Yang Bin, Wyman Charles E
Center for Environmental Research and Technology, Bourns College of Engineering, University of California, Riverside, CA, USA.
Methods Mol Biol. 2009;581:103-14. doi: 10.1007/978-1-60761-214-8_8.
Exposure of cellulosic biomass to temperatures of about 120-210 degrees C can remove most of the hemicellulose and produce cellulose-rich solids from which high glucose yields are possible with cellulase enzymes. Furthermore, the use of dilute sulfuric acid in this pretreatment operation can increase recovery of hemicellulose sugars substantially to about 85-95% of the maximum possible versus only about 65% if no acid is employed. The use of small-diameter tubes makes it possible to employ high solids concentrations similar to those preferred for commercial operations, with rapid heat-up, good temperature control, and accurate closure of material balances. Mixed reactors can be employed to pretreat larger amounts of biomass than possible in such small-diameter tubes, but solids concentrations are limited to about 15% or less to provide uniform temperatures. Pretreatment of large amounts of biomass at high solids concentrations is best carried out using direct steam injection and rapid pressure release, but closure of material balances in such "steam gun" devices is more difficult. Although flow of water alone or containing dilute acid is not practical commercially, such flow-through configurations provide valuable insight into biomass deconstruction kinetics not possible in the batch tubes, mixed reactors, or steam gun systems.
将纤维素生物质暴露于约120 - 210摄氏度的温度下，可以去除大部分半纤维素，并产生富含纤维素的固体物质，利用纤维素酶从中可获得高葡萄糖产率。此外，在这种预处理操作中使用稀硫酸可将半纤维素糖的回收率大幅提高至约最大可能回收率的85 - 95%，而如果不使用酸，回收率仅约为65%。使用小直径管道能够采用类似于商业操作中优选的高固体浓度，实现快速升温、良好的温度控制以及精确的物料平衡封闭。混合反应器可用于预处理比小直径管道中更多量的生物质，但固体浓度限于约15%或更低以确保温度均匀。在高固体浓度下对大量生物质进行预处理最好采用直接蒸汽注入和快速压力释放的方式，但在这种“蒸汽枪”装置中实现物料平衡封闭更为困难。尽管单独的水流或含稀酸的水流在商业上不实用，但这种流通式配置能为生物质解构动力学提供在间歇式管道、混合反应器或蒸汽枪系统中无法获得的有价值见解。
