How to Convert Carbon Dioxide (CO2) into Fuels

If the CO2 content of the atmosphere is not to increase any further, carbon dioxide must be converted into something else. However, as CO2 is a very stable molecule, this can only be done with the help of special catalysts. The main problem with such catalysts has so far been their lack of stability: after a certain time, many materials lose their catalytic properties.

At TU Wien (Austria), research is being conducted on a special class of minerals – the perovskites, which have so far been used for solar cells, as anode materials or electronic components rather than for their catalytic properties. Now scientists at TU Wien have succeeded in producing a special perovskite that is excellently suited as a catalyst for converting CO2 into other useful substances, such as synthetic fuels. The new perovskite catalyst is very stable and also relatively cheap, so it would be suitable for industrial use.

We are interested in the so-called reverse water-gas shift reaction,” says Prof. Christoph Rameshan from the Institute of Materials Chemistry at TU Wien. “In this process, carbon dioxide and hydrogen are converted into water and carbon monoxide. You can then process the carbon monoxide further, for example into methanol, other chemical base materials or even into fuel.”

This reaction is not new, but it has not really been implemented on an industrial scale for CO2 utilisation. It takes place at high temperatures, which contributes to the fact that catalysts quickly break down. This is a particular problem when it comes to expensive materials, such as those containing rare metals.

Christoph Rameshan and his team investigated how to tailor a material from the class of perovskites specifically for this reaction, and he was successful: “We tried out a few things and finally came up with a perovskite made of cobalt, iron, calcium and neodymium that has excellent properties,” says Rameshan.

Because of its crystal structure, the perovskite allows certain atoms to migrate through it. For example, during catalysis, cobalt atoms from the inside of the material travel towards the surface and form tiny nanoparticles there, which are then particularly chemically active. At the same time, so-called oxygen vacancies form – positions in the crystal where an oxygen atom should actually sit. It is precisely at these vacant positions that CO2 molecules can dock particularly well, in order to then be dissociated into oxygen and carbon monoxide.

We were able to show that our perovskite is significantly more stable than other catalysts,” says Christoph Rameshan. “It also has the advantage that it can be regenerated: If its catalytic activity does wane after a certain time, you can simply restore it to its original state with the help of oxygen and continue to use it.

Initial assessments show that the catalyst is also economically promising. “It is more expensive than other catalysts, but only by about a factor of three, and it is much more durable,” says Rameshan. “We would now like to try to replace the neodymium with something else, which could reduce the cost even further.“Theoretically, you could use such technologies to get CO2 out of the atmosphere – but to do that you would first have to concentrate the carbon dioxide, and that requires a considerable amount of energy. It is therefore more efficient to first convert CO2 where it is produced in large quantities, such as in industrial plants. “You could simply add an additional reactor to existing plants that currently emit a lot of CO2, in which the CO2 is first converted into CO and then processed further,” says Christoph Rameshan. Instead of harming the climate, such an industrial plant would then generate additional benefits.


How To Turn Seawater Into Fuel

For the first time, Rochester chemical engineers have demonstrated a ‘potassium-promotedcatalyst’s potential for use on an industrial scale. Now, the Navy’s quest to power its ships by converting seawater into fuel is nearer fruition.

University of Rochester chemical engineers—in collaboration with researchers at the Naval Research Laboratory, the University of Pittsburgh, and OxEon Energy—have demonstrated that a potassium-promoted molybdenum carbide catalyst efficiently and reliably converts carbon dioxide to carbon monoxide, a critical step in turning seawater into fuel.

Gulf of Aden, April 27, 2011- The Military Sealift Command fleet replenishment oiler USNS Joshua Humphreys (T-AO 188), left, refuels the amphibious assault ship USS Boxer (LHD 4) during a replenishment at sea. Boxer is underway supporting maritime security operations and theater security cooperation efforts in the U.S. 5th Fleet area of responsibility.

This is the first demonstration that this type of molybdenum carbide catalyst can be used on an industrial scale,” says Marc Porosoff, assistant professor in the Department of Chemical Engineering at Rochester. In a paper in the journal Energy & Environmental Science, the researchers describe an exhaustive series of experiments they conducted at molecular, laboratory, and pilot scales to document the catalyst’s suitability for scale-up.

If navy ships could create their own fuel from the seawater they travel through, they could remain in continuous operation. Other than a few nuclear-powered aircraft carriers and submarines, most navy ships must periodically align themselves alongside tanker ships to replenish their fuel oil, which can be difficult in rough weather.

In 2014, a Naval Research Laboratory team led by Heather Willauer announced it had used a catalytic converter to extract carbon dioxide and hydrogen from seawater and then converted the gases into liquid hydrocarbons at a 92 percent efficiency rate.

