Mesoporous aluminosilicate catalysts from FAU precursor under mild acidic conditions and with Al in totally tetrahedral coordination |
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Authors: | Conrad W Ingram Yohannes Ghirmazion Tesfamariam Mehreteab |
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Affiliation: | (1) Department of Chemistry, Clark Atlanta University, 223 James P. Brawley Drive, Atlanta, GA 30314, USA |
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Abstract: | Al-SBA-15 mesoporous catalyst with strong Brönsted acid sites and Al stabilized in a totally tetrahedral coordination was synthesized from the addition of hydrothermally aged zeolite Y precursor to SBA-15 synthesis mixture under mildly acidic condition of pH 5.5. The materials possessed surface areas between 690 and 850 m2/g, pore sizes ranging from 5.6 to 7.5 nm and pore volumes up to 1.03 cm3, which were comparable to parent SBA-15 synthesized under similar conditions. As much as 2 wt.% Al was present?in the most aluminated sample that was investigated, and the Al remained stable in totally tetrahedral coordination, even after calcination at 550 °C. Calcined Al-SBA-15 showed high hydrothermal stability when treated with steam (20% v/v in nitrogen) at 650 °C for 2 h. Textural characteristics are maintained on steam treatment, and very little or no conversion of Al from tetrahedral to octahedral coordination resulted. The Al-SBA-15 mesoporous catalyst showed significant catalytic activity for cumene dealkylation, and activity increased as the amount of zeolite precursor added to the SBA-15 mixture was increased. The catalyst’s activity was not affected by the aging time of the precursor for up to the 24 h aging time investigated. This method of introducing Al and maintaining it in a total tetrahedral coordination is very effective, in comparison to other direct and post synthesis alumination methods reported. |
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Keywords: | Al-SBA-15 Mesoporous aluminosilicate Acid catalyst Cumene conversion Mesostructures Zeolite seeds Catalysts preparation High surface area catalysts Bronsted acid catalysts Nanostructures Nanoporous |
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