Dynamic Gas and Vapour Phase adsorption

    • Gas phase adsorption breakthrough setup

      Brand/Model: in-house developed

      Breakthrough experiments are performed to study the separation of gases in different operating conditions. A column packed with pellets of the desired material is placed in a ventilated oven. A valve is used to switch the gas stream flowing through the column from pure Helium (or another inert gas) to a desired adsorbate mixture containing various gases (CO2, N2, CH4, H2 …). Gas flows are regulated with mass flow controllers (MFCs). The gas flow at the outlet of the column is measured online by means of a mass spectrometer (MS), so the separation can be followed in-situ. From these signals amount adsorbed and a separation factor can be calculated.

      Technical specifications:
      Temperature range: 293K to 673K
      Pressure range: 1 to 30 bar
      Flow rate range: 0 to 50 Nml/min
      1 inlet for regeneration gas
      2 inlets for adsorbate gases

      Experiment examples:
      Via this equipment CO2/CH4 separation characteristics were investigated in great detail on the metal-organic framework (MOF), amino-MIL-53. Separation in function of temperature, pressure and composition was carried out, in order to have a better view on the separation behaviour of that metal-organic framework.


    • Vapour phase adsorption breakthrough

      Brand/Model: in-house developed

      Two mass flow controllers (Bronkhorst) control the flows of helium to the two evaporators. The evaporators are filled with liquid adsorbate (e;g. ethylbenzene and styrene, respectively) and are each maintained at the desired temperature using a separate temperature control apparatus from Julabo. The helium flow is used as an inert carrier gas and takes an amount of adsorbate with it, governed by the vapor-liquid equilibrium of the adsorbate. The mixture can be diluted with additional helium just after the evaporators using a third mass flow controller. Using a multi position valve either the mixture or a pure helium flow coming from a fourth mass flow controller) can be sent through the column packed with adsorbent. The column is placed in an oven to maintain at a desired temperature during the measurements and to perform the thermal regeneration of the column. After passing through the column, the vapour is analyzed by a gas chromatograph (GC-FID) with an automatic sampling valve. The sample taken by this valve has a volume of 0,500ml. A method to perform the separation of a mixture of styrene and ethylbenzene in less than one minute has been developed.

      Technical specifications:
      Flow rate of MFCs at evaporators: 0-90 Nml/min
      Flow rate of dilutor MFC: 0-360 Nml/min
      Flow rate of fourth MFC: 0-180 Nml/min
      Temperature range oven: 30-250°C
      Max pressure: 3 bar

      Experiment examples:
      separation of C8 compounds (ethylbenzene, styrene, and xylene)


  • Binary gas phase adsorption

    Brand/Model: Magnetic suspension balance from Rubotherm.

    This gravimetric device can measure static and dynamic single component as well as multi-component isotherms (static) from gases. For single component isotherms, measurements are quite straight forward. A certain pressure is introduced to the sample holder containing ± 0.2 gram. The balance records the weight as it changes by increasing or decreasing pressure. From this recorded weight, the amount adsorbed is calculated. This can be done in either static or dynamic conditions. As for multi-component isotherms, an accompanying GC is necessary. 2 inlets can be used for the multi-component measurement.
    A known amount of a mixture, determined by the GC,is introduced to the sample holder. Weight is recorded as the material adsorbs certain gases from the mixture. After equilibrium is reached, the remaining gas phase is analyzed by the GC in order to determine what component was adsorbed. After measurement the sample can be regenerated by heat, vacuum or under inert gas flow.

    Technical specifications:
    Temperature range (isotherm): 293K to 423K
    Temperature range (activation): 293K to 673K
    Pressure range: 0 to 40 bar.
    Flow range: 0 to 500 ml/min (depending on the gas)

    Experiment examples:
    As this device is brand new, only single-component isotherms of CO2 en CH4 were measured on the MOF Amino-MIL-53.