The team heated a mixture of CO2 and benzene with the catalyst to a temperature of 150 ºC, at about three times atmospheric pressure. In a first step, the catalyst enabled the CO2 to form a reactive carbamate, like that made in plants. The catalyst's next useful step was to enable the benzene molecules to grab the oxygen atom from the CO2 in the carbamate, producing phenol and a reactive carbon monoxide (CO) species.
The Max Planck technique has only been demonstrated on a small scale and it has a low yield of 20%, he points out. "But it looks quite promising," he adds. "The catalyst can be made cheaply and it works at a relatively low temperature."
The products of the technique are well suited to making drugs or herbicides, says Wood, "so hopefully they can improve the efficiency and scale it up."