Progress made in developing ‘greener’ fertilizer

Scientists have reported a breakthrough in developing a ‘greener’ ammonia fertilizer which could have huge benefits for the environment and the future of agriculture.

Ammonia is one of the world’s largest chemical markets, but it requires a lot of energy to produce and contributes to 1% of all carbon dioxide emissions. There have also been reports of the chemical being harmful to the environment and contributing to air pollution.

Now researchers from the University of California, Berkeley, have developed a more energy efficient way of producing the chemical.

The process typically takes place at around 300°C-500°C, before the ammonia is removed by cooling the gas to -20°C to turn it into a liquid, all of which is powered by fossil fuels.

The UC Berkeley chemists have designed porous materials which bind and release ammonia at more moderate pressures and temperatures of around 175°C.

This opens up opportunities for smaller facilities closer to farmers replicating the process, rather than it being relegated to large, centralised chemical plants.

‘The dream here would be enabling a technology where a farmer in some economically disadvantaged area of the world now has much more ready access to the ammonia that they need to grow their crops,’ said Benjamin Snyder, a postdoctoral fellow who led the research. ‘To be clear, our material hasn’t gone and solved that problem outright. But we’ve put forward a new way of thinking about how you can use metal-organic frameworks in the context of ammonia capture for a modified Haber-Bosch process. I think this study represents a really important conceptual advance in that direction.’

Researchers have hopes the process could be replicated with other useful industrial molecules that have affinity for binding metals.

Snyder emphasized that ammonia capture is just one part of any modified process to make greener ammonia, which is still a work in progress.

‘There are lots of smart people thinking about catalyst and reactor design for a modified Haber Bosch process that’s designed to operate under more moderate temperatures and pressures,’ he said. ‘Where we come in is, after you’ve made the ammonia, our materials are what you would try to use to separate and capture the ammonia under these new reaction conditions.’

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