Valve for carrying out a mass transfer process

The invention relates to a valve for carrying out a mass transfer process, gas (13) flowing through a liquid (31) that is present on an upper plate (21), the liquid (31) flowing into a sluice (17) below the plate (21) when the gas supply is disrupted and the liquid (31) flowing off from the sluice (17) through a lower plate (19) delimiting the sluice (17) in a downward direction once the gas supply is re-established. The valve (1) comprises a closing element (5) which has a piston rod (5), an upper valve disk (9) and a lower valve disk (7) and is guided in a sleeve (3), the lower valve disk (7), in a first valve position, closing an opening (43) on the lower end of the sleeve (3). The upper valve disk (9) and the lower valve disk (7) are each movably connected to the piston rod (11).