The role of methanol in large icy moons uncovered

Scientists led by the ESRF find that the volatile compound methanol in icy moons gets trapped in hydrates at high pressure and low temperature. This finding is crucial for understanding evolution of subsurface oceans and interpreting data delivered by current and future space missions. The results are out in Earth and Planetary Science Letters.

Icy moons orbiting Jupiter and Saturn are some of the most intriguing bodies in our Solar System, as several of them are known to host liquid oceans beneath their frozen surfaces. Besides the Earth, these are the only places in the Universe, where the presence of liquid water has been confirmed. Subsurface oceans are the prime targets in search for extraterrestrial life and are central to several ongoing and upcoming space missions. Already launched ESA’s JUICE and NASA’s Europa Clipper missions will start exploration of Jupiter’s moons Europa, Ganymede and Callisto in less than a decade, while NASA’s rotorcraft Dragonfly will start its journey to Saturn’s moon Titan in 2028.

One of the most striking features of these icy moons is the size of their hydrospheres. For example, the largest moon Ganymede is believed to have ~1000 km deep hydrosphere, resulting in pressures at its base that are around 17 times higher than in the Earth’s ocean. Such high pressures can cause crystallization of the oceans at the bottoms. While many organic volatile compounds are expected to be present in the interior of icy moons, their fate at high pressures remains poorly understood.

Methanol, CH3OH, is a volatile of particular interest due to due to its expected abundance and debated role in ocean crystallization. Typically, it is considered as a powerful antifreeze agent that inhibits formation of ice and hydrates and contributes to long-term survival of the subsurface oceans. However, recent studies suggested that in chemically complex environments and in presence of promoters, small amounts of methanol can be incorporated in hydrate structures at low temperatures.

Now scientists led by the ESRF and in collaboration with the Laboratory of Planetology and Geosciences in Nantes (France), the University of Washington – Seattle (USA) and the University of Bayreuth (Germany) and have studied the fate of methanol in large icy moons. The team used high-pressure, low temperature, in situ single crystal X-ray diffraction on beamline ID15b.

“Our experiments show that, at high pressure, large amounts of methanol can be stored in hydrates that serve as a storage of methanol over geological timescales”, explains Anna Pakhomova, lead author and scientist at the ESRF.

Read more on ESRF website

Conversion of carbon dioxide into raw materials more effective with gold

Carbon dioxide, emitted mainly by combustion of fossil fuels, is harmful to the climate and the main reason for increased global warming. Diverting carbon dioxide into hydrogen carriers or chemicals such as methanol, a valuable raw material and energy carrier, is thus highly desired. Supported metal nanoparticle heterogeneous catalysts such as copper on zinc oxide is used for the catalytic conversion of carbon dioxide to methanol. Researchers have now discovered that it is possible to avoid by-products and at the same time make the process more sustainable by adding a small amount of gold to the catalyst.

Carbon dioxide can be converted into methanol and water by reaction with hydrogen. The reaction is only possible in the presence of a catalytic material such as Au or Cu nanoparticles supported on zinc oxide. The chemical reaction will then take place on the particle surfaces. In a recent study, a research team from Germany, Japan and Sweden have shown that modifying the typical ZnO-supported Cu nanoparticles by a small amount of gold (< 10 weight percent) makes the reaction more selective.

Read more on MAX IV website

Building better catalysts to close the carbon dioxide loop

The best way to stave off the worst effects of climate change is to reduce CO2 emissions around the world. And one way to do that, says Zhongwei Chen, a professor in the Department of Chemical Engineering at the University of Waterloo, is to capture the CO2 and convert it into other useful chemicals, such as methanol and methane for fuels. Stopping emissions at the source, and further reducing future ones by replacing CO2-producing fuels with cleaner ones “…is a way to close the circle,” Chen says.

In order to turn CO2 into methanol, you need a catalyst to jump-start the electrochemical reaction. Traditionally, these catalysts have either been made out of precious metals like gold or palladium, or base metals like copper or tin. However, they are expensive and break down easily, hindering large-scale implementation. “Right now we can’t meet industrial requirements,” says Chen, who holds a Canada Research Chair. “So we are trying to design catalysts with better activity, selectivity, and durability.”

Read more on the CLS website

Image: Chithra Karunakaran on the SM beamline at the Canadian Light Source

Credit: David Stobbe

Reaction insights help make sustainable liquid fuels

Methanol, produced from carbon dioxide in the air, can be used to make carbon neutral fuels. But to do this, the mechanism by which methanol is turned into liquid hydrocarbons must be better understood so that the catalytic process can be optimised. Now, using sophisticated analytical techniques, researchers from ETH Zürich and Paul Scherrer Institute have gained unprecedented insight into this complex mechanism.

As we struggle to juggle the impact of emissions with our desire to maintain our energy hungry lifestyle, using carbon dioxide in the atmosphere to create new fuels is an exciting, carbon neutral alternative. One way to do this is to create methanol from carbon dioxide in the air, using a process called hydrogenation. This methanol can then be converted into hydrocarbons. Although these are then burnt, releasing carbon dioxide, this is balanced by carbon dioxide captured to make the fuel.

To fully develop this sustainable fuel, a deeper understanding of the mechanism by which methanol – in a reaction catalysed by zeolites, solid materials with unique porous architectures – is turned into long chain hydrocarbons, is necessary. With this in mind, in the frame of NCCR Catalysis, a Swiss National Center of Competence in Research, researchers from ETH Zürich joined forces with researchers from the Paul Scherrer Institut PSI to reveal the details of this reaction mechanism, the findings of which are published in the journal Nature Catalysis.

“Information is key to developing more selective and stable catalysts,” explains Javier Pérez-Ramírez, Professor of Catalysis Engineering at ETH Zürich and director of NCCR Catalysis, who co-led the study. “Prior to our study, despite many efforts, key mechanistic aspects of the complex transformation of methanol into hydrocarbons were not well understood”.

The researchers were interested in comparing the methanol to hydrocarbon process with another process: that of turning methyl chloride into hydrocarbons. Oil refineries frequently burn large quantities of unwanted methane rich natural gas. This polluting and wasteful activity results in the typical flares associated with oil refineries. “Turning methyl chloride into hydrocarbons is a kind of bridge technology,” explains Pérez-Ramírez. “Of course, we would like to move away from fossil fuels but in the meantime this would be a way to avoid wasting the vast reserves of valuable methane”.

Read more on the PSI website

Image: Researchers (L to R) Javier Pérez-Ramírez, András Bödi and Patrck Hemberger at the Swiss Light Source SLS

Credit: Paul Scherrer Institute / Markus Fischer