State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074, PR China.
Shenzhen Huazhong University of Science and Technology Research Institute, Shenzhen 523000, China.
Environ Sci Technol. 2021 May 4;55(9):6373-6385. doi: 10.1021/acs.est.1c00676. Epub 2021 Apr 12.
Algae pyrolytic bio-oil contains a large quantity of N-containing components (NCCs), which can be processed as valuable chemicals, while the harmful gases can also be released during bio-oil upgrading. However, the characteristics of NCCs in the bio-oil, especially the composition of heavy NCCs (molecular weight ≥200 Da), have not been fully studied due to the limitation of advanced analytical methods. In this study, three kinds of algae rich in lipids, proteins, and carbohydrates were rapidly pyrolyzed (10-25 °C/s) at different temperatures (300-700 °C). The bio-oil was analyzed using a Fourier transform ion cyclotron resonance mass spectrometer equipped with electrospray ionization, and the characteristics and evolution of nitrogen in heavy components were first obtained. The results indicated that the molecular weight of most heavy NCCs was distributed in the 200-400 Da range. N compounds account for over 60% in lipid and protein-rich samples, while N and N components are prominent in carbohydrate-rich samples. As temperature increases, most NCCs become more aromatic and contain less O due to the strong Maillard and deoxygenation reactions. Moreover, the heavier NCCs were promoted to form lighter compounds with more nitrogen atoms through decomposition (mainly denitrogenation and deoxygenation). Finally, some strategies to deal with the NCCs for high-quality bio-oil production were proposed.
藻类热解生物油含有大量含氮成分（NCC），可作为有价值的化学物质进行加工，而在生物油升级过程中也会释放有害气体。然而，由于先进分析方法的限制，生物油中 NCC 的特性，特别是重 NCC（分子量≥200Da）的组成，尚未得到充分研究。在这项研究中，三种富含脂质、蛋白质和碳水化合物的藻类以不同的温度（300-700°C）快速热解（10-25°C/s）。利用配备电喷雾电离的傅里叶变换离子回旋共振质谱仪对生物油进行分析，首次获得了重质成分中氮的特性和演变。结果表明，大多数重质 NCC 的分子量分布在 200-400Da 范围内。脂质和富含蛋白质的样品中 N 化合物含量超过 60%，而富含碳水化合物的样品中 N 和 N 化合物则更为突出。随着温度的升高，由于强烈的美拉德和脱氧反应，大多数 NCC 变得更加芳香，含氧量减少。此外，较重的 NCC 通过分解（主要是脱氮和脱氧）促进形成含更多氮原子的较轻化合物。最后，提出了一些处理 NCC 以生产高质量生物油的策略。
