate for a larger concrete pad that could be present in an event involving an unintentional release of liquid anhydrous ammonia. Concrete coupons sized 5 cm × 5 cm × 1.9 cm were saturated in liquid anhydrous ammonia, and measurements of the subsequent evaporation from the coupons were made in an environmental chamber. The ambient air temperature within the chamber varied from 5 to 45°C, and the relative humidity varied from 5% to 75%. Mass‐difference calculation and Berthelot's reaction were used to determine the average evaporation rate from a concrete coupon across all trials, which was found to be 6.5 ± 1.9 mg/s. To validate these evaporation rates, the remaining ammonia in the concrete coupon was measured for each trial. We found that the time‐integrated calculated evaporation rates correlated well with the total mass of ammonia that was lost from the coupons. In addition, it was found that ambient air temperature and relative humidity had little influence on anhydrous ammonia evaporation from the concrete coupons. [ABSTRACT FROM AUTHOR]

By reaction of sodium electride or NaC2H with the anhydrous sodium salt of propiolic acid, Na(OOC−C≡C−H), in liquid ammonia crystalline powders of Na2C3O2 were obtained. The structure analysis based on synchrotron powder diffraction data revealed that Na2C3O2 crystallizes in a monoclinic unit cell (I2/a, Z=4) exhibiting the elusive Y‐shaped −C≡C−COO− anion, which is unprecedented in a crystalline compound up to now. IR/Raman and solid‐state NMR spectroscopic investigations with assignments supported by DFT‐based ab initio calculations confirm this finding. Reaction with sodium electride led to a higher crystallinity of the product, but additionally a by‐product apparently due to decomposition and polymerization of Na2C3O2 was formed. No such by‐product was observed in the reaction with NaC2H, which turned out to be a milder metalation route. However, the product of the latter reaction is less crystalline. [ABSTRACT FROM AUTHOR]

UCl4, UBr4, UBr5, or UO2Cl2 reacted with excess liquid ammonia – in adventitious presence of moisture and/or air – and formed some peculiar uranium compounds of which we present the crystal structures. [(NH3)7(N3)U(μ‐O)U(NH3)8]Cl5 ⋅ 7NH3 contains a dinuclear μ‐O‐bridged uranium(IV) cation, [{(NH3)4UO2}2(μ‐O)]Cl2 ⋅ 4NH3 features a dinuclear μ‐O‐bridged uranyl(VI) cation, while the compounds [(U(VI)O2)2(U(V)O2)2(μ3‐O)2(NH3)12]Br2 ⋅ 6NH3 and [(U(VI)O2)4(U(V)O2)4(μ3‐O)4(NH3)22]Br4 ⋅ 16NH3 are mixed‐valent containing uranyl(V)‐uranyl(VI) units. For these tetra‐ and octanuclear complex cations we observed that the O atoms of the uranyl(V) units can be μ2‐ and even μ3‐bridging to uranyl(VI) units, while the O atoms of the latter are acting as terminal ligands only. [(NH3)8U(μ‐N)U(NH3)5(μ‐N)UO2(NH3)4]Br6 ⋅ 18NH3 presents the first example of a compound where the isoelectronic species UO22+ and UN2 formed a complex with the NUN unit bridging to the U atom of the uranyl(VI) cation. As it is can be difficult to distinguish between N and O atoms with X‐ray diffraction, quantum‐chemical calculations at the DFT‐PBE0/TZVP level of theory were carried out which unequivocally confirmed the atom assignments in the crystal structures. The chemical bonding in the complex cations was studied using intrinsic bonding orbitals and allowed for an additional discrimination of the U(V) and U(VI) atoms in the mixed‐valent compounds. [ABSTRACT FROM AUTHOR]

Amorphous Si-B-N nanoparticles of uniform composition tunable over the entire range spanning pure Si3N4 to pure BN was synthesized through a simple homogeneous chemical reaction of the mixture of SiCl4 and BBr3 with Na in liquid ammonia. With these amorphous nanopowders, dense amorphous bulk material was obtained with SPS sintering at the temperature before the crystallization. The dense amorphous bulk of Si3B3N7 exhibited the highest value of hardness (8.8 GPa), flexural strength s (545 MPa), and fracture toughness KIC (10.6 MPa m1/2). These are significantly higher than those reported for other crystalline ceramics of the same composition and surpass those of the completely dense crystalline ceramics. The fully-dense amorphous bulk material exhibited excellent resistance to oxidation up to 1550 °C. [ABSTRACT FROM AUTHOR]

