Understanding the reaction pathways of cellulose hydrolysis in hot-compressed water (HCW) is crucial for the optimization of fermentable sugar and chemical production. Advanced analytical strategies are required to better assess the wide range of products from cellulose conversion in HCW. In this work, cellulose conversion in HCW was conducted in an autoclave with sampling upon the reaction time under isothermal conditions (180, 220, and 260 °C from 0 to 120 min). Total water-soluble carbohydrates were quantified (phenol/sulfuric acid method). These products were first characterized by size-exclusion chromatography coupled to evaporative light scattering detection and mass spectrometry (SEC–ELSD–MS). SEC is useful for screening the molecular weight distribution of soluble products. Then, the chemical structure of water solubles has been attributed by hydrophilic interaction liquid chromatography coupled to a linear trap quadrupole Orbitrap mass spectrometer (HILIC–LTQ–Orbitrap–MS). This method notably provides evidence of the formation of a cellobiose conformer under some HCW conditions. A specific high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC–PAD) method has been developed. This method allows for a selective separation of 5-hydroxymethylfurfural (5-HMF), glucose, fructose, mannose, and oligomers up to cellopentaose. Carboxylic acids were quantified by high-performance liquid chromatography with ultraviolet detection (HPLC–UV). Solid residues obtained after HCW conversion were characterized by X-ray diffraction (XRD) and permanent gas by micro-gas chromatography. The global reaction mechanism of cellulose liquefaction in HCW is rationalized on the basis of these complementary methods. Cellulose conversion first proceeds with heterogeneous hydrolysis (fiber surface) to produce soluble oligomers in competition with pyrolysis (inner fibers with limited mass transfer of water), producing levoglucosan (promoted at a higher temperature). Soluble oligomers produce glucose and isomers by homogeneous hydrolysis (liquid phase). C₆ sugars can then undergo further conversion to produce notably 5-HMF and erythrose.

中文翻译：

---

热压水中的纤维素分解：产品详细分析和操作条件的影响

了解纤维素在热压水（HCW）中水解的反应途径对于优化可发酵糖和化学产品至关重要。需要先进的分析策略来更好地评估来自HCW中纤维素转化的多种产品。在这项工作中，HCW中的纤维素转化是在高压釜中进行的，并在等温条件下（0至120分钟的180、220和260°C）采样反应时间。定量水溶性碳水化合物总量（苯酚/硫酸法）。这些产品首先通过尺寸排阻色谱法与蒸发光散射检测和质谱（SEC–ELSD–MS）结合进行表征。SEC可用于筛选可溶性产物的分子量分布。然后，水溶性的化学结构归因于亲水相互作用液相色谱与线性阱四极杆Orbitrap质谱仪（HILIC–LTQ–Orbitrap–MS）的结合。该方法特别提供了在某些HCW条件下形成纤维二糖构象异构体的证据。已开发出一种具有脉冲安培检测（HPAEC–PAD）方法的特殊高性能阴离子交换色谱。该方法允许选择性分离5-羟甲基糠醛（5-HMF），葡萄糖，果糖，甘露糖和寡聚体直至纤维素戊糖。通过高效液相色谱和紫外检测器（HPLC-UV）对羧酸进行定量。HCW转化后获得的固体残留物通过X射线衍射（XRD）进行表征，永久性气体通过微气相色谱进行表征。在这些补充方法的基础上，合理化了HCW中纤维素液化的整体反应机理。纤维素转化首先通过非均相水解（纤维表面）进行，以产生可溶的低聚物，与热解竞争（内部纤维具有有限的水质传递），从而产生左葡糖聚糖（在较高温度下被促进）。可溶性低聚物通过均相水解（液相）产生葡萄糖和异构体。C 可溶性低聚物通过均相水解（液相）产生葡萄糖和异构体。C 可溶性低聚物通过均相水解（液相）产生葡萄糖和异构体。C然后可以将_6种糖进行进一步转化，以产生显着的5-HMF和赤藓糖。