New Catalyst Recycles Greenhouse Gases into Fuel and Hydrogen Gas: KAIST and Rice University


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       The Korea Advanced Institute of Science and Technology (KAIST

Scientists have taken a major step toward a circular carbon economy by developing a long-lasting, economical catalyst that recycles greenhouse gases into ingredients that can be used in fuel, hydrogen gas, and other chemicals. The results could be revolutionary in the effort to reverse global warming, according to the researchers. The study was published on February 14 in Science.

“We set out to develop an effective catalyst that can convert large amounts of the greenhouse gases carbon dioxide and methane without failure,” said Cafer T. Yavuz, paper author and associate professor of chemical and biomolecular engineering and of chemistry at KAIST.

The catalyst, made from inexpensive and abundant nickel, magnesium, and molybdenum, initiates and speeds up the rate of reaction that converts carbon dioxide and methane into hydrogen gas. It can work efficiently for more than a month.

This conversion is called ‘dry reforming’, where harmful gases, such as carbon dioxide, are processed to produce more useful chemicals that could be refined for use in fuel, plastics, or even pharmaceuticals. It is an effective process, but it previously required rare and expensive metals such as platinum and rhodium to induce a brief and inefficient chemical reaction.

Other researchers had previously proposed nickel as a more economical solution, but carbon byproducts would build up and the surface nanoparticles would bind together on the cheaper metal, fundamentally changing the composition and geometry of the catalyst and rendering it useless.

“The difficulty arises from the lack of control on scores of active sites over the bulky catalysts surfaces because any refinement procedures attempted also change the nature of the catalyst itself,” Yavuz said.

The researchers produced nickel-molybdenum nanoparticles under a reductive environment in the presence of a single crystalline magnesium oxide. As the ingredients were heated under reactive gas, the nanoparticles moved on the pristine crystal surface seeking anchoring points. The resulting activated catalyst sealed its own high-energy active sites and permanently fixed the location of the nanoparticles — meaning that the nickel-based catalyst will not have a carbon build up, nor will the surface particles bind to one another. (Article continues below **)

Read More from Rice University: Rice reactor turns greenhouse gas into pure liquid fuel

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This schematic shows the electrolyzer developed at Rice to reduce carbon dioxide, a greenhouse gas, to valuable fuels. At left is a catalyst that selects for carbon dioxide and reduces it to a negatively charged formate, which is pulled through a gas diffusion layer (GDL) and the anion exchange membrane (AEM) into the central electrolyte. At the right, an oxygen evolution reaction (OER) catalyst generates positive protons from water and sends them through the cation exchange membrane (CEM). The ions recombine into formic acid or other products that are carried out of the system by deionized (DI) water and gas. Illustration by Chuan Xia and Demin Liu

 

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(** New catalyst recycles greenhouse gases into fuel and hydrogen gas continues)

“It took us almost a year to understand the underlying mechanism,” said first author Youngdong Song, a graduate student in the Department of Chemical and Biomolecular Engineering at KAIST. “Once we studied all the chemical events in detail, we were shocked.”

The researchers dubbed the catalyst Nanocatalysts on Single Crystal Edges (NOSCE). The magnesium-oxide nanopowder comes from a finely structured form of magnesium oxide, where the molecules bind continuously to the edge. There are no breaks or defects in the surface, allowing for uniform and predictable reactions.

“Our study solves a number of challenges the catalyst community faces,” Yavuz said. “We believe the NOSCE mechanism will improve other inefficient catalytic reactions and provide even further savings of greenhouse gas emissions.”

This work was supported, in part, by the Saudi-Aramco-KAIST CO2 Management Center and the National Research Foundation of Korea.

Other contributors include Ercan Ozdemir, Sreerangappa Ramesh, Aldiar Adishev, and Saravanan Subramanian, all of whom are affiliated with the Graduate School of Energy, Environment, Water and Sustainability at KAIST; Aadesh Harale, Mohammed Albuali, Bandar Abdullah Fadhel, and Aqil Jamal, all of whom are with the Research and Development Center in Saudi Arabia; and Dohyun Moon and Sun Hee Choi, both of whom are with the Pohang Accelerator Laboratory in Korea. Ozdemir is also affiliated with the Institute of Nanotechnology at the Gebze Technical University in Turkey; Fadhel and Jamal are also affiliated with the Saudi-Armco-KAIST CO2 Management Center in Korea.