The use of alternative fuels is a primary means for decarbonising the maritime industry. Liquefied natural gas (LNG), liquid hydrogen (LH2), and liquid ammonia (LNH3) are liquified gases among the alternative fuels. The safety risks associated with these fuels differ from traditional fuels. In addition to their low-temperature hazards, the flammability of LNG and LH2 and the high toxicity of LNH3 present challenges in fuel handlings due to their high likelihood of fuel release during bunkering. This study aims at drawing extensive comparisons of the evaporation and vapour dispersion behaviours for the three fuels after release accidents during bunkering and discuss their safety issues. The study involved the release event of the three fuels on the main deck area of a reference bulk carrier with a deadweight of 208,000 tonnes. Two release scenarios were considered: Scenario 1 involved a release of 0.3 m3 of fuel, and Scenario 2 involved a release of 100 kg of fuel. An empirical equation was used to calculate the fuel evaporation process, and the Computational Fluid Dynamic (CFD) code FDS was employed to simulate the dispersion of vapour clouds. The obtained results reveal that LH2 has the highest evaporation rate, followed by LNG and LNH3. The vapour clouds of LNG and LNH3 spread along the main deck surface, while the LH2 vapour cloud exhibits upward dispersion. The flammable vapour clouds of LNG and LH2 remain within the main deck area, whereas the toxic gas cloud of LNH3 disperses towards the shore and spreads near the ground on the shore side. Based on the dispersion behaviours, the hazards of LNG and LH2 are comparable, while LNH3 poses significantly higher hazards. In terms of hazard mitigations, effective water curtain systems can suppress the vapour dispersion. • The LNG, LH2, and LNH3 vapour dispersions are compared under identical release scenarios. • LH2 exhibits the highest evaporation rate, followed by LNG and LNH3. • The hazards associated with LNG and LH2 are comparable. • LNH3 poses greater hazards when compared to LH2 and LNG. [ABSTRACT FROM AUTHOR]

Due to the energy crisis, ammonia stands out as an efficient hydrogen energy carrier. However, liquid ammonia's nature of toxicity, corrosiveness, volatility, flammability, etc., make its storage highly risky. It is essential to analyze the risk of the ammonia storage facility for its safety improvement. Failure mode and effect analysis (FMEA) has been a popular risk analysis method due to its ease of implementation. However, traditional FMEA is insufficient to model the uncertainty of risk assessment information, enhance the consensus among experts, aggregate experts' risk evaluation information, and derive reliable risk analysis results. To address these limitations, we introduce a hybrid probabilistic linguistic FMEA framework to analyze failure risk in the ammonia storage facility. First, the probabilistic linguistic terms (PLTs) are introduced to express uncertain risk evaluation information of failure modes. Second, a risk acceptability-based consensus-reaching process is introduced to measure experts' consensus on each failure mode's risk and improve their consensus. Then, a consensus degree-based ordered weighted averaging operator is introduced to fuse experts' risk evaluation information, where experts' weight is determined by their consensus degree. Furthermore, the gained and lost dominance score method is improved on the basis of the expected value of the PLTs to prioritize failure modes' risk. Finally, a case study of the risk analysis for the ammonia storage facility is performed to show the efficiency of the extended FMEA. The case study indicated that condenser cooling water pump failure and failure of level transfer are the top two failure modes and have risk scores of 0.126 and 0.091, respectively. • A linguistic FMEA framework is constructed for the safety improvement of the ammonia storage process. • A consensus-reaching process considering risk acceptability is introduced for consensus improvement. • An OWA operator is extended based on the consensus degree among experts. • The linguistic GLDS method is introduced to prioritize the risk of failure modes. [ABSTRACT FROM AUTHOR]

It is advisable to design thermal management systems for high-power stationary satellites and specific ground applications using two-phase mechanically pumped loops with ammonia as the coolant. During prolonged operation in orbit, the accumulation of non-condensable gases can occur due to radiolysis and chemical reactions. The issues related to the effect of non-condensing gas on system parameters and performance have not yet received sufficient attention. The study of the distribution of non-condensable gas in the loop was performed by calculation-theoretical and experimental methods in a heat transfer loop with a Heat-Controlled Accumulator. Part of the gas accumulates in the steamgas zone of the Heat-Controlled Accumulator and affects the pressure value at a set temperature. The other gas is dissolved in liquid ammonia. This impacts the overheating of the cooled device when the heat load is switched on, the heat transfer intensity during boiling, and the cavitation reserve at the pump inlet. Accumulation of non-condensable gas up to ~0.075 mol nitrogen/kg ammonia, concentration of dissolved gas in the liquid up to ~5.3⋅10-4 mol/mol of the mixture does not significantly impact the parameters and performance of the system. But, if the aim is to precisely ensure the boiling temperature of the coolant or the cavitation reserve, the amount of necessary correction of the control parameters is up to 2.5 K. The results of the investigation can be used in the design of two-phase heat transfer loops for satellites and other applications, in particular, for the selection of the design and location of gas traps. [ABSTRACT FROM AUTHOR]

