Ammonium Hydrogen Research Articles

Loaded Catalysts for the Thermal Decomposition of Ammonia

As new energy sources receive more and more attention, the demand for the commercialization of hydrogen energy is also increasing. Hydrogen storage is one of the most important aspects. Currently, the more mature the physical storage technology, but in the future, with the requirements for hydrogen storage, safety, economic cost, hydrogen storage quality density and other indicators, chemical hydrogen storage technology will become a more important and promising research direction. Among them, liquid ammonia hydrogen storage technology has the advantages of product environmental protection, mild storage conditions, and no COx generation when releasing hydrogen. In this paper, several mainstream loaded catalysts used for the pyrolysis process of NH3 are discussed on the basis of literature review, and their respective mechanisms, carriers, and promoters are discussed according to the classification, and the factors affecting the catalysts as well as the suitable action conditions are elaborated, so as to provide some references for the future development of ammonia decomposition catalysts.

Sulphated TiO2 Reduced by Ammonia and Hydrogen as an Excellent Photocatalyst for Bacteria Inactivation.

This study presents a relatively low-cost method for modifying TiO2-based materials for photocatalytic bacterial inactivation. The photocatalytic inactivation of Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus epidermidis) bacteria using modified sulphated TiO2 was studied. The modification focused on the reduction of TiO2 by ammonia agents and hydrogen at 400-450 °C. The results showed a high impact of sulphate species on the inactivation of E. coli. The presence of these species generated acid sites on TiO2, which shifted the pH of the reacted titania slurry solution to lower values, around 4.6. At such a low pH, TiO2 was positively charged. The ammonia solution caused the removal of sulphate species from TiO2. On the other hand, hydrogen and ammonia molecules accelerated the removal of sulphur species from TiO2, as did heating it to 450 °C. Total inactivation of E. coli was obtained within 30 min of simulated solar light irradiation on TiO2 heat-treated at 400 °C in an atmosphere of Ar or NH3. The S. epidermidis strain was more resistant to photocatalytic oxidation. The contact of these bacteria with the active titania surface is important, but a higher oxidation force is necessary to destroy their cell membrane walls because of their thicker cell wall than E. coli. Therefore, the ability of a photocatalyst to produce ROS (reactive oxidative species) will determine its ability to inactivate S. epidermidis. An additional advantage of the studies presented is the inactivation of bacteria after a relatively short irradiation time (30 min), which does not often happen with photocatalysts not modified with noble metals. The modification methods presented represent a robust and inexpensive alternative to photocatalytic inactivation of bacteria.

Interface Engineering of PtZn Alloy and Nb2O5 for Promoting Ammonia Oxidation Reaction and Hydrogen Evolution Reaction.

Ammonia electrolysis is a promising technology to obtain green hydrogen with zero-carbon emission, in which ammonia oxidation reaction (AOR) and hydrogen evolution reaction (HER) occur at the anode and cathode, respectively. However, the lack of efficient catalysts hinders its practical application. Herein, PtZn alloy is combined with Nb2O5 to construct a bifunctional heterostructure catalyst (PtZn-Nb2O5/C). The optimal sample with Nb2O5 content of 7.05 wt % demonstrates the best performance with a peak current density of 304.1 mA mg-1Pt for AOR, and it is only reduced by 17.0% after 4000 cycles of durability tests. For HER, it has a low overpotential of 34 mV at -10 mA cm-2 under the alkaline condition. This can be ascribed to the interfacial interaction between the PtZn alloy and Nb2O5, which adjusts the adsorption behavior of OHad to concurrently promote AOR and HER activity. This work thus proposes a viable strategy to design an efficient bifunctional catalyst for hydrogen generation from ammonia electrolysis.

