| 氟离子与磺化反应改性多壁纳米碳管催化剂的制备、表征及催化酯化反应合成油酸甲酯性能 | |
| Sulfonation Reaction and F--Modified Multi-wall Carbon Nanotubes Catalyst: Preparation, Characterization and Performance in the Esterification Reaction for the Synthesis of Methyl Oleate | |
| 摘要: 通过高温浸渍法，对多壁纳米碳管进行了氟离子与浓硫酸磺化反应修饰改性处理，制备了一种新型Lewis酸型催化剂F--SO42-/MWCNTs，并通过透射电镜、拉曼光谱、X射线光电子能谱、吡啶吸附红外光谱、X射线荧光光谱、X射线衍射和NH3程序升温脱附等表征手段对其的物理化学性能进行了表征分析，进而对多壁纳米碳管经F-与浓硫酸磺化反应修饰改性后所出现的结构与催化性能变化的内在影响规律进行了探索。以F--SO42-/MWCNTs为催化剂，以甲醇和油酸为原料，对其在应用于催化酯化反应合成油酸甲酯过程中的活性进行了研究。结果表明：当反应温度为65℃、醇油物质的量之比为12：1、催化剂质量占反应物总质量的0.9%、反应时间为6 h，油酸的转化率最高，达到了90%。高催化活性可归因于随着氟元素的加入，提高了SO42-的插层作用效果，从而增加了酸性活性位的数量；此外，S=O键具有电子诱导效应，而F-有强负电性，两者之间发生强烈的相互作用后形成了F-S键，使S=O的吸电子效应大幅度增强，从而加剧了F--SO42-/MWCNTs催化剂的体系电荷不平衡趋势，导致催化剂中的正电荷过剩，使催化剂中的酸性活性位以Lewis酸为主，有效的避免了单纯磺化反应作用所生成的催化剂的酸性活性位以Brönsted酸型为主，而易在富含水的反应介质中发生水合作用而降低，甚至失去催化活性的现象发生。 | |
| 关键词: 催化剂 纳米碳管 生物柴油 磺化反应 固体酸 | |
| 基金项目: 国家自然科学基金（No.21206062，21466013）、江西省自然科学（青年）基金计划重大项目（No.20143ACB21018）、江西理工大学清江青年英才支持计划、化学工程联合国家重点实验室（清华大学）开放课题基金（No.SKL-chE-14A04）、华中科技大学大型电池关键材料与系统教育部重点实验室开放课题基金（No.201504）资助。 | |
| Abstract: A Lewis acid-type catalyst F--SO42-/MWCNTs was prepared from the modification treatment by the F-and sulfonation reaction with concentrated sulfuric acid through high temperature impregnation method. In order to know the internal mechanisms that related with the change of the structure and catalytic performance of the MWCNTs before and after the modification treatment with the F-and sulfonation reaction, F--SO42-/MWCNTs was characterized by transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, pyridine adsorption IR spectra, X-ray fluorescence spectroscopy, X-ray diffraction and NH3 temperature programmed desorption. The catalytic activity of the F--SO42-/MWCNTs catalyst was studied from the using of it in the catalytic synthesis of methyl oleate from the esterification reaction of oleic acid and methanol. The results showed that the highest conversion rate of oleic acid was 90% when the reaction temperature was 65℃, the molar ratio of methanol to oleic acid was 12:1, the catalyst accounts for 0.9% of total mass of reactants after 6 hours. High catalytic activity can be attributed to the modification effect of F-due to it improved the efficiency of the inserted layer function of SO42-, which increased the numbers of acid active sites and strength. In addition, the S=O can produce electronic induction effect, a strong interaction was occurred between S=O and F due to F has strong electro-negativity, resulting the formation of F-S bond, which increased the S=O electron-withdrawing effect further and improved the system charge imbalance of SO42-/MWCNTs catalyst. As a result, the trend of exhibition of an excess of positive charge was increased. Hence, the acid activity sites of the F--SO42-/MWCNTs catalyst is comprised by Lewis acid type mainly. It will be favorable for the avoiding of the acid activity sites of a catalyst was mainly comprised by Brönsted when it was prepared from the sulfonation treatment alone, so the occurrence of hydration to decrease, even more to lost catalytic activity can be avoid when it was existed in a reaction medium with large amounts of water. | |
| Keywords: catalyst carbon nanotube biodiesel sulfonation reaction solid acid | |
| 投稿时间：2016-01-26 修订日期：2016-08-15 | |
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| 舒庆,侯小鹏,唐国强,刘峰生,袁红,许宝泉,张彩霞,王金福.氟离子与磺化反应改性多壁纳米碳管催化剂的制备、表征及催化酯化反应合成油酸甲酯性能[J].无机化学学报,2016,32(10):1791-1801. | |
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