Since then, the focus has been on increasing the efficiency of the process and scaling it up to produce fuel in sufficient quantities.
The carbon dioxide extracted from seawater is extremely difficult to convert directly into liquid hydrocarbons with existing methods. So, it is necessary to first convert carbon dioxide into carbon monoxide via the reverse water-gas shift (RWGS) reaction. The carbon monoxide can then be converted into liquid hydrocarbons via Fischer-Tropsch synthesis.
Typically, catalysts for RWGS contain expensive precious metals and deactivate rapidly under reaction conditions. However, the potassium-modified molybdenum carbide catalyst is synthesized from low-cost components and did not show any signs of deactivation during continuous operation of the 10-day pilot-scale study. That’s why this demonstration of the molybdenum carbide catalyst is important.


How To Address Global Warming

Harvesting sunlight, researchers of the Center for Integrated Nanostructure Physics, within the Institute for Basic Science (IBS, South Korea) published in Materials Today a new strategy to transform carbon dioxide (CO2) into oxygen (O2) and pure carbon monoxide (CO) without side-products in water. This artificial photosynthesis method could bring new solutions to environmental pollution and global warming.

While, in green plants, photosynthesis fixes CO2 into sugars, the artificial photosynthesis reported in this study can convert CO2 into oxygen and pure CO as output. The latter can then be employed for a broad range of applications in electronics, semiconductor, pharmaceutical, and chemical industries. The key is to find the right high-performance photocatalyst to help the photosynthesis take place by absorbing light, convert CO2, and ensuring an efficient flow of electrons, which is essential for the entire system.

Titanium oxide (TiO2) is a well-known photocatalyst. It has already attracted significant attention in the fields of solar energy conversion and environmental protection due to its high reactivity, low toxicity, chemical stability, and low cost. While conventional TiO2 can absorb only UV light, the IBS research team reported previously two different types of blue-colored TiO2 (or “blue titania”) nanoparticles that could absorb visible light.

For the efficient artificial photosynthesis for the conversion of CO2 into oxygen and pure CO, IBS researchers aimed to improve the performance of these nanoparticles. The resulted  hybrid nanoparticles showed about 200 times higher performance than nanoparticles made of TiO2 alone and TiO2/WO3 without silver.


How To Neutralize Poisonous Carbon Monoxide

Scientists from the Nagoya Institute of Technology (NITech) in Japan have developed a sustainable method to neutralize carbon monoxide, the odorless poison produced by cars and home boilers.

Traditionally, carbon monoxide needs a noble metal – a rare and expensive ingredient – to convert into carbon dioxide and readily dissipate into the atmosphere. Although the noble metal ensures structural stability at a variety of temperatures, it’s a cost-prohibitive and finite resource and researchers have been anxious to find an alternative.

Now, a team led by Dr. Teruaki Fuchigami at the NITech has developed a raspberry-shaped nanoparticle capable of the same oxidation process that makes carbon monoxide gain an extra oxygen atom and lose its most potent toxicity.

Synthesis of cobalt oxide particles with complex, three-dimensional, raspberry-shaped nanostructures via hydrothermal treatment. Sodium sulfates functioned as bridging ligands to promote self-assembly and suppress particle growth. The highly ordered and complex surface nanostructure with 7-8 nm in diameter shows good structural stability and high activity in CO oxidation reaction.

We found that the raspberry-shaped particles achieve both high structural stability and high reactivity even in a single nanoscale surface structure,” said Dr. Fuchigami, an assistant professor in the Department of Life Science and Applied Chemistry at the NITech and first author on the paper.

The key, according to Dr. Fuchigami, is ensuring the particles are highly complex but organized. A single, simple particle can oxidize carbon monoxide, but it will naturally join with other simple particles. Those simple particles compact together and lose their oxidation abilities, especially as temperatures rise in an engine or boiler. Catalytic nanoparticles with single nano-scale and complex three-dimensional (3D) structures can achieve both high structural stability and high catalytic activity.

Th results were featured on the cover of the September issue of the journal, Nanomaterials.


Air Pollution Harms Your Brain And Your Intelligence

Chronic exposure to air pollution can cause harm to cognitive performance, a new study reveals. Researchers believe that the negative impact increases with age, and affects men with less education the worst. Over four years, the maths and verbal skills of some 20,000 people in China were monitored by the US-Chinese study.  Scientists believe the results have global relevance, with more than 80% of the world’s urban population breathing unsafe levels of air pollution.

The study was based on measurements of sulphur dioxide, nitrogen dioxide and particulates smaller than 10 micrometres in diameter where participants lived. It is not clear how much each of these three pollutants is to blame. Carbon monoxide, ozone and larger particulates were not included in the study. Described as an invisible killer, air pollution causes an estimated seven million premature deaths a year worldwide, according to the World Health Organization.

We provide evidence that the effect of air pollution on verbal tests becomes more pronounced as people age, especially for men and the less educated,” the study published  in the Proceedings of the National Academy of Sciences (PNAS) said.

Pollution also increases the risk of degenerative diseases such as Alzheimer’s and other forms of dementia, the study suggests. Exposure to high levels of polluted aircan cause everyone to reduce their level of education by one year…, which is huge,” one of the co-authors, Xi Chen of the Yale School of Public Health, told.

Previous studies found air pollution had a negative impact on students’ cognitive abilities. In this study, researchers tested people of both sexes aged 10 and above between 2010 and 2014, with 24 standardised maths questions and 34 word-recognition questions.