Tag Archives: Electrochemical Synthesis

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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Dense Metallic Membrane Reactor Synthesis of Ammonia at Moderate Conditions and Low Cost

Posted on October 1, 2017 by | 3 comments

Thomas Fuerst*, Sean Lundin, Zhenyu Zhang, Simona Liguori, Douglas Way, Colin Wolden
Colorado School of Mines, United States

NH3 Fuel Conference, Minneapolis, November 2, 2017
AIChE Annual Meeting, Topical Conference: NH3 Energy+

ABSTRACT

Commercial ammonia synthesis relies on the Haber–Bosch process that has remained largely unchanged for a hundred years. The equilibrium constant of this exothermic reaction quickly becomes unfavorable above 200 °C, but the catalyst requires temperatures above 400 °C to have sufficient activity. To overcome these conflicting requirements the process is conducted at extremely high pressure (100 – 200 atm) using multiple passes with inter-stage cooling to achieve sufficient conversion. A cost analysis reveals the compressors needed to reach the required pressures consist of 50% the capital cost for Haber-Bosch. Therefore, a longstanding scientific challenge has been to achieve NH3 synthesis at near ambient pressure which could reduce the ammonia production cost by as much as 30%. Continue reading →

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Exploring Peptide-Bound Catalysts for Electrochemical Ammonia Generation

Posted on October 1, 2017 by | 2 comments

Charles Loney1*, Ashley Graybill1, Cheyan Xu1, Julie Renner1, Prashant Acharya2, David Suttmiller2, Lauren Greenlee2, Luke Wiles3, Katherine Ayers3, Wayne Gellett3
[1] Case Western Reserve University; [2] University of Arkansas; and [3] Proton OnSite, United States

NH3 Fuel Conference, Minneapolis, November 2, 2017
AIChE Annual Meeting, Topical Conference: NH3 Energy+

ABSTRACT

Today, most ammonia (NH3) manufacturing occurs via the Haber-Bosch process. This process consumes hydrogen from fossil fuels, and as a result NH3 contributes the highest amount of greenhouse gas emissions out of the top 18 large-volume chemicals made globally. Because the process is high temperature (400°–500°C) and pressure (150–300 atm) with a low (15%) single-pass conversion efficiency, the plants have to be very large to be economical. This means that ammonia is shipped from centralized locations, further increasing greenhouse gas emissions because of the fuel consumed in transportation. Additionally, their large size makes it difficult to integrate with renewable sources of hydrogen, such as electrolysis. Continue reading →

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High Efficiency Electrochemical Synthesis of Ammonia from Nitrogen at Ambient Temperature and Pressure

Posted on October 1, 2017 by | Leave a comment

Greg Redden*, Fengling Zhou, Luis Azofra, Muataz Ali, Mega Kar, Alexandr Simonov, Ciaran McDonnell, Chenghua Sun, Angeline Bartholomeusz, Xinyi Zhang, Douglas MacFarlane
Monash University, Australia

NH3 Fuel Conference, Minneapolis, November 2, 2017
AIChE Annual Meeting, Topical Conference: NH3 Energy+

ABSTRACT

Ammonia as well as being an important fertiliser is being increasingly considered as an easily transported carrier of hydrogen energy. However, the traditional Haber-Bosch process for the production of ammonia from atmospheric nitrogen and fossil fuels is a high temperature and pressure process that is energy intensive. Newer technology is being investigated to produce sustainable ammonia from green energy. An ambient temperature, electrochemical synthesis of ammonia is an attractive alternative approach, but has, to date, not been achieved at high efficiency. Researchers from Monash University have obtained faradaic efficiency as high as 60% using liquid salt electrolytes under ambient conditions, viz. 25°C and 1 atmosphere pressure. We are developing a range of scaled prototypes for this technology. Continue reading →

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Design of Iron-Nickel Nanocatalysts for Low-Temperature Electrochemical Ammonia Generation

Posted on October 1, 2017 by | 1 comment

Lauren Greenlee1*, Shelby Foster1, Prashant Acharya1, David Suttmiller1, Charles Loney2, Julie Renner2, Wayne Gellett3, Katherine Ayers3
[1] University of Arkansas; [2] Case Western Reserve University; and [3] Proton OnSite, United States

NH3 Fuel Conference, Minneapolis, November 2, 2017
AIChE Annual Meeting, Topical Conference: NH3 Energy+

ABSTRACT

The Haber-Bosch industrial process for ammonia production is the cornerstone of modern commercial-fertilizer-based agriculture. Haber-Bosch ammonia fueled the global population growth of the 20th century, and approximately half of the nitrogen in human bodies today originates from ammonia-based fertilizer produced by the Haber-Bosch process. However, the Haber-Bosch process operates at high temperature and high pressure to achieve high conversion efficiencies, and the hydrogen input comes from steam reforming of coal or natural gas. In addition to the energy costs, the large production of carbon dioxide as a greenhouse gas and the large required economies of scale motivate research efforts to explore other possible options for ammonia production. One potential option is low temperature electrochemical synthesis of ammonia from nitrogen and water. An electrochemical process that directly synthesizes ammonia molecules from nitrogen gas and the hydrogen atoms of water molecules would eliminate the need for fossil-fuel-based hydrogen as a reactant and decrease CO2 emissions. Further, an electrochemical system based on already-developed technology in the fuel cell and electrolysis arenas would enable a modular, scalable, and energy efficient process that could be connected to renewables (i.e., wind or solar) as the energy input. Continue reading →

