Catalysis of Organic..

Kiss, Rothenberg and Dimian 40545. “Green” Catalystsfor Enhanced Biodiesel TechnologyAbstractAnton A. Kiss, Gadi Rothenberg and Alexandre C. DimianUniversity of Amsterdam, van ’t Hoff Institute for Molecular Sciences,Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlandsalexd@science.uva.nlThe benefits of using biodiesel as renewable fuel and the difficulties associated withits manufacturing are outlined. The synthesis via fatty acid esterification using solidacid catalysts is investigated. The major challenge is finding a suitable catalyst that isactive, selective, water-tolerant and stable under the process conditions. The mostpromising candidates are sulfated metal oxides that can be used to develop asustainable esterification process based on continuous catalytic reactive distillation.IntroductionDeveloping sustainable energy sources is a key scientific challenge of the 21stcentury. Automotive applications consume a large fraction of the available globalenergy, making the implementation of sustainable fuels a critical issue worldwide.Biodiesel is an environmentally-friendly renewable fuel (Figure 1) that can bemanufactured from vegetable oils, animal fats or even recycled greases from the foodindustry (1). It is also a viable alternative to petroleum diesel, especially followingthe tighter legislation on vehicle emissions. Remarkably, biodiesel is the only fuelwith an overall positive life cycle energy balance. It is a green fuel, with manyadvantages over conventional diesel (1-4): it is safe, non-toxic, biodegradable and agood lubricant. Moreover, it has a higher cetane number and an eco-friendly lifecycle. It also emits ~70% less gas pollutants and ~50% less soot particles. Moreover,it is easily blended with petroleum diesel, giving a mixture that can power regularvehicles without any changes to the engine or the fuel distribution infrastructure.Biodiesel is a mixture of fatty acid alkyl esters, derived typically from shortchain alcohols. Methanol is more suitable for biodiesel manufacturing, but otheralcohols can in principle also be used, depending on the feedstock available. Fattyacid methyl esters (FAME) are currently manufactured mainly by trans-esterificationusing a homogeneous base catalyst (NaOH). This catalyst is corrosive to theequipment and must be neutralized afterwards. Moreover, due to the presence of freefatty acids (FFA) it reacts to form soap as unwanted by-product, requiring expensiveseparation. In this process the biodiesel composition depends heavily on the types offatty acid groups building the triglycerides from the raw material.