Tag Archives: carbon dioxide

Carbon capture with asphalt

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I wish I could turn back the clock a few years, so I could mention this research from Rice University (Texas, US) on using asphalt for carbon capture (more on why at the end of this post). From a Sept. 13, 2016 news item on Nanowerk (Note: A link has been removed),

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.

A Sept. 12, 2016 Rice University news release, which originated the news item, further describes the work (Note: Links have been removed),

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.

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.”

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.

Here’s a link to and a citation for the paper,

Ultra-High Surface Area Activated Porous Asphalt for CO2 Capture through Competitive Adsorption at High Pressures by Almaz S. Jalilov, Yilun Li, Jian Tian, James M. Tour.  Advanced Energy Materials DOI: 10.1002/aenm.201600693  First published [online]: 8 September 2016

This paper is behind a paywall.

Finishing the story I started at the beginning of this post, I was at an early morning political breakfast a few years back when someone seated at our table asked me if there were any nanotechnology applications for carbon sequestration/capture. At the time, I could not bring any such applications to mind. (Sigh) Now I have an answer.

Cleaning up carbon dioxide pollution in the oceans and elsewhere

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I have a mini roundup of items (3) concerning nanotechnology and environmental applications with a special focus on carbon materials.

Carbon-capturing motors

First up, there’s a Sept. 23, 2015 news item on ScienceDaily which describes work with tiny carbon-capturing motors,

Machines that are much smaller than the width of a human hair could one day help clean up carbon dioxide pollution in the oceans. Nanoengineers at the University of California, San Diego have designed enzyme-functionalized micromotors that rapidly zoom around in water, remove carbon dioxide and convert it into a usable solid form.

The proof of concept study represents a promising route to mitigate the buildup of carbon dioxide, a major greenhouse gas in the environment, said researchers. …

A Sept 22, 2015 University of California at San Diego (UCSD) news release by Liezel Labios, which originated the news release, provides more details about the scientists’ hopes and the technology,

“We’re excited about the possibility of using these micromotors to combat ocean acidification and global warming,” said Virendra V. Singh, a postdoctoral scientist in Wang’s [nanoengineering professor and chair Joseph Wang] research group and a co-first author of this study.

In their experiments, nanoengineers demonstrated that the micromotors rapidly decarbonated water solutions that were saturated with carbon dioxide. Within five minutes, the micromotors removed 90 percent of the carbon dioxide from a solution of deionized water. The micromotors were just as effective in a sea water solution and removed 88 percent of the carbon dioxide in the same timeframe.

“In the future, we could potentially use these micromotors as part of a water treatment system, like a water decarbonation plant,” said Kevin Kaufmann, an undergraduate researcher in Wang’s lab and a co-author of the study.

The micromotors are essentially six-micrometer-long tubes that help rapidly convert carbon dioxide into calcium carbonate, a solid mineral found in eggshells, the shells of various marine organisms, calcium supplements and cement. The micromotors have an outer polymer surface that holds the enzyme carbonic anhydrase, which speeds up the reaction between carbon dioxide and water to form bicarbonate. Calcium chloride, which is added to the water solutions, helps convert bicarbonate to calcium carbonate.

The fast and continuous motion of the micromotors in solution makes the micromotors extremely efficient at removing carbon dioxide from water, said researchers. The team explained that the micromotors’ autonomous movement induces efficient solution mixing, leading to faster carbon dioxide conversion. To fuel the micromotors in water, researchers added hydrogen peroxide, which reacts with the inner platinum surface of the micromotors to generate a stream of oxygen gas bubbles that propel the micromotors around. When released in water solutions containing as little as two to four percent hydrogen peroxide, the micromotors reached speeds of more than 100 micrometers per second.

However, the use of hydrogen peroxide as the micromotor fuel is a drawback because it is an extra additive and requires the use of expensive platinum materials to build the micromotors. As a next step, researchers are planning to make carbon-capturing micromotors that can be propelled by water.

“If the micromotors can use the environment as fuel, they will be more scalable, environmentally friendly and less expensive,” said Kaufmann.

The researchers have provided an image which illustrates the carbon-capturing motors in action,

Nanoengineers have invented tiny tube-shaped micromotors that zoom around in water and efficiently remove carbon dioxide. The surfaces of the micromotors are functionalized with the enzyme carbonic anhydrase, which enables the motors to help rapidly convert carbon dioxide to calcium carbonate. Image credit: Laboratory for Nanobioelectronics, UC San Diego Jacobs School of Engineering.

