metal organic framework

Capturing hot carbon dioxide

December 13, 2024 By EarthWise Leave a Comment

Decarbonizing industries like steel and cement is a difficult challenge. Both involve emitting large amounts of carbon dioxide both from burning fossil fuels and from intrinsic chemical reactions taking place. A potential solution is to capture the carbon dioxide emissions and either use them or store them away. But this sort of carbon capture is not easy and can be quite expensive.

The most common method for capturing carbon dioxide emissions from industrial plants uses chemicals called liquid amines which absorb the gas. But the chemical reaction by which this occurs only works well at temperatures between 100 and 140 degrees Fahrenheit. Cement manufacturing and steelmaking plants produce exhaust that exceeds 400 degrees and other industrial processes produce exhaust as hot as 930 degrees.

Costly infrastructure is necessary to cool down these exhaust streams so that amine-based carbon capture technology can work.

Chemists at the University of California, Berkeley, have developed a porous material – a type of metal-organic framework – that can act like a sponge to capture CO2 at temperatures close to those of many industrial exhaust streams. The molecular metal hydride structures have demonstrated rapid, reversible, high-capacity capture of carbon dioxide that can be accomplished at high temperatures.

Removing carbon dioxide from industrial and power plant emissions is a key strategy for reducing greenhouse gases that are warming the Earth and altering the global climate. The captured CO2 can be used to produce value-added chemicals or can be stored underground or chemically-reacted into stable substances.

**********

Web Links

Breakthrough in capturing ‘hot’ CO2 from industrial exhaust

Photo, posted March 3, 2010, courtesy of Eli Duke via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

A better way to produce green hydrogen

September 9, 2024 By EarthWise Leave a Comment

Hydrogen has great potential as a fuel and an energy carrier for many applications. Burning it or consuming it in fuel cells does not produce carbon emissions. As a result, there has long been the vision for a future hydrogen economy. Whether the hydrogen economy would ever come about given how various other technologies have evolved over time is questionable. But regardless, hydrogen is valuable for many industrial and commercial applications including the manufacture of ammonia and the refining of metals.

Hydrogen is produced in industrial quantities from natural gas by a carbon-dioxide-producing process known as methane-steam reforming. To take its place as a green energy source, hydrogen needs to be produced by splitting water into its constituent oxygen and hydrogen components by the process of electrolysis.

The problem is economic. Methane-steam reforming produces hydrogen at a cost of about $1.50 per kilogram. Green hydrogen costs about $5 a kilogram.

Researchers at Oregon State University have developed a new photocatalyst that enables the high-speed, high-efficiency production of hydrogen. The material, called RTTA, is a metal organic framework containing ruthenium oxide and titanium oxide. Ruthenium oxide is expensive, but very little is needed. For industrial applications, if the catalyst shows good stability and reproducibility, the cost of the small amount of this exotic material becomes less important.

The photocatalyst, when exposed to sunlight, quickly and efficiently splits water yielding hydrogen. The Oregon State discovery has real potential.

**********

Web Links

Oregon State University research uncovers better way to produce green hydrogen

Photo, posted July 7, 2023, courtesy of Bill Abbott via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Generating Hydrogen From Poor-Quality Water | Earth Wise

September 8, 2020 By EarthWise Leave a Comment

Hydrogen could be the basis of a complete energy system. It could be stored and transported and could be used to power vehicles and to generate electricity in power plants. Proponents of the so-called hydrogen economy contend that hydrogen is the best solution to the global energy challenge. But among the challenges faced by a hydrogen economy is the development of an efficient and green method to produce hydrogen.

The primary carbon-free method of producing hydrogen is to break down water into its constituent elements – hydrogen and oxygen. This can be done in a number of ways, notably by using electricity in a process called electrolysis. A method that seems particularly attractive is to use sunlight as the energy source that breaks down the water molecule.

While there is an abundance of water on our planet, only some of it is suitable for people to drink and consume in other ways. Much of the accessible water on earth is salty or polluted. So, a technique to obtain hydrogen from water ideally should work with water that is otherwise of little use to people.

Researchers in Russia and the Czech Republic have recently developed a new material that efficiently generates hydrogen molecules by exposing water – even saltwater or polluted water – to sunlight.

The new material is a three-layer structure composed of a thin film of gold, an ultra-thin layer of platinum, and a metal-organic framework or MOF of chromium compounds and organic molecules. The MOF layer acts as a filter that gets rid of impurities.

Experiments have demonstrated that 100 square centimeters of the material can generate half a liter of hydrogen in an hour. The researchers continue to improve the material and increase its efficiency over a broad range of the solar spectrum.

**********

Web Links

New Material Can Generate Hydrogen from Salt and Polluted Water

Photo courtesy of Tomsk Polytechnic University.

Earth Wise is a production of WAMC Northeast Public Radio.