Researchers have unlocked an industrial process that harnesses excess atmospheric carbon dioxide to produce acetic acid. Lead researcher Akshat Tanksale sat down with Manufacturers’ Monthly to discuss details of this cutting-edge development and its implications for the wider industry.
As the world grapples with the growing threat of climate change, scientists and researchers are exploring innovative solutions to combat rising carbon dioxide levels. In a remarkable breakthrough, a team of chemical engineers at Monash University has developed an industrial process to produce acetic acid that not only utilises excess carbon dioxide from the atmosphere but also has the potential to create negative carbon emissions.
This ground-breaking discovery showcases how sustainable technology can transform a greenhouse gas into a valuable resource.
Carbon dioxide, a greenhouse gas primarily produced from burning fossil fuels, accounts for a significant portion of the world’s greenhouse gas emissions, which contribute to global warming.
Importance of carbon capture and utilisation
The pressing need to combat the current climate crisis and reduce carbon dioxide (CO2) emissions has driven researchers to explore carbon capture and utilisation. The challenge of carbon capture has loomed large, with various attempts to store excess carbon dioxide underground yielding limited success.
“Carbon capture and storage is important and has been researched and trialled for decades now. It is important to sequester carbon dioxide so that it does not go back into the atmosphere. Carbon sequestration has yielded limited success so far, including at the Gorgon Carbon Capture and Storage (CCS) project,” said lead researcher Professor Akshat Tanksale.
The Gorgon project is one of the world’s largest carbon storage endeavours by gas giant Chevron and is located on Barrow Island in Western Australia. Traditional approaches to carbon capture and storage involve capturing CO2 at the emission sources and storing it in underground sites, with specific geological requirements.
“Once the CO2 is captured, the question was could we do something useful with it? As part of our research, we were exploring products or chemicals that can be made from that carbon dioxide, but with a process that does not emit CO2 back into the atmosphere. The product would also need to be commercially useful, where sales from the products would also offset the cost of capturing the carbon dioxide.”
Akshat Tanksale’s journey in this research space began in 2019. A chemical engineer by trade, he has been studying sustainable chemicals and fuel production for several years, which eventually led him to narrow down on acetic acid as a focal point of the research.
Acetic acid is a vital chemical with various household and industrial applications and is an ingredient in vinegar, vinyl paints and some glues. Global demand for acetic acid is currently estimated at six and a half million tonnes per year. There are also significant carbon emissions associated with its production from natural gas.
“If we could successfully use carbon dioxide to make acetic acid, which is then used to make polymers used in vinyl paints for instance, the polymers essentially lock away the CO2 for a long time,” Tanksale explained.
The power of solid catalysts
While current processes have explored the conversion of CO2 to acetic acid, it predominantly relied on conventional commercial processes that used liquid- based catalysts.
“We wanted to come up with a new sustainable and cost-effective catalyst and there was not a lot of literature where solid catalysts were used to make acetic acid,” Tanksale said.
Determined to break away from expensive metals like rhodium or iridium, the team created a novel metal organic framework (MOF) – a highly crystalline substance comprising repeating units of iron atoms linked with organic bridges.
Through controlled heating, these MOFs transformed into iron nanoparticles embedded in a porous carbon layer, forming a unique and efficient solid catalyst. The solid iron catalyst represents a significant leap forward in acetic acid manufacturing. It boasts several advantages, with Tanksale emphasising its economic viability.
“We really wanted to move away from expensive metals because when you’re attempting to solve one problem, you don’t want to create a new one – in this case, the new problem would be extracting those metals. Iron, on the other hand, is found close to the surface of the earth and is available abundantly currently and would be easy to source,” he said.
Moreover, the solid catalyst can be employed in a fixed-bed reactor, eliminating the need for a separate purification step, thus streamlining the production process and reducing energy consumption.
This also presents an opportunity to significantly improve current manufacturing processes that pollute the environment as well as a solution to slow down or potentially reverse climate change while providing economic benefits to the industry from the sales of acetic acid products.
