Enhancing pyrolysis gas and bio-oil formation through transition metals as in situ catalysts
Enhancing pyrolysis gas and bio-oil formation through transition metals as in situ catalysts
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DOI：
10.1016/j.fuel.2021.121900
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发表时间：
2021-09-17
期刊：
影响因子：
7.4
通讯作者：
Goldfarb, Jillian L.
中科院分区：
文献类型：
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作者：
Hubble, Andrew H.;Ryan, Emily M.;Goldfarb, Jillian L.
由木质纤维素材料热解产生的生物基燃料存在几个关键问题。仅一部分生物质原料转化为热解油，并且该油中仅一部分化合物代表所需的最终产品。生物油含有多种含氧化合物和芳香族化合物，其中许多会形成焦油并赋予高酸度、粘度和不稳定性。这就需要进行大量升级才能产生稳定、有价值的产品。在热解过程中加入原位催化剂可以通过促进焦油化合物的裂解和较小的呋喃和酚的形成来改善热解油。本研究探讨了原位过渡金属催化剂对纤维素热解的影响，量化了生物油成分和不凝气体产生的变化。将纤维素用浓度为 0.05 M 的六种不同金属醋酸盐湿法浸渍，并在 600 摄氏度下热解，一些样品另外在 350 摄氏度下热解。这些金属增强了脱挥发分，增加了高温和低温下的氢气产量，提高了生物油收率，同时降低了油化合物的平均分子量。事实证明，镍在产生氢气和生产更广泛的轻质生物油化合物方面是最有效的。铜在较低温度下辅助脱氢，并通过生成左旋葡萄糖烯酮和吡喃葡萄糖开始初级热解的初始阶段。这些发现揭示了金属与生物质的相互作用，并有助于不断丰富原位生物油升级知识。通过了解催化剂如何改善生物油，我们可以生产高密度且燃烧更清洁的液体燃料，以取代化石燃料的使用。
Biobased fuels resulting from the pyrolysis of lignocellulosic materials suffer from several key issues. Only a portion of the biomass feedstock is converted to pyrolysis oil, and only a portion of compounds in that oil represent desired end products. Bio-oil contains myriad oxygenated and aromatic compounds, many of which form tars and impart high acidity, viscosity, and instability. This necessitates substantial upgrading to generate a stable, valuable product. The inclusion of in situ catalysts during pyrolysis can improve the pyrolysis oil by promoting the cracking of tarry compounds and formation of smaller furans and phenols. This study examines the impact of in situ transition metal catalysts on cellulose pyrolysis, quantifying changes in bio-oil composition and non-condensable gas generation. Cellulose was wet impregnated with six different metal acetates at a concentration of 0.05 M and pyrolyzed at 600 degrees C, and some samples additionally pyrolyzed at 350 degrees C. The metals enhanced devolatilization, increasing hydrogen gas production at high and low temperatures and improved biooil yields while decreasing the average molecular weight of the oil compounds. Nickel proved to be the most effective at generating hydrogen gas and producing a wider array of light-weight bio-oil compounds. Copper aided dehydrogenation at lower temperatures and began the initial stages of primary pyrolysis by generating levoglucosenone and glucopyranose. These findings shed light on metal-biomass interactions and contribute to the growing body of knowledge of in situ bio-oil upgrading. By understanding how catalysts improve bio-oils we can generate high-density and cleaner-burning liquid fuels to displace the use of fossil fuels.