International Journal of Applied Science and Engineering 2003. 1, 2: 89-100 Int. J. Appl. Sci. Eng., 2003. 1, 2 89 Immobilization of a Homogeneous RU Catalyst for Hexene and Canola Oil Hydrogenation: Synthesis and Activity Amanda J. Wright a , Stephan Reynier a , Stanislaw Skonieczny b , and Levente L. Diosady a∗ a Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario, Canada b Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada Abstract: Dichlorodicarbonylbis (triphenylphosphine) ruthenium (II), a cis-selective and homo- geneous catalyst, was immobilized on two types of inert solid supports: phosphinated polysty- renes and phosphinated silica gel. In both cases, spacer chains of different length were inserted between the phosphine attachment of the Ru complex and the support surface. Ru attachment efficiencies were determined by neutron activation analysis (NAA). The ability of the heteroge- nized catalysts to hydrogenate both 1-hexene and canola oil was also tested and the influence of linkage structure on activity was evaluated. In the case of the silica-supported catalysts, Ru dis- sociated from the support during hydrogenation. In contrast, the polymer-bound Ru remained immobilized during the catalytic reactions. Those polymer catalysts with the shortest linkage chains demonstrated the highest activity in the hydrogenation of 1-hexene. Despite this demon- strated activity, none of the polymer-bound Ru catalysts were active for canola oil hydrogenation. Keywords: canola oil; hydrogenation; ruthenium; immobilization; 1-hexene; attachment effi- ciency. ∗ Corresponding author: e-mail: diosady@chem-eng.toronto.edu Accepted for Publication: July 22, 2003 © 2003 Chaoyang University of Technology, ISSN 1727-2394 1. Introduction Hydrogenation of vegetable oils using typical Ni catalysts results in the formation of trans fatty acids. Because trans fats are harm- ful to human health (Asherio et al., 1999; Hu et al., 1997; Mensik and Katan, 1990), alter- native catalysts that demonstrate minimal or no cis to trans isomerization during hydro- genation have been sought. We previously identified a homogeneous Ru complex (di- chlordicarbonylbis (triphenylphosphine) ru- thenium (II), (Cl 2 (CO) 2 (PPh 3 ) 2 Ru(II)) which is cis-selective for canola oil hydrogenation (Bello et al., 1985). Because industrial edible oil hydrogenation processes were designed to use heterogeneous catalysts, the homogeneous Cl 2 (CO) 2 (PPh 3 ) 2 Ru(II) catalyst will have to be immobilized to allow its recovery and reuse prior to commercial application. Previous studies have shown that the catalytic proper- ties of transitional metal complexes can be retained when the catalysts are supported on silica gel (Czakova and Capka, 1981; Michal- ska et al., 1981; Skupinski and Malinowsky, 1975 and 1976). Other researchers have sup- ported homogeneous catalysts on polymeric supports and demonstrated hydrogenation ac- tivity (Azran et al., 1984; Strukul et al., 1975). Pittman et al. (1975) supported Wilkinson’s catalyst (Rh(PPh 3 )Cl) on cross-linked phosphinated polystyrenes and Cl 2 (CO) 2