Nanoengineers have invented tiny tube-shaped micromotors that zoom around in water and efficiently remove carbon dioxide. The surfaces of the micromotors are functionalized with the enzyme carbonic anhydrase, which enables the motors to help rapidly convert carbon dioxide to calcium carbonate. Image credit: Laboratory for Nanobioelectronics, UC San Diego Jacobs School of Engineering.

Here’s a link to and a citation for the paper,

Micromotor-Based Biomimetic Carbon Dioxide Sequestration: Towards Mobile Microscrubbers by Murat Uygun, Virendra V. Singh, Kevin Kaufmann, Deniz A. Uygun, Severina D. S. de Oliveira, and oseph Wang. Angewandte Chemie DOI: 10.1002/ange.201505155 Article first published online: 4 SEP 2015

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This article is behind a paywall.

Carbon nanotubes for carbon dioxide capture (carbon capture)

In a Sept. 22, 2015 posting by Dexter Johnson on his Nanoclast blog (located on the IEEE [Institute for Electrical and Electronics Engineers] website) describes research where carbon nanotubes are being used for carbon capture,

Now researchers at Technische Universität Darmstadt in Germany and the Indian Institute of Technology Kanpur have found that they can tailor the gas adsorption properties of vertically aligned carbon nanotubes (VACNTs) by altering their thickness, height, and the distance between them.

“These parameters are fundamental for ‘tuning’ the hierarchical pore structure of the VACNTs,” explained Mahshid Rahimi and Deepu Babu, doctoral students at the Technische Universität Darmstadt who were the paper’s lead authors, in a press release. “This hierarchy effect is a crucial factor for getting high-adsorption capacities as well as mass transport into the nanostructure. Surprisingly, from theory and by experiment, we found that the distance between nanotubes plays a much larger role in gas adsorption than the tube diameter does.”

Dexter provides a good and brief summary of the research.

Here’s a link to and a citation for the paper,

Double-walled carbon nanotube array for CO2 and SO2 adsorption by Mahshid Rahimi, Deepu J. Babu, Jayant K. Singh, Yong-Biao Yang, Jörg J. Schneider, and Florian Müller-Plathe. J. Chem. Phys. 143, 124701 (2015); http://dx.doi.org/10.1063/1.4929609

This paper is open access.

The market for nanotechnology-enabled environmental applications

Coincident with stumbling across these two possible capture solutions, I found this Sept. 23, 2015 BCC Research news release,

A groundswell of global support for developing nanotechnology as a pollution remediation technique will continue for the foreseeable future. BCC Research reveals in its new report that this key driver, along with increasing worldwide concerns over removing pollutants and developing alternative energy sources, will drive growth in the nanotechnology environmental applications market.

The global nanotechnology market in environmental applications is expected to reach $25.7 billion by 2015 and $41.8 billion by 2020, conforming to a five-year (2015-2020) compound annual growth rate (CAGR) of 10.2%. Air remediation as a segment will reach $10.2 billion and $16.7 billion in 2015 and 2020, respectively, reflecting a five-year CAGR of 10.3%. Water remediation as a segment will grow at a five-year CAGR of 12.4% to reach $10.6 billion in 2020.

…

As nanoparticles push the limits and capabilities of technology, new and better techniques for pollution control are emerging. Presently, nanotechnology’s greatest potential lies in air pollution remediation.

“Nano filters could be applied to automobile tailpipes and factory smokestacks to separate out contaminants and prevent them from entering the atmosphere. In addition, nano sensors have been developed to sense toxic gas leaks at extremely low concentrations,” says BCC research analyst Aneesh Kumar. “Overall, there is a multitude of promising environmental applications for nanotechnology, with the main focus area on energy and water technologies.”

You can find links to the report, TOC (table of contents), and report overview on the BCC Research Nanotechnology in Environmental Applications: The Global Market report webpage.

Carbon capture with ‘diamonds from the sky’

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Before launching into the latest on a new technique for carbon capture, it might be useful to provide some context. Arthur Neslen’s March 23, 2015 opinion piece outlines the issues and notes that one Norwegian Prime Minister resigned when coalition government partners attempted to build gas power plants without carbon capture and storage facilities (CCS), Note : A link has been removed,

At least 10 European power plants were supposed to begin piping their carbon emissions into underground tombs this year, rather than letting them twirl into the sky. None has done so.

Missed deadlines, squandered opportunities, spiralling costs and green protests have plagued the development of carbon capture and storage (CCS) technology since Statoil proposed the concept more than two decades ago.

But in the face of desperate global warming projections the CCS dream still unites Canadian tar sands rollers with the UN’s Intergovernmental Panel on Climate Change (IPCC), and Shell with some environmentalists.