Chemical recycling polymer waste is a highly required technology to follow the current carbon‐neutral trend. Here, we present practical recycling methods for poly (bisphenol A carbonate) (PC) and poly(ϵ‐caprolactone) (PCL). PC can be converted to bisphenol A and urea with excellent product yield at 80 °C via ammonolysis using ammonium salt (ammonium‐formate or ‐carbonate) instead of liquid ammonia that is usually used in previous PC recycling. PCL can be converted to methyl 6‐hydroxy‐hexanoate monomer with excellent yield at 80 °C via methanolysis catalyzed by KOH. [ABSTRACT FROM AUTHOR]

With the continuous promotion of energy revolution and energy transition, the product oil consumption in China will peak, and the trend of low delivery volume of product oil pipelines becomes evident increasingly, which puts enormous pressure on product oil pipeline companies. At the same time, as the “ammonia-hydrogen” green energy and “liquid sunshine” carbon neutralization technical routes are hotly promoted, and the related industries are developed vigorously, the production of liquid ammonia and methanol is bound to grow massively in the future. Therefore, a technical route for the large-scale batch transportation of liquid ammonia, methanol and other liquid new energy through the existing product oil pipeline systems was proposed, aiming to help the product oil pipeline companies create new growth poles.The batch transportation technology of liquid ammonia/methanol in product oil pipelines was systematically overviewed. Besides, five major technical challenges, including the hydraulic and thermal characteristics in batch transportation, prediction of mixed oil development,batch establishment and mixed oil cutting and treatment, applicability of pipeline materials and equipment, and leakage diffusion and safety protection, were elaborated. This could provide reasonable suggestions and reference directions for the field application of the batch transportation technology of liquid ammonia/methanol/product oil.

Reactions involving Zintl ions are typically carried out in N‐based solvents such as liquid ammonia (NH3(l)), ethane‐1,2‐diamine (en), pyridine (py), or acetonitrile (CH3CN). We are currently investigating the application of other solvents as alternatives. Herein, we present the synthesis of the (Sn4Bi4)2− anion, obtained as its [K(crypt‐222)]+ salt (crypt‐222=4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane), from reactions of the binary, pseudo‐tetrahedral Zintl anion (Sn2Bi2)2− in the presence of phosphines as oxidation agents in ortho‐difluorobenzene (o‐DFB). The cluster comprises 38 valence electrons, hence, represents an arachno‐type architecture according to Wade‐Mingos rules. Micro‐X‐ray fluorescence (μ‐XFS) spectroscopy rationalized the elemental composition of the anion, and quantum chemical studies served to compare the stability of possible structural isomers of the global minimum structure. [ABSTRACT FROM AUTHOR]

Reactions involving Zintl ions are typically carried out in N‐based solvents such as liquid ammonia (NH3(l)), ethane‐1,2‐diamine (en), pyridine (py), or acetonitrile (CH3CN). We are currently investigating the application of other solvents as alternatives. Herein, we present the synthesis of the (Sn4Bi4)2− anion, obtained as its [K(crypt‐222)]+ salt (crypt‐222=4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane), from reactions of the binary, pseudo‐tetrahedral Zintl anion (Sn2Bi2)2− in the presence of phosphines as oxidation agents in ortho‐difluorobenzene (o‐DFB). The cluster comprises 38 valence electrons, hence, represents an arachno‐type architecture according to Wade‐Mingos rules. Micro‐X‐ray fluorescence (μ‐XFS) spectroscopy rationalized the elemental composition of the anion, and quantum chemical studies served to compare the stability of possible structural isomers of the global minimum structure. [ABSTRACT FROM AUTHOR]

