Solid Oxide Cell Enabled Ammonia Synthesis and Ammonia Based Power Production

John B. Hansen
Haldor Topsøe, Denmark

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

ABSTRACT

Haldor Topsøe’s leading role as supplier of ammonia synthesis catalysts and technology is well known. The company has, however, also been active for decades in developing Solid Oxide Cell based stacks and systems.

The presentation will describe a novel, highly integrated process for ammonia synthesis based on Solid Oxide Electrolysis. The energy efficiency is very high due to ability of the SOEC to use steam generated from the synthesis reaction heat in the ammonia synthesis loop and the favorable thermodynamics of high temperature electrolysis. Continue reading

Screening Binary Redox Pairs for Solar Thermochemical Ammonia Synthesis Using Machine Learned Predictions of Gibbs Formation Energies at Finite Temperatures

Christopher J. Bartel*1, John R. Rumptz1, Aaron M. Holder1,2, Alan W. Weimer1, Charles B. Musgrave1
[1] University of Colorado Boulder; and [2] National Renewable Energy Laboratory, United States

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

ABSTRACT

Solar thermochemical ammonia synthesis (STAS) is a reduction/oxidation (redox) cycle which enables the production of ammonia (NH3) from air, water, and concentrated sunlight. In this process, a metal nitride (MN) is oxidized by steam to produce a metal oxide (MO) and NH3; the resulting MO is reduced at high temperature (driven by concentrated solar radiation) and subsequently used to reduce atmospheric nitrogen (N2) and reform the MN and restart the NH3 synthesis cycle. The identification of optimal redox pairs (MO/MN) for this process has been historically limited by the lack of thermochemical data (i.e., Gibbs formation energies at finite temperatures) available for these materials, especially nitrides.

Prior work by our group has demonstrated the use of machine learning to enable the prediction of Gibbs formation energies up to very high temperatures (1800 K) using low-cost DFT calculations (e.g., PBE+U), thus eliminating the need for experimentally measured thermochemistry. Utilizing this approach, we’ve screened the reaction energetics and thermodynamic stability of all known binary (i.e., monometallic) MN/MO pairs, increasing the number of redox pairs considered for this process by an order of magnitude. In addition to the consideration of new redox pairs, we also assess the effects of operating conditions and reaction scheme on the viability of candidate materials. Within this work, we gain insights into new candidate materials for NH3 synthesis, the effects of operating conditions on the viability of the overall process, and the correlated stability of metal oxides and metal nitrides. Continue reading

Process Synthesis and Global Optimization of Novel Ammonia Production Processes

Doga Demirhan*, William Tso, Efstratios Pistikopoulos
Texas A&M University, United States

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

ABSTRACT

Synthetic ammonia production has played a huge role in sustaining population growth by providing the nitrogen in fertilizers that are widely used in modern agriculture. Even long after it was first commercially developed by Fritz Haber and Carl Bosch in the 1930s, the Haber-Bosch process remains the basis for industrial ammonia production today. Through reducing energy requirements by half in the last 50 years, centralized industrial plants have kept their technical and economic advantage over other modes of operation. However, the centralized production also comes with high transportation costs, since plant capacities usually exceed local ammonia consumption [1]. This and the fact that conventional ammonia production is a major contributor of world greenhouse gas emissions (due to natural gas being one of its feedstocks) are motivating factors for researchers to consider alternative methods for smaller-scale and more environmentally-friendly ammonia production [2]. Continue reading

Our Iowa Renewable Hydrogen and Ammonia Generation System

Jay Schmuecker1*, David Toyne2*
[1] Pinehurst Farm; and [2] Solutions for Automation, United States

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

ABSTRACT

The presentation will summarize the development of the demonstration size renewable fuel and fertilizer system on my Iowa farm. Solar power, water, and air are used to make hydrogen and ammonia fuel used to power a modified John Deere 7810 tractor. The ammonia can also be used to fertilize corn cropland. The development of the ammonia reactor will be described and its performance discussed. There are no carbon emissions in either the generation or consumption of the hydrogen and ammonia. Continue reading

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

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

Nitride-Based Step Catalysis for Ammonia Synthesis at Atmospheric Pressure

Peter Pfromm, Michael Heidlage*, Bin Liu, Nannan Shan, Viktor Chikan, Hongfu Luo, Nate Flesher
Kansas State University, United States

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

ABSTRACT

Formation of metal nitrides to activate dinitrogen is one avenue to ammonia and other nitrogen compounds. Attractive aspects are operation at atmospheric pressure and moderate temperatures, formation of stable chemical intermediates rather than reliance on somewhat sensitive heterogeneous catalysis, and inexpensive materials. If a single metal is used, however, one encounters tradeoffs somewhat akin to the well-known tradeoffs for Haber-Bosch catalysts. Results will be presented for metal nitride-based ammonia synthesis, and new metal alloys that can address some of the tradeoffs between affinity for nitrogen, and formation of ammonia when hydrogen is added. Options using water instead of hydrogen will also be included. Continue reading

Exploring Peptide-Bound Catalysts for Electrochemical Ammonia Generation

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