Posts Tagged ‘carbon dioxide’
Monday, August 10, 2015 @ 05:08 PM gHale
When it comes to carbon dioxide, the words capture and convert sum it all up.
That is because that is the process that stops the greenhouse gas before it escapes from chimneys and power plants into the atmosphere and turns it into a useful product.
One possible end product is methanol, a liquid fuel and the focus of a study conducted at the U.S. Department of Energy’s (DoE) Argonne National Laboratory.
The chemical reactions that make methanol from carbon dioxide rely on a catalyst to speed up the conversion, and Argonne scientists identified a new material that could fill this role. With its structure, this catalyst can capture and convert carbon dioxide in a way that ultimately saves energy.
Enter the copper tetramer. It consists of small clusters of four copper atoms each, supported on a thin film of aluminum oxide. These catalysts work by binding to carbon dioxide molecules, orienting them in a way that is ideal for chemical reactions. The structure of the copper tetramer is such that most of its binding sites are open, which means it can attach more strongly to carbon dioxide and can better accelerate the conversion.
The current industrial process to reduce carbon dioxide to methanol uses a catalyst of copper, zinc oxide and aluminum oxide. A number of its binding sites end up occupied merely in holding the compound together, which limits how many atoms can catch and hold carbon dioxide.
“With our catalyst, there is no inside,” said Stefan Vajda, senior chemist at Argonne and the Institute for Molecular Engineering and co-author of a paper on the subject. “All four copper atoms are participating because with only a few of them in the cluster, they are all exposed and able to bind.”
To compensate for a catalyst with fewer binding sites, the current method of reduction creates high-pressure conditions to facilitate stronger bonds with carbon dioxide molecules. But compressing gas into a high-pressure mixture takes a lot of energy.
The benefits of enhanced binding is the new catalyst requires lower pressure and less energy to produce the same amount of methanol.
Carbon dioxide emissions are an ongoing environmental problem, and according to the authors, it’s important that research identifies optimal ways to deal with the waste.
“We’re interested in finding new catalytic reactions that will be more efficient than the current catalysts, especially in terms of saving energy,” said Larry Curtiss, an Argonne Distinguished Fellow who co-authored this paper.
Copper tetramers could allow us to capture and convert carbon dioxide on a larger scale — reducing an environmental threat and creating a useful product like methanol that can transport and burn for fuel.
This is just the beginning, though as the catalyst still has a long journey from the lab to industry.
Potential obstacles include instability and figuring out how to manufacture mass quantities. There’s a chance that copper tetramers may decompose when put to use in an industrial setting, so ensuring long-term durability is a critical step for future research, Curtiss said. And while the scientists needed only nanograms of the material for this study, that number would have to be multiplied dramatically for industrial purposes.
Meanwhile, the researchers are interested in searching for other catalysts that might even outperform their copper tetramer.
These catalysts can vary in size, composition and support material, which results in a list of more than 2,000 potential combinations, Vajda said.
But the scientists don’t have to run thousands of different experiments, said Peter Zapol, an Argonne physicist and co-author of this paper. Instead, they will use advanced calculations to make predictions, and then test the catalysts that seem most promising.
“We haven’t yet found a catalyst better than the copper tetramer, but we hope to,” Vajda said. “With global warming becoming a bigger burden, it’s pressing that we keep trying to turn carbon dioxide emissions back into something useful.”
Monday, February 16, 2015 @ 12:02 PM gHale
Removing harmful greenhouse gas, carbon dioxide, from smokestacks — called carbon capture and storage — could end up being a way to deal with climate change because of the sheer number and size of power plants that burn fossil fuels.
The catch always comes down to cost because that ends up being a costly endeavor. But that may change.
The brainiacs at the Massachusetts Institute of Technology are looking to develop a lower-cost way to do the job. Last year, they got $80,000 in funding to make a small-scale commercial prototype.
The MIT project seeks to lower the energy needed to remove carbon dioxide by using an electrochemical device similar in concept to a rechargeable battery. The technique promises to be less expensive and easier to add to existing power plants than current systems.
The new system could cut energy requirements by as much as 25 percent, according to very rough estimates made in the lab. But researchers need to get closer to building a commercial system to get a firm idea of the capital costs.
