Selective CO2 hydrogenation into methanol in a supercritical flow process
Methanol plays a crucial role in the novel cycle of carbon capture, recycling and valorisation of anthropogenic carbon dioxide (CO2). Even though hydrogenation of CO2 to methanol has favourable thermodynamics, catalyst and processes development is needed for improving stability, reaction rate and selectivity to higher values than of the currently used copper oxide on zinc oxide (CuO/ZnO) catalysts. Here we report an efficient supercritical flow process for the selective valorisation of CO2 into methanol. At optimized conditions, rhenium oxide on titanium dioxide (ReOx/TiO2) catalyst converts CO2 into methanol with 98% selectivity and at 18% CO2 conversion rate at 200 °C, 100 bar and CO2/H2 ratio of 1/4. A higher conversion of 41% can be achieved at 250 °C, but the selectivity towards methanol decreases to 64%. This strategy has enabled the development of an efficient high-pressure flow process without compromising methanol selectivity.