Science

Methane converted into methanol at room temperature – just add light

An artist's impression of the MOF catalyst converting methane into methanol, with the help of sunlight
ORNL/Jill Hemman
An artist's impression of the MOF catalyst converting methane into methanol, with the help of sunlight
ORNL/Jill Hemman

Scientists have developed an efficient new way to convert methane into methanol at room temperature. The technique could help reduce greenhouse gas emissions and provide a cleaner way to make key products.

While carbon dioxide gets most of the attention, it’s not the only greenhouse gas changing the Earth’s climate. Methane is emitted in smaller amounts but is 34 times more potent, so reducing its levels remains a priority. Excess methane from industrial processes is often burned off, but that produces CO2.

A commonly sought alternative is to convert methane into methanol, which can be used to make a range of products like fuels, plastics and construction materials. The problem is, the conversion process usually requires high temperatures and pressures, which makes it energy-intensive.

In recent years, scientists have been experimenting with new catalysts that show promise in converting methane into methanol at room temperature and ambient pressure, including a titanium and copper catalyst and ways to improve iron zeolite crystals.

For the new study, researchers at the University of Manchester and Oak Ridge National Laboratory developed a new technique using a metal-organic framework (MOF) as a catalyst. These structures are extremely porous, and in this case those pores contain a variety of components that each play a role in the catalytic process.

First, methane and oxygen are mixed into water, which is then continuously flowed through the MOF granules. Exposing the MOF to sunlight triggers a chemical reaction that converts the gaseous methane into liquid methanol, which can then be easily extracted from the water.

The main thing that makes this particular conversion so tricky is breaking the carbon-hydrogen bond in methane in order to insert an oxygen atom to form a new bond and make methanol. In this case, the components held in the MOF absorb the light and generate electrons, which are then passed on to the oxygen and methane flowing through, causing them to combine to form methanol.

In tests, the solid catalyst was able to work efficiently, and could be washed and reused at least 10 times, for a minimum of 200 hours of reaction time. With further refinement, the technique could help reduce methane emissions, as well as the environmental footprint of methanol production.

"This process has been termed the 'holy grail of catalysis’,” said Martin Schröder, corresponding author of the study. “Instead of burning methane, it may now be possible to convert the gas directly to methanol, a high-value chemical that can be used to produce biofuels, solvents, pesticides and fuel additives for vehicles. This new MOF material may also be capable of facilitating other types of chemical reactions by serving as a sort of test tube in which we can combine different substances to see how they react."

The research was published in the journal Nature Materials.

Source: Oak Ridge National Lab via Phys.org

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6 comments
TechGazer
Doesn't oxidizing methane into methanol release energy, meaning that you are lowering the energy value of the material, and thus not a good idea for producing fuels? The new process would be useful for products that need that extra oxygen atom. Except for applications that absolutely need a liquid fuel, it might be better for the world if we encouraged electric storage rather than trying to continue 'the old way of carrying energy around energy'.

I wonder what a proper evaluation of total energy transfer would show between converting methane to methanol and using it as a fuel, vs converting the methane to electricity and using storage cells.
jerryd
How does one mix methane, O2 in water at atmospheric pressure? And where does the O2 come from?
DJ's "Feed Me Doggie"
Next, we try the chili to produce gas, OK?
Malcolm Jacks
Great Stuff,
Larry W
Holy Grails are usually pipe dreams. But promising if they can get the catalyst more stable than 10 cycles and at low cost to produce. If the catalyst is too expensive like being made from gold, platinum or palladium or something then forget it.
drzarkov99
Making methanol more affordable would make methanol fuel cells more available, with a much more energy dense hydrogen storage medium. Cleaner internal combustion engines can run on methanol as well, so this could be a promising development, with a useful product as opposed to the waste involved in methane flaring.