Category Archives: Conference Paper

Highly-Selective Electrochemical Reduction of Dinitrogen to Ammonia at Ambient Temperature and Pressure

Posted on December 16, 2018 by | Leave a comment

Qiang Zhang*, Xiaoyang Cui, Cheng Tang, Tsinghua University, China

15th Annual NH3 Fuel Conference, Pittsburgh, PA, October 31, 2018
NH3 Energy+ Topical Conference at the AIChE Annual Meeting

ABSTRACT

Catalytic conversion of dinitrogen (N2) into ammonia under ambient conditions represents one of the Holy Grails in catalysis and surface science. As a potential alternative to the Haber-Bosch process, electrochemical reduction of N2 to NH3 is attractive owing to its renewability and flexibility, as well as sustainability for producing and storing value-added chemicals from the abundant feedstock of water and nitrogen on earth. However, owing to the kinetically complex and energetically challenging N2 reduction reaction (NRR) process, NRR electrocatalysts with high catalytic activity and high selectivity are rare. In this contribution, as a proof-of-concept, we demonstrate that both the NH3 yield and NH3 faradaic efficiency (FE) at ambient conditons can be improved by modification of the hematite nanostructure surface. Continue reading →

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Identifying the Prospects of Electrochemical Ammonia Synthesis on Mxenes Using First Principles Calculations

Posted on December 16, 2018 by | Leave a comment

Gurjyot Sethi, Venkat Viswanathan*, Carnegie Mellon University, USA

15th Annual NH3 Fuel Conference, Pittsburgh, PA, October 31, 2018
NH3 Energy+ Topical Conference at the AIChE Annual Meeting

ABSTRACT

Electrochemical synthesis of ammonia is a major challenge aimed at making production of ammonia sustainable. Currently ruthenium is the transition metal of choice for catalyzing the industrial Haber-Bosch process. However, electrochemical ammonia synthesis on ruthenium suffers from high overpotential and the competing hydrogen evolution reaction. Recently layered transition metals carbides and nitrides (MXenes) have been identified as a potential material class for ammonia synthesis. MXenes are particularly interesting owing to the high degree of tunability in surface chemistry due to the transition metal choice, interlayer distance, number of layers in the material, and surface termination. These choices affect the electron density of the surface and hence the binding strength of MXenes with key intermediates. In this work, we use density functional theory (DFT) to compute adsorption free energies of relevant intermediates to identify MXenes that are promising for ammonia synthesis. Using uncertainty quantification capabilities within the Bayesian error estimation functional (BEEF), we also compute the probability density functions for catalytic activity predictions. We obtain free energy diagrams and scaling relations and finally report prediction confidence values on the limiting potential and insights into the prospects of using MXenes for nitrogen fixation. Continue reading →

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Analysis of influence of operating pressure on dynamic behavior of ammonia production over ruthenium catalyst under high pressure condition

Posted on December 14, 2018 by | 1 comment

Hideyuki Matsumoto*, Javaid Rahat, Yuichi Manaka, Mika Ishii, Tetsuya Nanba, Renewable Energy Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Japan

15th Annual NH3 Fuel Conference, Pittsburgh, PA, October 31, 2018
NH3 Energy+ Topical Conference at the AIChE Annual Meeting

ABSTRACT

Process technologies on energy conversion of renewable electricity into hydrogen energy carrier are significant to deploy long-term storage and long-distance transport of much more renewable inside and outside Japan. Ammonia is a potential hydrogen carrier that contains 17.6 wt% of hydrogen. Moreover, as an energy carrier, ammonia is thought to be a clean fuel as only water and nitrogen are produced on direct combustion.

Many researchers and engineers consider that ammonia plants using hydrogen produced by solar electricity or wind electricity will be much smaller than those currently used [1]. There is an issue of low pressure condition for feed of raw material gas, since hydrogen and nitrogen are produced by water electrolysis and pressure swing adsorption (or cryogenic air separation) respectively. Ammonia synthesis under the conventional pressure conditions needs increase in power for compression of the feed gas. Moreover, low temperature operation has advantage in getting higher ammonia concentration of equilibrium limitation. In order to promote the reaction under the lower pressure conditions, lower reaction temperature condition is desirable due to a limitation of equilibrium.

