(275d) Total Reflux Dual Piston-PSA: a Novel Apparatus for Testing Adsorbent Materials

The Dual Piston-Pressure Swing Adsorption apparatus is a unique system suited to test novel materials for their efficiency in separating a binary mixture. The equipment can be assimilated to a distillation column with total reflux and allows the direct measurement of the maximum separation achievable with the material. The unique advantage of having two pistons is that, during the experiment, the binary mixture is separated with the strongly adsorbing component accumulating in one piston, while the weakly adsorbing one is collected on the other side. The small amount of solid material (a few grams) required together with the possibility of fast cycle times (down to 1 Hz) allow the rapid testing of the material in various configurations. The system is therefore particularly suitable to measure kinetic and equilibrium properties of novel adsorbent materials. As an example, we extensively tested materials for the separation of carbon dioxide from a binary mixture with nitrogen. We will describe the automation of the set up and its control by a real time computer with a Labview interface. The control system allows setting the piston movement to near sinusoidal, thus allowing both linear and non-linear frequency response experiments to be carried out in sequence. The variable operation conditions available include different pistons configurations (stroke lengths, phase angle and cycle shapes), different starting pressures (0.1 bar to 20 bar) and temperatures (20°C to 200°C). We present also the modelling and simulation work that is needed to interpret the experiments. Our suite of adsorption simulation tools has been applied to the DP-PSA system at total reflux to allow full non-linear parameter estimation and model selection.