…

With 2bn people in the developing world expected to hook up to the world’s dirty energy system by 2050, CCS holds out the tantalising prospect of fossil-led growth that does not fry the planet.

…

…
“With CCS in the mix, we can decarbonise in a cost-effective manner and still continue to produce, to some extent, our fossil fuels,” Tim Bertels, Shell’s Glocal CCS portfolio manager told the Guardian. “You don’t need to divest in fossil fuels, you need to decarbonise them.”

The technology has been gifted “a very significant fraction” of the billions of dollars earmarked by Shell for clean energy research, he added. But the firm is also a vocal supporter of public funding for CCS from carbon markets, as are almost all players in the industry.

Enthusiasm for this plan is not universal (from Neslen’s opinion piece),

Many environmentalists see the idea as a non-starter because it locks high emitting power plants into future energy systems, and obstructs funding for the cheaper renewables revolution already underway. “CCS is is completely irrelevant,” said Jeremy Rifkin, a noted author and climate adviser to several governments. “I don’t even think about it. It’s not going to happen. It’s not commercially available and it won’t be commercially viable.”

I recommend reading Neslen’s piece for anyone who’s not already well versed on the issues. He uses Norway as a case study and sums up the overall CCS political situation this way,

In many ways, the debate over carbon capture and storage is a struggle between two competing visions of the societal transformation needed to avert climate disaster. One vision represents the enlightened self-interest of a contributor to the problem. The other cannot succeed without eliminating its highly entrenched opponent. The battle is keenly fought by technological optimists on both sides. But if Norway’s fractious CCS experience is any indicator, it will be decided on the ground by the grimmest of realities.

On that note of urgency, here’s some research on carbon dioxide (CO2) or, more specifically, carbon capture and utilization technology, from an Aug. 19, 2015 news item on Nanowerk,,

Finding a technology to shift carbon dioxide (CO2), the most abundant anthropogenic greenhouse gas, from a climate change problem to a valuable commodity has long been a dream of many scientists and government officials. Now, a team of chemists says they have developed a technology to economically convert atmospheric CO2    directly into highly valued carbon nanofibers for industrial and consumer products.

An Aug. 19, 2015 American Chemical Society (ACS) news release (also on EurekAlert), which originated the news time, expands on the theme,

The team will present brand-new research on this new CO2 capture and utilization technology at the 250th National Meeting & Exposition of the American Chemical Society (ACS). ACS is the world’s largest scientific society. The national meeting, which takes place here through Thursday, features more than 9,000 presentations on a wide range of science topics.

“We have found a way to use atmospheric CO2 to produce high-yield carbon nanofibers,” says Stuart Licht, Ph.D., who leads a research team at George Washington University. “Such nanofibers are used to make strong carbon composites, such as those used in the Boeing Dreamliner, as well as in high-end sports equipment, wind turbine blades and a host of other products.”

Previously, the researchers had made fertilizer and cement without emitting CO2, which they reported. Now, the team, which includes postdoctoral fellow Jiawen Ren, Ph.D., and graduate student Jessica Stuart, says their research could shift CO2 from a global-warming problem to a feed stock for the manufacture of in-demand carbon nanofibers.

Licht calls his approach “diamonds from the sky.” That refers to carbon being the material that diamonds are made of, and also hints at the high value of the products, such as the carbon nanofibers that can be made from atmospheric carbon and oxygen.

Because of its efficiency, this low-energy process can be run using only a few volts of electricity, sunlight and a whole lot of carbon dioxide. At its root, the system uses electrolytic syntheses to make the nanofibers. CO2 is broken down in a high-temperature electrolytic bath of molten carbonates at 1,380 degrees F (750 degrees C). Atmospheric air is added to an electrolytic cell. Once there, the CO2 dissolves when subjected to the heat and direct current through electrodes of nickel and steel. The carbon nanofibers build up on the steel electrode, where they can be removed, Licht says.

To power the syntheses, heat and electricity are produced through a hybrid and extremely efficient concentrating solar-energy system. The system focuses the sun’s rays on a photovoltaic solar cell to generate electricity and on a second system to generate heat and thermal energy, which raises the temperature of the electrolytic cell.

Licht estimates electrical energy costs of this “solar thermal electrochemical process” to be around $1,000 per ton of carbon nanofiber product, which means the cost of running the system is hundreds of times less than the value of product output.

“We calculate that with a physical area less than 10 percent the size of the Sahara Desert, our process could remove enough CO2 to decrease atmospheric levels to those of the pre-industrial revolution within 10 years,” he says. [emphasis mine]

At this time, the system is experimental, and Licht’s biggest challenge will be to ramp up the process and gain experience to make consistently sized nanofibers. “We are scaling up quickly,” he adds, “and soon should be in range of making tens of grams of nanofibers an hour.”