Story Source:

Materials provided by The Korea Advanced Institute of Science and Technology (KAIST)Note: Content may be edited for style and length.


Journal Reference:

  1. Youngdong Song, Ercan Ozdemir, Sreerangappa Ramesh, Aldiar Adishev, Saravanan Subramanian, Aadesh Harale, Mohammed Albuali, Bandar Abdullah Fadhel, Aqil Jamal, Dohyun Moon, Sun Hee Choi, Cafer T. Yavuz. Dry reforming of methane by stable Ni–Mo nanocatalysts on single-crystalline MgOScience, 2020; 367 (6479): 777 DOI: 10.1126/science.aav2412

Rice University: Carbon-Capture from Asphalt Based Nano-Materials: 154% of its Weight in CO2


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A Rice University laboratory has improved its method to turn plain asphalt into a porous material that can capture greenhouse gases from natural gas. In research detailed this month in Advanced Energy Materials (“Ultra-High Surface Area Activated Porous Asphalt for CO2 Capture through Competitive Adsorption at High Pressures”), Rice researchers showed that a new form of the material can sequester 154 percent of its weight in carbon dioxide at high pressures that are common at gas wellheads.

Raw natural gas typically contains between 2 and 10 percent carbon dioxide and other impurities, which must be removed before the gas can be sold. The cleanup process is complicated and expensive and most often involves flowing the gas through fluids called amines that can soak up and remove about 15 percent of their own weight in carbon dioxide. The amine process also requires a great deal of energy to recycle the fluids for further use.

“It’s a big energy sink,” said Rice chemist James Tour, whose lab developed a technique last year to turn asphalt into a tough, sponge-like substance that could be used in place of amines to remove carbon dioxide from natural gas as it was pumped from ocean wellheads.

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Rice University scientists have improved their asphalt-derived porous carbon’s ability to capture carbon dioxide, a greenhouse gas, from natural gas. The capture material derived from untreated Gilsonite asphalt has a surface area of 4,200 square meters per gram. (Image: Almaz Jalilov/Rice University) 

 

Initial field tests in 2015 found that pressure at the wellhead made it possible for that asphalt material to adsorb, or soak up, 114 percent of its weight in carbon at ambient temperatures.

Tour said the new, improved asphalt sorbent is made in two steps from a less expensive form of asphalt, which makes it more practical for industry.

“This shows we can take the least expensive form of asphalt and make it into this very high surface area material to capture carbon dioxide,” Tour said. “Before, we could only use a very expensive form of asphalt that was not readily available.”

 

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A scanning electron microscope image shows micropores in carbon capture material derived from common asphalt. The material created at Rice University sequesters 154 percent of its weight in carbon dioxide at 54 bar pressure, a common pressure at wellheads. (Image: Tour Group/Rice University)

 

 

The lab heated a common type asphalt known as Gilsonite at ambient pressure to eliminate unneeded organic molecules, and then heated it again in the presence of potassium hydroxide for about 20 minutes to synthesize oxygen-enhanced porous carbon with a surface area of 4,200 square meters per gram, much higher than that of the previous material.

The Rice lab’s initial asphalt-based porous carbon collected carbon dioxide from gas streams under pressure at the wellhead and released it when the pressure was released. The carbon dioxide could then be repurposed or pumped back underground while the porous carbon could be reused immediately.
In the latest tests with its new material, Tours group showed its new sorbent could remove carbon dioxide at 54 bar pressure. One bar is roughly equal to atmospheric pressure at sea level, and the 54 bar measure in the latest experiments is characteristic of the pressure levels typically found at natural gas wellheads, Tour said.
Source: Rice University

 

Harvesting Energy From Carbon Dioxide Emissions


Energy: Device generates electricity from the entropy created when the greenhouse gas mixes with fresh air

An electrochemical cell could someday generate electricity from carbon dioxide emitted by power plants as the gas wafts into the atmosphere. Researchers demonstrate that the cell harvests energy released by the entropy created when CO2 mixes with fresh air (Environ. Sci. Technol. Lett. 2013, DOI: 10.1021/ez4000059). The device could help power plants increase electricity output without producing additional CO2.

