Staged Pyrolytic Conversion of Acid-Loaded Woody Biomass for Production of High-Strength Coke and Valorization of Volatiles
Staged Pyrolytic Conversion of Acid-Loaded Woody Biomass for Production of High-Strength Coke and Valorization of Volatiles
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DOI：
10.1021/acs.energyfuels.2c01352
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发表时间：
2022-06
期刊：
影响因子：
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通讯作者：
Fu Wei;Shinji Kudo;Shusaku Asano;J. Hayashi
中科院分区：
文献类型：
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作者：
Fu Wei;Shinji Kudo;Shusaku Asano;J. Hayashi
木质纤维素生物质是一种有吸引力的冶金焦炭资源。粉末状生物质的热造粒，然后碳化，产生高强度的生物焦。然而，碳化后大部分生物质的命运是产生低价值挥发物。在这里，我们通过在木材上装载无机酸和主要由烘焙、造粒和碳化组成的阶段性转化，使木质生物质作为有价值的化学品（如脱水糖和酚类）和强焦炭得到了增值。在300-320 °C下，以等于或略低于木材中固有的金属的量加载H2SO 4或H3 PO 4，具有促进碳水化合物形成无价值的轻质含氧化合物的催化作用，可有效地钝化这些金属并显著提高干燥糖的产率。木材中脱水糖的总收率和纤维素中主要脱水糖左旋葡聚糖的收率分别达到12.1wt%和25.3wt%。值得注意的是，焙烧改变了木材中组分的组成，并对通过造粒和碳化制备的焦炭的强度产生积极影响。特别是，焙烧在H2SO 4的存在下，导致显着的致密化的颗粒在碳化过程中。所得焦炭具有高达24.2MPa的强度（抗拉强度），这比直接造粒和从木材中分离的焦炭（9.0MPa）高得多。此外，富含木质素的焙烧木材在炭化过程中选择性地产生酚类和以H2为主要成分的可燃气体。在本工作中考察的最佳条件下，45.7wt%的木材转化为所需的产品，其余为水和重质可冷凝挥发物，而轻质含氧化合物的产率大大降低。
Lignocellulosic biomass is an attractive resource for metallurgical coke. The hot pelletization of powdered biomass followed by carbonization produces a high-strength biocoke. However, the fate of a major portion of biomass after carbonization is the production of low-value volatiles. Here, we enabled the valorization of woody biomass as valuable chemicals, such as anhydrosugars and phenols, and strong coke by loading mineral acid over wood and staged conversion consisting mainly of torrefaction, pelletization, and then carbonization. The loading of H2SO4or H3PO4at an amount equal to or slightly less than that of metals inherent in the wood, having catalysis for promoting the formation of valueless light oxygenates from carbohydrates, was effective for passivating those metals and drastically improving the anhydrosugar yield in torrefaction at 300–320 °C. The total yield of anhydrosugars from wood and the yield of levoglucosan, a dominant anhydrosugar, from cellulose in the wood reached 12.1 and 25.3 wt %, respectively. It was noteworthy that torrefaction altered the composition of components in wood and positively influenced the strength of coke prepared by pelletization and carbonization. In particular, torrefaction in the presence of H2SO4led to a remarkable densification of pellets during carbonization. The resulting coke had a strength (tensile strength) of up to 24.2 MPa, which was much higher than that of coke directly pelletized and carbonized from wood (9.0 MPa). Moreover, the lignin-enriched torrefied wood selectively produced phenols and combustible gas with H2as the major component in the carbonization. Under the most optimal conditions examined in this work, 45.7 wt % of the wood was converted into the desired products with the remainder being water and heavy condensable volatiles, while the yield of light oxygenates was greatly reduced.