Licht explains that one advance the group has recently achieved is the ability to synthesize carbon fibers using even less energy than when the process was initially developed. “Carbon nanofiber growth can occur at less than 1 volt at 750 degrees C, which for example is much less than the 3-5 volts used in the 1,000 degree C industrial formation of aluminum,” he says.

A low energy approach that cleans up the air by converting greenhouse gases into useful materials and does it quickly is incredibly exciting. Of course, there are a few questions to be asked. Are the research outcomes reproducible by other teams? Licht notes the team is scaling the technology up but how soon can we scale up to industrial strength?

Speeding up the process for converting carbon dioxide into hydrocarbon fuel

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This is a personal thrill; it’s the first time in seven years that I’ve received a press release directly from an institution in Asia.

A March 10, 2015 MANA, the International Center for Materials Nanoarchitectonics at NIMS (National Institute for Materials Science) press release announces and describes hydrocarbon fuel research from Japan and China first published online in Nov. 2014 and later in print in January 2015,

A combination of semiconductor catalysts, optimum catalyst shape, gold-copper co-catalyst alloy nanoparticles and hydrous hydrazine reducing agent enables an increase of hydrocarbon generation from CO2 by a factor of ten.

“Solar-energy-driven conversion of CO2 into hydrocarbon fuels can simultaneously generate chemical fuels to meet energy demand and mitigate rising CO2 levels,” explain Jinhua Ye and her colleagues at the International Center for Materials Nanoarchitectonics in their latest report. Now the research team have identified the conditions and catalysts that will maximise the yield of hydrocarbons from CO2, generating ten times previously reported production rates.

Carbon dioxide can be converted into a hydrocarbon by means of ‘reduction reactions’ -a type of reaction that involves reducing the oxygen content of a molecule, increasing the hydrogen content or increasing the electrons. In photocatalytic reduction of CO2 light activates the catalyst for the reaction.

Ye and his team introduced four approaches that each contributed to an increased reaction rate. First, they combined two known semiconductor photocatalysts strontium titanate (STO) and titania [titanium dioxide] (TiO2) – which led to the separation of the charges generated by light and hence a more effective photocatalyst. Second, the high surface area of the nanotubes was made greater by holes in the tube surfaces, which enhances catalysis by increasing the contact between the gases and catalysts. Third, the tubes were decorated with gold-copper (Au3Cu) nanoparticle co-catalysts to further enhance the catalysis, and fourth, they used hydrous hydrazine (N2H4•H2O) as the source of hydrogen.

Although the high hydrogen content of hydrous hydrazine is widely recognised in the context of hydrogen storage there are no previous reports of its use for reduction reactions. The researchers demonstrated that the reducing properties of hydrous hydrazine were so great that oxidation of the co-catalytic nanoparticles – a problem when water or hydrogen are used – was avoided.

The researchers conclude their report, “This opens a feasible route to enhance the photocatalytic efficiency, which also aids the development of photocatalysts and co-catalysts.”

Affiliations

The researchers on this project are associated with the following institutions:

International Center for Materials Nanoarchitectonics (MANA), and the Environmental Remediation Materials Unit,  National Institute for Materials Science (NIMS) 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan

Graduate School of Chemical Science and Engineering, Hokkaido University, Sapporo 060-0814, Japan

TU-NIMS Joint Research Center, School of Material Science and Engineering, Tianjin University 92 Weijin Road, Tianjin,  P.R. China

Here’s a link to and a citation for the paper,

Photocatalytic Reduction of Carbon Dioxide by Hydrous Hydrazine over Au–Cu Alloy Nanoparticles Supported on SrTiO3/TiO2 Coaxial Nanotube Arrays by Dr. Qing Kang, Dr. Tao Wang, Dr. Peng Li, Dr. Lequan Liu, Dr. Kun Chang, Mu Li, and Prof. Jinhua Ye. Angewandte Chemie International Edition Volume 54, Issue 3, pages 841–845, January 12, 2015 DOI: 10.1002/anie.201409183 Article first published online: 24 NOV 2014

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This research is behind a paywall.

Carbon dioxide as a source for new nanomaterials

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Polish researchers have made a startling suggestion (from a Jan. 23, 2014 news item on Nanowerk),

In common perception, carbon dioxide is just a greenhouse gas, one of the major environmental problems of mankind. For Warsaw chemists CO2 became, however, something else: a key element of reactions allowing for creation of nanomaterials with unprecedented properties.

