Reducing carbon emissions from roads, railways and shipping requires the simultaneous implementation of a range of solutions. When it comes to cars, reducing the number of journeys (by making it easier to walk and cycle and improving public transport), changing fuel in vehicles and upgrading vehicles already in circulation must all play a part. part. None of these solutions is sufficient on its own.
In 2030, the sale of new diesel and petrol passenger cars will be banned in the UK. The future of the passenger car will be electric. But recent parts supply issues and the high carbon cost of manufacturing electric vehicles could delay the climate benefits of this transition.
To get the most out of existing gasoline and diesel vehicles – and the carbon that has been invested in creating them – drivers and manufacturers can reduce emissions of a family of compounds called nitrogen oxides, which are linked to disease. breathing, thanks to better treatment of exhaust gases. fumes. This way, the communities most affected by air pollution can at least be protected before harmful vehicle emissions are finally eradicated.
My research team is developing a new generation of catalytic converters, these devices mounted on exhaust pipes to reduce the release of toxic gases. Inspired by the chemistry observed on the surface of extremely hot planets like Venus, we produced a synthetic material that could improve air quality.
From Venus to vehicle exhausts
Sunlight destroys carbon dioxide (CO₂) in the atmospheres of planets, producing carbon monoxide (CO). Not fast enough to avoid climate change, but fast enough that atmospheres like Venus contain far more CO than we observe there.
Our group studies the effects of meteoric matter (dust arriving from space) in atmospheres. An iron silicate powder we made that replicates this dust can accelerate the conversion of CO to CO₂. This is what the first car catalytic converters were designed for, because CO is a toxic gas.
This led us to wonder if this material could help solve other problems, such as nitrogen oxide pollution, which exceeds legal limits in the air of many UK cities. Poor air quality from vehicle exhaust costs tens of thousands of lives each year.
We have found that not only can the powder clean CO and nitrogen oxide emissions simultaneously, but it can convert nitrogen dioxide (NO₂, a specifically regulated harmful gas) into harmless molecular nitrogen (N₂) and water at room temperature.
The nitrogen oxide (NOx) treatment catalysts installed in modern diesel vehicles only work at exhaust temperatures above 150°C. Even if your car uses a fluid additive to reduce nitrogen oxide emissions, it is unlikely to work while driving slowly when the exhaust is colder. This is when vehicles emit the most NO₂ – often in traffic jams where the most polluted air can accumulate.
When the power grid is decarbonized and robust enough to charge millions of electric vehicles, catalytic converters capable of removing nitrogen oxides can still be important. For example, natural gas fuel for industrial furnaces will probably be replaced by hydrogen.
Unlike hydrogen-powered buses and cars, which produce energy via a reaction in a fuel cell, larger applications such as furnaces in steel mills will burn hydrogen directly. This high temperature combustion will transform the molecular nitrogen in the air into nitrogen oxide pollution, which must be eliminated.
Read more: Hydrogen: where is the most useful low-carbon fuel for decarbonization?
That’s why we’re excited to develop a prototype emissions converter that can work in most situations, with the potential to drastically reduce toxic emissions from combustion engines and other sources in the future.