Jupiter Ionics, an Australian cleantech startup founded in 2021, develops a modular ammonia synthesis reactor that produces green ammonia via electrochemical processes using nitrogen gas, water, and renewable energy.
Challenges: green ammonia
Ammonia (NH₃) is a crucial compound for agriculture. In 2021, the global production of ammonia was 185 million metric tons, with over 80% being used for fertilizer production. As the global population increases, so does the demand for ammonia.
However, ammonia production consumes about 2% of worldwide fossil fuel due to the energy-intensive nature of the process. This generates over 420 million tons of carbon dioxide (CO₂) annually, which accounts for 1.5% of global greenhouse gas emissions.
The primary method of ammonia production is the Haber-Bosch process, which converts hydrogen (H₂) and nitrogen (N₂) into ammonia. The Haber-Bosch process requires extreme reaction conditions involving high pressure (150–350 atm) and temperature (400–550 ºC), along with pure hydrogen, usually obtained from the steam reforming process of natural gas.
Therefore, there is an urgent need to develop technologies for ammonia synthesis in a sustainable manner. The utilization of renewable energy to convert N₂ into NH₃ represents a promising approach for the production of green ammonia.
Jupiter Ionics Technology
Jupiter Ionics has developed an ammonia synthesis reactor that uses water, nitrogen gas, and renewable electrical power to produce ammonia through a continuous lithium-mediated electrochemical nitrogen reduction reaction.
The discovery of this electrochemical ammonia synthesis method dates back to the 1990s. However, this technology shows limited ammonia yield rates, a faradaic efficiency (the fraction of charge that produces ammonia) of 50–60%, and inadequate operational stability. Jupiter Ionics has improved this technology by developing innovative catholytes that enable stabilized ammonia yield rates of 150 nmol s⁻¹ cm⁻² and a current-to-ammonia efficiency (faradaic efficiency) that is close to 100%.
Jupiter Ionics ammonia synthesis reactor
The diagram below depicts the ammonia synthesis reactor of Jupiter Ionics.
The ammonia synthesis reactor has cathodic and anodic chambers, which are separated by a proton-permeable membrane separator, such as Nafion. In the cathodic chamber, a cathode and reference electrode are immersed in a catholyte. In the anodic chamber, an anode is immersed in an anolyte. The electrodes are connected to a power source capable of applying a voltage between cathode and anode.
The cathodic chamber is equipped with an inlet for nitrogen gas feed and an outlet for ammonia gas product output. The anodic chamber has an outlet for oxygen gas. Each chamber has its own electrolyte inlet and outlet for replenishing the electrolyte.
Cathode is typically made of nickel (Ni), and anode is made of platinum (Pt). The catholyte comprises lithium cations (Li⁺), fluorinated sulfonyl imide anions, and phosphonium cations that function as proton carriers. Anolyte is water. The Nafion membrane separator prevents the transmission of substances other than protons between the cathodic and anodic reaction chambers.
How Jupiter Ionics makes green ammonia
The diagram below depicts the processes of continuous lithium-mediated electrochemical NH₃ synthesis reaction.
During operation, pressured nitrogen is fed into the cathodic chamber. A voltage is applied between the cathode and anode.
At the anode, water undergoes electrochemical oxidation to generate protons (H⁺) and oxygen (O₂):
2H₂O → O₂ + 4H⁺ + 4e⁻
Protons migrate across the membrane separator to maintain charge neutrality. They enter the catholyte and regenerate the proton carrier by protonation of the proton acceptor. O₂ is removed from the anodic chamber.
At the cathode, the current flow causes the reduction of nitrogen to ammonia through the following electrochemical processes:
Li⁺ + e⁻ ⇆ Li
6Li + N₂ ⇆ 2Li₃N
Li₃N + 3BH → 3Li⁺ + 3B⁻ + NH₃
B⁻ + H⁺ → BH
Lithium ions in the catholyte are reduced to lithium metal. Li metal reduces N₂ spontaneously under ambient conditions to form lithium nitride (Li₃N). Li₃N reacts with a suitable proton carrier (BH) to produce ammonia and release the Li⁺ to reinitiate the electrocatalytic cycle. The deprotonated proton carrier is regenerated by accepting the protons which migrate from the anodic chamber through the membrane separator. Ammonia product is extracted from the cathodic chamber.
