溶剂强化制备生物柴油
文献类型：学位论文
| 作者 | 曾建立 |
| 学位类别 | 博士 |
| 答辩日期 | 2009-06-03 |
| 授予单位 | 中国科学院过程工程研究所 |
| 授予地点 | 过程工程研究所 |
| 导师 | 王玉春 |
| 关键词 | 生物柴油 酯交换反应 强化 共溶剂 高值化 |
| 其他题名 | Preparation of Biodiesel with Solvent Intensification |
| 学位专业 | 生物化工 |
| 中文摘要 | 油脂通过酯交换反应制备的生物柴油是优良的石化柴油替代燃料，具有可再生、环境相容性好、污染排放少、燃烧完全和使用安全等优点，是世界各国重点发展的可再生能源之一。酯交换反应中存在的醇、油传质障碍是导致酯交换反应效率低下的主要原因之一，本文采用溶剂强化的方法改善醇、油传质，提高酯交换反应速率，为开发高效、低成本价生物柴油生产工艺提供了参考。 建立了适合酯交换反应研究的高温气相色谱双内标分析方法。样品经过硅烷化处理后，在如下色谱条件下进行分析：VF-5HT毛细柱；进样口温度为350℃，分流比40:1；FID检测器温度为385℃；升温程序从150℃起，150℃保持1min后以5℃/min的速度升至190℃，再以20℃/min的速度升至370℃，在370℃保持10min。以十三酸甲酯和辛酸三甘油酯为双内标，分别对脂肪酸甲酯和甘油酯进行定量。 以四氢呋喃强化酯交换反应为对象，研究了溶剂强化下的酯交换反应特点，并建立了反应动力学模型。结果表明：溶剂强化下的酯交换反应没有明显延迟期，反应时间大大缩短，证明反应过程中的传质得到明显改善。通过计算，求出TG→DG、DG→MG和MG→ME三步反应的活化能分别为3.90MJ/mol、19.16MJ/mol和6.45MJ/mol。 筛选到一类适合于油脂酯交换反应的新型共溶剂——双醚类溶剂，并确定了二乙氧基甲烷强化酯交换反应的最佳反应条件：醇/油摩尔比为9:1，KOH浓度为6.9g/L，反应温度为25℃。在此条件下，反应7min后脂肪酸甲酯的浓度达到97.0%。 以溶剂强化为手段，建立了快速原位酯交换反应体系。通过均匀实验确定了各因素对快速原位酯交换反应的影响程度，并建立了重要因素与粗生物柴油产量、游离脂肪酸含量和脂肪酸甲酯浓度之间的数学模型。在催化剂/油摩尔比为0.5:1、醇/油摩尔比为101.39:1、溶剂/油摩尔比为57.85:1和20℃的条件下，反应13min就可以得到脂肪酸甲酯浓度和游离脂肪酸含量分别为97.7%和0.74%的粗生物柴油。与普通原位酯交换反应相比，反应时间从几个小时缩短到十几分钟，催化剂用量减少75%，甲醇减少82.3%，总溶剂体积减少32.4%，脂肪酸甲酯得率提高17.1%。 此外，对高酸值、低不饱和度脂肪酸乙酯进行了高值化研究，包括固体氧化钙降酸值和环氧化反应。向20g酸值为11.99mgKOH/g的脂肪酸乙酯加入0.5g氧化钙和0.1mL水，25℃下反应5min，酸值可降到0.2mgKOH/g以下。通过均匀实验确定环氧化反应条件为：向50g碘值为99gI2/100g的脂肪酸乙酯中加入0.2mL浓硫酸、11.61mL甲酸和24.14mL双氧水，50℃下150r/min搅拌反应2.51h。在此条件下，环氧脂肪酸乙酯的环氧值可达3.96%。 |
| 英文摘要 | Biodiesel prepared via the oil transesterification is a good substitute for fossil diesel. Biodiesel has more advantages than fossil diesel, such as being renewable and environmentally friendly, having less emissions and good combustion performances, etc. Lots of countries in the world pay more attentions to developing biodiesel. The mass transfer resistance between the oil and methanol in the transesterification is the key factor which results in lower reaction efficiency. The solvent intensification method was adopted in this study to improve the mass transfer between the oil and methanol, and increase the reaction efficiency. The results in this research were helpful to develop efficient and economical process of biodiesel production. A high temperature gas chromatography method with double internal standards was developed to analyze the products in the transesterification. Silylated sample was analyzed in a VF-5HT capillary column with the following operation parameters: injector, 350℃; spilt ratio of 40:1 ; detector, FID, 385℃; temperature raising procedure, 1 min at 150 ℃, heating at a rate of 5℃/min to 190℃, then at a rate of 20℃/min to 370℃ and holding for 10min. Methyl tridecanoate and glyceryl trioctanoate served as internal standards respectively when the quantities of FAMEs and glycerides were determined. The characteristcs of the transesterification with solvent intensification were studied by taking the tetrahydrofuran as a solvent, the kinetic model of the solvent intensified transesterification was also established. No marked delay phase was observed in the transesterification, and the reaction time was greatly shortened. Those phenomena were the results of the improvement of mass transfer in the transesterification due to the addition of the solvent. The calculated active energies of the three steps TG→DG, DG→MG and MG→ME were 3.90MJ/mol, 19.16MJ/mol and 6.45MJ/mol, respectively. A new kind of cosolvent (diether) was evaluated to intensify the transesterification between oil and methanol. The optimal conditions of transesterification intensified by diethoxymethane were as follows: molar ratio of methanol/oil, 9:1; KOH concentration, 6.9g/L; reaction temperature, 25℃. A fatty acid methyl ester concentration of 97.0% was reached after only 7 min under the above reaction conditions. By means of the solvent intensification, a rapid in situ transesterification process was established. Effects of each influence factor on the in situ transesterification were studied by a series of uniform design experiments. The models reflected the mathematical relationship of several important factors and three responses, including crude biodiesel yield, FFA content and FAME concentration, were also deduced based on the uniform design experiments. A product containing 97.7% FAME and 0.74% FFA was obtained in only 13min when the molar ratio of catalyst/oil was 0.5:1, the molar ratio of methanol/oil was 101.39:1, the molar ratio of DEM/oil was 57.85:1, the agitation speed was 150 r/min, and reaction temperature was 20℃. Compared with the in situ transesterification without any solvent intensification, the reaction time was shortened from several hours to 13min; the catalyst amount, the methanol volume and the total solvent volume used in the reaction were reduced by 75%, 82.3% and 32.4%; while the FAME yield was increased by 17.1%. In addition, value-increments (include reducing the acid value and epoxidation) of the fatty acid ethyl ester with high acid value and low unsaturated degree were investigated. When 0.5g CaO and 0.1ml H2O were added into 20g ethyl ester, and reacted for 5min at 25℃, the acid value was reduced from 11.99mgKOH/g to less than 0.2mgKOH/g. Epoxy fatty acid ethyl ester with the epoxy value of 3.96% was prepared under the following optimal epoxidation conditions determined by uniform design experiments: 50g fatty acid ethyl ester (iodine value = 99gI2/100g), 0.2mL sulfate acid, 11.61mL formic acid and 24.14mL hydrogen peroxide, 2.51h reaction at the agitation speed of 150r/min at 50℃. |
| 语种 | 中文 |
| 公开日期 | 2013-09-13 |
| 页码 | 148 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1256]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 曾建立. 溶剂强化制备生物柴油[D]. 过程工程研究所. 中国科学院过程工程研究所. 2009. |
入库方式： OAI收割
来源：过程工程研究所
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