Abby L. Harvey
GHG Monitor
8/22/2014
Using copper foam can provide a new, potentially more specialized, means to convert carbon dioxide into useful chemicals like hydrocarbons, researchers at Brown University assert in a paper published earlier this month. Research into using copper as an electrocatalyst for the reduction of CO2 has been ongoing for decades, Tayhas Palmore, professor of engineering and senior author of the new research told GHG Monitor this week, although the use of the metal has both benefits and weaknesses. “Copper has been really sort of seen as the best metal electrocatalyst for CO2 reduction. There are a couple of things that are attractive about it. It makes hydrocarbons, so it’ll produce things like methane and ethanol and ethylene etc. that are of value as part of downstream products,” Palmore explained. “The negative thing about copper is that you make a bunch of different products. Ideally what you want to be able to do is to use an electrode to make one product or a couple of products.”
More recent research has been conducted to try to narrow the products made by the CO2 reduction process, this research gave Palmore and her team the inspiration to see what they could do using copper foam. “The more recent studies are suggesting that a roughened surface may favor the formation of hydrocarbons,” Palmore said. “They saw some increase in hydrocarbon formation. We just sort of thought, why don’t you just go further? Go completely to the three dimensional structure?”
Copper foam is a fairly new development, according to a Brown University press release, and is created by “depositing copper on a surface in the presence of hydrogen and a strong electric current. Hydrogen bubbles cause the copper to be deposited in an arrangement of sponge-like pores and channels of varying sizes.” The experiments done by Palmore’s team, though still in a fundamental phase, showed promising results, Palmore said. “We got really surprising results in that we completely shut down all reactions except for the formation of formic acid. So we have a system that is copper just like everybody else is using, but now it only is making formic acid as well as having the competing reaction of water reduction and very little, almost a constant level, of carbon monoxide at all voltages,” she said. “What that tells us is that it’s not just the metal and it’s not just its roughness, but it’s also really the architecture of the electrode that can have an impact on what is observed in terms of a product formation in this reaction.”
What this could mean for the carbon capture and sequestration industry is perhaps an increased interest in utilization of carbon. The research was done as part of a larger effort at Brown within the university’s Center for the Capture and Conversion of CO2. The Center, which receives its funding from the National Science Foundation, is tasked with exploring catalysts that can convert CO2 into usable forms of carbon. By developing advantageous uses for CO2, the center hopes to add an incentive to reduce the release of CO2 into the atmosphere. “If you add value and alternative approaches to these kinds of compounds for the chemical industry, then it’s sort of priming the pump to begin to think about more sustainable ways of doing chemistry and CO2 is a great source of carbon and we have plenty of it so there’s a lot of us looking at catalysis for that,” Palmore said, later stressing the importance of utilization in the CCS conversation. “Now the ‘U’ has been put in there because we have to do something with this stuff, you can’t only sequester it and that’s really what our center is all about.”
Moving forward, Palmore and her team will explore different architectures to the copper foam to try to discover ways to produce other chemicals in the reduction, Palmore told GHG Monitor. The center may also look into how these findings could be applied to emissions from power plants. “Somebody might think about the flue gas at a power plant for example. There’s a lot of CO2 in that. How much do you have to scrub it before being used with this? … That’s something that our center activity will explore,” Palmore said. “For me individually with this particular paper, all we know is that we’ve changed the morphology of an electrode and we’ve dramatically switched the product results that we get from it.” Palmore however, doesn’t foresee any reason the process couldn’t be used with scrubbed flue gas. “I think that scrubbed flue gas is the equivalent of just a concentrated version of CO2. It’s going to have a little bit of nitrogen etc. in it, but I think that that shouldn’t be a problem,” Palmore said, stressing however that those experiments have not yet been done.