“It’s certainly addressing an area where we haven’t seen a lot of promising new technologies,” said Tibor Toth, managing director of investments at the Massachusetts Clean Energy Center, which helped fund the work. “This project will allow them to really explore commercial applications and be that catalyst to attract future funding.”
Given the rate of ongoing pollution — and the tons of carbon dioxide already in the atmosphere — the country needs more innovation related to carbon capture and storage, said MIT professor T. Alan Hatton and PhD candidate Aly Eltayeb, who are leading the research project.
“Carbon capture and storage is one of those things that doesn’t sound sexy, but it really solves the problem,” Eltayeb said. “Especially if you can do something with that CO2 and stop treating it as a waste — and treat it as a valuable product.”
A single 500-megawatt coal-fired power station puts out roughly 10,000 tons of carbon dioxide each day, Hatton said. Massachusetts alone has about 20 times that capacity in fossil fuel power generation. Replacing hundreds of billions of dollars’ worth of fossil fuel infrastructure with renewable energy systems would be costly and take many years.
Last year, a large carbon capture and storage project went online at a coal plant in Canada, and another is on tap to start this year in Mississippi. But overall, the pace of development for such technology has been slow, with little activity on a commercial scale, the International Energy Agency said.
The problem is the traditional process diverts roughly 30 percent of a plant’s power output to remove carbon dioxide, Hatton said. All of that energy costs money, which is ultimately paid by consumers and businesses.
Today, carbon capture ends up achieved with a combination of chemistry and brute force. Flue gases flow into a tank filled with a liquid that contains material called amines. The carbon dioxide latches onto the amine compounds, separating most of the carbon dioxide from the flue gas. That creates a liquid mixture of amine and carbon dioxide.
That solution then ends up blasted with steam. The heat forces carbon dioxide molecules to break off from the amines. Once separated, carbon dioxide ends up compressed and pumped into underground formations like aquifers or transported via pipelines. The amines recycle to capture more gas.
The MIT researchers want to continue using amines but create a more energy-efficient and elegant way to split off the carbon dioxide. Four years ago, a former student in Hatton’s lab, Michael Stern, proposed using metals in an electrical device instead of steam. The idea: Introduce a substance that amines would rather bind to than carbon dioxide.
He settled on a common metal, copper, because of the cost and the speed at which reactions take place.
An early prototype of an electrochemical cell consists of two metal plates, each about a foot long and a few inches wide, separated by a paper-like membrane. In a working device, a flow of electricity would create a voltage across the two plates, much the way a battery has positive and negative electrodes.
As in a traditional system, amines capture carbon dioxide from incoming flue gases. Then, the solution would flow between the two plates, which have grooves of exposed copper. Because of their chemical properties, amines and charged copper atoms have a strong attraction to each other and form a tight bond. That causes the amines to release the carbon dioxide, which ends up captured in a separate vessel.
The electrochemical method still requires energy — a flow of electricity — but significantly less than the steam-based carbon capture method, Hatton and Eltayeb said. They think they can improve the device and chemistry to further increase its efficiency. A commercial carbon capture machine would require hundreds or thousands of individual cells stacked together to handle a steady flow of flue gases.
Using a simple chemical process means that carbon capture gear can bolt onto existing facilities relatively easily. It could even install in settings that don’t use steam, such as concrete factories, commercial buildings, spacecraft, and submarines.
“There are so many benefits when you do this electrically,” Hatton said.
If their experiments go well, Hatton and Eltayeb might choose to start a company to commercialize the technology, they said, although that would take a few years. To demonstrate the process is commercially viable, they will need to run tests with actual flue gases from power plants, rather than gases in a lab, said Richard Noble, a professor at the University of Colorado.
“This work certainly has the potential to be an alternative to conventional amine scrubber technology,” he said.
In the long term, the technology could install at huge power plants to separate carbon dioxide and simply sequester it underground. But initially, Hatton and Eltayeb expect the carbon dioxide will pumped into oil and gas wells. Drillers often pump compressed carbon dioxide into wells to push out more oil.
It might seem strange to use a carbon-mitigation technology to produce more fossil fuels, but oil and gas drillers are willing to pay for pure carbon dioxide normally considered a waste product.
In the absence of “strong carbon policy,” creating an economic incentive for carbon dioxide is critical to getting carbon capture and storage deployed, said Howard Herzog, senior research engineer at the MIT Energy Initiative. In fact, all carbon capture projects in the works plan to sell carbon dioxide for enhanced oil recovery, he said.
