QUB team converts aluminum foil waste to highly active alumina; biofuel catalyst, other applications
Researchers at Queen’s University Belfast have developed a novel green route to convert aluminium foil waste into highly active nano-mesoporous alumina (γ-Al2O3) (designated as ACFL550). The material shows higher surface area, larger pore volume, and stronger acidity compared to γ-Al2O3 that is produced from the commercial AlCl3 precursor, AC550. An open access paper on the work appears in Nature’s Scientific Reports.
Aluminum oxide, alumina (Al2O3), is one of the most attractive ceramic materials for its various applications due to its thermal, chemical and mechanical stability. Alumina has direct application as a catalyst and catalyst support in the automotive and petroleum industries. The oxide offers a favorable combination of textural properties—such as surface area, pore volume, and pore-size distribution—and its acid/base characteristics, which are mainly related to surface chemical composition, local microstructure, and phase composition (Trueba and Trasatti, 2005).
In the UK, around 20,000 tonnes of aluminium foil packaging is wasted each year. Most of this is landfilled or incinerated as it’s usually contaminated by grease and oils, which can damage recycling equipment.
Ahmed Osman, an Early Career Researcher from Queen’s University’s School of Chemistry and Chemical Engineering, worked with engineers at the university to create an innovative crystallisation method, which obtains 100% pure single crystals of aluminium salts (AlCl3.6H2O and Al(NO3)3.9H2O) from the contaminated foil. This is the starting material for the preparation of alumina catalyst.
Foil waste was dissolved in a 6 M HCl solution to form an aluminum chloride solution. The solution was kept under a desiccator until crystalline AlCl3.6H2O formed. These crystals were then dissolved in deionized water and filtered to remove any impurities. After that, the single crystals were purified. This step was repeated three times to obtain high purity AlCl3.6H2O.
The crystalline Al(NO3)3.9H2O was prepared from the AlCl3 solution prepared by dissolving the foil in the 6 M HCl solution, then a required amount of 15.6 M HNO3 was added then followed by heating to form the Al(NO3)3.9H2O solution. This was kept under desiccator to form a pure crystals.
Osman, who took on the project under the University’s Sustainable Energy, Pioneering Research Programme, created a solution which is more environmentally-friendly, effective and cheaper than the commercial catalyst which is currently available on the market for the production of dimethyl ether. Osman says making the catalyst from aluminium foil cost about £120/kg while the commercial alumina catalyst comes in at around £305/kg.
Ahmed I. Osman, Jehad K. Abu-Dahrieh, Mathew McLaren, Fathima Laffir, Peter Nockemann & David Rooney (2017) “A Facile Green Synthetic Route for the Preparation of Highly Active γ-Al2O3 from Aluminum Foil Waste” Scientific Reports 7, Article number: 3593 doi: 10.1038/s41598-017-03839-x
Trueba, M. and Trasatti, S. P. (2005), “γ-Alumina as a Support for Catalysts: A Review of Fundamental Aspects.” Eur. J. Inorg. Chem. 3393–3403 doi: 10.1002/ejic.200500348