Recent progress in electrochemical synthesis of carbon-free hydrogen carrier ammonia and ammonia fuel cells:A review

Ammonia(NH3)is a cornerstone widely used in the modern agriculture and industry,the annual global production gradually increases to almost 200 million tons.Nearly 80%of the produced NH3 is used in the fertilizer industry and is essential for the development of global agriculture and consequently for maintaining population growth.Furthermore,NH3 can power hydrogen(H2)fueled devices,such as H2 fuel cells(FC),to use the interconversion between chemical energy and electric energy of nitrogen(N2)cycle,which can effectively alleviate the intermittent problems of renewable energy.However,the problems faced by NH3 in storage and release still restrict its development.Herein,this review introduces the latest research and development of electrochemical NH3 synthesis and direct NH3 FC,as well as outlines the technical challenges,possible improvement measures and development perspectives.N2 reduction reaction(NRR)and nitrate reduction reaction(NO3RR)are two potential approaches for electrochemical NH3 synthesis.However,the existing research foundation still faces challenges in achieving high selectivity and efficiency.Direct NH3 FC are easy to transport and are expected to be widely used in mobile energy consuming equipment,but also limited by the lack of highly active and stable NH3 oxidation electrocatalysts.The perspectives of ammonia fuel cells as an alternative green energy are discussed.

Research on Properties of Metasilicate Bonded Carbon-free Basic Dry Vibration Mix

Carbon-free basic dry vibration mix was prepared using middle grade magnesia and fused magnesia as main starting materials,metasilicate replacing phenolic resin as binder,adding a certain amount of medium and low temperature intensifiers. Effects of binder,grain composition,and additives on basic dry vibration mix for tundish were studied,and the bonding mechanism was also analyzed. The results show that：（1） when using metasilicate as binder,the higher strength can be acquired; （2） the suitable grain composition is q=0.48,the critical granularity is 5 or 3 mm,the fines addition is 10%-20% （mass percent）; （3） the strength and corrosion resistance of the basic dry vibration mix can be improved by the melting compound of metasilicate and additives; （4） with temperature rising,the bonding type in dry vibration mix changes from cohere bonding to reaction bonding,and then to ceramic bonding at last.

Development and Application of Carbon-free Al_(2)O_(3)-MgO Dense Bricks for Steel Ladles

Carbon-free Al_(2)O_(3)-MgO dense bricks were produced by the pressing method,using tabular alumina,white fused alumina,alumina micro-powder as main raw materials,and inorganic powder as the binder.The comprehensive properties and performance in steel ladle side wall were made a comparison between Al_(2)O_(3)-MgO dense bricks and precast blocks.The results show that Al_(2)O_(3)-MgO dense bricks exhibit high dense structure and strength,as well as superior thermal shock resistance and better penetration and corrosion resistance to slag than precast blocks.While replacing precast blocks with dense bricks in 250 t steel ladle side wall in some domestic steel mills,the thickness of the metamorphic layer from slag penetration and the corrosion rate decrease evidently.The damage of dense bricks during service is mainly caused by the corrosion from molten steel and slag,and the structure spalling of the metamorphic layer also plays an important role.

Influence of Tungsten and Cobalt Contents on the Microstructure Changes and Fracture Behavior of New Carbon-Free Steel-alloy Composites

The ever increasing demand for steel materials that have good combinations between strength and toughness urged all researchers working in the field of material science to find new alloys that can approach that requirement.Unfortunately strength and toughness of materials are always counter acting properties.However,carbon contents in the steel define to a great extent its strength and toughness.In this research an effort is paid to produce steel alloy composites that can give higher strength together with good toughness without alloying with carbon.The mechanism of strengthening in Iron-Cobalt-Tungsten composite alloys with variations in Co and W contents is investigated.The fracture toughness and hardness,are measured for all alloy composites under investigation.The changes in microstructures after heat treatment are emphasized using metallurgical microscopy and SEM-aided with EDX analyzing unit.

From non-carbon host toward carbon-free lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries with advantages of high energy densities(2600 Wh·kg^(-1)/2800 Wh·L^(-1))and sulfur abundance are regarded as promising candidates for next-generation high-energy batteries.However,the conventional carbon host used in sulfur cathodes suffers from poor chemical adsorption towards Li-polysulfides(LPS)in liquid electrolyte and sluggish redox kinetics,leading to low capacity and rate capability.Besides,carbon host used in Li metal anode with the intrinsic property of poor lithiophilicity and high Li-nucleation barrier gives rise to uncontrollable dendrite growth and further battery failure.Therefore,non-carbon hosts with chemical adsorption toward LPS and catalytic activity for accelerating LPS redox conversion as well as lithiophilic property for guiding uniform Li deposition are proposed and demonstrated a high efficiency in both sulfur cathodes and Li metal anodes.In this review,the principle and challenges of Li-S batteries are first presented,then recent work using non-carbon hosts in Li-S batteries is summarized comprehensively,and the mechanism of non-carbon host in improving sulfur utilization and stabilizing Li metal anode is discussed in detail.Furthermore,remaining challenges and outlook on the implementation of non-carbon host for practical carbon-free Li-S batteries are also provided.