Urea (H2NCONH2) is a commercially indispensable chemical as a fertilizer and starting material for the manufacture of many other products. Currently, commercial urea can be prepared with an energy‐consuming process by combining liquid ammonia (NH3) and liquid carbon dioxide (CO2) under high‐temperature and high‐pressure conditions. An alternative approach for synthesis of urea may involve electrochemical synthesis reactions that occur under aqueous and ambient conditions. Here, we propose synthesis of urea via nucleophilic addition reaction during an electrochemical CO2 reduction process in NH4HCO3‐containing electrolytes. The urea formation at a rate of 0.11 mmol g−1 h−1 was achieved on a polycrystalline Au electrode (area: 1 cm2) at a potential of −1.4 V (vs. saturated calomel electrode). Furthermore, the detailed investigations including in‐situ spectroscopic analysis and isotopic labeling characterization reveal the capability of producing urea could be mainly attributed to a spontaneous reaction between the NH3 molecule and the CO2⋅− intermediate. This study promotes the exploration of electrochemical synthesis of high‐value‐added products. [ABSTRACT FROM AUTHOR]

Liquid ammonia stored at elevated pressures undergoes phase change during tank venting. The paper describes a CFD model able to reproduce the INERIS experiment performed using 12 m3 volume tank when 300 kg of ammonia were vented during 460 s from the ullage through the pipe to the atmosphere. The model is based on the volume-of-fluid method combined with Lee's model for mass transfer between phases. Extensive calibration trials were conducted to examine the impact of surrounding temperature conditions. It allowed to establish the range of time relaxation parameter values of Lee evaporation-condensation model specific for liquid ammonia tank venting. Simulations reproduced accurately the experimentally measured final pressure in the tank and the amount of ammonia released during venting. Liquid ammonia boiling is triggered by reduction of pressure and takes place throughout the liquid causing the pressure recovery phenomenon. Numerical simulations demonstrated that pressure recovery phenomenon is driven by the characteristic time delay associated with the rise of vapour bubbles generated by flash boiling and the subsequent release of evaporated ammonia into the tank ullage space. The developed CFD model can be used as a contemporary tool for safety engineering and development of tank management strategies for liquid ammonia storage. [ABSTRACT FROM AUTHOR]

This study investigates the novel approach of direct liquid ammonia injection into the combustion chamber of a compression ignition engine. Unlike traditional gaseous ammonia port injection, this method shows promise in reducing ammonia slip and emissions. To simulate and analyze the behavior of the liquid ammonia spray, we employed numerical models based on existing literature on flashing and non-flashing spray simulations, as well as recent experimental studies on ammonia spray characteristics using a gasoline direct injection (GDI) injector. Our approach utilized a Lagrangian discrete phase modelling technique to perform a series of three-dimensional computational fluid dynamics (CFD) simulations. The primary objectives of this research were to evaluate the evaporation process of ammonia and its cooling effect, as well as to gain insights into mixture formation within the engine cylinder under different operating conditions. The simulations encompassed the entire engine cycle, considering a multi-hole GDI ammonia spray in conjunction with pilot n-heptane, a diesel surrogate, in equal proportions on an energy basis. Three distinct injection timings for ammonia were examined, leading to varying thermodynamic conditions within the combustion chamber during each spray formation. Consequently, different modelling parameters and initial conditions were necessary to accurately replicate the spray behavior. To address this, we proposed a systematic procedure for assigning pre-defined spray angles. The non-reacting, evaporating spray simulations yielded valuable insights into the mixture formation process, which guided our analysis. Finally, reacting conditions were considered to evaluate engine performance and resulting exhaust gas emissions. This study provides a comprehensive overview of critical aspects related to direct ammonia injection in internal combustion engine (ICE) systems. Moreover, it uncovers performance trends that can serve as a foundation for future investigations in this field. • Simulations of liquid ammonia injection in CI engine. • Assessment of different ammonia injection timings. • Late injections more effective than early. • Nitrous oxides largely contribute to greenhouse gas emissions. • Flash-boiling less important than other spray interactions. [ABSTRACT FROM AUTHOR]