“Carbon capture has one primary purpose — to reduce CO2 emissions,” he said. “So without policy to create markets for this, it is amazing that progress has been as good as it’s been to date.”
Thursday, February 13, 2014 @ 09:02 AM gHale
One person suffered injuries following a chemical spill in Mayes County, OK.
The injury occurred when a mechanic was working last Thursday at Pryor Chemical in Mayes County when anhydrous ammonia hit him in the face.
The incident occurred just after 3 p.m. and has since been contained and blocked off with caution tape. The company is conducting an internal investigation into the cause of the chemical spill.
Pryor operates a 47-acre facility on a 104-acre site in Pryor, OK. It produces anhydrous ammonia, urea, nitric acid, urea ammonium nitrate (UAN) and carbon dioxide.
The plant never evacuated its employees, although a large company across the street sent their employees home because of winds headed in their direction, said RAE Corporation’s Terry Titsworth. He said his company has an emergency response team in charge of watching out for emergencies at the fertilizer plant.
Tuesday, July 16, 2013 @ 06:07 PM gHale
A water-soluble catalyst can electrocatalytically transform carbon dioxide into a useful chemical feedstock.
With the global demand for fuel is rising along with carbon dioxide levels in the atmosphere, this new development could actually fall into the category of a win-win situation.
Studies attempted to address the global carbon imbalance by exploring ways to recycle carbon dioxide into liquid fuels. Formate, the anion of formic acid, is an intermediate of carbon dioxide reduction and can end up used as a fuel in formic acid fuel cells.
The catch is, however, the selective production of formate, without using organic solvents, is challenging. Water, being inexpensive and environmentally-friendly, is obviously preferred over organic solvents as a reaction medium. On the other hand, the reduction of carbon dioxide in water ends up complicated by the reduction of water to hydrogen being a more kinetically favorable process.
But that all may change as Thomas Meyer, Maurice Brookhart and Peng Kang at the University of North Carolina designed an iridium pincer catalyst that can selectively reduce carbon dioxide into formate in almost pure water. Formate ends up made in a 93 percent yield with no other reduced carbon products formed at the same time. Notably, the catalyst does not catalyze proton reduction to form hydrogen molecules although a small amount of background hydrogen ends up at the electrode.
Wenzhen Li, an expert in the electrochemical reduction of carbon dioxide at Michigan Technological University said this exciting work reports such a catalyst for the first time. The only problem he sees is that formate and the catalyst are both water-soluble, so an input of energy would end up required to separate formate from the solution.
“It would be even more interesting to develop a [similar] catalyst to further reduce carbon dioxide to carbon monoxide or even hydrocarbons,” he said.
The group is now hunting for more efficient catalysts and ways to immobilize them on electrodes.
Monday, June 24, 2013 @ 09:06 AM gHale
There is a new and inexpensive catalyst that uses electricity generated from solar energy to convert carbon dioxide into synthetic fuels for powering cars, homes and businesses.
Gold and silver represent the “gold standard” in the world of electrocatalysts for conversion of carbon dioxide to carbon monoxide. University of Delaware (UD) chemist Joel Rosenthal and his research team have pioneered the development of a much cheaper alternative to these pricey, precious metals. It is bismuth, a silvery metal with a pink hue that’s a key ingredient in Pepto-Bismol, the same cure all for settling an upset stomach.
An ounce of bismuth is 50 to 100 times cheaper than an ounce of silver, and 2,000 times cheaper than an ounce of gold, Rosenthal said. Bismuth is more plentiful than gold and silver, it is well distributed globally and is a byproduct in the refining of lead, tin and copper.
Moreover, Rosenthal said his UD-patented catalyst offers other important advantages: Selectivity and efficiency in converting carbon dioxide to fuel.
“Most catalysts do not selectively make one compound when combined with carbon dioxide — they make a whole slew,” Rosenthal said. “Our goal was to develop a catalyst that was extremely selective in producing carbon monoxide and to power the reaction using solar energy.”
Many of us hear ‘”carbon monoxide” and think “poison.”
“It’s true that you do not want to be in a closed room with carbon monoxide,” Rosenthal says. “But carbon monoxide is very valuable as a commodity chemical because it’s extremely energy rich and has many uses.”
