NH3 is important as the raw material for fertilizer production and high hydrogen density (17.7 wt. %) energy carrier. Conventionally, NH3 is synthesized through the well-known Haber-Bosch process at 400-500°C and P~150 bar. Both critical reaction conditions and massive production (145 mt NH3 in 2014 globally) make it one of the most energy extensive process, consuming 1-2% of the world’s total energy expense. Here we introduce YSZ as a more active Ru catalyst support than traditionally used supports such as Al2O3. The addition of Cs promoter increased rates an order of magnitude higher by reducing the apparent activation energy from…

Traditional ammonia cracking is achieved at 850-950 °C in the presence of a nickel catalyst. The reaction is highly endothermic, and maintaining these high temperatures at high flow rates of ammonia gas can be difficult. Here, we present work using our advanced ammonia synthesis catalyst in an ammonia cracking setup. We use a metallic monolith catalyst support to minimize pressure drop at high flow rates. Full NH3 cracking occurs at 600 °C, with the onset of cracking at 400 °C. An output flame can be achieved with a fully tunable ratio of hydrogen to ammonia, depending on the temperature setpoint…

In this presentation, we provide an overview of an ambitious project to store renewable energy through electrochemical synthesis of ammonia. The joint project between the Colorado School of Mines (Golden, CO) and FuelCell Energy, Inc. (Danbury, CT) is supported through the U.S. Department of Energy ARPA-E ‘REFUEL’ program. The research and development team seeks to harness the unique properties of proton-conducting ceramics to activate chemical and electrochemical reactions for efficient and cost-effective synthesis of ammonia. The system concept is shown in Figure 1; renewable electricity is used to drive electrolysis of the H2O feedstock to form hydrogen. This electrochemically produced…

Last week, Forbes.com published Power-To-X In The German Experience: Another In The List Of Growing Energy Transition Strategies.  The article in effect nominates ammonia as a singularly promising up-and-comer in the field of the alternative energy vectors.  Such an endorsement is heartening, but the article is notable as much for who is delivering the message – and the fact of its delivery under the Forbes masthead – as for what the message is.

The traditional Haber-Bosch (HB) synthesis of anhydrous ammonia will adapt to clean power by sourcing the hydrogen from renewable electrolysis. However, the very large scale of current HB plant designs are not well-matched to smaller and more distributed clean power resources. Plant/reactor designs need to be made at a smaller scale in order to best utilize clean hydrogen. Small, megawatt scale HB reactors have an additional advantage of being better able ramp up and down with variable renewable power. This talk will detail ARPA-e funded work into the design and optimization of these smaller, clean NH3 reactors, which utilize much…

The deployment of fuel cell electric vehicles is constrained by the paucity of hydrogen fueling stations and price, which is dominated by the costs of hydrogen storage and transportation. With more hydrogen per volume than liquid H2 and an extensive distribution infrastructure in place, ammonia is a promising vector for efficient hydrogen distribution. In this talk we describe the development of innovative catalytic membrane reactor (CMR) technology for the delivery of high purity H2 from ammonia cracking. The CMR integrates state-of-the art catalysts with thin metal membranes in an innovative design. Conventionally, the catalyst is supplied to CMRs in the…

I wrote recently about two pathways for ammonia production technology development: improvements on Haber-Bosch, or electrochemical synthesis. Last week, I covered some of these Haber-Bosch improvements; next week, I'll write about electrochemical processes. This week, I want to write about some innovations that don't fit this two-way categorization: they don't use electrochemistry and they don't build upon the Haber-Bosch process, and that might be the only thing that links them.

At the recent NH3 Energy+ Topical Conference, Grigorii Soloveichik described the future of ammonia synthesis technologies as a two-way choice: Improvement of Haber-Bosch or Electrochemical Synthesis. Two such Haber-Bosch improvement projects, which received ARPA-E-funding under Soloveichik's program direction, also presented papers at the conference. They each take different approaches to the same problem: how to adapt the high-pressure, high-temperature, constant-state Haber-Bosch process to small-scale, intermittent renewable power inputs. One uses adsorption, the other uses absorption, but both remove ammonia from the synthesis loop, avoiding one of Haber-Bosch's major limiting factors: separation of the product ammonia.

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…

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…

It is well known that ammonia is being considered as a method of storing hydrogen. Although some fuel cells are being developed that can use ammonia directly as a fuel source, many fuel cell technologies still require an outside cracker to revert ammonia back into hydrogen for efficient use. In this regard, hydrogen permeable membranes, such as Pd and its alloys, have been targeted as potential membrane reactors in which the ammonia is cracked while the hydrogen is simultaneously separated. Pd and its alloys are expensive, but offer potentially perfect hydrogen purity that is highly preferable for certain fuel cells…

Proton-conducting ceramics synthesized with solid-state reactive sintering are employed as electrolytes for the synthesis of ammonia from hydrogen and nitrogen gases in electrolytic cells. Additionally, these cells function with excellent long-term stability and high efficiency when operated in galvanic (fuel cell) mode using ammonia fuel. Advances in electrolyte compositions and synthesis techniques are discussed alongside cell performance metrics.

NH3 fuel for water and space heating Jason Ganley and Chris Siebarth, Colorado School of Mines

Mixed Protonic and Electronic Conductors for Solid State Ammonia Synthesis and Direct Ammonia Fuel Cells J. Ganley, T. Olszanski, and N. Sullivan, Colorado School of Mines

Intermediate-Temperature Tubular Direct Ammonia Fuel Cells Sean Babinec, Anthony Manerbino, Shay Robinson, Jason Ganley, and Neal Sullivan, Colorado School of Mines

Performance of a Ceramic, Intermediate-Temperature Direct NH3 Fuel Cell Nigel Sammes, Colorado School of Mines

Ammonia Synthesis in a Modified IT-SOFC System Nigel Sammes and G. Restuccia, Colorado School of Mines, and Jason Ganley, NHThree LLC