Simulation Study of Diesel Spray Tilt Angle and Ammonia Energy Ratio Effect on Ammonia-Diesel Dual-Fuel Engine Performance

Ammonia-diesel dual fuel(ADDF)engines for transportation applications are an important way to reduce carbon emissions.In order to achieve better combustion of ammonia in diesel engines.A small-bore single-cylinder engine was converted into an ADDF engine with the help of mature computational fluid dynamics(CFD)simulation software to investigate the performance of an engine with a high ammonia energy ratio(AER),and to study the effect of spray tilt angle on ADDF engine.The results showed that the increase in AER reduced nitric oxide(NO)and nitrogen dioxide(NO2)emissions but increased nitrous oxide(N2O)and unburned ammonia emissions.AER in the range of 50%-70%achieved lower greenhouse gases(GHG)emissions than the pure diesel mode.Relative to the pure diesel mode,when the AER was 60%,the indicated thermal efficiency(ITE)was increased by 0.2%and the GHG emissions were decreased by 22.3%,but carbon monoxide(CO)and Hydrocarbon(HC)emissions were increased.Increasing the in-cylinder combustion temperature or high-temperature region range of the ADDF engine could reduce GHG emissions.At an AER of 60%,an increase in the spray tilt angle helped the ammonia combustion in the residual gap to reduce the unburned ammonia emissions.Compared to the pure diesel mode with a spray tilt angle of 75°,an AER of 60%with a spray tilt angle of 77.5°improved the ITE by 1.5%,and reduced theGHGemissions by 25.7%.Adjusting the spray tilt angle of theADDFengine also reducedCOandHCemissions.This is an effective way to improve ADDF engine performance by adjusting the spray tilt angle.

无碳复写字迹的化学消退特征初探

无碳复写消退变造文书案件近年呈增多趋势。采用多种常见有机溶剂对无碳复写字迹进行化学消退实验,并比较消退效果及消退特征,为化学消退无碳复写字迹的检验提供基础性研究数据,具有重要的现实意义。

Current Situation and Development of Refractories for Clean Steel Production

The low cost and high efficient clean steels metallur- gy has been focused much attention in China. Among the factors affecting the cleanliness and consequent quali- ty of steel products, refractories are one of the key fac- tors. Meanwhile the restriction of resource, energy and environment is getting stronger, thus the improvement of refractories becontes much more important. In this paper, refractories selection principle Jbr clean steel production according to their thermodynamic features was ex- plained; refractories for tundLsh and flow control in con- tinuous casting, which play important roles in prohibi- ring secondary contamination of molten steel, were intro- duced. Moreover, new development of low-carbon and carbon-free refractory materials was also described.

Refractories with Improved Thermal Shock Performance Serving Low Carbon Economy

Nanoengineered carbon bonded refractories as well as fine grained carbon free refractories with improved thermal shock performance are presented in terms of this contribution.

Carbon-free energetic metal pentazolate hydrates

Subject Code:E04With the support by the National Natural Science Foundation of China,a major breakthrough has been made by the group led by Prof.Lu Ming(陆明)from Nanjing University of Science&Technology.The related research achievement entitled“A series of energetic metal pentazolate hydrates”was published

Innovative Lining of Unburnt Al_(2)O_(3)-MgO Brick for 300t Steel Ladle in Baosteel

The manufacture of clean steel needs high performance carbon-free bricks for ladle lining.Based on long term application experiences of the prefab Al_(2)O_(3)-MgO blocks,unburnt Al_(2)O_(3)-MgO brick has been developed by pressing a mix of alumina,spinel and magnesia as major raw materials and Al_(2)O_(3)-MgO gel powder as binder.In addition to low open porosity and high strength,the unburnt Al_(2)O_(3)-MgO brick shows superior corrosion resistance and thermal shock resistance to the prefab block.Field trials in a 300t steel ladle have indicated the residual lining of unburnt Al_(2)O_(3)-MgO bricks showed smooth surface without large spalling and seldom steel infiltration,consequently longer service life than the prefab blocks.The reliable,unburnt Al_(2)O_(3)-MgO bricks have more advantages of high efficiency,energy-saving and eco-friendly production.It will be one of the best options for ladle lining in the manufacture of high-purity steel.