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Electricity From CO2            
 A new electrochemical cell generates electricity from carbon dioxide dissolved in water solutions. When dissolved, the gas forms carbonic acid (H2CO3), which then dissociates into H+ and HCO3 ions. These ions adsorb selectively onto one of the two electrodes (left and right), depending on the type of membrane on the electrode (yellow and red). This process generates a current between the electrodes.            Credit: Environ. Sci. Technol. Lett
Bert Hamelers of Wetsus, a research center focused on water treatment technology in Leeuwarden, the Netherlands, and his team developed the new device based on one they created to tap energy released when seawater and freshwater mix. The previous cell consisted of electrodes coated with ion-exchange membranes. As seawater and freshwater flowed through the cell, the membranes absorbed and released sodium and chloride ions, creating a current.

Hamelers realized that the same cell design could harvest the energy released when two gases mix. To do so with CO2, the team first mixed it with a liquid, using either deionized water or a 0.25 M water solution of monoethanolamine (MEA), which is often used to remove CO2 from exhaust gases. In water, the CO2 forms carbonic acid, which then dissociates into H+ and HCO3 ions. These ions act like the sodium and chloride ions in the previous entropy-harvesting device. As the solution passes through the cell, ion-exchange membranes on the cell’s electrodes absorb the ions, H+ on one electrode and HCO3 on the other. This process produces current between the electrodes.

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                       Mixing Gases            
To harvest energy from mixing CO2 and fresh air, researchers first must dissolve the gases in water solutions (CO2, right; air, left). The water then passes by membranes in an electrochemical cell (rectangular block in the middle) in alternating pulses. The cell generates electricity as ions in the solutions adsorb onto and desorb from the electrodes.    Credit: Bert Hamelers/Wetsus        
Then water with dissolved fresh air flushes through the cell. Since this water is mostly ion free, the membranes release the H+ and HCO3 ions into the water, producing current in the opposite direction as before. This now ion-laden water leaves the cell and gets flushed with air. The CO2 gas reforms and is then released. The fluidics system continually repeats this cycle, sending alternating pulses of the dissolved CO2 and dissolved air through the cell.

With the small-scale system the researchers built in their lab, they could harvest 24% of the energy released when they used deionized water and 32% when they used MEA. At its most efficient, the lab setup generates only milliwatts of power. But with a scaled-up system, the researchers calculate that power plants could produce megawatts of power using CO2 emissions. They estimate that flue gases from power plants worldwide contain enough CO2 to generate 850 TWh of energy every year.

But the system has a few obstacles to overcome before it can be used in such large-scale applications, the team and outside experts say. For example, impurities in a power plant’s flue gas, such as sulfur dioxide or nitrogen oxides, could foul the cell’s membranes. The immediate problem is getting CO2 emissions dissolved into a liquid upon exiting the stacks. With current technology, dissolving that much gas in liquid would require more energy than the researchers’ system could generate. So it will take more research to find the optimal process to dissolve CO2 using as little energy as possible, Hamelers says.

Still, the concept is “marvelous,” says Volker Presser of the Leibniz Institute for New Materials in Germany. Now the researchers “need to envision a system that can take up tonnes and tonnes of CO2,” over multiple cycles, he says. With such a system generating extra electricity, Presser says, coal plants could produce energy more efficiently, without emitting more CO2.

Chemical & Engineering News
ISSN 0009-2347
Copyright © 2013 American Chemical Society

Investing in Renewable Energy and Efficiency Can Significantly Lower Water Use


QDOTS imagesCAKXSY1K 8The U.S. could dramatically lower the power industry’s draw on strained water supplies by replacing aging power plants with water-smart options such as renewable energy and efficiency, according to a study recently released by the Union of Concerned Scientists-led “Energy and Water in a Warming World” Initiative.

Water-Smart Power: Strengthening the U.S. Electricity System in a Warming World claims the choices the industry makes now will decide how much the energy sector will tax the nation’s threatened water supplies and contribute to climate change in the decades to come.

More than 40 percent of U.S. freshwater withdrawals are used for power plant cooling, the report says. These plants also lose several billion gallons of freshwater every day through evaporation and increasing demand and drought are putting a greater strain on water resources.

Low water levels and high water temperatures also can cause power plants to cut their electricity output in order to avoid overheating or harming local water bodies. Such energy and water collisions can leave customers with little or no electricity or with added costs because their electric supplier has to purchase power from elsewhere, as occurred during the past two summers.

However, low natural gas prices and a rash of retirements of old and uncompetitive coal-fired power plants have prompted significant change in the power industry.

