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Quantachrome Instruments has introduced the Asiqwin v2 software to complement the ultra-low pressure range XR version of its Autosorb-IQ gas sorption analyser.

The Asiqwin v2 software includes six new pore size calculation models based on microscopic density functional theory (DFT) to bring the library up to a total of 22.

The Quenched Solid DFT (QSDFT) kernels are applicable to micro-mesoporous carbons of various types, including structures derived from hard and soft templates, and those having complex pore networks, plus a variety of pore geometries (slit, cylindrical and spherical), covering pore sizes up to 50nm.

The entire DFT library encompasses other adsorbent types, such as zeolites and silicas, a variety of adsorbates (N2, Ar and CO2), temperatures, plus specific (different) models for adsorption data and desorption data.

Quantachrome said the comprehensive nature of this calculation module ensures its applicability to a range of traditional and start-of-the-art porous materials.

The software also includes an intelligent ‘wizard’ to automatically select those data points to be used in the so-called BET surface area calculation, ensuring proper exclusion of measured data points that lie at too high a relative pressure for accurate micropore surface area measurements.

The company claimed that this represents the first known commercial software implementation of the strategy for specific surface area determination of microporous materials as described in the BET surface area standard ISO 9277:2010 (Annex C).

Manual selection of BET data points is also enhanced – by the inclusion of a user-friendly graphical point selector, tagging of such points in a tabular format is no longer necessary.

To support extra-long analysis times that are sometimes unavoidable when measuring fully equilibrated (in other words, accurate) micro-mesopore analyses, the user can now opt to have the Autosorb-IQ automatically re-measure the system’s effective void volume (otherwise known as dead space or free space) during the analysis to account for subtle temperature changes that can occur over tens of hours.

This feature is implemented without the need to access the sample cell volume directly (in other words, neither adsorbate nor helium is added/subtracted from the sample cell in order to make the adjustment), without software-only calculation of intermediate temperature zones, without adjusting coolant level, and without enlarging the cold zone.

This is said to ensure high sensitivity.

In addition, the new capability works not only for liquid nitrogen but also for other cryogens at other temperatures, and without any additional hardware.

An incorrect void volume impacts the quality of sorption isotherms, and so some means of minimising it, controlling it and/or correcting it are essential in order to obtain the best results.

Users of the chemisorption-enabled model, the Autosorb-IQ-C and C-XR equipped with a TCD for flow-based measurements, can now mix and match static manometric analyses (in other words, pressure-based adsorption isotherms) with TPR/TPO/TPD and pulse titration measurements.

This enhancement will be of particular interest for scientists researching heterogeneous catalysts.

The software and measurement features will be available on all newly ordered Autosorb-IQ instruments as standard, and will shortly be available to existing users as upgrade packages.

Quantachrome Instruments

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