A brand new way of constructing ammonia by harnessing the unique power of liquid metal may lead to significant cuts in carbon emissions attributable to production of the widely-used chemical.
Ammonia is utilized in fertiliser to grow much of our food, but in addition plays a task in clean energy as a carrier to securely transport hydrogen.
The worldwide production of ammonia, nonetheless, comes at a high environmental cost: it consumes over 2% of world energy and produces as much as 2% of world carbon emissions.
RMIT Research Fellow and study lead creator, Dr Karma Zuraiqi, said their greener alternative used 20% less heat and 98% less pressure than the century-old Haber-Bosch process used today for splitting nitrogen and hydrogen into ammonia.
“Ammonia production worldwide is currently liable for twice the emissions of Australia. If we are able to improve this process and make it less energy intensive, we are able to make a big dent in carbon emissions,” said Zuraiqi, from the School of Engineering.
Results of the RMIT-led study published in Nature Catalysis show their low-energy approach to be as effective at producing ammonia as the present gold standard by relying more on effective liquid metal catalysts and fewer on the force of pressure.
“The copper and gallium we use can also be less expensive and more abundant than the valuable metal ruthenium used as a catalyst in current approaches,” Zuraiqi said. “These benefits all make it an exciting latest development that we’re keen to take further and test outside the lab.”
Liquid metal to the rescue
The team including RMIT’s Professor Torben Daeneke is on the forefront of harnessing the special properties of liquid metal catalysts for ammonia production, carbon capture and energy production.
A catalyst is a substance that makes chemical reactions occur faster and more easily without itself being consumed.
This latest study showcased their latest technique by creating tiny liquid metal droplets containing copper and gallium — named ‘nano planets’ for his or her hard crust, liquid outer core and solid inner core structure — because the catalyst to interrupt apart the raw ingredients of nitrogen and hydrogen.
“Liquid metals allow us to maneuver the chemical elements around in a more dynamic way that gets every part to the interface and enables more efficient reactions, ideal for catalysis,” Daeneke said.
“Copper and gallium individually had each been discounted as famously bad catalysts for ammonia production, yet together they do the job extremely well.”
Tests revealed gallium broke apart the nitrogen, while the presence of copper helped the splitting of hydrogen, combining to work as effectively as current approaches at a fraction of the price.
“We essentially found a approach to benefit from the synergy between the 2 metals, lifting their individual activity,” Daeneke said.
RMIT is now leading commercialisation of the technology, which is co-owned by RMIT and QUT.
Upscaling for industry
While ammonia produced via the normal Haber-Bosch process is barely viable at huge facilities, the team’s alternative approach could suit each large-scale and smaller, decentralised production, where small amounts are made cheaply at solar farms, which in turn would slash transport costs and emissions.
In addition to obvious applications in producing ammonia for fertiliser, the technology could possibly be a key enabler for the hydrogen industry and support the move away from fossil fuels.
“One good approach to make hydrogen safer and easier to move is to show it into ammonia,” Daeneke explained.
“But when we use ammonia produced through current techniques as a hydrogen carrier, then emissions from the hydrogen industry could significantly increase global emissions.”
“Our vision is to mix our green ammonia production technology with hydrogen technologies allowing green energy to be shipped safely all over the world without huge losses on the best way,” he said.
The subsequent challenges are to upscale the technology — which has up to now been proven in lab conditions — and to design the system to operate at even lower pressures, making it more practical as a decentralised tool for a broader range of industries.
“At this stage, we’re really excited by the outcomes and are keen to talk with potential partners eager about scaling this up for his or her industry,” he said.
This research was supported by the Australian Research Council and the Australian Synchrotron (ANSTO). Evaluation of molecular interactions was carried out at RMIT’s cutting-edge Microscopy and Microanalysis Facility, in addition to QUT’s Central Analytical Research Facility, the Australian Synchrotron and via the NCI Australia supercomputing facility.
