Membrane Fractionation of Liquors from Lignin‐First Biorefining

Abstract

For the utilization of each lignin fraction in the lignin liquors, the development of separation strategies to fractionate the lignin streams by molecular weight ranges constitutes a timely challenge to be tackled. Herein, membrane filtration was applied to the refining of lignin streams obtained from a lignin‐first biorefining process based on H‐transfer reactions catalyzed by Raney Ni, by using 2‐PrOH as a part of the lignin extraction liquor and as an H‐donor. A two‐stage membrane cascade was considered to separate and concentrate the monophenol‐rich fraction from the liquor. Building on the results, an economic evaluation of the potential of membrane filtration for the refining of lignin streams was undertaken. In this proof‐of‐concept report, a detailed analysis is presented of future developments in the performance required for the utilization of membrane filtration for lignin refining and, more aspiringly, solvent reclamation.

Recent Advances in the Catalytic Depolymerization of Lignin towards Phenolic Chemicals: A Review

“…Lignin, as the by‐product of paper mill, is generally burned to generate heat, which is not environmentally benign or sustainable . Therefore, the exploitation and development of cost‐effective and environmentally sustainable lignin‐first biorefinery strategies for the efficient valorization of lignin to phenolic chemicals and its further upgrading becomes the core and focus among scientific researchers . Emerging lignin valorization strategies are currently revisiting the biorefinery concept .…”

Assessing the Viability of Recovery of Hydroxycinnamic Acids from Lignocellulosic Biorefinery Alkaline Pretreatment Waste Streams

“…In an industrial-scale biorefinery,p otential processes that could be used to isolate pCA and FA include distillation, membrane separation, adsorption, and extraction. [35,51,52] pCA and FA are (hot-)water-soluble, nonvolatile chemicals;d istillation of the water of the APL would, therefore, yield ac oncentrated mixture of pCA, FA,a nd waxes/oligomers.T he distillation of pCA and FA to pure products is not viable as they decarboxylate thermally to form 4-vinylphenol and 4-vinylguaiacol. [53] Furthermore, the distillation of an APL would require the evaporation of al arge portion of water,w hich would increasee nergy costs significantly.A lternatively,m embranesc an be used to separate pCA and FA as permeates or to concentrate them by the dehydration of the APL.…”

“…Variations of the extraction strategies revolve arounds ome general principles;1 )highers olution alkalinity increases the solubility of hydroxycinnamic acids and waxes/oligomers;2 )sugarsh ave poor solubility in alcohol (ethanolo rm ethanol); 3) hydroxycinnamic acids are less soluble at lower temperatures. Here, we de-signed ap rocess ( Figure 1) based on severali solation strategies reported previously [20,23,24,51,52,54,57] based around these general principles and assessed the economic viability of the approach. The process includes:1 )neutralization of the alkaline supernatant using sulfuric acid;2 )ethanol extraction to separatet he impurities (waxes and oligomers)f rom the pCA and FA ;3 )recovery and recycling of the ethanol;4 )acidification of the neutral aqueous solution to precipitate pCA and FA ;a nd 5) acid neutralization using caustic soda before the chemically cleanerw aste stream is sent to wastewater treatment.…”

Development of ‘Lignin-First’ Approaches for the Valorization of Lignocellulosic Biomass

“…A proof-of-concept membrane filtration was demonstrated by Rinaldi and co-workers in 2019, for the separation and concentration of the monophenol-rich fraction (entry 64 in Table 1 ) from the lignin liquors (poplar, Raney Ni catalyst, isopropanol/water solvent/H-donor mixture) [ 83 ]. In a further paper, the impact of process severity (reaction temperature) was studied by the same group, using the same feedstock, catalysts, and solvent mixture in the second one [ 84 ].…”