Comparative study of mixed ammonium fluoride complex-derived single metal hydroxides based on cobalt and nickel for energy storage applications

Zeolitic imidazolate framework 67 (ZIF67) have been intensively applied as efficient active materials for energy storage. Structure directing agents (SDA) play important roles on morphology and electrochemical performance of active materials. Incorporating SDA in synthesis is expected to confine growth of ZIF67 derivatives and create efficient active materials. Ammonium fluoride (NH4F) has been widely applied as an effective SDA for synthesizing active materials in electrochemical systems. Inspired by the confiner of NH4+ and the conductive agent of F−, two novel SDA of ammonium hydrogen fluoride (NH4HF2) and ammonia borane fluoride (NH4BF4) are introduced to synthesize Ni-based or Co-based ZIF67 derivatives via a one-step solution process at room temperature. Substituting 2-methylimidazole with HF2− and BF4− improves conductivity of ZIF67. Effects of NH4HF2 to NH4BF4 ratio for synthesizing ZIF67 derivatives are investigated. The main compositions of ZIF67 derivatives are cobalt and nickel hydroxides. The largest specific capacitance (CF) of 1112.4 F/g is attained for the optimized Ni-based ZIF67 derivative (NiHB) at 20 mV/s. An asymmetric supercapacitor with the NiHB and activated carbon electrodes shows a maximum energy density of 32 Wh/kg at the power density of 750 W/kg, and the CF retention of 70% and Coulombic efficiency of 90.6% after 10,000 cycles.

Modeling of an ammonia decomposition membrane reactor including purity with complex geometry and non-isothermal behavior

A fully coupled mass, momentum, and heat balance model was constructed in axisymmetric 2D for an ammonia decomposition packed bed membrane reactor using computational fluid dynamics and compared to experimental results for a Pd/YSZ membrane surrounded by Ru/Al2O3 catalyst. In addition to the complex geometry of the fittings used to seal the membrane, a total of 16 design variables were found to be required to fully specify the tubular integrated membrane reactor. Aside from emissivity, all input variables were experimentally determined or obtained from tabulated material property data, and no correlation fitting was performed. Experimental data were obtained for temperatures of 450 °C–530 °C, trans-membrane pressures of 0 MPa–0.4 MPa, and gas hourly space velocity feed rates of 375 h−1 to 620 h−1, chosen such that the ammonia conversion and hydrogen recovery spanned a broad range with maximum values of 99.9 % conversion or 88 % recovery with greater than 99.8 % purity. The model was able to successfully determine the ammonia conversion and hydrogen recovery of the experimental results to within an average error of −0.31 % and −2.4 %, respectively. The purity was determined within +0.0071 %, but experimental detection limitations of the impurities affected the fit between experiment and model of the N2 and NH3 in the permeate. The sensitivity of the model to various assumptions and input variables was explored. Notably, the inclusion of purity is a rarity in published models and this study adds to the discussion on the ability of modeling to predict high purity results. Compared to the relatively minimal effects of using the full geometry, the inclusion of heat transfer and radial diffusion were critical in successfully predicting the experimental results.

Room‐Temperature Synthesis of a Compositionally Complex Rare‐Earth Carbonate Hydroxide and its Conversion into a Bixbyite‐Type High‐Entropy Sesquioxide

AbstractIn the present work, the solvent‐deficient synthesis of the high‐entropy rare‐earth carbonate hydroxide RE(CO3)(OH) (RE=La, Ce, Pr, Nd, Sm, and Gd) and its thermal conversion into bixbyite‐type sesquioxide RE2O3 are reported for the first time. The high‐entropy rare earth carbonate hydroxide was prepared via mechanochemical reaction of the corresponding metal nitrate hydrates with ammonium hydrogen carbonate followed by the removal of the NH4NO3 by‐product. Calcination of the carbonate hydroxide precursor in ambient atmosphere at temperatures in the range from 500 to 1000 °C led to the high‐entropy rare earth sesquioxide which exhibited a bixbyite‐type structure ( ) independent of the calcination temperature. Transmission electron microscopy (TEM) investigation revealed the homogeneous distribution of all six rare earth cations in the high‐entropy sesquioxide lattice, however, with some compositional variation between individual grains. The bixbyite‐type structure may be considered as the result of heavy doping of the fluorite‐type CeO2 lattice with the other rare earth cations, which leads to a high concentration of oxygen vacancies, as revealed by electron diffraction and Raman spectroscopy data. The solvent‐deficient synthesis method used in the present study is considered as a valuable, straightforward and easily up‐scalable method to synthesize compositionally complex oxide ceramics.