In reaction with carbon dioxide, appropriately designed chemicals allowed researchers from the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) in Warsaw and the Faculty of Chemistry, Warsaw University of Technology, (WUT) for production of unprecedented nanomaterials.

Here’s an image the researchers use to illustrate their work,

Yellow tennis balls, spatially integrated in an adamant-like structure, symbolise crystal lattice of the microporous material resulting from self-assembly of nanoclusters. Orange balls imitate gas molecules that can adsorb in this material. The presentation is performed by Katarzyna Sołtys, a doctoral student from the Institute of Physical Chemistry of the Polish Academy of Sciences in Warsaw. (Source: IPC PAS, Grzegorz Krzyżewski).

Yellow tennis balls, spatially integrated in an adamant-like structure, symbolise crystal lattice of the microporous material resulting from self-assembly of nanoclusters. Orange balls imitate gas molecules that can adsorb in this material. The presentation is performed by Katarzyna Sołtys, a doctoral student from the Institute of Physical Chemistry of the Polish Academy of Sciences in Warsaw. (Source: IPC PAS, Grzegorz Krzyżewski).

The Jan. 23, 2014 IPC news release, which originated the news item, describes the work in more detail,

Carbon dioxide (CO2) is a natural component of Earth’s atmosphere. It is the most abundant carbon-based building block, and is involved in the synthesis of glucose, an energy carrier and building unit of paramount importance for living organisms.

“Carbon dioxide has been for years used in industrial synthesis of polymers. On the other hand, there has been very few research papers reporting fabrication of inorganic functional materials using CO2”, says Kamil Sokołowski, a doctoral student in IPC PAS.

Prof. Lewiński’s [Janusz Lewiński (IPC PAS, WUT)] group has shown that appropriately designed precursor compounds in reaction with carbon dioxide lead to fabrication of a microporous material (with pore diameters below 2 nm) resulting from self-assembly of luminescent nanoclusters. Novel microporous material, composed of building blocks with zinc carbonate core encapsulated in appropriately designed organic shell (hydroxyquinoline ligands), is highly luminescent, with photoluminescence quantum yield significantly higher than those of classical fluorescent compounds used in state-of-the-art OLEDs.

“Using carbon dioxide as a building block we were able to construct a highly porous and really highly luminescent material. Can it be used for construction of luminescent diodes or sensing devices? The discovery is new, the research work on the novel material is in progress, but we are deeply convinced that the answer is: yes”, says Sokołowski.

Already now it can be said that the novel material enjoys considerable interest. Polish and international patent applications were filed for the invention and the implementation work in cooperation with a joint venture company is in progress.

The design of precursors was inspired by nature, in particular by the binding of carbon dioxide in enzymatic systems of carbonic anhydrase, an enzyme responsible for fast metabolism of CO2 in human body. Effective enzyme activity is based on its active centre, where a hydroxyzinc (ZnOH) type reaction system is located.

“A hydroxyzinc reaction system occurs also in molecules of alkylzinc compounds, designed by us and used for fixation of carbon dioxide”, explains Sokołowski and continues: “These compounds are of particular interest for us, because in addition to hydroxyl group they contain also a reactive metal-carbon bond. It means that both the first and the second reaction system can participate in consecutive chemical transformations of such precursors”.

The research related to the chemistry of alkylhydroxyzinc compounds has an over 150 years of history and its roots are directly connected to the birth of organometallic chemistry. It was, however, only in 2011 and 2012 when Prof. Lewiński’s group has presented the first examples of stable alkylhydroxyzinc compounds obtained as a result of rationally designed synthesis.

The strategy for materials synthesis using carbon dioxide and appropriate alkylhydroxyzinc precursors, discovered by the researchers from Warsaw, seems to be a versatile tool for production of various functional materials. Depending on the composition of the reagents and the process conditions, a mesoporous material (with pore diameter from 2 to 50 nm) composed of zinc carbonate nanoparticles or multinuclear zinc nanocapsules for prospective applications in supramolecular chemistry can be obtained in addition to the material described above.

Further research of Prof. Lewiński’s group has shown that the mesoporous materials based on ZnCO3-nanoparticles can be transformed into zinc oxide (ZnO) aerogels. Mesoporous materials made of ZnO nanoparticles with extended surface can be used as catalytic fillings, allowing for and accelerating reactions of various gaseous reagents. Other potential applications are related to semiconducting properties of zinc oxide. That’s why the novel materials can be used in future in photovoltaic cells or as a major component of semiconductor sensing devices.

Good luck to the researchers as they find ways to turn a greenhouse gas into something useful.