压力对磨木木质素和酸洗杂种杨木热解的影响,Industrial & Engineering Chemistry Research

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压力对磨木木质素和酸洗杂种杨木热解的影响
Industrial & Engineering Chemistry Research ( IF 3.8 ) Pub Date : 2017-08-04 00:00:00 , DOI: 10.1021/acs.iecr.7b02085
M. Brennan Pecha ₁ , Evan Terrell ₁ , Jorge Ivan Montoya _{1,

2} , Filip Stankovikj ₁ , Linda J. Broadbelt ₃ , Farid Chejne ₂ , Manuel Garcia-Perez ₁

Affiliation

将杂种杨和酸洗杂种杨制成的碾磨木质素的薄膜（约115μm厚）在500°C和约55°C / s的五个压力（4、250、500、750和1000 mbar）下热解确定次级液体中间反应对产物分布的影响。对于从杨木中提取的经碾磨的木质素和经酸洗的杂种杨木，压力对薄膜热解在4至1000 mbar之间的产物分布均具有显着影响。对于木质素，将压力从1000 mbar降低至4 mbar会使焦炭产率从36％降低至23％，并提高了大簇热解木质素的产量。但是，压力并未显着影响气体产量（CO ₂，CO，甲烷，H ₂，乙烷，丙烷和丁烷），也不会显着影响单体酚类化合物的释放。ICR-MS显示木质素低聚物的组成变化有限。通过紫外荧光观察到的大型木质素低聚物产量的增加以及真空状态下焦炭产率的降低证实了在液体中间体中形成大的多芳族结构的低聚组合反应的重要性。对于杂种杨，将压力从1000 mbar降低到4 mbar，使焦炭产量从19降低到7％，并增加了重糖（纤维二糖和纤维二糖）的产量。ICR-MS结果清楚地表明了液体中间体中脱水反应的重要性。降低压力还提高了CO，CO _2的产生以及甲烷是由于实木基质中残留的碱金属和碱土金属的多相催化作用所致。然而，它也使左旋葡聚糖的产量从10重量％降低至6.1重量％。如果热解产物是杂种杨成分的累加作用的结果，则杂种杨获得的左旋葡聚糖和纤维二糖的产率分别较高和较低。该结果可以通过木质素液体中间体剧烈起泡的趋势来解释，以这种方式有助于从液体中间体中除去纤维素低聚物。

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Effect of Pressure on Pyrolysis of Milled Wood Lignin and Acid-Washed Hybrid Poplar Wood

Thin films (∼115 μm thick) of milled wood lignin from hybrid poplar and acid-washed hybrid poplar were pyrolyzed at 500 °C and ∼55 °C/s at five pressures (4, 250, 500, 750, and 1000 mbar) to determine the impact of secondary liquid intermediate reactions on the product distribution. For both milled wood lignin extracted from poplar and acid-washed hybrid poplar wood, pressure had a significant effect on the product distribution for thin film pyrolysis between 4 and 1000 mbar. For lignin, lowering the pressure from 1000 mbar to 4 mbar reduced the char yield from 36 to 23% and enhanced production of large cluster pyrolytic lignin. However, the pressure did not dramatically impact the gas yield (CO₂, CO, methane, H₂, ethane, propane, and butane), nor did it significantly impact the release of monomeric phenolic compounds. ICR-MS shows limited changes in the composition of lignin oligomers. The increase in the production of large lignin oligomers observed by UV fluorescence and the reduction of char yield with vacuum confirm the importance of oligomeric combination reactions to form large polyaromatic structures in the liquid intermediate. For hybrid poplar, lowering the pressure from 1000 mbar to 4 mbar decreased the char yield from 19 to 7% and enhanced production of heavy sugars (cellobiosan and cellotriosan). ICR-MS results clearly show the importance of dehydration reactions in the liquid intermediate. Lowering the pressure also enhanced production of CO, CO₂, and methane due to heterogeneous catalysis by residual alkali and alkaline earth metals in the solid wood matrix. However, it also decreased production of levoglucosan from 10 to 6.1 wt %. The yields of levoglucosan and cellobiosan obtained for hybrid poplar were higher and lower, respectively, compared with those expected if the pyrolysis products were the result of the additive contribution of hybrid poplar constituents. This result could be explained by the tendency of lignin liquid intermediate to bubble vigorously, contributing in this way to the removal of cellulose oligomers from the liquid intermediate.

更新日期：2017-08-05

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