Adsorption and Diffusion in HZSM-5 Zeolite Studied by an Oscillating Microbalance

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Title:Adsorption and Diffusion in HZSM-5 Zeolite Studied by an Oscillating Microbalance
Creators:
Rebo, Hans P.
Chen, De
Brownrigg, Marit S. A.
Moljord, Kjell
Holmen, Anders
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 62, 12, pp. 1832-1842
Uncontrolled Keywords:Oscillating microbalance, Diffusion, Adsorption, Zeolites

Abstract

A novel microbalance technique has been used to study diffusion and adsorption in a commercial HZSM-5 zeolite. This new technique uses an inertial microbalance TEOM (Tapered Element Oscillating Microbalance) to measure mass changes in the zeolite bed. Time resolution as short as 0.1 s, a flow-through design where all the probe molecules see the zeolite bed and high sensitivity allowing zeolite loadings down to a few milligrams are the three most important properties of the TEOM. The probe molecules studied were <i>o</i>-xylene, <i>p</i>-xylene and toluene which were introduced at 303, 373 or 473 K and at partial pressures in the range of 0.2-10 kPa. The inverse characteristic uptakes (<i>D/L</i><sup>2</sup>), corrected (<i>D</i><sub>0</sub>/<i>L</i><sup>2</sup>) and steady-state (<i>D</i><sub>ss</sub>/<i>L</i><sup>2</sup>) diffusion times are reported. The thermodynamic correction used for <i>D</i><sub>0</sub>/<i>L</i><sup>2</sup> calculations almost eliminated the concentration dependence of the diffusivities. The <i>D</i><sub>ss</sub>/<i>L</i><sup>2</sup> values were found to be rather unaffected by both temperature (373-473 K) and concentration, suggesting a certain degree of unification for diffusivities. <i>o</i>-Xylene uptake rates in the TEOM were found to be significantly higher than in a gravimetric microbalance under identical conditions, probably as a result of additional mass transfer resistance other than intracrystalline diffusion caused by poor contact between the gas phase and the zeolite in a conventional gravimetric microbalance.

Title:Adsorption and Diffusion in HZSM-5 Zeolite Studied by an Oscillating Microbalance
Creators:
Rebo, Hans P.
Chen, De
Brownrigg, Marit S. A.
Moljord, Kjell
Holmen, Anders
Uncontrolled Keywords:Oscillating microbalance, Diffusion, Adsorption, Zeolites
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:62
Number:12
Page Range:pp. 1832-1842
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19971832UNSPECIFIED
ID Code:1257
Item Type:Article
Deposited On:06 Feb 2009 17:08
Last Modified:06 Feb 2009 16:08

Citation

Rebo, Hans P.; Chen, De; Brownrigg, Marit S. A.; Moljord, Kjell; Holmen, Anders (1997) Adsorption and Diffusion in HZSM-5 Zeolite Studied by an Oscillating Microbalance. Collection of Czechoslovak Chemical Communications, 62 (12). pp. 1832-1842. ISSN 0010-0765

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