“Our electricity system clearly isn’t able to effectively meet our needs as we battle climate change and face a future of expanding electricity demand and increasing water strain,” said Doug Kenney, director of the Western Water Policy Program at the University of Colorado Law School. “As old plants are retired or retrofitted and new plants are built, we’ve got to untangle our competing demands for water and energy.”

Examining different paths the nation’s electricity production can take in the coming decades, the study says that while utilities’ ongoing shift to natural gas would decrease water use in the coming decades, its ongoing requirements could still harm water-strained areas. This shift to natural gas also would do little to lower the power sector’s carbon emissions.

“In our water-constrained world, a 20-year delay in tackling the problem leaves the power industry unnecessarily vulnerable to drought and exacerbates competition with other water users,” said John Rogers, co-manager of EW3 and a senior energy analyst with UCS’s Climate and Energy Program. “We can bring water use down faster and further, but only by changing how we get our electricity.”

According to the report, strong investments in renewables and energy efficiency could greatly reduce power generation’s water use and carbon emissions. Under such a scenario, water withdrawals would drop by 97 percent from current levels by 2050, with most of that drop within the next 20 years. This approach also would cut carbon emissions by 90 percent from current levels. A renewables path would also be a much cheaper path for consumers, the report found.

“We have a tremendous opportunity before us,” said Robert Jackson, an environmental scientist at Duke University. “By increasing energy efficiency and renewables, we can cut greenhouse gas emissions and water use, improve the quality of our water and air, and save money and lives at the same time. How often do we get a chance like that?”

The study concludes that many short-term options exist to reduce power sector water and climate risks such as prioritizing low-carbon, water-smart energy choices, such as renewable energy and energy efficiency; upgrading power plant cooling systems with technologies that ease local water stress; and instituting integrated resource planning that connects energy and water decision making.

Last month, Coca-Cola announced a new set of environmental goals, including returning 100 percent of the water from its manufacturing facilities back to the environment at a level that supports aquatic life by 2020. On Tuesday, Molson Coors Brewing Company announced that in 2012, its water intensity was seven percent lower than in 2008. Since 2008, the company reduced total water consumption by over 12.6 million hectoliters, equivalent to 504 Olympic swimming pools. Lower than expected volumes made it difficult to reduce water intensity and caused the company to fall short of its 2012 target of 15 percent reduction.

Nanotechnology material could help reduce CO2 emissions from coal-fired power plants


QDOTS imagesCAKXSY1K 8(Nanowerk News) University of Adelaide researchers have  developed a new nanomaterial that could help reduce carbon dioxide emissions  from coal-fired power stations.
The new nanomaterial, described in the Journal of the  American Chemical Society (“Post-synthetic Structural Processing in a  Metal–Organic Framework Material as a Mechanism for Exceptional CO2/N2 Selectivity”), efficiently separates the  greenhouse gas carbon dioxide from nitrogen, the other significant component of  the waste gas released by coal-fired power stations. This would allow the carbon  dioxide to be separated before being stored, rather than released to the  atmosphere.
“A considerable amount of Australia‘s – and the world’s – carbon  dioxide emissions come from coal-fired power stations,” says Associate Professor  Christopher Sumby, project leader and ARC Future Fellow in the  University’s School of Chemistry and Physics.
“Removing CO2 from the flue gas  mixture is the focus of a lot of research. Most of Australia’s energy generation  still comes from coal. Changing to cleaner energies is not that straightforward  but, if we can clean up the emissions, we’ve got a great stop-gap technology.”
The researchers have produced a new absorbent material, called a  ‘metal-organic framework‘, which has “remarkable selectivity” for separating  CO2 from nitrogen.
“It is like a sponge but at a nanoscale,” says Associate  Professor Sumby. “The material has small pores that gas molecules can fit into –  a CO2 molecule fits but a nitrogen molecule is  slightly too big. That’s how we separate them.”
Other methods of separating CO2 from nitrogen are energy-intensive and expensive. This material has the  potential to be more energy efficient. It’s easy to regenerate (removing the  CO2) for reuse, with small changes in temperature  or pressure.
“This material could be used as it is but there are probably  smarter ways to implement the benefits,” says Associate Professor Sumby.
“One of the next steps we’re pursuing is taking the material in  powder form and dispersing it in a membrane. That may be more practical for  industrial use.”
The project is funded by the Science Industry Endowment Fund and  is a collaboration between researchers in the Centre of Advanced  Nanomaterials, in the School of Chemistry and Physics, and the CSIRO.
Source: University of Adeleide

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