Xueli Chen1,2,3, Dingping He1, Tao Hou1, Minsheng Lu4, Nathan S Mosier2,3, Lujia Han1, Weihua Xiao5. 1. Engineering Laboratory for AgroBiomass Recycling & Valorizing, College of Engineering, China Agricultural University (East Campus), 17 Qing-Hua-Dong-Lu, Haidian district, P.O. Box 191, Beijing, 100083, China. 2. Laboratory of Renewable Resources Engineering (LORRE), Purdue University, West Lafayette, IN, 47907, USA. 3. Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN, 47907, USA. 4. School of Light Industry and Food Engineering, Guangxi Key Laboratory of Clean Pulp and Papermaking and Pollution Control, Guangxi University, Nanning, 530004, China. 5. Engineering Laboratory for AgroBiomass Recycling & Valorizing, College of Engineering, China Agricultural University (East Campus), 17 Qing-Hua-Dong-Lu, Haidian district, P.O. Box 191, Beijing, 100083, China. xwhddd@163.com.
Abstract
BACKGROUND: Valorization of lignocellulosic biomass to obtain clean fuels and high-value chemicals is attractive and essential for sustainable energy and chemical production, but the complex structure of biomass is recalcitrant to catalytic processing. This recalcitrance can be overcome by pretreating biomass into deconstructable components, which involves altering the structural complexities and physicochemical properties. However, the impact of these alterations on biomass deconstruction varies considerably, depending on the pretreatment and subsequent conversion type. Here, we systematically describe the changes in structure and properties of corn stover after ball milling as well as their influence on the following enzymatic saccharification and acid-catalyzed alcoholysis, with the aim of elucidating the relationships between structures, properties and deconstructable potential of lignocellulosic biomass. RESULTS: Ball milling causes dramatic structural changes, since the resistant plant cell walls are destroyed with size reduction to a cellular scale, leading to the increase in surface area and reducing ends, and decrease in crystallinity and thermal stability. As a result, ball-milled corn stover is more susceptible to enzymatic saccharification to fermentable sugars and provides more industrially viable processing approaches, as it is effective at high solids loading and minor enzyme loading, without any other pretreatment. Acid-catalyzed alcoholysis of corn stover to biofuels, on the other hand, is also enhanced by ball milling, but additional processing parameters should be tailored to the needs of efficient conversion. Further, a detailed examination of process variables coupled with a kinetic study indicates that acid-catalyzed alcoholysis is limited by the process variables rather than by the substrate parameters, whereas ball milling facilitates this reaction to some extent, especially under mild conditions, by lowering the activation energy of corn stover decomposition. CONCLUSIONS: The efficient catalytic conversion of biomass is closely related to its structure and properties, an understanding of which offers prospects for the rational improvement of methods aimed at more economic commercial biorefineries.
BACKGROUND: Valorization of lignocellulosic biomass to obtain clean fuels and high-value chemicals is attractive and essential for sustainable energy and chemical production, but the complex structure of biomass is recalcitrant to catalytic processing. This recalcitrance can be overcome by pretreating biomass into deconstructable components, which involves altering the structural complexities and physicochemical properties. However, the impact of these alterations on biomass deconstruction varies considerably, depending on the pretreatment and subsequent conversion type. Here, we systematically describe the changes in structure and properties of corn stover after ball milling as well as their influence on the following enzymatic saccharification and acid-catalyzed alcoholysis, with the aim of elucidating the relationships between structures, properties and deconstructable potential of lignocellulosic biomass. RESULTS: Ball milling causes dramatic structural changes, since the resistant plant cell walls are destroyed with size reduction to a cellular scale, leading to the increase in surface area and reducing ends, and decrease in crystallinity and thermal stability. As a result, ball-milled corn stover is more susceptible to enzymatic saccharification to fermentable sugars and provides more industrially viable processing approaches, as it is effective at high solids loading and minor enzyme loading, without any other pretreatment. Acid-catalyzed alcoholysis of corn stover to biofuels, on the other hand, is also enhanced by ball milling, but additional processing parameters should be tailored to the needs of efficient conversion. Further, a detailed examination of process variables coupled with a kinetic study indicates that acid-catalyzed alcoholysis is limited by the process variables rather than by the substrate parameters, whereas ball milling facilitates this reaction to some extent, especially under mild conditions, by lowering the activation energy of corn stover decomposition. CONCLUSIONS: The efficient catalytic conversion of biomass is closely related to its structure and properties, an understanding of which offers prospects for the rational improvement of methods aimed at more economic commercial biorefineries.
Authors: Daniel Klein-Marcuschamer; Piotr Oleskowicz-Popiel; Blake A Simmons; Harvey W Blanch Journal: Biotechnol Bioeng Date: 2011-11-21 Impact factor: 4.530
Authors: Nathan Mosier; Charles Wyman; Bruce Dale; Richard Elander; Y Y Lee; Mark Holtzapple; Michael Ladisch Journal: Bioresour Technol Date: 2005-04 Impact factor: 9.642