Carbon dioxide dissociation in a microwave plasma reactor operating in a wide pressure range and different gas inlet configurations

•CO2 MW dishcarge operating in a wide pressure range (200 mbar–1 bar) is presented.•Different gas flow configurations are explored: a direct, reverse and a vortex one.•CO2 conversion and energy efficiency drop almost linearly with increasing pressure.•The highest conversion of 73% was achieved at energy efficiency of 12%.•The highest energy efficiency of 25% was achieved with the conversion of 20%.