Catalytic deoxygenation of unsaturated renewable feedstocks for production of diesel fuel hydrocarbons M. Sna ˚re, I. Kubic ˇkova ´, P. Ma ¨ki-Arvela, D. Chichova, K. Era ¨nen, D.Yu. Murzin * Laboratory of Industrial Chemistry, Process Chemistry Centre, A ˚ bo Akademi University, Biskopsgatan 8 FIN-20500 A ˚ bo-Turku, Finland Received 25 October 2006; received in revised form 4 June 2007; accepted 5 June 2007 Available online 16 July 2007 Abstract The liquid-phase deoxygenation reaction of unsaturated renewables has been investigated in a semi-batch reactor. The reactants examined were the monounsaturated fatty acid, oleic acid, the diunsaturated fatty acid, linoleic acid and the monounsaturated fatty acid ester, methyl oleate. The reactions were carried out over a Pd/C catalyst under constant pressure and temperature in the following domain, 15–27 bar and 300–360 °C, respectively. The influence of carrier gas was additionally investigated. The impact as solvent (mesit- ylene) was studied as well and reaction pathways were proposed. Furthermore, continuous deoxygenation experiments were conducted, facilitating understanding of the catalyst stability and catalyst deactivation. The deoxygenation catalyst was characterized by physisorp- tion, temperature programmed desorption (TPD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Deoxygenation; Renewables; Diesel 1. Introduction There are several reasons for the growing interest of uti- lizing renewable feedstocks as alternative fuels for the future, such as the rapid decrease of fossil fuel reservoirs and currently existing major environmental concerns. Natural oils and fats are renewable feeds that could be used for energy utilization. Approximately 100 million tons of oils and fats were produced worldwide in 2003 [1], from animal and vegetable feedstocks. At that time the produc- tion of biodiesel (defined as alkyl fatty acid esters) was, nevertheless, relatively low, 1.4 million tons [2]. The annual production of oils and fats, however, could be largely increased, without touching the sensitive ethical dilemma of using farmland for energy production. Recently, novel solutions have been made in order to increase availability and oil yields. Typically, an oil-bearing crop can yield ca. 100,000 kg oil/km 2 , but oil yields of 10–20 times are reported [3]. Moreover, non-edible and high oil yielding crops that can withstand desert like areas and grow with a minimal amounts of water are being developed [4–7]. Natural oils and fats are complex mixtures of triglycer- ides, which contain three fatty acids and a glycerol moiety [8]. As it is demonstrated in Table 1 [9–11], natural oils and fats comprise of saturated and unsaturated fatty acids with a carbon numbers of C4 and C24, typically C16 and C18. The high carbon numbers, hence high heating values, of the fatty acid alkyl chains in the natural oils and fats make them promising potential candidates as diesel fuel if selec- tively deoxygenated. The selective deoxygenation can be done by direct removal of the carboxyl group via carbon dioxide and/or carbon monoxide release [12] (decarboxyl- ation and/or decarbonylation). It has recently been demon- strated that saturated feeds over heterogeneous catalysts in the liquid-phase tend to deoxygenate [13–15], when the reactants are brought together with, i.e. Pd/C catalyst under elevated temperatures and pressures. 0016-2361/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.fuel.2007.06.006 * Corresponding author. Tel.: +358 2 215 4985; fax: +358 2 215 4479. E-mail address: dmurzin@abo.fi (D.Yu. Murzin). www.fuelfirst.com Available online at www.sciencedirect.com Fuel 87 (2008) 933–945