Membrane Separation of the Base-Catalyzed Depolymerization of Black Liquor Retentate for Low-Molecular-Mass Compound Production

Membranes

Ola Wallberg¹  Kena Li¹  Per Tunå¹  Christian Hulteberg¹  Basel Al-Rudainy¹  Mingzhe Sun² 

[1] Department of Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden;Department of Chemistry, Centre for Analysis and Synthesis, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden;

关键词: Kraft lignin;    depolymerization;    membrane filtration;    low-molecular-mass compounds;   

DOI  :  10.3390/membranes9080102

来源: DOAJ

【 摘 要 】

One way of valorizing the lignin waste stream from the pulp and paper industries is depolymerizing it into low-molecular-mass compounds (LMMC). However, a common problem in the depolymerization of Kraft lignin is the low yields of small aromatic molecules obtained. In the present work, the combination of the repeated depolymerization of lignin and the separation of LMMC from depolymerized lignin to upgrade them into value-added chemicals was studied. In so doing, we investigated the possibility of depolymerizing black liquor retentate (BLR). The base-catalyzed depolymerization of BLR was performed using a continuous flow reactor at 170−210 °C, with a 2 min residence time. The results obtained indicate that BLR can be depolymerized effectively under the experimental conditions. Depolymerized lignin LMMC can be successfully separated by a GR95PP membrane, and thus be protected from repolymerization. Through combining membrane filtration with base-catalyzed depolymerization, more than half of the lignin could be depolymerized into LMMC. Around 46 mg/g of lignin monomers (guaiacol, vanillin, acetovanillone, and acetosyringone), which can potentially be upgraded to high-valued chemicals, were produced. On the basis of our results, we suggest use of a recycling Kraft lignin depolymerization and filtration process for maximizing the production of LMMC under mild alkaline conditions.

【 授权许可】

Unknown