Fast screening of Depolymerized Lignin Samples Through 2D‐Liquid Chromatography Mapping

Abstract

Lignin valorization and particularly its depolymerization into bio‐aromatics, has emerged as an important research topic within green chemistry. However, screening of catalysts and reaction conditions within this field is strongly constrained by the lack of analytical techniques that allow for fast and detailed mapping of the product pools. This analytical gap results from the inherent product pool complexity and the focus of the state‐of‐the‐art on monomers and dimers, overlooking the larger oligomers. In this work, this gap is bridged through the development of a quasi‐orthogonal GPC‐HPLC‐UV/VIS method that is able to separate the bio‐aromatics according to molecular weight (hydrodynamic volume) and polarity. The method is evaluated using model compounds and real lignin depolymerization samples. The resulting color plots provide a powerful graphical tool to rapidly assess differences in reaction selectivity towards monomers and dimers as well as to identify differences in the oligomers.

Enhancing the performance of heterogeneous palladium based catalysts in the mild reductive depolymerization of soda lignin through addition of a non-noble metal and tuning of the preparation strategy

“…43,44 Previous research has also related higher degrees of depolymerization to increased average 1 t R in the GPC-HPLC-UV/ VIS analysis. 37,38 Indeed, PC2 values decrease as a function of reaction time for all experiments as shown in Fig. 3.…”

“…Previous research has concluded that group 1 mainly contains monomers with propyl and propenyl chains as para -substitutions, group 2 contains monomers with propyl or propenyl chains with oxygen functionalities and group 3 mainly contains dimeric products. 37,38 …”

“…The twodimensional GPC-HPLC-UV/VIS analyses of the low molecular weight region of all samples were conducted using a recently developed method. 37,38 In brief, 7 fractions, 0.5 min in width at 0.8 mL min −1 , were collected between a rst dimension retention time ( 1 t R ) of 20-23.5 min from the GPC-UV/VIS-RID analysis described above and analyzed offline using a second Agilent Technology 1260 Innity II system, equipped with a reversed phase HPLC column, namely, a YMC Triart BIO C4 column kept at 45 °C and a variable wavelength UV/VIS detector set to 280 nm at a scan rate of 5 Hz. The ow rate is set to 1.2 mL min −1 and the mobile phases used are A, i.e., water (HPLC grade, Chemlab) + 0.1 vol% triuoracetic acid (TFA, HPLC-MS grade, Chemlab) and B, i.e., acetonitrile (ACN, HPLC gradient grade, Chemlab) + 0.1 vol% TFA.…”

Sustainable lignin modifications and processing methods: green chemistry as the way forward

“…Thus, to tackle this challenge, De Saegher et al introduced a 2D-liquid chromatography mapping technique (GPC-HPLC-UV/VIS) to characterize and gain insight into the high molecular-weight fragments. 191 We believe that the in-depth characterization of oligolignins will substantially contribute to the valorization of lignin in the future.…”

“…Thus, to tackle this challenge, De Saegher et al introduced a 2D-liquid chromatography mapping technique (GPC-HPLC-UV/VIS) to characterize and gain insight into the high molecular-weight fragments. 191 We believe that the indepth characterization of oligolignins will substantially contribute to the valorization of lignin in the future. The different depolymerization techniques are categorized into biocatalytic and chemical techniques, and the latter can be further subdivided into thermal-, acid-and base-catalyzed and oxidative and reductive depolymerization (an overview can be found in Fig.…”