Emission reduction and cost-benefit analysis of the use of ammonia and green hydrogen as fuel for marine applications

Increasingly stringent emission standards have led shippers and port operators to consider alternative energy sources which can reduce emissions while minimizing capital investment. It is essential to understand whether there is a certain economic investment gap for alternative energy. The present work mainly focuses on the simulation study of ships using ammonia and hydrogen fuels arriving at Guangzhou Port to investigate the emission advantages and cost-benefit analysis of ammonia and hydrogen as alternative fuels. By collecting actual data and fuel consumption emissions of ships arriving at Guangzhou Port, the present study calculated the pollutant emissions and cost of ammonia and hydrogen fuels substitution. As expected, it is shown that with the increase of NH3 in fuel, mixed fuels will effectively reduce CO and CO2 emissions. Compared to conventional fuel, the injection of NH3 increases the NOx emission. However, the cost savings of ammonia fuel for CO2, SOx and PM10 reduction are higher than that for NOx. In terms of pollutants, ammonia is less expensive than conventional fuels when applied to the Guangzhou Port. However, the cost of fuel supply is still higher than conventional energy as ammonia has not yet formed a complete fuel supply and storage system for ships. On the other hand, hydrogen is quite expensive to store and transport, resulting in higher overall costs than ammonia and conventional fuels, even if no pollutants are produced. At present, conventional fuels still have advantage in terms of cost. With the promotion of ammonia fuel technology and application, the cost of supply will be reduced. It is predicted that by 2035 ammonia will not only have emission reduction benefits, but also will have a lower overall economic cost than conventional fuels. Hydrogen energy will need longer development and technological breakthroughs due to the limitation of storage conditions.

Evaluation of Effective Catalysts for Treating Ammonia Hydrogen Peroxide Wastewater by Hydrothermal Reaction

Evaluation of Effective Catalysts for Treating Ammonia Hydrogen Peroxide Wastewater by Hydrothermal Reaction

Innovative Method for the Mass Preparation of α″-Fe16N2 Powders via Gas Atomization

The iron nitride materials, especially α″-Fe16N2, are considered one of the most promising candidates for future rare-earth-free magnets. However, the mass production of α″-Fe16N2 powders as a raw material for permanent magnets is still challenging. In this work, starting from iron lumps as a raw material, we have managed to prepare the α″-Fe16N2 powders via the gas atomization method, followed by subsequent nitriding in an ammonia–hydrogen gas mixture stream. The particle size was controlled by changing the gas atomization preparation conditions. X-ray diffractograms (XRD) analyses show that the prepared powders are composed of α″-Fe16N2 and α-Fe phases. The α″-Fe16N2 volume ratio increases with decreasing powder size and increasing nitriding time, reaching a maximum of 57% α″-Fe16N2 phase in powders with size below 32 ± 3 μm after 96 h nitridation. The saturation magnetization reaches the value of 237 emu/g and a reasonable coercivity value of 884 Oe. Compared to the saturation magnetization values of α-Fe powders, the α″-Fe16N2 powders prepared through our proposed approach show an increase of up to 10% in saturation and demonstrate the possibility of mass production of α″-Fe16N2 powders as precursors of permanent magnets without rare earths.

A Computational Study of a Prebiotic Synthesis of Folic Acid (Vitamin B9)

The planetary molecules cyanogen, cyanoacetylene, hydrogen cyanide, ammonia, and carbon monoxide and hydrogen are invoked in a synthesis of the pteridine precursor of the vitamin folic acid. This is followed by the formation of a p-methylamino benzoyl α-glutamic acid from the planetary gases diacetylene, acetylene, hydrogen cyanide, carbon monoxide, ammonia, water and hydrogen. This latter requires a surface catalyzed, photochemically activated synthesis on the magnesium metalloporphyrin catalyst. The addition of several 5-amide glutamic acid entities may be added on the same catalyst surface. Finally the pteridine derivative and the p-methylamino benzoyl-α-glutamic acid derivative are combined to give the folic acid vitamin. The reactions have been shown to be feasible from the overall enthalpy changes in the ZKE approximation at the HF and MP2 /6-31G* level, and with acceptable activation energies.

