Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

PP-V-21KINETICS OF THE HYDROXYMATAIRESINOL HYDROGENOLYSISOVER PALLADIUM CATALYSTSHeidi Bernas, Dmitry Yu. MurzinLaboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre,Åbo Akademi University, Biskopsgatan 8, FI-20500 Turku, FinlandIntroductionKnots, e.g. the part of the branch that is embedded in the tree, are harmful in pulp andpaper manufacturing and should be removed before pulping [1]. Some years ago, largequantities 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 andtechnical 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 startingfrom HMR. The lignan matairesinol (MAT) has high application potential. In our previousstudies related to HMR hydrogenolysis, we have investigated the influence of support acidityfor palladium catalysts supported on carbon [5], zeolites [6] and carbon nanofibres (CNF) [7].It was concluded that the acidity of the support material has a great influence on the activity;for carbon and CNF supported palladium catalysts, the activity increased when the acidityincreased. For palladium supported by H-Beta zeolites, having higher concentration of acidsites than carbon materials, the activity decreased with the acidity increase. Since the choiceof catalyst support and the concentration of acid sites on the support have a great influence onthe hydrogenolysis to HMR, it is important to study the effect of reaction conditions. Theinfluence of mass transfer, temperature, reactant concentration and hydrogen pressure wasstudied.Results and discussionThe main reaction network is presented in Fig. 1. There are two diastereomers of HMR,the isomer with RRR configuration (HMR 1) and the one with RRS configuration (HMR 2).The influence of hydrogen pressure was studied using a 5% Pd/C catalyst (Degussa) in anautoclave at hydrogen pressures from 5 to 40 bars. At low pressures the reaction rateincreased, but at pressures higher than 25 bar the reaction rate decreased dramatically. It canbe concluded that there is an optimum in activity not only as a function of acid siteconcentration but also as a function of hydrogen concentration. These observations are inagreement with the reaction mechanism presented in [5], where the first step is protonation of496