A frustrated solution

The conversion of carbon dioxide into methanol has been achieved by a metal-free homogeneous process.

Credit: © 2009 Wiley

The transformation of carbon dioxide into useful chemicals, such as fuels and chemical feedstocks, is an important challenge in the battle to combat climate change. Methanol represents a useful end product to the reduction of carbon dioxide because it is a precursor to many organic chemicals and also a fuel that can be stored and transported easily. Metal oxide catalysts have been reported for this process, but these often give unwanted products such as methane and carbon monoxide.

Now, Dermot O'Hare, Andrew Ashley and Amber Thompson at the University of Oxford have developed¹ a metal-free homogeneous process for the conversion of carbon dioxide into methanol. They achieved this by heating an equimolar mixture of a Lewis acid and a Lewis base with carbon dioxide and dihydrogen. A sterically hindered piperidine and an arylborane were chosen as they form a 'frustrated Lewis pair' in which the steric hindrance around the donor and acceptor atoms prevents a strong donor–acceptor interaction. When heated in the presence of this frustrated Lewis pair, heterolytic fission of dihydrogen occurs, forming an intermediate salt that can react with carbon dioxide to give methanol.

The researchers hope to further develop this process so it is catalytic. This would be a step along the way towards a scaleable process for converting this greenhouse gas into a renewable resource.