In Japan, the Japan Science and Technology Agency (JST) supports the research and development of catalyst with high catalytic activities in the low-temperature region, and our research group investigates performance of developed ruthenium catalysts by small-scale ammonia plant that is built in Fukushima Renewable Energy Institute, AIST (FREA). Continue reading →

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A Low Pressure Membrane Based Renewable Ammonia Synthesis

Posted on December 14, 2018 by | Leave a comment

Sarbjit Giddey, CSIRO, Australia

15th Annual NH3 Fuel Conference, Pittsburgh, PA, October 31, 2018
NH3 Energy+ Topical Conference at the AIChE Annual Meeting

ABSTRACT

Ammonia is currently mostly produced by the highly energy and carbon-intensive Haber–Bosch process, which requires temperatures of 450–500 °C and pressures of up to 200 bar. The feedstock for this process is hydrogen from natural gas (NG), coal or oil, and nitrogen produced from air by cryogenic route or pressure swing adsorption (PSA). The share of NG, coal and fuel oil feedstock for the global production of ammonia is 72%, 22% and 4% respectively, contributing to approximately 420 million tons of CO2 emissions per annum, representing over 1% of global energy related emissions. The energy consumed for ammonia synthesis by Haber-Bosch process is in the 10 to 15 MWh/tonne range, depending on the type of fossil fuel feedstock used.

In an alternative route renewable hydrogen produced by an electrolyser can be fed to the Haber-Bosch reactor along with nitrogen for ammonia synthesis, and this route has been suggested to consume energy around 12 MWh/tonne of ammonia.

CSIRO has developed a metal membrane based ammonia synthesis process that uses hydrogen and nitrogen as feedstock. The materials and catalyst developed for the process allow the synthesis process at much lower pressures (~ 10 bar) at 450 °C. The synthesis rates achieved are two orders of magnitude higher than with any electrochemical route. The catalyst and the metal / catalyst interfacial structure have been specifically tailored for low pressure ammonia synthesis. The low pressure membrane reactor allows direct coupling to an electrolyser and air separation unit (ASU) operated by a renewable source, thus promising over 25% reduction in the energy input, substantial capital savings on reactors compared to conventional Haber-Bosch process, and allows distributed or centralised ammonia production. Continue reading →

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Exploring ammonia’s potential as a marine fuel

Posted on December 14, 2018 by | Leave a comment

Niels de Vries, C-Job Naval Architects, Netherlands

15th Annual NH3 Fuel Conference, Pittsburgh, PA, October 31, 2018
NH3 Energy+ Topical Conference at the AIChE Annual Meeting

ABSTRACT

International shipping is responsible for approximately 90% of the world trade. Looking to the relative emissions, in gram CO2 per ton km, maritime transport score significantly better compared to others like rail, road and airfreight. However, since most of the transport is done by ships the absolute contribution of greenhouse gases (GHG) by the maritime industry is clearly visible. Of all the global emissions the maritime industry is responsible for 3% CO2, 13% SOx, and 15% NOx.

To reduce SOx and NOx several regulations are either upcoming or already in play. Current regulations require the sulphur emissions to be less than 0.1% in all Environmental Control Areas (ECA). A global sulphur cap is upcoming in 2020 limiting the sulphur emissions to 0.5%. NOx emissions are currently regulated by IMO Tier II where IMO Tier III is already in affect in the ECAs yet IMO Tier III is still pending for global enforcement. Basic regulations have also been arranged to reduce CO2 emissions by means of an Energy Efficiency Design Index (EEDI). However, the EEDI requirements are not very strict yet.

To comply with these new and upcoming regulations the marine industry is moving towards the application of natural gas as a fuel, exhaust gas treatment and usage of cleaner marine diesel fuels. With the goals of IMO to reduce the total GHG by at least 50% by 2050 (compared to 2008) this shift alone will not be enough to meet up with these ambitions. Since shipping (and aviation) were not covered by the Paris agreement these IMO goals are an important push towards renewable fuels. The challenges for implementation of renewable fuels in the maritime industry regard both a significant expansion of renewable energy production and viable business cases for ship owners. For the ship owner this can come for either a cargo owner willing to pay more for clean transport or taxations on harmful emissions.

Applying renewable fuels for the maritime industry one can think of several options like: liquid methane, ethanol, methanol, liquid ammonia, liquid hydrogen and compressed hydrogen. Considering the importance of volumetric energy density [GJ/m3] and also renewable synthetic production cost [MJ/MJ] ammonia turns out to be a very balanced solution. Ammonia has a significant higher volumetric energy than liquid hydrogen yet requiring clearly less energy for renewable synthetic production than the carbon carriers. These are the main reasons to further investigate the potential of ammonia as a fuel.

