University of Lisbon, School of Agriculture, Forest Research Center (CEF), Tapada da Ajuda, 1349-017, Lisbon, Portugal.
Carbohydr Polym. 2019 Feb 15;206:80-85. doi: 10.1016/j.carbpol.2018.10.106. Epub 2018 Oct 31.
Polyoxometalate (POM) catalyzed hydrolysis of wood and agro-crop hemicelluloses by mixed-addenda molybdic α-Keggin-type heteropolyacids (HPAs), such as molybdovanadophosphate heteropolyacids (Mo-V-P)-HPAs of series H[PMoVO] with n = 3 and 4 (so-called HPA-3 and HPA-4), have been assessed in comparison with conventional sulfuric acid catalysis. In very diluted (20 mM) aqueous solutions of (Mo-V-P)-HPAs, up to 90% of total biomass xylan was readily converted into soluble sugars (mono and oligosaccharides) after 60 min hydrolysis reaction at 130 °C, vs only ca. 25% conversion (as a max.) for sulfuric acid solutions. Low cellulose degradation in (Mo-V-P)-HPA solutions resulted in a significant improvement in the selectivity of hydrolysis (by up to 70%) compared with sulfuric acid. The oxidative capacity of (Mo-V-P)-HPAs caused increased dissolution of lignin during the hydrolysis reaction (by up to 13% over the sulfuric acid), thus providing favorable conditions for the sustainable recovery of cellulose fibers from the xylan-free residues in subsequent biorefining stages.
多金属氧酸盐（POM）催化水解木质素和农业作物半纤维素，采用混合配体钼α-Keggin 型杂多酸（HPA），如钼钒磷杂多酸（Mo-V-P）-HPA 系列 H[PMoVO]，其中 n=3 和 4（分别称为 HPA-3 和 HPA-4），与传统硫酸催化进行了比较。在（Mo-V-P）-HPA 的非常稀释（20mM）水溶液中，在 130°C 下水解 60 分钟后，高达 90%的总生物质木聚糖很容易转化为可溶性糖（单糖和寡糖），而硫酸溶液的转化率仅约为 25%（最大）。与硫酸相比，（Mo-V-P）-HPA 溶液中纤维素的低降解导致水解的选择性显著提高（高达 70%）。（Mo-V-P）-HPA 的氧化能力导致在水解反应过程中木质素的溶解增加（比硫酸增加 13%），从而为随后的生物精炼阶段中从无木聚糖的残渣中可持续回收纤维素纤维提供了有利条件。
