Advantages of dynamic sorption methods

The dynamic sorption method is an unique technique to investigate a lot of valuable properties of adsorbent materials. From a practical point of view not only pure component isotherms should be known, also cycle stability, long time stability, competitive adsorption, and the kinetic are important properties for the choice of an optimal adsorbent. These properties are often difficult to access with static methods and in some cases the results can not easily transferred to an industrial scale. Especially kinetic data from static experiments suffer from poor transmissibility to industrial separation processes, because of different macroscopic conditions (i.e. pressure, presence of other components etc.).

Why is the determination of sorption characteristic with dynamic methods so important?

  • Most industrial separation processes by adsorption work under dynamic conditions
  • Different Kinetics of guest molecules can be play a key-role during separation
  • In industrial separation and purification tasks always gas mixtures are present
  • In most cases, the adsorbent is arranged as a fixed bed and a gas mixture is forced through it.

Based on this points it can be figured out, that the knowledge of selectivity, kinetic and the dynamic of heat generation and -release is very important for choice of an adsorbent and for process design.

In industrial gas separation or gas cleaning processes often the product requirements of the effluent gas is given in form of a required purity. Due to the interplay of macroscopic conditions like gas velocity, concentration of impurities or feed temperature and phyiscal properties like co-adsorption, kinetics, and heat effects, an estimation of the usable sorption capacity based on pure component isotherms is not always possible. Usually, this sorption capacity is much lower than the equilibrium loading of the pure components. In such cases the determination of breakthrough curves under downscaled process conditions gives a valuable insight into the performance of the adsorbents. Considering these points, the dynamic sorption method is further beneficial for:

 

  • Downscaling of industrial processes
  • Investigation of adsorbents under relevant gas velocities
  • Investigation of cycle stability of materials
  • Determination of optimal regeneration conditions.

A reliable statement of the usuable sorption capacity under process relevant contitions is only possible by breakthrough experiments.