Direct conversion of triglycerides to olefins and paraffins over noble metal supported catalysts Martina Chiappero, Phuong Thi Mai Do, Steven Crossley, Lance L. Lobban ⇑ , Daniel E. Resasco School of Chemical, Biological and Materials Engineering, University of Oklahoma, Norman, OK 73019, USA article info Article history: Received 21 March 2010 Received in revised form 6 October 2010 Accepted 13 October 2010 Available online 27 October 2010 Keywords: Deoxygenation Methyl esters Triglycerides Vegetable oils abstract Deoxygenation of methyl esters and triglycerides was studied for production of either a-olefins or diesel components. The reactions were carried out in a reactive distillation fashion in which products are quickly removed from the reaction mixture in flowing He. The effects of He flow rate, reaction temperature, active component and support were studied. PtSnK supported on silica was found to be the best catalyst for selective production of a-olefins. Palm kernel oil and coconut oil were also deoxygenated to produce a- olefins or diesel components, depending on reaction conditions. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction In the last few years, interest in producing green fuels or chemicals has increased significantly. Natural fats and oils are a po- tential feedstock for production of surfactants and other chemicals traditionally based on petroleum. Transesterification of triglycer- ides with methanol is commonly used to convert triglycerides to so-called biodiesel, which consists of fatty acid methyl esters (FAMEs). This conversion method, which uses homogeneous catalysts, is efficient and well understood. However, the FAMEs have some undesirable fuel properties [1–3]. Fungible diesel fuel is produced by conversion of non- petroleum feedstocks to straight chain hydrocarbons comparable to conventional diesel. A selective conversion path to olefins, particularly a-olefins, would also be valuable for the production of starting materials for a variety of specialty chemicals. Produc- tion of hydrocarbons from various renewable feedstocks has been extensively studied for many years. More than ten years ago, Del- mon et al. [4] and Krause et al. [5] have shown the effectiveness of hydrotreating catalysts in hydrodeoxygenating oxygenates from bio-oils. The products are resulted from direct hydrogenolysis and hydrogenation activity of these catalysts. Recently conversions of triglycerides or vegetable oils to hydrocarbons have been reported over various catalysts in both flow and batch modes. Selective deoxygenations of vegetable oils over supported NiMo and CoMo hydrotreating catalysts have been observed in flow reactions by Kubicka et al. [6,7]. The products are corresponding hydrocarbons of the same nature as hydrocarbons present in diesel fuels. Thermal or catalytic cracking of vegetable oils in batch reactors produces hydrocarbons in the gasoline rather than diesel range; and undesirable oxygenates such as carboxylic acids [8–10]. Thus, catalytic conversion with better product control would be preferred. Hydrogenation of vegetable oils over Ni containing catalyst has been extensively studied [11,12]. In these studies the main products were linear chains of hydrocarbons from either hydrogenation or deoxygenation reactions. However, there are some disadvantages when using these catalysts. In the studies previously mentioned, researchers have showed that unacceptable amounts of cyclic and aromatics products were formed. Another work [13] showed that trace amounts of cyclic and aromatics com- pounds were present but extremely high H 2 to TG ratio (1000:1) and a long-time sulfidation process were needed to achieve better results. Recently both Murzin et al. [14–16] and Crocker et al. [17] have reported high activity of noble metals (i.e. Ni, Pd, Pt) sup- ported on activated carbon in the deoxygenation of triglycerides under inert atmosphere. High yields of linear corresponding alkanes and alkenes were obtained. The proposed reaction path- way includes formation of fatty acid intermediates accompanied by elimination of CO 2 from the acids. In the present work we focus on the production of long chain hydrocarbons from methyl esters and/or triglycerides via deoxygenation over a series of supported Pt catalysts. A reactive- distillation process was used to achieve high selectivity to a- olefins in particular. In this process, the primary products (which have higher vapor pressures than the reactant and solvent) are continuously removed as they are formed, minimizing secondary isomerization or oligomerization reactions. At the same time low 0016-2361/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.fuel.2010.10.025 ⇑ Corresponding author. Tel.: +1 405 325 4390; fax: +1 405 325 5813. E-mail address: llobban@ou.edu (L.L. Lobban). Fuel 90 (2011) 1155–1165 Contents lists available at ScienceDirect Fuel journal homepage: www.elsevier.com/locate/fuel