An integrated 0D/1D/3D numerical framework to predict performance, emissions, knock and heat transfer in ICEs fueled with NH3–H2 mixtures: The conversion of a marine Diesel engine as case study

In the maritime transportation, e-fuels represent a valid alternative to fossil energy sources, in order to accomplish the European Union goals in terms of climate neutrality. Among the e-fuels, the ammonia-hydrogen mixtures can play a leading role, as the combination of the two allows to exploit the advantages of each one, simultaneously compensating their gaps.The main goal of the present publication is the proposal of a robust numerical framework based on 0D, 1D and 3D tools for CFD analyses of internal combustion engines fueled with ammonia-hydrogen mixtures.The 1D engine model provides boundary conditions for the multi-dimensional investigations and estimates the overall engine performance. 3D in-cylinder detailed analyses are proficiently used to predict combustion efficiency (via the well-established G-equation model supported by laminar flame speed correlations for both ammonia and hydrogen) and emissions (with a detailed chemistry based approach). Heat transfer and knock tendency are evaluated as well, by in-house developed models. As for the 0D/1D chemical kinetics calculations, firstly they support 3D analyses (for example via the generation of ignition delay time tables). Moreover, they allow insights on aspects such as NOx formation, to individuate mixture qualities able to strongly reduce the emissions.The present paper offers also indications for designers on the effectiveness of NH3–H2 as valid substitutes of traditional fuels in marine applications. In fact, the proposed framework is preliminary tested to convert an existing marine Diesel engine to ammonia-hydrogen mixtures. Different proportions (among the two fuels) are investigated, included pure ammonia and pure hydrogen and the NH3–H2 80mol%-20mol% mixture is selected as the best compromise. Thanks to both the anti-knock quality of the ammonia and the (limited) addition of hydrogen as combustion enhancer, the engine supplied with NH3–H2 mixtures is able to operate free of knock and keep the same performance as the original one. Simultaneously (neglecting the presence of lubricant oil in the combustion chamber) unburned hydrocarbons, carbon monoxide and carbon dioxide are eliminated. Still in comparison with the Diesel version, the heat transfer is similar, the NOx formation is much greater and the engine range (here evaluated in terms of working hours) noticeably reduces.

High-Temperature Materials for Complex Components in Ammonia/Hydrogen Gas Turbines: A Critical Review

This article reviews the critical role of material selection and design in ensuring efficient performance and safe operation of gas turbine engines fuelled by ammonia–hydrogen. As these energy fuels present unique combustion characteristics in turbine combustors, the identification of suitable materials becomes imperative. Detailed material characterisation is indispensable for discerning defects and degradation routes in turbine components, thereby illuminating avenues for improvement. With elevated turbine inlet temperatures, there is an augmented susceptibility to thermal degradation and mechanical shortcomings, especially in the high-pressure turbine blade—a critical life-determining component. This review highlights challenges in turbine design for ammonia–hydrogen fuels, addressing concerns like ammonia corrosion, hydrogen embrittlement, and stress corrosion cracking. To ensure engine safety and efficacy, this article advocates for leveraging advanced analytical techniques in both material development and risk evaluation, emphasising the interplay among technological progress, equipment specifications, operational criteria, and analysis methods.

Thermal analysis of bioconvective nanofluid flow over a sphere in presence of multiple diffusions and a periodic magnetic field

The current work intends to describe the heat and mass transfer in the mixed bioconvective flow of nanofluid along the sphere. This analysis also takes into account the influences of a periodic magnetic field and the diffusions of species concentrations such as liquid ammonia and liquid hydrogen. The physical problem is represented as a collection of connected nonlinear partial differential equations with appropriate boundary constraints using the Boussinesq approximation. The Buongiorno two-phase model is utilized to examine the nanoparticle's effect on the fluid. The governing equations are represented in the dimensionless form by using nonsimilar transformations. Further, the implicit finite difference scheme and the technique of quasilinearization are employed for numerical computation. Graphs are used to discuss the findings. The skin friction coefficient increases by about 27%, and the heat transfer rate to the fluid from the surface decreases by about 30% when the periodic magnetic field escalates from 0 to 1. The nanoparticle's mass transfer rate increases by about 35% when the Lewis number grows from 5 to 10. Higher Peclet numbers are favorable to the skin friction coefficient and heat transfer rate, but not the microorganism's density number. The present numerical results obtained in this analysis were compared to earlier published work and found to be in excellent agreement.

