AutoSorb-iQ-C: a unique chemisorption analyser for Catalyst Characterisation

The AutoSorb-iQ-C offers a unique series of options, which allow a very wide range of chemisorption analyses for catalyst analysis. Based on the iQ-MP micropore analyser, it retains all of the physisorption measurement functions necessary for detailed surface area and porosity analysis. The additional functions depend on the specific version, as described below:

AutoSorb-iQ-C base system for dynamic pretreatments and static chemisorption.

When used in its flowing mode, the AutoSorb-iQ-C makes it possible to perform dynamic oxidation, reduction or desorption preparations at temperatures up to 1100°C, to prepare the sample for high resolution static chemisorption measurement.

A typical static chemisorption measurement might involve:

• an initial degassing of the sample with a flow of dry inert gas, to remove adsorbed moisture and other impurities,
• followed by reduction using a flow of hydrogen (often diluted in Argon, or another inert gas, which simplifies the handling and safety, compared to use of large quantities of pure hydrogen).
• Finally, after cooling under a flow of inert gas,
• and vacuum degassing,
• a static manometric measurement of isothermal oxygen adsorption is performed, and then repeated.

The first isotherm shows the strong chemisorption of oxygen to metallic sites, plus some weak chemisorption and physisorption to non-reactive surface. The second isotherm shows only the weak chemi- plus physisorption. The difference between the two isotherms quantifies the strong chemisorption. This method is called the Bracketing or Dual Isotherm method.

Other methods of quantification include:

• Extrapolation to zero pressure, to separate physisorption from chemisorption.
• Langmuir isotherm fitting,
• and the related Temkin isotherm and Freundlich isotherm methods.

AutoSorb-iQ-C/TCD: Temperature programmed analysis

The AutoSorb-iQ-C/TCD integrates a sensitive, chemically-resistant Thermal Conductivity sensor, which allows the experimenter to exploit the precise temperature ramping of the Autosorb furnace for a wide range of Temperature Programmed Experiments, such as TPO, TPR, TPD.

For additional flexibility, an integrated cold-trap allows selective removal of unwanted components from the effluent stream, for improved linearity and sensitivity in some reactions. For example, in the reaction:
        M + N₂O → MO + N₂
the removal of un-reacted N₂O simplifies detection of the product N₂.

AutoSorb-iQ-C/TCD-Pulse: Pulse titration of metal surface area

The TCD sensor is not only useful for measurements at varying temperature. Pulse titration involves using a series of constant-volume pulses of reagent gas at fixed temperature, which makes it possible to titrate the quantity of gas required to fully react with the activated surface.

Peak area integration allows precise quantification of the amount of gas irreversibly adsorbed by the active sites of the sample. Pulse titration is an interesting alternative to static chemisorption method.

AutoSorb-iQ-C/TCD/MS: Mass spectrometric analysis of reaction products (TPx-MS, etc.)

Addition of a mass spectrometer allows the measurement of reaction products in the effluent stream.

If any of these techniques is of interest, then we would be delighted to discuss your application with you.

For brochures, detailed specifications or pricing information, please contact us via our webform, or by telephone at the number below.