The transition from fossil fuels to renewable energy sources is seen as an essential step toward a more sustainable future. Hydrogen is being recognized as a promising renewable energy carrier to address the intermittency issues associated with renewable energy sources. For hydrogen to become the "ideal" low or zero-carbon energy carrier, its storage and transportation shortcomings must be addressed. This paper will provide the current large-scale green hydrogen storage and transportation technologies, including ongoing worldwide projects and policy direction, an assessment of the different storage and transportation methods (compressed hydrogen storage, liquid hydrogen, blending hydrogen into natural gas pipelines, and ammonia as green hydrogen carrier), as well as economic factors that influence the viability of large-scale green hydrogen storage and transportation. The results of our study highlight several significant findings concerning the cost, challenges, and potential advancements in the green hydrogen storage and transportation field. Our analysis demonstrates that the cost associated with storing and transporting green hydrogen is anticipated to decrease over time due to technological advancements and economies of scale being achieved. However, the commercialization of this technology requires addressing challenges related to storage methods, transportation modes, efficiency optimization, and technology adoption. For example, our research highlights the need for thorough technical and economic evaluations of using salt caverns for hydrogen storage. The efficiency of hydrogen storage and transportation utilizing existing infrastructure, such as storage tanks and natural gas pipelines. By elucidating these aspects, our research contributes valuable insights that can guide future endeavors toward achieving a sustainable and economically viable green hydrogen industry. • Role of government support in green hydrogen storage remains crucial. • Different storage and transportation methods is analyzed and compared. • Cost of hydrogen is expected to decrease for economies of scale. [ABSTRACT FROM AUTHOR]

The dynamics and structure of Cs+ solvation in an aqueous ammonia solution have been investigated using the Quantum Mechanical Charge Field Molecular Dynamics (QMCF‐MD) simulation method. The system contained 18.6% ammonia in aqueous solution at 298.15 K. The QM region was set to a radius of 7.0 Å to include the first and second solvation shells. The Hartree‐Fock (HF) level was applied to calculate the ion‐ligand and ligand–ligand interactions in the QM region using the LANL2DZ‐ECP basis set for the ion and DZP‐Dunning for the ligands. The radial distribution revealed only one solvation shell, indicating a labile solvation structure. The various coordination number of ligands suggests an instant exchange between them. The mean residence times of 1.29 and 0.9 ps were less than in the pure water and liquid ammonia system, indicating higher mobility ligands of the aqueous ammonia system. The preferential factor 0.55 supports the hypothesis that the Cs+ ion prefers to be dissolved in water. As the ligands moves further away from the ion, the observed number of hydrogen bonds increases, revealing the "structure‐breaking" property of the Cs+ ion. The minimum angle ligand‐ion‐ligand tends to be higher near the ion, confirming this phenomenon. [ABSTRACT FROM AUTHOR]

Ammonia is a carbon-free fuel with significant potential to minimize carbon emissions. However, ammonia has weak combustion properties, necessitating more study to improve its combustion performance in engines. A numerical simulation was conducted to evaluate the impact of fuel composition and injection-ignition synergy strategy on the performance of an ammonia-hydrogen spark ignition engine with liquid ammonia direct injection and hydrogen port injection. Specifically, two distinct injection modes were investigated: injection after intake valve close (IAIVC) and injection before top dead center (IBTDC). The outcomes reveal that the IBTDC mode generates a strong stratification of ammonia near the top dead center, resulting in ammonia-rich combustion, then leading to enriched hydrogen production and finally enhancing ammonia combustion and shorting the combustion duration. Liquid ammonia in-cylinder direct injection reduces the combustion temperature and decreases NO emissions. Optimizing the injection timing and spark timing based on a split injection strategy results in lower fuel consumption and emissions. Specifically, NO emissions decrease from 30.5 g/kWh to 21.7 g/kWh at a similar ITE (≈43.5%), and ITE increased from 43.3% to 44.3% for similar NO emission (≈30.0 g/kWh), respectively, with the reduction in both NH 3 and N 2 O emissions. • Ammonia-rich combustion in engines can produce hydrogen. • Ammonia pyrolysis to produce hydrogen shortens combustion duration. • Late injection of ammonia improves thermal efficiency and reduces emissions. • Liquid ammonia in-cylinder direct injection reduces NO emissions. [ABSTRACT FROM AUTHOR]

In order to improve the surface properties of wool fiber, the wool fabric was treated with liquid ammonia and protease treatments successively. The results showed that liquid ammonia pretreatment could cause certain damage to the surface structure and disulfide bonds in keratin, which enhanced the action of protease on wool surface and catalytic hydrolysis of the cuticle. The joint treatment of liquid ammonia and protease changed the secondary structure of wool. The content of α‐helix and random crimp increased, while the content of β‐sheet decreased. In addition, the shrink resistance of wool fabric was significantly improved without obvious losses in tensile strength and elongation. The combination of liquid ammonia and protease treatments provides a potential new method for the surface modification and eco‐friendly shrink‐resistant finishing of wool and further widens the application of liquid ammonia in textile industry. [ABSTRACT FROM AUTHOR]