This continuous Li-mediated electrochemical NH₃ synthesis reaction was first discovered in 1930 by Fichter et al. and was further optimized by Tsuneto et al. in 1993 (Efficient Electrochemical Reduction of N₂ to NH₃ Catalyzed by Lithium). However, the technology is hindered by faradaic efficiencies of 50–60%, limited ammonia yield rates, and poor stability. The problem stems from the parasitic reactions occurring at the cathode, resulting in the formation of by-products such as lithium hydride (LiH) and H₂.
Jupiter Ionics has boosted the performance of Li-mediated electrochemical NH₃ synthesis reaction with stabilized ammonia yield rates of 150 nmol s⁻¹ cm⁻² and a current-to-ammonia efficiency that is close to 100%.
Innovations of Jupiter Ionics
Jupiter Ionics has two crucial innovations to achieve this breakthrough of Li-mediated electrochemical NH₃ synthesis.
The first innovation is the introduction of a phosphonium cation proton carrier, such as trihexyltetradecylphosphonium, into the catholyte. The phosphonium cation functions as a proton shuttle and enhances ionic conductivity, resulting in a significant improvement in both the faradaic efficiency and ammonia yield rate.
The phosphonium salt has good chemical, thermal, and electrochemical stability. The protons located on the carbon atoms directly bonded to the phosphorus center of the cation are reactive. Reversible deprotonation of such cations produces an ylide structure that can be accessed through reaction with organolithium compounds. The reversible deprotonation of phosphonium proton carrier is described by the following chemical reaction:
The second innovation involves the use of fluorinated sulfonyl imide anion salts, such as lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), in the catholyte. LiTFSI with a high concentration in the catholyte significantly improves the yield rate or faradaic efficiency in the continuous Li-mediated electrochemical NH₃ synthesis reaction.
The bulky and electrochemically stable fluorinated sulfonyl imide anions form a protective ionic assembly layer at the interface between the catholyte and the cathode when undergoing electrochemical reduction. Fluorinated sulfonyl imide anions have been used in lithium-based electrolytes for lithium-ion batteries to enhance cycling stability via the formation of a stable solid-electrolyte interface (SEI) layer on the electrodes. An analogy exists between the interfaces formed by the electrolyte and electrodes during the cycling of lithium batteries and the lithium-mediated nitrogen reduction reaction.
Jupiter Ionics Patent
- WO2022256858A1 A method and cell for reducing dinitrogen to ammonia
Jupiter Ionics Technology Applications
Agriculture
Green ammonia can be used as a carbon-neutral fertilizer, significantly reducing the carbon footprint of farming. Using green ammonia for fertilizer could drive down farming’s carbon footprint by as much as 90% for corn and small grain crops.
Transportation fuel
Green ammonia can be used as a transport fuel, replacing highly polluting gasoline, diesel, and propane to run engines, generators, and turbines. It has applications in transportation including heavy goods vehicles, trains, aviation, and shipping.
Energy storage
Green ammonia has the potential to be used for large-scale, long-term energy storage. It has nine times the energy density of Li-ion batteries, and three times that of compressed hydrogen, making it a competitive option against electrochemical batteries, pumped hydro, and capacitors to balance consumption and renewable generation. Countries including Japan, Australia, the Netherlands, and the United Kingdom have national plans to use green ammonia to store (and export) their renewable energy surpluses.
Jupiter Ionics Products
Jupiter Ionics is working on a flexible, modular system to make green ammonia from water, nitrogen, and renewable electricity. The technology is housed within a unit the size of a shipping container, which makes it simple to transport and install. This technology is scalable and can produce green ammonia at local, regional, or national scale.
Jupiter Ionics Funding
Jupiter Ionics has raised a total of $2.5M in funding over a Seed round on Dec 1, 2021.
Jupiter Ionics Investors
Jupiter Ionics is funded by Tenacious Ventures.
Jupiter Ionics Founder
Douglas MacFarlane is Founder.
Jupiter Ionics CEO
Charlie Day is CEO.