Comparison of green ammonia and green hydrogen pathways in terms of energy efficiency

The global energy system transition necessitates new energy carriers with low greenhouse gas emissions. Chemical energy storage technologies provide a viable basis for long-term energy storage. Ammonia is a promising approach in this regard. This study takes a closer look on the energetic potential of ammonia as energy carrier compared to hydrogen. The efficiencies of five green ammonia and four green hydrogen pathways are evaluated for production, storage and utilisation on a power-to-X-to-power basis. The round-trip efficiency for each pathway is calculated by comparing the energy demand that each individual technology requires along the pathways and the usable electric energy that is provided at the end of the pathways. The most efficient pathway for ammonia turns out to be a combination of a decomposition-unit and a solid-oxide fuel cell with a round-trip efficiency of 28 ± 5 % for 30-day storage duration. This is similar to the value for the most efficient pathway using hydrogen. Pathways utilising ammonia are energetically particularly beneficial compared to the hydrogen pathways in case of long storage duration.

Boron nanoclusters endowed NiFe layered double hydroxides with efficient bifunction toward ammonia oxidation reaction and hydrogen evolution reaction

Coupling ammonia oxidation reaction (AOR) and hydrogen evolution reaction (HER) provides a hybrid water splitting system to reduce the energy consumption of hydrogen production significantly, solve the safety problem of H2/O2 mixing in the overall water splitting, and remove ammonia nitrogen from wastewater. Herein, amorphous boron nanoclusters are deposited onto NiFe layered double hydroxide nanosheets (B-NiFe-LDH/NF) via in-situ electroreduction, proposed to form a bifunctional catalyst toward the AOR and HER. Since the electron-deficient boron induces surface electronic recombination of LDH and facilitates the exposure of substantial high-valent Ni and Fe metal active sites, this B-NiFe-LDH/NF exhibited high activity with a voltage of 1.781 V at a current density of 100 mA cm-2, 202 mV lower than that required in overall splitting water, accompanying with 78.6% of the ammonia removal rate after 24 h of electrolysis. In addition, density functional theory (DFT) simulation indicated that the induction of boron nanoclusters decreased the energy barrier, facilitating the adsorption–desorption of ammonia and the Volmer step.

A Review of Current Advances in Ammonia Combustion from the Fundamentals to Applications in Internal Combustion Engines

The energy transition from hydrocarbon-based energy sources to renewable and carbon-free energy sources such as wind, solar and hydrogen is facing increasing demands. The decarbonization of global transportation could come true via applying carbon-free fuel such as ammonia, especially for internal combustion engines (ICEs). Although ammonia has advantages of high hydrogen content, high octane number and safety in storage, it is uninflammable with low laminar burning velocity, thus limiting its direct usage in ICEs. The purpose of this review paper is to provide previous studies and current research on the current technical advances emerging in assisted combustion of ammonia. The limitation of ammonia utilization in ICEs, such as large minimum ignition energy, lower flame speed and more NOx emission with unburned NH3, could be solved by oxygen-enriched combustion, ammonia–hydrogen mixed combustion and plasma-assisted combustion (PAC). In dual-fuel or oxygen-enriched NH3 combustion, accelerated flame propagation speeds are driven by abundant radicals such as H and OH; however, NOx emission should be paid special attention. Furthermore, dissociating NH3 in situ hydrogen by non-noble metal catalysts or plasma has the potential to replace dual-fuel systems. PAC is able to change classical ignition and extinction S-curves to monotonic stretching, which makes low-temperature ignition possible while leading moderate NOx emissions. In this review, the underlying fundamental mechanism under these technologies are introduced in detail, providing new insight into overcoming the bottleneck of applying ammonia in ICEs. Finally, the feasibility of ammonia processing as an ICE power source for transport and usage highlights it as an appealing choice for the link between carbon-free energy and power demand.

