Alkaline in situ transesterification of Chlorella vulgaris
Alkaline in situ transesterification of Chlorella vulgaris
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DOI：
10.1016/j.fuel.2011.11.045
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发表时间：
2012-04-01
期刊：
影响因子：
7.4
通讯作者：
Harvey, A.
中科院分区：
文献类型：
--
作者：
Velasquez-Orta, S. B.;Lee, J. G. M.;Harvey, A.
藻类生物质中的脂质的原位酯交换或“反应性提取”具有极大地简化藻类生物柴油的生产并降低其成本的潜力，因为其通过使生物质直接与将脂质转化成其烷基酯（生物柴油）所需的醇和催化剂接触来减少单元操作的数量。进行实验设计以了解工艺变量在由小球藻微藻生产脂肪酸甲酯（FAME）中的影响。三个过程变量（催化剂的比例，溶剂的比例和反应时间）进行了研究，基于他们的过程意义。使用0.15：1的催化剂：脂质（NaOH）摩尔比和600：1的甲醇：脂质摩尔比，在75分钟的反应时间下获得77.6 +/-2.3重量%的最大FAME回收率。在最佳甲醇比率（600：1）下进行另外的实验以比较使用碱性催化剂与酸性催化剂获得的结果。在时间方面，碱性催化剂（氢氧化钠）优于酸性催化剂（硫酸），在较低的反应时间获得较高的转化率。然而，使用0.35：1的酸催化剂比率进行更长的反应时间导致更高的转化率，高达96.8 +/-6.3wt%，并且可能促进微藻细胞壁的破裂。总之，藻类生物质的碱性原位酯交换可以在比酸催化剂更短的时间内实现高转化率，使用更低的催化剂比例。催化剂类型的最终选择将取决于原位酯交换的特性（间歇与连续）和成本（包括催化剂和甲醇成本）以及获得可销售的生物柴油所需的下游工艺。(C)2011爱思唯尔有限公司保留所有权利。
In situ transesterification, or "reactive extraction", of lipids in algal biomass has the potential to greatly simplify and reduce costs of the production of algal biodiesel, as it reduces the number of unit operations by contacting the biomass directly with the alcohol and catalyst required to convert lipids to their alkyl esters (biodiesel). A design of experiments was conducted to understand the impact of process variables in the production of Fatty Acid Methyl Ester (FAME) from Chlorella vulgaris microalgae. Three process variables (catalyst ratio, solvent ratio and reaction time) were studied, based on their process significance. The maximum FAME recovery of 77.6 +/- 2.3 wt% was obtained at a reaction time of 75 min, using a catalyst: lipid (NaOH) molar ratio of 0.15:1 and a methanol: lipid molar ratio of 600:1. Additional experiments were performed at the optimum methanol ratio (600: 1) to compare results obtained using an alkaline catalyst with an acid catalyst. In terms of time, the alkaline catalyst (sodium hydroxide) outperformed the acid catalyst (sulphuric acid) obtaining higher conversions at lower reaction times. Nevertheless, using an acid catalyst ratio of 0.35:1 for longer reaction times resulted in higher conversions, up to 96.8 +/- 6.3 wt%, and may have facilitated the breakage of microalgae cell walls. In conclusion, the alkaline in situ transesterification of algal biomass can achieve high conversion in less time than an acid catalyst, using a lower ratio of catalyst. The final selection of the type of catalyst will depend on the characteristics (batch vs continuous) and cost of the in situ transesterification including catalyst and methanol costs, and the downstream processes required to obtain a saleable biodiesel. (C) 2011 Elsevier Ltd. All rights reserved.