Thermal-driven refrigeration technologies, e.g., absorption- or adsorption-type, are gathering momentum since they can utilize low-grade heat from industrial, solar or geothermal energy. However, heat sources and end users are usually mismatched, which could lead to potential heat pollution and increased carbon emissions. Long-distance thermal energy transportation is good for district heating and cooling, which is of great significance if it can achieve a high energy-transportation density and low heat loss. In this paper, a compression-assisted chemisorption chiller driven by a low-temperature heat source for cold transportation is initially proposed, which aims to transport liquid ammonia with chemical potential and generate a cooling effect for end users. A feasibility analysis of the compression-assisted chemisorption chiller is preliminarily performed for 2 km cold transportation. The results show that the highest theoretical coefficient of performance and the energy efficiency of the compression-assisted adsorption chiller using a sodium bromide–ammonia working pair can reach 0.46 and 0.25, respectively, when the evaporation temperature is 20 °C. Among the three selected low-temperature salts, ammonium chloride–ammonia shows the best performance, which is up to about 40% higher than those of sodium bromide–ammonia and barium chloride–ammonia. It is demonstrated that compared with common absorption chillers, a compression-assisted adsorption system has a reasonable working efficiency to transport cold energy when the low- or ultralow-temperature heat source, e.g., lower than 60 °C, is required to be utilized. [ABSTRACT FROM AUTHOR]

In this paper, the effect of Na+ concentration on the crystalline phase, morphology, and content of vaterite in a system with different Ca2+ and CO32− ratios using steamed ammonia liquid waste as the calcium source was investigated, and the effect of Na+ on the yield of vaterite was studied systematically for the first time. The obtained products were characterized by powder X-ray diffraction (XRPD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, laser particle size analysis (LPSA), and so on. The results show that the variation of Na+ concentration in different Ca2+ and CO32− ratio systems has an effect on the particle size, morphology, content, and CaCO3 yield of vaterite. Thermogravimetric (TG) analysis indicates that Na+ is involved in forming CaCO3 but does not enter the interior of the vaterite crystals. Mechanistic analysis shows that changes in Na+ concentration can alter the initial pH of the reaction system and the conductivity of the solution, thus changing the processes such as early nucleation and crystal growth of vaterite as well as inhibiting the vaterite phase transition, which determines the particle size of the vaterite obtained. This study reveals to a certain extent the influence of Na+ on the early nucleation and crystal growth of vaterite and provides theoretical support for the realization of large-scale industrial production of vaterite. [ABSTRACT FROM AUTHOR]

In this work we present the simulation of a plant for the exploitation of renewable hydrogen (e.g. from biomass gasification) with production of renewable ammonia as hydrogen vector and energy storage medium. The simulation and sizing of all unit operations were performed with Aspen Plus® as software. Vegetable waste biomass is used as raw material for hydrogen production, more specifically pine sawdust. The hydrogen production process is based on a gasification reactor operating at high temperature (700–800 °C), in the presence of a gasifying agent such as air or steam. At the outlet, a solid residue (ash) and a certain amount of gas, which mainly contains H 2 , CH 4 , CO and some impurities (e.g. sulphur or chlorine compounds) are obtained. Subsequently this gas stream is purified and treated in a series of reactors in order to maximize the hydrogen yield. In fact, after the removal of the sulphur compounds through an absorption column with MEA (to avoid poisoning of the catalytic processes), 3 reactors are arranged in series: Methane Steam Reforming (MSR), High temperature Water-Gas Shift (HT-WGS), Low temperature Water-Gas Shift (LT-WGS). In the first MSR reactor, methane reacts at 1000 °C in presence of steam and a nickel-based catalyst, in order to obtain mainly H 2 , CO and CO 2. Subsequently two steps of WGS are present to convert most of the CO into H 2 and CO 2. Also these reactions are carried out in the presence of a catalyst and with an excess of water. All the oxygenated compounds must be carefully eliminated: the remaining traces of CO are methanated while CO 2 is removed by a basic scrubbing with MEA (35 wt%) inside an absorption column. The Haber-Bosch synthesis of ammonia was carried out at 200 bar and in a temperature range between 300 and 400 °C, using two catalysts: Fe (wustite) and Ru/C. As overall balance, from an hourly flow rate of 1000 kg of dry biomass and 600 kg of nitrogen, 550 kg of NH 3 at 98.8 wt% were obtained, demonstrating the proof of concept of this newly designed process for the production of hydrogen from renewable waste biomass and its transformation into a liquid hydrogen vector to be easily transported and stored. • Simulation of hydrogen production by gasification of waste biomass. • Full purification steps detailed with rate based units. • Ammonia synthesis loop based on multibed quenched reactors. • Overall mass balance: 550 kg/h of ammonia from 1000 kg/h dry biomass. [ABSTRACT FROM AUTHOR]