Collaboration and the path to commercialisation
After the research team discovered the catalyst and its properties, the next step was to understand how it worked. Tanksale explained that while Monash University had world-class facilities, they did not have all the necessary tools and needed further expertise from other stakeholders. Two of the team’s key collaborators came from Hokkaido University in Japan and The Pennsylvania State University in the United States.
“Assistant Prof Abhijit Shrotri from Hokkaido University, who was also my first PhD graduate, supported us with materials testing to understand the properties of this catalyst,” Tanksale said.
“At Penn State, I worked with Prof Adri van Duin, who invented a computational program over 15 years ago that can predict the properties of materials in difficult circumstances. Some things happen at an atomic scale or molecular scale, and within a very short timeframe, hence making it impossible to observe experimentally.”
“In such cases, we use computer simulations to observe minute changes in the properties of materials. Prof van Duin’s software helped us simulate the behaviour of our material, and how the material evolves with thermal treatment,” he said.
Tanksale’s research project was supported by Monash University’s Engineering Researcher Accelerator Award. The project will also receive future support from the Industry Transformation Research Hub by the Australian Research Council (ARC).
Announced in July last year, Monash University will receive $5 million for the ARC Research Hub for Carbon Utilisation and Recycling to develop technology that harvests CO2 emissions and creates pathways to recycle that CO2 into new valuable products.
The research team’s vision extends beyond academia, as they actively collaborate with industry partners with plans to send the development to market.
When asked about challenges he anticipated, Tanksale said there would always be challenges when boundaries are pushed, and the team is currently working towards understanding these challenges. The immediate goal for the research team is to de-risk the technology by understanding and overcoming potential challenges of industrial implementation. Over the next two years, they aim to scale up the process to take the technology to commercial success.
“Given the scale of this process, requiring tons and tons of material, carbon capture and conversion, it needs to be demonstrated millions of times not just thousands of times,’ Tanksale said.
“That is beyond the scope of the university. Therefore, it will eventually have to go out of the laboratory and be implemented on an industrial scale.” “We’ll either have a spinoff from Monash University or license it to an established company and then, it will be the task for the companies to scale that beyond the laboratory,” he said.
Achieving true net negative emissions
To achieve truly net negative carbon emissions, Tanksale recognises the importance of integrating the innovative process with green hydrogen production.
“Acetic acid is currently made from natural gas . Natural gas is first converted into what is known as synthesis gas – which is carbon monoxide and hydrogen – and then you react a part of the same gas with methanol to make acetic acid; this is a long sequence of processes as it stands currently,” Tanksale said.
This process can be simplified by using just carbon dioxide and hydrogen. Currently, hydrogen is derived from natural gas, but with advancements in green hydrogen technology, which relies on renewable electricity to split water into hydrogen and oxygen, a completely carbon-free source of hydrogen could be used in tandem with the carbon dioxide capture from the air.
“This process is still being researched and hasn’t reached its full potential for commercialisation yet,” Tanksale said.
“To really achieve the net negative carbon emissions that we are aiming for, you need carbon dioxide capture from the air as well as green hydrogen, and both these technologies are in their nascent stage.”
“In the future, when the commercial potential has been developed for both these enabling technologies, we can complete the sustainable cycle,” he said.
Tanksale added that their research was always ongoing and would constantly look to optimise existing processes.
“There are scientific questions that always come from research. Research doesn’t give solutions; it throws new questions as well,” he said.
“For instance, one of the questions we want to answer with this is how can we increase the rate further?”
“Currently, the reaction takes a few hours to finish but can we reduce that to a few minutes? We are also attempting to work on the size of the reactor. If we can potentially increase the rate of reaction and have smaller reactors, this would mean lower capital cost and lower energy consumption,” Tanksale said.
Speaking about his personal vision for the future, Professor Tanksale said he would like to explore what the project could further to do achieve true negative carbon emissions.
“We’re trying to reduce carbon dioxide emissions in the first place from all the energy production and chemical industries. But reduction alone will not be enough, we need to actively remove carbon dioxide from the atmosphere so that we can reduce the effect of global warming faster,” he said.
“By capturing carbon dioxide from the air and converting that carbon dioxide into materials that do not emit carbon dioxide back into the atmosphere – I’m hoping that one day we can achieve true net negative emissions.”