Carbon monoxide works industrially in the water-gas shift reaction to make hydrogen gas. It also is a prime feedstock for the Fischer-Tropsch process, which allows for the production of synthetic petroleum, gasoline and diesel.
Commercial production of synthetic petroleum is under way or in development in a number of countries, including Australia and New Zealand, China and Japan, South Africa and Qatar.
Rosenthal said if carbon dioxide emissions become taxed in the future due to continuing concerns about global warming, his solar-driven catalyst for making synthetic fuel will compete even better economically with fossil fuels.
“This catalyst is a critically important linchpin,” Rosenthal said. “Using solar energy to drive the production of liquid fuels such as gasoline from CO2 is one of the holy grails in renewable energy research. In order to do this on a practical scale, researchers need inexpensive catalysts that can convert carbon dioxide to energy-rich compounds. Our discovery is important in this regard, and demonstrates that development of new catalysts and materials can solve this problem. Chemists have a big role to play in this area.”
Rosenthal credits a scientific article published during America’s first energy crisis in the 1970s for piquing his interest in bismuth. At that time, researchers were examining the conversion of carbon dioxide to carbon monoxide using electricity and metal electrodes. The research went bust in the early 1980s when federal funding dried up. Rosenthal picked up the trail and blazed a new one.
“With this advance, there are at least a dozen things we need to follow up on,” Rosenthal notes. “One successful study usually leads to more questions and possibilities, not final answers.”
Thursday, September 6, 2012 @ 07:09 PM gHale
Shell, Chevron and Marathon Oil will build a carbon capture and sequestration mechanism into their 225,000 barrels per day Athabasca Oil Sands Project, which they feel when the system is ready in 2015, it will be able to capture 1 million metric tons a year of carbon dioxide and inject it a mile underground.
The oil sands are more carbon intensive than other sources of oil because the sludge must undergo a partial refining process, or an upgrade, before it’s thin enough to flow through pipelines. That upgrading process requires a lot of heat, which comes from burning natural gas, which generates quite a bit of carbon dioxide.
The Quest CCS project will capture the carbon dioxide that comes out of the Scotford Upgrader near Edmonton, Alberta, then take it by pipe about 50 miles north where it will inject underground between impermeable layers of rock. Eliminating all that carbon dioxide will effectively reduce the emissions by 35%.
Quest will cost $1.4 billion, about half of which will be put up by the government of Alberta, paid out of a $2 billion fund specifically created to finance carbon capture technologies.
Chevron is no stranger to CCS; at its giant Barrow Island LNG project in Australia, the oil giant is building a system to inject 3.4 million tons of carbon dioxide a year into the earth. That CO2, however, separates out of the natural gas harvested from the Gorgon fields.
Tuesday, June 12, 2012 @ 04:06 PM gHale
A new property of flames allows for the ability to control reactions at a solid surface in a flame now opens up a whole new field of chemical innovation.
Chemists now say their previous understanding of how flames interact with a solid surface was incorrect, said researchers at the University College London (UCL). For the first time, they showed they can control a particular type of chemistry, called redox chemistry, at the surface.
This finding has wide implications for future technology, for example in detection of chemicals in the air, and in developing our understanding of the chemistry of lightning. It also opens up the possibility of being able to perform nitrogen oxide and carbon dioxide electrolysis at the source for the management of greenhouse gases.
Results of the study show that depending on the chemical make-up of the flame, scientists can record a distinctive electrical fingerprint. The fingerprint is a consequence of the behavior of specific chemical species at the surface of a solid conducting surface, where electrons can exchange at a very precise voltage.
“Flames can be modeled to allow us to construct efficient burners and combustion engines,” said Dr. Daren Caruana, from the UCL Department of Chemistry. “But the presence of charged species or ions and electrons in flames gives them a unique electrical property.”
“By considering the gaseous flame plasma as an electrolyte, we show that it is possible to control redox reactions at the solid/gas interface,” Caruana said.
The team developed an electrode system that can probe the chemical make-up of flames. By adding chemical species to the flame they were able to pick up current signals at specific voltages giving a unique electrochemical finger print, called a voltammogram.