A clean, green, and efficient procedure has been developed for the synthesis of organic isothio-cyanates using zinc peroxide as a desulfurizing agent. The reaction between amines and carbon disulfide in the presence of liquid ammonia and zinc peroxide was performed at room temperature under mild conditions. Zinc peroxide proved to be a better desulfurizing agent than the previously reported desulfurizing agents. Linear, cyclic, and aromatic isothiocyanates can be synthesized by this method in high yield. Antimicrobial screening of the synthesized compounds revealed good activity of isothiocyanatobenzene, 1-chloro-2-isothiocyanatobenzene, and 2-phenylethyl isothiocyanate against C. albicans, E. coli, and B. subtilis. [ABSTRACT FROM AUTHOR]

Venlafaxine, primarily available in dosage in Venlafaxine hydrochloride (VEN.HCl) form, is a discriminating serotonin and norepinephrine reuptake inhibitor (SNRI) anti-depressant drug. The 4-methoxybenzyl chloride (4-MBC) is a genotoxic impurity present in VEN.HCl. A reverse-phase high-performance liquid chromatography (RP-HPLC) method is developed for the determination of 4-MBC content this method is validated employing ICH (International Council on Harmonisation) guidelines. During the method development, Purospher STAR end-capped (250mmx4.0mm), 5µm HPLC column, and gradient profile for mobile phase with constant 1.0 mL/min flow rate are used. Mobile phase A is a buffer of pH 8.5 containing 0.1% v/v of liquid ammonia in water with adjusted pH using 10% orthophosphoric acid, whereas mobile phase B is acetonitrile. The injection volume, column oven temperature, and autosampler temperature were 50 µL, 55°C, and 5°C, respectively. The data is acquired at 225 nm wavelength. The method yields a well-separated peak of 4-MBC from Venlafaxine and its impurities. This method is linear in the range of LOQ to 150% level of specification concentration of impurity and the observed correlation coefficient is 0.999. The repeatability and intermediate precision are evaluated and the respective values of %RSD for 4-MBC content are 0.43 and 0.93. Robustness studies show insignificant change for the system suitability criteria like %RSD, theoretical plates, and tailing factor, their values being well within the acceptance limit. The new method for the quantification of genotoxic impurity 4-MBC is precise, sensitive, rugged, and accurate; it also qualifies all the criteria of stability, linearity, and robustness. [ABSTRACT FROM AUTHOR]

This study is a numerical investigation of the potentials of liquid ammonia (LNH3) spray combustion in a gas turbine-like combustor at moderately high pressure. The energy costs for the vaporization of LNH3 and the compression of the fuel vapor in the gaseous ammonia (GNH3)/air combustion systems, as well as the capital cost for the equipment involved, can be mitigated by employing LNH3 spray combustion. Additionally, responsiveness to power demand can easily be controlled using direct liquid ammonia. In the first part of this study, the spray characteristics of pure LNH3 were extensively studied numerically and experimentally using a hollow cone nozzle to validate the numerical models and codes. In modeling LNH3 sprays at atmospheric pressure or moderately high ambient pressures, accounting for the flash (superheat) evaporation phenomenon in addition to equilibrium evaporation is very important. Measured and simulated data both show that LNH3 spray (both vapor and droplet phases) reached a minimum equilibrium temperature of 215 K (−60 °C) when LNH3 at a pressure of 0.9 MPa was injected into an environment at 0.1 MPa and 283 K. This minimum temperature is much lower than the saturation temperature of LNH3 of 240 K (−33 °C) at ambient pressure of 0.1 MPa due to occurrence of non-equilibrium flashing. The measured average LNH3 droplet size approximately varied from 15 ∼ 20 µm and the numerical results agreed with these measured values. In the second part of the study, numerical simulations of LNH3 spray combustion were carried out at a moderately high pressure of 0.3 MPa. First, the LNH3 spray was co-fired with gaseous hydrogen (GH2) while maintaining approximately 50 %, 60 %, and 70 % of ammonia in the fuel by energy fraction (ENH3) based on the lower heating value at a moderately high pressure of 0.3 MPa. Finally, 100 % LNH3 spray flame was simulated. Preheated swirling airflow at 600 K was used to enhance the stability of the LNH3 spray flames, enabling stable combustion over a wide range of global equivalence ratios from 0.99 through 1.43. Moreover, the simulated emission characteristics of LNH3/GH2/air flames at ENH3 = 60 % were compared to those of GNH3/GH2/air flames (ENH3 = 60 %) at the same equivalence ratios. The NO and unburnt emissions of LNH3/GH2/air (ENH3 = 50 % ∼ 100 %) flames and GNH3/GH2/air (ENH3 = 60 %) flames show a trade-off relation.

