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Poster De Conférence Année : 2022

Controlling Lignin Catalytic Depolymerization ?

Résumé

In recent years, catalytic depolymerization of lignin has been widely performed to obtain aromatic monomers under reductive or oxidative operating conditions [1]. However, starting with a recalcitrant technical lignin, co-produced in pulp industry or cellulosic biorefinery, the depolymerization only lead to poor monomers yield that prevent a valuable process. Another option to valorize technical lignin is to use it as a macromer in polymer applications. For instance, lignin can be used to replace polyol in polyurethane synthesis [2]. Other approaches were proposed using either lignin or lignin-derivatives to be incorporated into polymer synthesis [3]. Lignin derivatives might be more interesting than lignin if they are well-defined and possess higher amount of OH groups that can be further functionalized. Thus, one approach would consist in depolymerizing softly the lignin to create OH- groups that are phenolics or aliphatics. This can be done by cleavage of the ether inter-units linkages in lignin (-O-4, -O-4 or 4-O-5) and also by demethylation of the methoxy groups in the syringyl and guaiacyl units of the macromolecule. In literature, catalysts with lewis acidity were prone to be efficient to cleave these ether functions. However, until now, the most efficient demethylation method proposed is using HI acid formed in situ by using Iodocyclohexane in DMF [4]. This suggests that lewis acids are not the only candidates of choice for this process. We thus undertook a study to develop heterogeneous catalysts able to cleave selectively ether bonds of a technical lignin. In order to make a large screening of catalysts, we have chosen Pd/C already successfully used in lignin depolymerization, CoMo catalysts in oxide and sulfide forms active under reductive conditions, tungstated alumina (AlW) prepared to have only lewis acid sites [6], a silica-supported phosphotungstic acid and a well-known H-ZSM5 zeolite.
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Dates et versions

hal-03675712 , version 1 (23-05-2022)

Identifiants

  • HAL Id : hal-03675712 , version 1

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L. Olivier, D. Laurenti, C. Geantet. Controlling Lignin Catalytic Depolymerization ?. NAM27, May 2022, New York, United States. ⟨hal-03675712⟩
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