The voltammograms for three different metal oxides — tungsten oxide, molybdenum oxide and vanadium oxide — are all unique. Furthermore, the team also demonstrated the size of the current signatures depend on the amount of the oxide in the flame. While this is possible and routinely done in liquids, this is the first time they saw it works in the gas phase.
UCL chemists showed there are significant differences between solid/gas reactions and their liquid phase equivalents. Liquid free electrochemistry presents access to a vast number of redox reactions, current voltage signatures that lie outside potential limits defined by the liquid.
The prospect of new redox chemistries will enable new technological applications such as electrodeposition, electroanalysis and electrolysis, which will have significant economic and environmental benefits.
“The mystique surrounding the properties of fire has always captivated our imagination,” Caruana said. “However, there are still some very significant technical and scientific questions that remain regarding fire and flame.”
Wednesday, May 16, 2012 @ 06:05 PM gHale
Fracking is undergoing more scrutiny in California as oil and gas regulators want to propose new regulations and re-examine existing rules for underground injection wells.
The Department of Conservation’s Division of Oil, Gas, and Geothermal Resources (DOGGR) released a “road map” earlier this month outlining its plan to revisit the state’s oversight of underground injection wells to better protect drinking water supplies and workers.
As part of the process, the division said it would look at the use of carbon dioxide as an enhanced oil recovery tool, the storing of carbon dioxide in injection wells, and the reinjection of waste gas.
“It’s a to-do list of Division priorities for the near-term, some of which involve hydraulic fracturing regulations,” said DOGGR spokesman Don Drysdale.
Hydraulic fracturing, or fracking, involves pumping water, chemicals, and other substances into shale formations at high pressure to enhance natural gas extraction. Injection wells are for deep-underground storage of wastewater, including “flowback” water from fracking.
DOGGR said it will hold a series of public workshops to gather input for new fracking regulations, which it plans to propose by the end of the summer. Also, DOGGR said it will commission an independent study of the impact of fracking in California.
Monday, March 26, 2012 @ 02:03 PM gHale
The “hydrogen economy” is here and available and could begin commercial production in this decade, a scientist said.
Heat from existing nuclear plants could see use in the more economical production of hydrogen, with future plants custom-built for hydrogen production, said International Atomic Energy Agency’s (IAEA) Ibrahim Khamis, Ph.D., at the 243rd National Meeting & Exposition of the American Chemical Society (ACS).
“There is rapidly growing interest around the world in hydrogen production using nuclear power plants as heat sources,” Khamis said. “Hydrogen production using nuclear energy could reduce dependence on oil for fueling motor vehicles and the use of coal for generating electricity. In doing so, hydrogen could have a beneficial impact on global warming, since burning hydrogen releases only water vapor and no carbon dioxide, the main greenhouse gas. There is a dramatic reduction in pollution.”
Khamis said scientists and economists at IAEA and elsewhere are working intensively to determine how current nuclear power reactors — 435 are operational worldwide — and future nuclear power reactors could work in hydrogen production.
Most hydrogen production at present comes from natural gas or coal and results in releases of the greenhouse gas carbon dioxide. On a much smaller scale, some production comes from a cleaner process called electrolysis, in which an electric current flowing through water splits the H2O molecules into hydrogen and oxygen. This process, termed electrolysis, is more efficient and less expensive if water heats to form steam, with the electric current passed through the steam.
Khamis said nuclear power plants are ideal for hydrogen production because they already produce the heat for changing water into steam and the electricity for breaking the steam down into hydrogen and oxygen. Experts envision the current generation of nuclear power plants using a low-temperature electrolysis which can take advantage of low electricity prices during the plant’s off-peak hours to produce hydrogen. Future plants, designed specifically for hydrogen production, would use a more efficient high-temperature electrolysis process or couple with the thermochemical processes, which are currently under research and development.
“Nuclear hydrogen from electrolysis of water or steam is a reality now, yet the economics need to be improved,” Khamis said. He noted some countries are considering construction of new nuclear plants coupled with high-temperature steam electrolysis (HTSE) stations that would allow them to generate hydrogen gas on a large scale in anticipation of growing economic opportunities.
Khamis described how IAEA’s Hydrogen Economic Evaluation Programme (HEEP) is helping. IAEA has designed its HEEP software to help its member states take advantage of nuclear energy’s potential to generate hydrogen gas. The software assesses the technical and economic feasibility of hydrogen production under a wide variety of circumstances.