Abstract
A set of three commercial zeolites (13X, 5A, and 4A) of two distinct shapes have been characterized: (i) pure zeolite powders and (ii) extruded spherical beads composed of pure zeolite powders and an unknown amount of binder used during their preparation process. The coupling of gas porosimetry experiments using argon at 87 K and CO2 at 273 K allowed determining both the amount of the binder and its effect on adsorption properties. It was evidenced that the beads contain approximately 25 wt% of binder. Moreover, from CO2 adsorption experiments at 273 K, it could be inferred that the binder present in both 13X and 5A zeolites does not interact with the probe molecule. However, for the 4A zeolite, pore filling pressures were shifted and strong interaction with CO2 was observed leading to irreversible adsorption of the probe. These results have been compared to XRD, IR spectroscopy, and ICP-AES analysis. The effect of the binder in shaped zeolite bodies can thus have a crucial impact on applications in adsorption and catalysis.
Highlights
Zeolites are porous materials that have been widely used in industrial applications of adsorption and catalysis for more than 60 years [1]
A control protocol based on gas porosimetry is proposed to assess the shaping effect on adsorption properties in shaped zeolites
The comparison of the adsorption of an inert probe molecule such as argon on powdered and shaped samples allows quantifying the amount of binder and its effect on structural properties for adsorbents with a pore size greater than 4.5 Å
Summary
Zeolites are porous materials that have been widely used in industrial applications of adsorption (gas or liquid) and catalysis for more than 60 years [1]. Chen et al [11] studied the impact of the interactions between a silica binder and a NaY zeolite using XRD, Transmission Electron Microscopy (TEM), and Fourier Transform Infrared (FTIR) spectroscopy techniques, regarding both the structure and the surface effects. They observed that the interactions between the zeolite and the binder, combined with the dealumination of the framework, leads to a decrease in crystal size and crystallinity, and an increase of Si/Al ratio, hydrophobicity, and thermal stability. Emission Spectroscopy (ICP-AES) analysis, not to identify the binder but rather to assess the protocol
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