Characterization and Optimization of Plasma Electrolytic Process for Conversion of Molecular Nitrogen to Ammonia in Aqueous Water at Atmospheric Pressure

Ammonia (NH3) is widely used in the chemical and agricultural industries and is of growing interest as a potential energy carrier. Most of the current global NH3 production utilizes the Haber-Bosch process which has a large environmental and physical footprint. For this reason, there have been substantial efforts to develop an alternative process that can be sustainable and distributed. Recently, plasma-based electrolysis reactors have shown promise to convert molecular nitrogen to various forms of fixed nitrogen such as ammonia, nitrate, and nitrite in water at atmospheric pressure. However, selectivity and control over the products has not been adequately demonstrated. In this work, we studied a plasma formed in pure nitrogen gas or mixtures containing nitrogen gas at the surface of liquid water. Various products were characterized in the liquid phase including ammonium ions, nitrate ions, nitrite ions, and hydrogen peroxide as a function of pH, discharge current, and time. In addition, continuous direct current (DC) was compared to pulsed DC voltage plasma operation. We find that the selectivity to different nitrogen products depends on the solution conditions. These results could be used to inform optimization and scale up of similar plasma-liquid systems for sustainable nitrogen fixation.

Heat release rate surrogate for ammonia–hydrogen premixed flames under various conditions

Blending hydrogen has proven an efficient method to enhance the combustion stability of gaseous ammonia flames. Heat release rate (HRR), as an important parameter to indicate combustion process, is hard to be directly measured and highly dependent on the fuel components, equivalence ratios, and operation conditions. This paper presents a comprehensive study on developing a general HRR surrogate (HRRS) for ammonia–hydrogen premixed flames under various conditions. Firstly, reaction mechanisms for ammonia/hydrogen premixed combustion are evaluated under various conditions, by comparing the predicted laminar flame speeds with the experimental data collected from published literature. The reaction mechanism developed by Shrestha et al., (2021) performs the best under various conditions. Then, series of one-dimensional freely propagating premixed flames under various conditions are calculated using this reaction mechanism and analyzed to explore the effects of blending ratios, pre-heat temperatures, equivalence ratios, and pressures on the HRR reconstruction for ammonia–hydrogen premixed flames from the viewpoint of chemical kinetics, and also serve as a database for the identification of HRRS. It is found that equivalence ratio and blending ratio have significant effects on the HRR reconstruction, while the effects of pressure and initial temperature are relatively limited. Subsequently, the general HRRS, [NH2]1.53[OH]0.28, is identified for ammonia–hydrogen premixed flames under various conditions using a grid-research optimization method. Finally, the general HRRS is further comprehensively validated on several 2D and 3D turbulent premixed flames of ammonia–hydrogen under various conditions. The comparisons with the two previous HRRSs also demonstrate that the present developed HRRS is superior and more stable temporally.

Molecular simulations of understanding the Na+ ion structure, dynamic and thermodynamic behavior in ionic liquids: Butyl ammonium hydrogen bisulfate and tri-butyl ammonium hydrogen bisulfate

This manuscript presents the all-atom molecular dynamics simulations to investigate intermolecular structure and solvation thermodynamics of Na+ ion in two different ammonium-based protic ionic liquids (1) Butyl Ammonium hydrogen bisulfate [BA+][HSO4−], (2) Tri-butyl ammonium hydrogen bisulfate [TBA+][HSO4−]. The ionic liquid [BA+][HSO4−] show a more coordinated behavior when compared to [TBA+][HSO4−], which is observed over the temperature range from 278 K to 348 K. Hydrogens of the cations show a hydrogen bonding interaction with oxygens of anions. The cationic [TBA+] molecules show more solvation behavior with anions when compared to the [BA+]. The Na+ ion show a strong coordination structure with [HSO4−] in [TBA+][HSO4−] when compared to the [BA+][HSO4−]. We further calculate the detailed solvation free energy (ΔG) calculations using thermodynamic integration. We found that the ΔG of Na+ is more favorable in [TBA+][HSO4−] when compared to [BA+][HSO4−] in the temperature range varying from 278 K to 348 K. With the temperature rise, we observe the more favorable solvation of Na+ in both ionic liquids. On the other hand, the solvation of Cl− becomes less favorable. Overall, this manuscript provides detailed molecular level structural and thermodynamic origins of Na+ in protic ionic liquids useful for designing and developing sustainable electrolytes for Na+ battery applications.

Numerical investigation of ammonia-rich combustion produces hydrogen to accelerate ammonia combustion in a direct injection SI engine

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 NH3 and N2O emissions.