Suitable types of marine power generation need to be able to cope with the marine environment. Dynamic behaviour and load response are crucial aspects for configurations which have the engine directly connected to the propeller. Furthermore, part load conditions are also important aspects since most operational profiles cover several modes.

To realise ammonia as marine fuel the internal combustion engine seems to be a good solution for now. Ammonia + hydrogen (obtained from ammonia cracking) mixtures are capable to approach similar characteristics as fossil fuels like methane. Therefore, scaling up the ammonia combustion engine should not be a problem. In the future fuel cells could be replacing the combustion engine as they are capable delivering higher efficiencies and do not emit NOx. Yet nowadays fuel cells capable using ammonia directly lack power density and cost effectiveness.

Read the abstract at the AIChE website.

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Experimental and Computational Study for Reduction of NOx Emissions in the Ammonia / Methane Co-Combustion in a 10 KW Furnace

Posted on December 14, 2018 by | Leave a comment

Ryuichi Murai*, Ryohei Omori, Takahiro Kitano, Hidetaka Higashino, Noriaki Nakatsuka, Fumiteru Akamatsu, Osaka University, Japan; Yuya Yoshizuru, UBE Industries, Japan; Jun Hayashi, Kyoto University, Japan

15th Annual NH3 Fuel Conference, Pittsburgh, PA, October 31, 2018
NH3 Energy+ Topical Conference at the AIChE Annual Meeting

ABSTRACT

There are severe issues on increasing amount of carbon dioxide (CO2) emission in the world. Many studies are devoted to alternative fuels. One of promising candidates is the utilization of ammonia which is zero emission of CO2, a hydrogen energy carrier, and also can be burned directly as a fuel.

For direct combustion of ammonia in industrial furnaces, there were two issues which were weaker radiative heat flux and a huge amount of NOx emission compared with the combustion of methane. We already have reported [1] the solution of the former issue by using the oxygen enriched combustion.

The objective of this research is to study the reduction mechanism of NOx emissions in the ammonia / methane co-combustion in an industrial furnace both experimentally and numerically. Experimentally we measured the radiation spectra and the total radiative thermal flux under the condition of the ammonia fuel burned in a 10 kW furnace with a coaxial jet flame and additional two oxidizer inlets for the staging combustion. The spectrum measurement results show that the amount of NOx emission was in reverse proportion with the intensity of N2O spectrum in the downstream of the reaction zone in the furnace. This indicates that N2O, which is one of main intermediate species of NH3, reacts with NOx as a reduction reactant to nitrogen molecule. Continue reading →

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Auto-Ignition Kinetics of Ammonia at Intermediate Temperatures and High Pressures

Posted on December 14, 2018 by | Leave a comment

Xiaoyu He, Bo Shu, Kai Moshammer, Ravi Fernandes*, Physikalisch-Technische Bundesanstalt, Germany; David Nascimento, Mario Costa, Instituto Superior Técnico – Universidade de Lisboa, Portugal

15th Annual NH3 Fuel Conference, Pittsburgh, PA, October 31, 2018
NH3 Energy+ Topical Conference at the AIChE Annual Meeting

ABSTRACT

The anxiety over global greenhouse gas emissions has intensified the demand for the development and use of CO2-neutral energy technologies. Ammonia is now attracting attention as a carbon-free energy carrier, because it has good energy density (22.5 MJ/kg) and can be easily liquefied (about 10 bar at 298 K). In addition, ammonia is produced according to the Haber-Bosch process, which makes it one of the most widely-produced inorganic chemical in the world. It could also be produced with renewable energy sources such as wind and solar energy using P2X technology.

As a potential fuel for applications in gas turbines and gas engines, ammonia is less reactive than most hydrocarbons and its ignition and combustion characteristics are not yet well understood. A major part of the previous research has focused on the ammonia oxidation at high temperatures or low pressures [1-3], while ignition measurements for pure ammonia or ammonia mixed with other gaseous fuels (such as hydrogen or methane) at high pressures and low-to-intermediate temperature is rare.

Rapid compression machines (RCMs) are regarded as an important experimental apparatus for investigating auto-ignition behavior at low-to-intermediate temperature conditions, which are quite relevant to the application in internal combustion engines and gas turbines [4,5].

