Zeng Yining, Lin Kuan-Ting, Happs Renee M, Leal Juan H, Kang Xihui, Dou Chang, Kruger Jacob S, Ding Ling, Sale Kenneth L, Semelsberger Troy A, Ray Allison E, Sun Ning, Donohoe Bryon S
Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
Energy and Environmental Science and Technology, Idaho National Laboratory, Idaho Falls, Idaho 83415, United States.
ACS Sustain Chem Eng. 2025 Jul 18;13(30):12178-12187. doi: 10.1021/acssuschemeng.5c04284. eCollection 2025 Aug 4.
Lignin plays a vital role in the economics of biorefineries, serving as a source of process energy and a feedstock for sustainable fuels and chemical production. While understanding lignin's chemical composition is crucial, emerging evidence suggests that a more comprehensive understanding of its macromolecular structure is critical to explaining its complex behavior in the biorefinery. This study investigated the collapse of the lignin network in corn stover feedstock after harvest and storage as a result of the microbial digestion of hemicellulose. Fluorescence microscopy was used to detect the collapse of lignin by the changes in lignin's fluorescence lifetime, anisotropy, and the number of effective emitters. Our in situ microscopic results revealed lignin's coil-globule transition phenomena, which was only previously predicted by molecular dynamics modeling of extracted lignin in solvent. This collapse of lignin macromolecular structure was supported by results from NMR, IR, Raman, and powder X-ray diffraction. Our study revealed that the two major approaches for lignin valorization in the lignin-first biorefinery model, namely, monomer extraction and milled wood lignin extraction, were negatively impacted by the lignin collapse. As changes during storage are a source of feedstock variability, our study highlights the importance of understanding the effect of feedstock handling on biorefinery operations and economics.
木质素在生物炼制的经济性方面发挥着至关重要的作用，它可作为工艺能源的来源以及可持续燃料和化学品生产的原料。虽然了解木质素的化学组成至关重要，但新出现的证据表明，更全面地了解其大分子结构对于解释其在生物炼制中的复杂行为至关重要。本研究调查了收获和储存后玉米秸秆原料中木质素网络因半纤维素的微生物消化而发生的塌陷。利用荧光显微镜通过木质素荧光寿命、各向异性和有效发射体数量的变化来检测木质素的塌陷。我们的原位显微镜结果揭示了木质素的卷曲-球状转变现象，这一现象此前仅通过溶剂中提取的木质素的分子动力学建模预测过。核磁共振、红外光谱、拉曼光谱和粉末X射线衍射的结果支持了木质素大分子结构的这种塌陷。我们的研究表明，木质素优先生物炼制模型中木质素增值的两种主要方法，即单体提取和磨木木素提取，均受到木质素塌陷的负面影响。由于储存期间的变化是原料变异性的一个来源，我们的研究突出了了解原料处理对生物炼制操作和经济性影响的重要性。
