New reactor turns carbon dioxide into green fuels
One of the main goals of researchers looking to mitigate the effects of climate change is a way to turn greenhouse gases such as methane and carbon dioxide into something more useful, such as fuel sources.
|An electrocatalysis reactor built at Rice University recycles carbon dioxide to produce pure liquid fuel solutions using electricity. The researchers who developed the invention hope that it will become an efficient and cost-effective way to reuse greenhouse gas and keep it out of the atmosphere. (Image Source: Jeff Fitlow)|
Rice University researchers have made a breakthrough in this goal with a new reactor which uses renewable energies to produce pure liquid fuels from carbon dioxide.
The catalytic reactor, also known as an electrolyzer and developed in the lab of chemical and biomolecular engineer Rice, Haotian Wang, produces high concentrations of formic acid which is purer than what can usually be produced, he said. .
“Formic acid is an energy carrier,” Wang said in a press release. “It’s a fuel cell fuel that can generate electricity and emit carbon dioxide – which you can recover and recycle again.”
Usually, formic acid produced by traditional carbon dioxide devices requires a series of purification steps, which can be expensive and time consuming, he said. With the reactor he and his team developed, pure formic acid can be produced directly, making the conversion of carbon dioxide into fuel more accessible on a larger scale, Wang said.
Secrets of success
The researchers cited two key developments they made to enable the reactor design: a bismuth catalyst and a solid state electrolyte that does not need salt for a reaction.
Using bismuth created a very stable catalyst for several reasons, Wang said. One is that bismuth is a very heavy atom – compared to transition metals like copper, iron, or cobalt – and its mobility is much lower, especially under the reaction conditions. “So that stabilizes the catalyst,” he said in a press release.
The researchers also structured the reactor to prevent water from coming into contact with the catalyst, another reason for its stability, Wang added.
The team also knew that using an electrolyte that did not require salt would prevent the removal of the salt from the formic acid created in the chemical reaction, Wang said.
Typically, people reduce carbon dioxide for fuel in a traditional liquid electrolyte such as salt water, which helps ions move freely in an electrolyte to conduct electricity optimally, has t -he declares.
“But when you generate formic acid this way, it mixes with the salts,” he said in the statement. “For the majority of applications, you have to remove salts from the end product, which requires a lot of energy and costs. We have therefore used solid electrolytes which conduct protons and can be made of insoluble polymers or inorganic compounds, thus eliminating the need for salts.
The researchers also coated their solid polymer-based electrolyte with sulfonic acid ligands to drive positive charge or amino functional groups to drive negative ions, Wang said.
The team detailed their work in a paper in the review Natural energy.
Design in action
In testing, the new electrocatalyst achieved an energy conversion efficiency of about 42%, so that about half of the electrical energy generated by it can be stored in formic acid as liquid fuel.
In a catalyst like the one built by the Rice team, the rate at which water flows through the product chamber determines the concentration of the resulting solution, the researchers said.
The performance of the current device produces a solution containing almost 30 percent formic acid by weight, they reported. However, faster flows would allow for customization of focus, which the team is aiming for in future iterations of the design, according to the team.
The lab used the device to generate formic acid continuously for 100 hours without too much degradation of reactor components, including nanoscale catalysts, Wang said. In addition, he believes that the reactor could also produce higher value fuels, such as acetic acid, ethanol or propanol.
“The big picture is that reducing carbon dioxide is very important for its effect on global warming as well as for green chemical synthesis,” Wang said in a press release. “If the electricity comes from renewable sources like the sun or the wind, we can create a loop that turns carbon dioxide into something important without emitting more of it.”
Elizabeth Montalbano is a freelance writer who has written about technology and culture for over 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York. In her spare time, she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.
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