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Thermal stability of alumina aerogel doped with yttrium oxide, used as a catalyst support for the thermocatalytic cracking (TCC) process: An investigation of its textural and structural properties

Paper ID Volume ID Publish Year Pages File Format Full-Text
44133 46004 2007 9 PDF Available
Title
Thermal stability of alumina aerogel doped with yttrium oxide, used as a catalyst support for the thermocatalytic cracking (TCC) process: An investigation of its textural and structural properties
Abstract

Undoped and yttria doped alumina aerogel are prepared by the (solution) sol–gel method using a supercritical drying technique. The doping concentrations are in the range of 2.5–20.0 wt.% Y2O3, using yttrium(III) nitrate as a precursor. The effect of yttria doping on the structural and textural properties of alumina aerogel is investigated by BET surface area measurement, X-ray diffraction (XRD), TEM and 27Al MAS NMR.This method of preparation of alumina aerogel provides the most important increases in surface area at 750 °C and up to 1000 °C, when compared to conventional alumina that is obtained via thermal dehydration of boehmite. These results show that the much smaller size of crystallites of alumina aerogel is quite efficient to retard the sintering occurring at these high temperatures.Further improvements in thermal stability are obtained by incorporation of yttrium species during the aerogel preparation. The stabilizing effect goes through a maximum with a yttrium content of ca. 10 wt.%. The presence of yttrium significantly delays the lattice rearrangement into new phases, as normally experienced by the conventional alumina when the temperature increases. These yttrium species induce the formation of distorted tetrahedral Al sites. Such binding effect of Y to Al is clearly detected by 27Al MAS NMR already at 750 °C. However, at 1200 °C, even the doped aerogel cannot withstand the combined effect of sintering and α-phase transformation, so that extremely low surface areas corresponding to those of alumina α-phase and segregated Y-Al2O3 are obtained.

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Keywords
Yttria doped alumina aerogel; Conventional Al2O3; Thermal stability; BET surface area; XRD; 27Al MAS NMR
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Thermal stability of alumina aerogel doped with yttrium oxide, used as a catalyst support for the thermocatalytic cracking (TCC) process: An investigation of its textural and structural properties
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 317, Issue 2, 7 February 2007, Pages 275–283
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us