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首页> 外文期刊>ACS Sustainable Chemistry & Engineering >Characterization of Biomass Pyrolysis Oils by Diffusion Ordered NMR Spectroscopy
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Characterization of Biomass Pyrolysis Oils by Diffusion Ordered NMR Spectroscopy

机译：扩散有序NMR光谱法的生物质热解油的表征

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The complete chemical characterization of biomass pyrolysis oils (bio-oil) is challenging because they are a complex mixture of numerous compounds containing many functional groups and have a large molecular weight range. Gas chromatography is a very effective method for detailing the chemical composition of the volatile portion of the bio-oil, but the chemical characterization of the higher molecular weight portions remains challenging. Advances have been made using NMR to get a broader picture of the chemical makeup of the biooils, but the manner in which the various functional groups or chemical classes are distributed over molecules often requires prior tedious separation. Herein, diffusion ordered ~1H NMR is applied to three biomass pyrolysis oils produced from switchgrass at temperatures of 500, 600, and 700 °C. Diffusion NMR provides a plot of the ~1H NMR spectra resolved on the basis of their molecular diffusivity, which can be used to estimate the molecular weight of the compound. Furthermore, quantification of the relative signal intensity from the diffusion NMR experiments allows for comparison of how various functional groups are distributed over the estimated molecular weight ranges. In this work, diffusion NMR has provided a detailed comparison of these bio-oils. It reveals that carbohydrates are present mostly as monosaccharides, disaccharides, and trisaccharides but their relative proportions are temperature dependent. It also indicates that the aromatics in 500 and 600 °C samples primarily consist of pyrolytic lignin, most of which exists as dimeric or trimeric phenolic units. In contrast, the 700 °C sample is shown to consist mostly of polyaromatic hydrocarbons (PAH) containing two or three rings, but PAHs with up to eight rings may be present. A detailed comparison of the three bio-oils based on the quantitative chemical information gained via diffusion NMR is presented in this manuscript.
机译：生物质热解油（生物油）的完全化学表征是挑战性的，因为它们是含有许多官能团的许多化合物的复杂混合物并且具有大的分子量范围。气相色谱是一种非常有效的方法，用于详细说明生物油的挥发性部分的化学成分，但较高分子量部分的化学表征仍然挑战。使用NMR进行了进展，以获得更广泛的生物化学化妆品的化妆品，而是各种官能团或化学类分布在分子上的方式通常需要先前繁琐的分离。在此，将〜1H NMR的扩散〜1H NMR施加到从500,600和700℃的温度下的SwitchGrass生产的三种生物质热解油。扩散NMR在其分子扩散率的基础上提供〜1H NMR光谱的曲线图，其可用于估计化合物的分子量。此外，来自扩散NMR实验的相对信号强度的定量允许比较各种官能团的分布在估计的分子量范围内。在这项工作中，扩散NMR提供了这些生物油的详细比较。它揭示了碳水化合物主要作为单糖，二糖和三糖存在，但它们的相对比例是温度依赖性。它还表明500和600°C样品中的芳烃主要由热解木质素组成，其中大部分是二聚体或三聚酚类单位。相反，700℃样品显示主要由含有两个或三个环的多芳芳烃（PAH）组成，但是可以存在高达八环的PAHS。在该稿件中提出了基于通过扩散NMR获得的定量化学信息的三种生物油的详细比较。

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