A two-stage alkaline-oxidative pretreatment of hybrid poplar was investigated at scale (20 L reactor volume) with the goal of understanding how reaction conditions as well as interstage mechanical refining impact downstream process responses. The pretreatment comprises a first stage of alkaline delignification (alkaline pre-extraction) followed by a second delignification stage employing Cu-catalyzed alkaline hydrogen peroxide with supplemental O₂ (O₂-enhanced Cu-AHP). Increasing pre-extraction severity (i.e., temperature and alkali loading) and pretreatment oxidation (increasing H₂O₂ loading) were found to increase mass and lignin solubilization in each stage. Lignin recovered from the first stage was subjected to oxidative depolymerization and led to aromatic monomer yields as high as 23.0% by mass. Lignins recovered from the second-stage Cu-AHP pretreatment liquors were shown to exhibit aliphatic hydroxyl contents more than 6-fold higher than a typical hardwood kraft lignin, indicating that these lignins could serve as a biobased polyol for a range of polyurethane applications.

中文翻译：

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杂交杨两阶段铜催化碱性氧化预处理的放大

对混合杨树的两阶段碱氧化预处理进行了大规模研究（反应器体积为 20 L），目的是了解反应条件以及阶段间机械精炼如何影响下游工艺响应。预处理包括碱脱木质素的第一阶段(碱预萃取)，随后是使用Cu催化的碱性过氧化氢和补充O ₂ (O ₂增强的Cu-AHP)的第二脱木质素阶段。发现增加预提取强度（即温度和碱负荷）和预处理氧化（增加H ₂ O ₂负荷）可以增加每个阶段的质量和木质素溶解。第一阶段回收的木质素经过氧化解聚，芳香族单体收率高达23.0质量%。从第二阶段 Cu-AHP 预处理液中回收的木质素的脂肪族羟基含量比典型硬木牛皮纸木质素高 6 倍以上，表明这些木质素可以作为一系列聚氨酯应用的生物基多元醇。