Facile Synthesis and High-Value Utilization of Ammonia

Ammonia is a key component in fertilizer and the carbon-free hydrogen carrier.Catalytic ammonia synthesis and utilization have played a central role in the development of chemical engineering.The industrial production of ammonia remains dependent on the energy-and carbon-intensive Haber-Bosch process.A major effort has been devoted to developing robust and efficient catalysts,as well as alternative benign processes.Herein,we detail our endeavors that develop the ammonia synthesis and decomposition catalysts,and utilize the ammonia energy.We firstly discuss the catalysts for ammonia synthesis via dissociative and associative process,and the regulation of catalysts'properties.Then,we review the burgeoning electrocata-lytic nitrogen reduction process,focusing on the enhanced catalytic performances by the regulation of the catalysts and the electrode.Additionally,we provide a novel high-value utilization of ammonia to achieve the"zero-carbon"circular economy.The promising catalysts,reactors,and ammonia energy systems have been discussed in detail.We end this Account that offers future research directions and prospects of ammonia.

Evaluation of Electricity Generating System's Technology Mix Using 3E Indicator

For the purpose of the research, the technologies for electricity generation are classified in four categories: CO_2-free-desspatchable(hydro, nuclear, and biomass fired), CO_2-free-non-desspatchable(wind generators and photo voltaic), CO_2-dependent-despatchable and CO_2-dependent-non-despatchable ones. 3E indicator is introduced purposely to enable quantitative evaluation of the considered complex technology structures, as well as to provide support for decision making during the design and operation procedures of electricity generating systems. The application of the indicator is demonstrated with appropriate model numerical simulations for the general European conditions. In the model calculations are analyzed simplified technology mixes with CO_2 free, non-despatchable technologies in overall load, two technologies in base part of the residual load(lignite fired and nuclear), one technology in intermediate part of the residual load and one in the pick part of the residual load both CO_2 dependent, despatchable ones. The results show that the introduced 3E indicator is suitable for analysis of the technological combinations for electricity generation within considered countries. The results also show that increase participation of nuclear power plants in residual load domain contribute to better(lower) value of 3E indicator. The results obtained for technology structures in nine analyzed European countries(Germany, France, Austria, Greece, Serbia, Hungary, Bulgaria, Belgium and Netherlands) point out that the country with higher participation of CO_2 free despatchable and lower participation of CO_2 free non-despatchable technologies in electricity generation has tendency toward better i.e. lower value of 3E indicator. On the other hand the country with the higher participation of CO_2 free non-despatchable and lower to moderate participation of CO_2 free despatchable technologies has tendency toward the higher value of 3E indicator. These results are in accordance with the results obtained by numerical simulations with simplified technology mixes.

FreestandingMo_(3)N_(2) nanotubes for long-term stabilized 2e−intermediate-based high energy efficiency Li-CO_(2) batteries

Li–CO_(2) batteries are considered one of the promising power sources owing to ultrahigh energy density and carbon fixation.Nevertheless,the sluggish reaction kinetics of 4e−discharged process(Li_(2)CO_(3))impede its potential application.One of the efficient strategies for developing cathode catalysts is to stabilize 2e−intermediate Li_(2)C_(2)O_(4) and improve reaction reversibility.However,longterm catalysts of stabilized Li_(2)C_(2)O_(4) are barely achieved,whereas cycle stability is far from satisfactory level.Herein,non-noble metal–based Mo_(3)N_(2) is synthesized and employed as freestanding cathodes for Li–CO_(2) batteries.Owing to rich delocalized electrons of Mo^(2+)and reversible electron localization structure,freestanding Mo_(3)N_(2) cathodes exhibit a low charge potential(3.28 V)with an ultralow potential gap(0.64 V),high energy efficiency of up to 80.46%,fast rate capability,and outstanding cycle stability(>910 h).In situ experiments and theoretical calculation verify that Mo_(3)N_(2) stabilizes 2e−Li_(2)C_(2)O_(4) intermediate by the interaction of Mo^(2+)as active sites where Mo^(2+)promotes the transfer of outer electrons to O,prevents its disproportionation to Li_(2)CO_(3),and promotes reaction kinetics,contributing to high energy efficiency and outstanding cycle reversibility.In addition,the pouch-cells deliver ultrahigh energy density of up to 6350.7W h kg^(−1) based on the mass of cathode materials.