Plant-inspired power plants: Developing catalysts that turn excess atmospheric CO2 into liquid fuel

December 8, 2015 by Matthew Cichowicz
Hybrid porous catalysts can be “grown” to capture and convert carbon dioxide to useful fuels, in analogy to a plant’s ability to turn carbon dioxide into biomass. Computer modeling showed how to tune catalytic functional groups embedded within a nano-porous solid to facilitate fast reaction rates for converting carbon dioxide and hydrogen to valuable products. Credit: Jingyun Ye

A team of chemical engineers at the University of Pittsburgh recently identified the two main factors for determining the optimal catalyst for turning atmospheric CO2 into liquid fuel. The results of the study, which appeared in the journal ACS Catalysis, will streamline the search for an inexpensive yet highly effective new catalyst.

Imagine a power plant that takes the excess (CO2) put in the atmosphere by burning fossil fuels and converts it back into fuel. Now imagine that power plant uses only a little water and the energy in sunlight to operate. The power plant wouldn't burn fossil fuels and would actually reduce the amount of CO2 in the atmosphere during the . For millions of years, actual plants have been using water, sunlight, and CO2 to create sugars that allow them to grow. Scientists around the globe are now adopting their energy-producing behavior.

"We're trying to speed up the natural carbon cycle and make it more efficient," said Karl Johnson, the William Kepler Whiteford Professor in the Department of Chemical & Petroleum Engineering at the University of Pittsburgh and principal investigator of the study. "You don't have to waste energy on all the extra baggage it takes to grow plants, and the result is a man-made carbon cycle that produces liquid fuel."

There's one catch. CO2 is a very stable molecule, and enormous amounts of energy are required to get it to react. One common way to make use of excess CO2 involves removing an oxygen atom and combining the remaining CO with H2 to create methanol. However, during this process parts of the conversion reactor need to heat as high as 1000 degrees Celsius, which can be difficult to sustain, especially when the only energy source is the sun.

A catalyst can get the CO2 to react at much lower temperatures. Some researchers have been experimenting with different materials that can get the CO2 to split—even at room temperature. But these, and most, reactive catalysts already identified are too expensive to mass-produce, and fossil fuels still offer a cheap source of energy. The low price and abundance of prevents a lot of companies from investing in the expensive trial and error process of researching new catalysts.

The study, "Screening Lewis Pair Moieties for Catalytic Hydrogenation of CO2 in Functionalized UiO-66" provides researchers with a good idea of how they should start looking for an optimal catalyst. Johnson, along with study co-author and post-doctoral researcher Jingyun Ye at the University of Pittsburgh, examined a series of eight different functional groups of Lewis acid and base pairs (Lewis pairs for short), which are highly reactive compounds often used as catalysts. They found that the two factors qualifying a material as a good are its hydrogen adsorption energy and the Lewis pair's hardness—a measurement of the difference between its ionization potential and electron affinity.

Using this framework, Johnson plans to work with experimentalists to screen for catalysts more effectively, and hopefully, bring researchers closer to creating that create while reducing atmospheric CO2. Imagine contributing to the reduction of CO2 in the atmosphere every time you fill up your gas tank.

Explore further: New step towards producing cheap and efficient renewable fuels

More information: Screening Lewis Pair Moieties for Catalytic Hydrogenation of CO2 in Functionalized UiO-66, ACS Catalysis, DOI: 10.1021/acscatal.5b01191

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6 comments

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Sonhouse
5 / 5 (2) Dec 08, 2015
But wouldn't burning the resultant fuel make more CO2? How does this help the overall balance of CO2 in the atmosphere?
bertibus
5 / 5 (3) Dec 08, 2015
@Sonhouse Presumably it would help because the CO2 is being recycled rather than new CO2 being created on a continuing basis.
RichManJoe
not rated yet Dec 08, 2015
@bertibus yes, but it takes energy to convert the CO2 - where does that energy come from
Zzzzzzzz
5 / 5 (2) Dec 08, 2015
@bertibus yes, but it takes energy to convert the CO2 - where does that energy come from

If plant processes are used, that is supplied by the sun
Dug
not rated yet Dec 08, 2015
Two things:
1. If plant photosynthesis processes are used - it takes more than the sun and CO2. It takes NPK at scale, and 2. NPK and its three components are is petroleum dependent to produce and any biofuel energy source will compete with food uses.

This " fuel from atmospheric CO2+catalyst" has been around for a while. Like a lot of energy research you will note another commonality - "If we just had a little more money to search for better catalyst." We've got less than 30 years before we bump up against peak phosphates changing the global food/cost paradigms creating a lot more chaos and violence than we are currently experiencing. Combustible energy sources are not a solution to excess CO2 and biofuels are a critical resource trap. We should be looking harder and faster at more appropriate energy sources.
Tessellatedtessellations
not rated yet Dec 13, 2015
Two things:
1. If plant photosynthesis processes are used - it takes more than the sun and CO2. It takes NPK at scale, and 2. NPK and its three components are is petroleum dependent to produce and any biofuel energy source will compete with food uses..


They aren't talking about using plants. They are researching inexpensive catalysts to transform CO2 and Hydrogen into fuel like plants do. The hydrogen can come from water, like in a plant, but using solar panels to split the water. It is very green.

Like all research, it requires money, so stop FUDding about conspiracies.

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