Structure and catalytic activity of Al-MCM-48 materials synthesised at room temperature: Influence of the aluminium source and calcination conditions
authors Russo, PA; Carrott, MMLR; Carrott, PJM; Lopes, JM; Ribeiro, FR; Rocha, J
nationality International
journal MICROPOROUS AND MESOPOROUS MATERIALS
author keywords Al-MCM-48; room temperature synthesis; aluminium source; structural characterisation; acid catalysis
keywords MESOPOROUS MOLECULAR-SIEVES; ETHYLENIC HYDROCARBONS; MCM-48 MATERIALS; ACIDITY; ISOMERIZATION; STABILITY; ALKYLATION; BEHAVIOR; SITES; WATER
abstract MCM-48 aluminosilicates with different aluminium contents were synthesised by a room temperature procedure using tetraethoxy-silane and aluminium sulfate, isopropoxide or tert-butoxide as metal sources. The samples were characterised by X-ray diffraction, nitrogen adsorption at 77 K, and (27)Al MAS NMR and the catalytic activity tested in the reaction of l-butene double bond position isomerisation. The influence of the synthesis time and calcination conditions, such as heating rate and time at final temperature, on the structural and catalytic properties of the materials was also evaluated. Aluminium isopropoxide and sulfate allowed the preparation of well structured Al-MCM-48 materials, with high specific pore volume and uniform pore size, and with the majority of the aluminium incorporated in tetracoordinated environment after calcination, at least down to Si/Al of 15. The highest initial conversions were found for samples with Si/Al = 20 and 30 prepared With aluminium isopropoxide and calcined using a heating rate of 3 K min(-1) with those of samples prepared with aluminium sulfate being slightly lower. Al-MCM-48 materials with high specific pore volume and uniform size were also synthesised using aluminium tert-butoxide, but the materials were less well ordered, presented a higher proportion of hexa-and pentacoordinated Al species and exhibited lower initial conversions, independently of the synthesis time or calcination conditions tested. It is concluded that aluminium isopropoxide and sulfate are more adequate metal Sources than aluminium tert-butoxide to prepare Al-MCM-48 catalysts by this room temperature method and a calcination heating rate of 3 K min(-1) instead of I K min-1 produces more effectively active catalysts. (C) 2008 Elsevier Inc. All rights reserved.
publisher ELSEVIER SCIENCE BV
issn 1387-1811
year published 2008
volume 114
issue 1-3
beginning page 293
ending page 302
digital object identifier (doi) 10.1016/j.micromeso.2008.01.015
web of science category Chemistry, Applied; Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary
subject category Chemistry; Science & Technology - Other Topics; Materials Science
unique article identifier WOS:000258432100028
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journal impact factor 3.649
5 year journal impact factor 3.538
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