Gold Catalysts for Selective Aerobic Oxidation of the Lignan Hydroxymatairesinol to Oxomatairesinol: Catalyst Deactivati
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Gold Catalysts for Selective Aerobic Oxidation of the Lignan Hydroxymatairesinol to Oxomatairesinol: Catalyst Deactivation and Regeneration Olga A. Simakova • Elena V. Murzina • Anne-Riikka Leino • Pa¨ivi Ma¨ki-Arvela Stefan Willfo¨r • Dmitry Yu Murzin
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Received: 28 May 2012 / Accepted: 8 June 2012 / Published online: 22 June 2012 Ó Springer Science+Business Media, LLC 2012
Abstract The lignan oxomatairesinol was synthesized from the biomass-derived lignan hydroxymatairesinol via selective aerobic oxidation over a heterogeneous gold catalyst. The catalyst was prepared by direct ion-exchange and characterized by XRD, TEM and ICP-OES methods. The reaction was carried out at 70 °C and atmospheric pressure in a semi-batch reactor. To reveal the origin of catalyst deactivation, spent catalysts were studied by TEM, XRD, nitrogen physisorption, ICP-OES, TPO, and DSCTGA techniques. Several regeneration procedures were applied—extraction by several solvents and calcinations in the oxidizing atmosphere. The former one was found to be the most effective way for the catalyst regeneration. Keywords Gold catalysts Selective oxidation Biomass Lignans Oxomatairesinol Hydroxymatairesinol Catalyst deactivation
O. A. Simakova E. V. Murzina P. Ma¨ki-Arvela D. Y. Murzin (&) Laboratory of Industrial Chemistry and Reaction Engineering, ˚ bo Akademi University, FI-20500 Process Chemistry Centre, A Turku, Finland e-mail: [email protected] O. A. Simakova ˚ bo Akademi Graduate School of Chemical Engineering, A University, FI-20500 Turku, Finland A.-R. Leino Microelectronics and Materials Physics Laboratories, EMPART Research Group of Infotech Oulu, University of Oulu, FI-90014 Oulu, Finland S. Willfo¨r Laboratory of Wood and Paper Chemistry, Process Chemistry ˚ bo Akademi University, FI-20500 Turku, Finland Centre, A
1 Introduction Oxomatairesinol (oxoMAT) is a naturally occurring lignan, which has demonstrated a number of valuable properties for the cosmetic, textile and pharmaceutical industries. Recent studies have shown that lignans are active as human healthpromoting agents by decreasing the risk for various cancers and cardiovascular diseases [1]. Studies of lignan radical and superoxide scavenging activities have shown that oxoMAT exhibits the highest superoxide scavenging activity [2]. Lignans or lignan derivatives, having antioxidative activity [3] and UV-protection properties [4], can be applied for cosmetic and pharmaceutical uses (skin- and hair-care products), as well as color-keeping agents for textile industry. However, oxoMAT cannot be obtained in large quantities from wood or any other biomass, while it can be synthesized by using hydroxymatairesinol (HMR) as a starting material [5, 6]. The former one is a naturally occurring lignan, which can be extracted in considerable amounts from Norway spruce (Picea abies) knotwood, constituting 65–85 wt% of the total lignans and occurring in an unconjugated free form [7]. The formation of oxoMAT from HMR by light-irridation was reported in [8], while in [9] 2,3-dich
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