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Atmospheric-Pressure Synthesis of Ammonia Using Non-Thermal Plasma with the Assistance of Ru-Based Multifunctional Catalyst

Posted on October 1, 2017 by | 1 comment

Peng Peng*, Yanling Cheng, Nan Zhou, Raymond Hatzenbeller, Paul Chen, Roger Ruan
University of Minnesota, United States

NH3 Fuel Conference, Minneapolis, November 2, 2017
AIChE Annual Meeting, Topical Conference: NH3 Energy+

ABSTRACT

Ammonia has much more uses than being a fertilizer. Its emerging applications include hydrogen carrier, fuel cells, clean transportation fuels, and other off-grid power applications. The traditional Haber Bosch process used to synthesize ammonia must be achieved at high temperature and pressure. The non-thermal plasma (NTP) allows for the synthesis of ammonia at a lower temperature and pressure conditions. It is proposed that the moderate process conditions can potentially allow a more economical construction and operation of ammonia production systems on distributed farms and renewable hydrogen production sites. In this study, we report the NTP synthesis of ammonia using dielectric discharge, and a Ru-based, multi-functional catalytic system deposited on mesoporous silica MCM-41. Continue reading →

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Nitrogenase Inspired Peptide-Functionalized Catalyst for Efficient, Emission-Free Ammonia Production

Posted on October 1, 2017 by | 1 comment

Stephen Szymanski*, Wayne Gellett
Proton OnSite, United States

NH3 Fuel Conference, Minneapolis, November 1, 2017
AIChE Annual Meeting, Topical Conference: NH3 Energy+

ABSTRACT

Ammonia-based fertilizers have enabled increases in food production to sustain the world’s population. Currently the major source of ammonia is the Haber-Bosch process, which requires high temperature and pressure and has low conversion efficiency, such that very large plants are required for economical production. Ammonia is therefore one of the most energy and carbon intensive chemical processes worldwide, largely due to the steam methane reforming step to produce the required hydrogen. Because of the very large plant scale and resulting centralization of production, ammonia may also be transported long distances to point of use, adding additional energy and emissions. Distributed, sustainable ammonia production would therefore have a huge impact on global energy use and related carbon emissions. Electrochemical solutions are well-suited to modularity and integration with renewable energy sources and can operate at much milder temperatures and pressures, but a catalyst is needed which is selective to ammonia generation vs competing reactions. Continue reading →

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Fast-Ramping Reactor for CO2-Free NH3 Synthesis

Posted on October 1, 2017 by | 4 comments

Joseph Beach1*, Jonathan Kintner1, Adam Welch1, Jason Ganley2, Ryan O’Hayre2
[1] Starfire Energy; and [2] Colorado School of Mines, United States

NH3 Fuel Conference, Minneapolis, November 1, 2017
AIChE Annual Meeting, Topical Conference: NH3 Energy+

ABSTRACT

Starfire Energy is developing a fast-ramping reactor for making CO2-free NH3 for fuel, energy storage, and agricultural applications. A fast-ramping reactor is desired to follow (a) variable electricity generation from CO2-free sources such wind and solar power plants or (b) variable availability from CO2-free baseload electricity generation such as nuclear or hydroelectric power plants. The reactor builds upon the Haber-Bosch process by (a) introducing a higher activity supported Ru catalyst (over 4.5 mmol g-1 h-1 at 1 atm and over 45 mmol g-1 h-1 at 10 atm) and (b) further enhancing the catalysis by applying an electric potential or electric field to the catalyst. The catalysts and processes are the subjects of PCT patent application PCT/US17/20201. The catalysts and processes have been characterized in a differential reactor and are being incorporated into a prototype reactor designed to produce 3 kg NH3 per day. The presentation will feature data from the differential reactor and prototype reactor testing and modeled cost of CO2-free NH3 at larger production scales. Continue reading →

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Future of Ammonia Production: Improvement of Haber-Bosch Process or Electrochemical Synthesis?

Posted on October 1, 2017 by | 2 comments

Grigorii Soloveichik
US Department of Energy – ARPA-E, United States

NH3 Fuel Conference, Minneapolis, November 1, 2017
AIChE Annual Meeting, Topical Conference: NH3 Energy+

ABSTRACT

Ammonia, the second most produced chemical in the world (176 million tons in 2014), is manufactured at large plants (1,000 – 1,500 t/day) using Haber-Bosch process developed more than hundred years ago. A simple reaction of nitrogen and hydrogen (produced by steam methane reforming or coal gasification) consumes about 2% of world energy, in part due to the use of high pressure and temperature. With the global transition from fossil fuels to intermittent renewable energy sources there is a need for long term storage and long range transmission of energy, for which ammonia is perfect fit. To make it practical, it is necessary to match the scale of ammonia production with the scale of renewable energy sources, at the same or better capital cost per ton of NH3, and reduce the energy consumption. Continue reading →

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