Two new ternary trielides Na7KTr4 (Tr=In, Tl) have been prepared by classical solid‐state reaction from the elements in tantalum ampoules. Both are isostructural to Na7RbTl4 and therefore crystallize in the orthorhombic space group Pbam, Pearson symbol oP96 (a=b=16.3283(2)/16.2860(6), c=11.3094(17)/11.2771(4), V=3015.25(8)/2991.07(18), Z=8, R1, wR2=0.0249, 0.0386/0.0447, 0.0608). The trielide subunit is built by two crystallographically independent [Tr4]8− tetrahedra. 23Na‐MAS‐Nuclear Magnetic Resonance (NMR) as well as EPR spectroscopy was employed to characterize the compounds further. DOS calculations showed a (pseudo) band gap at EF for both compounds. Dissolution experiments in liquid ammonia were carried out for the two alkali metal indides Na7KIn4 and Na2In according to the chemistry of group 14 and 15 Zintl anions. After evaporating the solvent, the remaining material was analyzed by powder X‐ray diffraction and proved the formation of NaIn and NaNH2. [ABSTRACT FROM AUTHOR]

UO2F2 abstracts F− anions from TlF in liquid ammonia solution and the compound [Tl2(NH3)6][{UO2F2(NH3)}2(μ‐F)2] is formed. The compound has been characterized by single crystal X‐ray diffraction, Raman spectroscopy and quantum‐chemical calculations for the solid state. Quantum‐chemical investigation of the [{UO2F2(NH3)}2(μ‐F)2]2− anion showed that the U−(μ‐F)−U σ‐3c‐4e‐bond is essentially ionic. The [Tl2(NH3)6]2+ cation shows a thallophilic Tl⋅⋅⋅Tl interaction. Fluoride ion affinities (FIAs) were calculated for different UO22+ species [UO2Fx]2−x and [UO2Fx(NH3)5−x]2−x with x=0 to 4. [ABSTRACT FROM AUTHOR]

Black phosphorene quantum dots (BPQDs) are most commonly derived from high‐cost black phosphorus, while previous syntheses from the low‐cost red phosphorus (Pred) allotrope are highly oxidised. Herein, we present an intrinsically scalable method to produce high quality BPQDs, by first ball‐milling Pred to create nanocrystalline Pblack and subsequent reductive etching using lithium electride solvated in liquid ammonia. The resultant ~25 nm BPQDs are crystalline with low oxygen content, and spontaneously soluble as individualized monolayers in tertiary amide solvents, as directly imaged by liquid‐phase transmission electron microscopy. This new method presents a scalable route to producing quantities of high quality BPQDs for academic and industrial applications. [ABSTRACT FROM AUTHOR]

The reaction between the heteroleptic metal carbonyl complex [W(CO)4(tmeda)] ((tmeda)=N,N,N′,N′‐Tetramethylethane‐1,2‐diamine) with [Si9]4− silicon Zintl clusters in presence of [2.2.2]crypt ([2.2.2]crypt=4,7,13,16,21,24‐Hexaoxa‐1,10‐diazabicyclo[8.8.8]‐hexacosane) in liquid ammonia yielded the compound [(K,Rb)@([2.2.2]crypt)]2(K,Rb)4[Si9W(CO)4] ⋅ 13.4 NH3. The compound was analyzed by single crystal X‐ray diffraction and crystallizes in the space group P1‾ ${P\bar{1}}$ (a=11.48390(10) Å, b=19.7383(2) Å, c=19.8983(2) Å, α=112.5760(10)°, β=97.4210(10)°, γ=95.3760(10)°, V=4079.01(7) Å3). The compound represents the first group 6 carbonylate‐functionalized silicon Zintl cluster. The central moiety is composed of a tricapped trigonal prismatic nine‐atom silicon species which coordinates with the lone pair of one capping atom to the tungsten tetracarbonylate, forming a pseudo trigonal bipyramidal carbonylate cluster anion [Si9W(CO)4]6−. The chemical bonding in the new cluster entity is analyzed using theoretical calculations and subsequent analysis using QTAIM and NBO. [ABSTRACT FROM AUTHOR]