Usami Ryo, Fujii Kengo, Fushimi Chihiro
Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan.
ACS Omega. 2020 Mar 19;5(12):6684-6696. doi: 10.1021/acsomega.9b04468. eCollection 2020 Mar 31.
Bio-oil production from microalgae by using hydrothermal liquefaction (HTL) has been conducted extensively in the last decade. In this work, we conducted two-stage HTL of a microalga (, JPCC DA0580) in the presence of 5.0 g/L carbon solid acid or a 0.02-0.50 M HCl catalyst to increase bio-oil yield and nitrogen recovery into the aqueous phase (AP). The first stage (HTL 1), to hydrolyze proteins, carbohydrates, and lipids and elute nitrogen components into the AP, was conducted at 100-250 °C for 30-120 min. The second stage (HTL 2), to produce the bio-oil, was conducted at 280-320 °C for 0-30 min. The best conditions to obtain a high bio-oil yield and NH recovery in the AP were 200 °C and 30 min of residence time for HTL 1 and 320 °C and 0 min residence time for HTL 2. We found that 0.50 M HCl decreased the bio-oil yield while greatly increasing NH in the AP and decreasing the nitrogen content in the bio-oil. This was probably due to the catalytic effect of HCl promoting hydrolysis of protein and deamination of amino acids during HTL 1. The fractions of water-soluble products were greatly increased by performing HTL 2 in neutral conditions while this maintained low nitrogen content in the bio-oil. From GC-MS analyses of the bio-oil, it was observed that, by using 0.50 M HCl, peak intensities of all the GC peaks decreased and MS spectra of amines decreased. The carbon solid acid had an insignificant influence on bio-oil and NH yields.
在过去十年中，利用水热液化（HTL）从微藻中生产生物油的研究广泛开展。在本研究中，我们在5.0 g/L碳固体酸或0.02 - 0.50 M HCl催化剂存在的条件下，对一种微藻（，JPCC DA0580）进行了两阶段水热液化，以提高生物油产量并使氮回收至水相（AP）中。第一阶段（HTL 1），用于水解蛋白质、碳水化合物和脂质并将氮成分洗脱至水相中，在100 - 250 °C下进行30 - 120分钟。第二阶段（HTL 2），用于生产生物油，在280 - 320 °C下进行0 - 30分钟。在水热液化1中获得高生物油产量和水相中氨回收的最佳条件是200 °C和30分钟的停留时间，在水热液化2中是320 °C和0分钟停留时间。我们发现，0.50 M HCl降低了生物油产量，同时极大地增加了水相中的氨并降低了生物油中的氮含量。这可能是由于HCl在水热液化1期间促进蛋白质水解和氨基酸脱氨的催化作用。通过在中性条件下进行水热液化2，水溶性产物的比例大大增加，同时生物油中的氮含量保持较低。通过对生物油的气相色谱 - 质谱（GC - MS）分析观察到，如果使用0.50 M HCl，所有GC峰的峰强度都会降低，并且胺的质谱图也会减少。碳固体酸对生物油和氨产量的影响不显著。
