Editorial

Green chemistry in Ireland

Green chemistry in Ireland

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This editorial is being written at the time of the European Catalysis Conference (‘Europacat’)—one of the major events in the calendar for academic and industrial chemists interested in catalysis, regularly attracting over 1000 delegates. For the first time Europacat is being held in Ireland at the University of Limerick, and also for the first time a Green Chemistry Session has been included, with a large number of oral and poster presentations. In the light of this, one of Limerick’s most senior professors Kieran Hodnett has co-authored this editorial to give us an outline of green chemistry in Ireland, and especially at the University of Limerick.

The chemical industry in Ireland is dominated by the pharmaceuticals sector with smaller numbers of plants in fine and bulk chemicals; in the last 10 years the electronics manufacturing sector has also become very important. Manufacturing licenses, however, are being issued by the Environmental Protection Agency with ever more stringent conditions.

An increasing number of projects at universities in Ireland are under way in the general area of green chemistry addressing the twin aspects of clean and end-of-pipe technologies. Several research groups in Limerick are involved in such green chemistry research projects. A novel low-waste Friedel–Crafts acylation process based on trifluoroacetic anhydride–phosphoric acid has been developed by T. Smyth and successfully applied to an intermediate in the manufacture of Tamoxifen; it has also recently been applied to the synthesis of 2-tetralones (Scheme 1).

Scheme 1 Synthesis of 2-tetralones, involving a low-waste Friedel– Crafts acylation process.

The high cost of virgin vegetable oil as well as EU land use policies has restricted the utilisation of biodiesel, but this can be overcome by using waste cooking oil and tallow as alternative low-cost feedstocks. Research work at Limerick led by J. J. Leahy focuses on pretreating the waste cooking oil to reduce moisture, free fatty acids and peroxides so as to increase the yield and quality of the methyl ester.

Several research groups at Limerick are involved in research on catalytic oxidation. These include low-temperature catalytic oxidation over hydrophobic catalysts (J. B. McMonagle); the selective oxidation of hydrocarbons to olefins and oxygenates (J. R. H. Ross); the CuO/Al₂O₃ catalysed oxidation of SO₂ to SO₃, followed by capture of the latter species to form CuSO₄/Al₂O₃ (B. K. Hodnett); and the study of adsorption and activity of proteins and enzymes on and inside mesoporous silicates (E. Magner and G. Wall). The last of these is directed towards developing the next generation of heterogeneous catalysts with selectivities in excess of those that can be achieved with current catalysts. Peroxidative activity profiles over a range of adsorbed protein concentrations is typically twice that of the free protein in aqueous solution.

T. Curtin and P. O’Sullivan are researching the vapour phase Beckmann rearrangement of cyclohexanone oxime to caprolactam using a range of solid acid catalysts varying from boron oxide-treated aluminas to zeolites. They have shown that there is a direct relationship between the amount of coke that forms on the surface and the loss in catalytic activity. They have postulated that polymerisation of caprolactam and the condensation of aniline with cyclohexanone to a Schiff base on basic sites represents a possible starting point for coke formation.

The management of industrial waste is a topic of major concern to industry, government and the public. Many industries have adopted new processing technologies to reduce or eliminate waste, but some, e.g. the alumina industry, continue to produce very large quantities of waste residue. For every tonne of alumina produced, 500–700 kg of waste red mud is generated. The vast majority of this is stockpiled close to the production plant. Though much research has been done throughout the world, no viable use for the red mud has been found to make any appreciable impact on the quantities generated. However, one technology that has spread from Australia is to use the red mud waste to treat another industrial waste—tailings from mines. The latter contain high levels of heavy metals such as lead and arsenic, contaminating soil and water and posing a major environmental threat. Red mud can adsorb up to 99.99% of these heavy metals, producing a very inert and stable material that supports plant growth and vegetation; the run-off water is of drinkable quality. This technology is now a commercial reality with a number of projects starting in Europe. Given the number of mining tailing areas throughout Europe, possibly in the thousands, the use of red mud to rehabilitate these sites may be a cost-effective means of solving two problems at once. Aughinish Alumina and the University of Limerick are working together to apply this technology in Ireland and work under the direction of R. Moles at the university and M. Fennel of Aughinish Alumina is under way.

James Clark and Kieran Hodnett
Limerick, Eire

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