In this study, autoignition properties of NH3/O2 and NH3/H2/O2 mixtures have been studied in a RCM at pressures from 20 to 60 bar, temperatures from 950 to 1150 K, and at equivalence ratios from 0.5 to 2. The effect of hydrogen-ammonia ratio in fuel has been also investigated. Continue reading →

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Improved Method of Using Hydrogen and Ammonia Fuels for an Internal Combustion Engine

Posted on December 14, 2018 by | Leave a comment

David Toyne*, Solutions for Automation, USA; Jay Schmuecker, Pinehurst Farm, USA

15th Annual NH3 Fuel Conference, Pittsburgh, PA, October 31, 2018
NH3 Energy+ Topical Conference at the AIChE Annual Meeting

ABSTRACT

A tractor mounted internal combustion engine is fueled by Hydrogen or a combination of Hydrogen and Ammonia.

Developments of an improved method of fuel injection and ignition control. Hydrogen is port injected in the intake manifold, and liquid ammonia is injected in the throttle body. A dual fuel ECU, Engine Control Unit, controls the fuel mixtures and the firing of multiple coils for ignition.
The paper will address significant engine performance improvements and the resulting fuel consumption and engine emissions levels. Continue reading →

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Ignition of an Aqueous Ammonia/Ammonium Nitrate Fuel

Posted on December 14, 2018 by | Leave a comment

Bar Mosevitzky*, Gennady E. Shter, Gideon S. Grader, Technion – Israel Institute of Technology, Israel

15th Annual NH3 Fuel Conference, Pittsburgh, PA, October 31, 2018
NH3 Energy+ Topical Conference at the AIChE Annual Meeting

ABSTRACT

To achieve a truly renewable energy market, the intermittent power generation of sources such as solar and wind must be overcome. Renewable ammonia can be synthesized using these sources to be used as a long-term energy storage medium. For this reason, the use of ammonia as a synthetic fuel has garnered significant attention in recent years. Aqueous AAN (ammonia/ammonium nitrate) is a carbon-free ammonia based monofuel suitable for energy storage applications. This fuel is safe to store and transport, and its combustion products consist mainly of water and nitrogen. Effective use of this fuel requires an in-depth understanding of the reaction pathways dominating its ignition.

In this work, the accumulated results from experiments conducted to test the effects of water content, equivalence ratio, and diluent pressure on AAN ignition will be reviewed. The use of simulations to reproduce these results will be evaluated, and the data generated by rate-of-production and sensitivity analyses will be reviewed. Finally, the reaction pathways involved in AAN ignition and their relation to its water content, equivalence ratio and diluent pressure will be presented, and the implications of the rate-determining steps for AAN ignition will be discussed. Continue reading →

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Optimization of the NOx Reduction Condition in the Combustion Furnace for the Combustion of “Heavy-Oil – NH3 System” Using CFD

Posted on December 14, 2018 by | Leave a comment

Yuya Yoshizuru*, Takeshi Suemasu, Masayuki Nishio, UBE Industries, Japan; Ryuichi Murai, Fumiteru Akamatsu, Osaka University, Japan

15th Annual NH3 Fuel Conference, Pittsburgh, PA, October 31, 2018
NH3 Energy+ Topical Conference at the AIChE Annual Meeting

ABSTRACT

In late years the discharge of the CO2 became the very big problem. The combustion of the fossil fuel in particular exhausts much CO2. Our project team (SIP) is intended to reduce CO2 by using NH3 (10%~30%) in substitution for heavy oil. The ‘SIP energy carriers’ was launched in 2014 (SIP: Strategic Innovation Promotion Program). Ammonia direct combustion team was formed. We conducted a co-research program with Osaka University in this project. We performed experiment of heavy oil – NH3 mixed combustion in the 10kW furnace. As the results, we obtained much experimental data. When we were combusted NH3 and heavy-oil, a large quantity of NOx is exhausted. We need to conduct that out under many different conditions for NOx reduction (for example, temperature, flow rate and so on.). However, it is impossible to perform it in limited time. Therefore I found some conditions to reduce NOx using CFD. Furthermore, we introduce some conditions to optimize NOx reduction. The combustion mechanism compared the model using the detailed chemical reaction and the simplification reaction mechanism with the experiment. As a result, we became able to be combusted NH3 (30%) under a NOx condition same as heavy-oil (100%). Continue reading →

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