Influence of Reaction Parameters on the Hydrogenolysis of Hydroxymatairesinol Over Carbon Nanofibre Supported Palladium
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Influence of Reaction Parameters on the Hydrogenolysis of Hydroxymatairesinol Over Carbon Nanofibre Supported Palladium Catalysts Heidi Bernas Æ Arie J. Plomp Æ Johannes H. Bitter Æ Dmitry Yu. Murzin
Received: 28 April 2008 / Accepted: 2 June 2008 / Published online: 24 June 2008 Ó Springer Science+Business Media, LLC 2008
Abstract The influence of catalyst particle size, stirring rate, catalyst mass (0.2–0.6 g), reaction temperature (60–70 °C), and reactant concentration (1.3–4 mmol/L, with constant reactant/catalyst ratio) on the hydrogenolysis of the lignan hydroxymatairesinol (HMR) to matairesinol (MAT) was studied under hydrogen atmosphere using a carbon nanofibre supported palladium catalyst. When the temperature or HMR concentration was increased, the reaction rate increased as expected. However, the reaction rate was inversely dependent on the stirring rate, e.g., was influenced by external mass transfer, which was explained by the fact that the reaction rate decreases at higher hydrogen concentrations. Keywords Kinetics
Lignan Carbon nanofibres Mass transfer
1 Introduction Knots, e.g., the part of the branch that is embedded in the tree, are harmful in pulp and paper manufacturing and H. Bernas D. Yu. Murzin (&) Laboratory of Industrial Chemistry and Reaction Engineering, ˚ bo Akademi University, Process Chemistry Centre, A Biskopsgatan 8, 20500 Turku, Finland e-mail: [email protected] H. Bernas e-mail: [email protected] A. J. Plomp J. H. Bitter Department of Inorganic Chemistry and Catalysis, Utrecht University, P.O. Box 80083, Utrecht, 3508 TB, The Netherlands e-mail: [email protected] J. H. Bitter e-mail: [email protected]
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should be removed before pulping [1]. Some years ago, large quantities of the lignan hydroxymatairesinol (HMR) were discovered in Norway spruce (Picea abies) knots [2]. Since lignans have anticarcinogenic [3] and antioxidative [4] effects, the waste material from pulping industry can be used for synthesis of pharmaceuticals and technical antioxidants. No other lignan has been found in substantial amounts in nature, therefore other lignans that are of great interest and importance should be synthesized starting from HMR. The lignan matairesinol (MAT) has high application potential due to the fact that MAT was concluded to be superior to HMR in studies performed in vivo; more precisely the quantity of the mammalian lignan enterolactone, which reduces the cancer risk, was over twofold when MAT was used as precursor compared to HMR [5]. High radical and superoxide scavenging activities were also observed for MAT [6]. In our previous studies related to HMR hydrogenolysis, we have investigated the influence of support acidity for palladium catalysts supported on carbon [7], zeolites [8] and carbon nanofibres (CNF) [9]. For both carbon [7] as well as CNF [9] supported palladium catalysts, it was concluded that the activity increased when the amount of acid sites was increased. For Pd/CNF also the selectivity to MAT increased with acidity. On the other hand, in the case of
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