酸性离子液体在乙醇脱水反应中的应用

以浓硫酸和几种酸性离子液体为催化剂,对乙醇脱水制乙烯反应进行了研究。探讨了催化剂类型、反应温度、乙醇流量等因素对反应的影响。实验结果表明,180℃时,以酸性离子液体1-丁磺酸基-3-甲基咪唑硫酸氢盐(HSO3-BMIM]HSO4)为催化剂,乙醇的转化率(73.8%)及乙烯的选择性(86.6%)与浓硫酸为催化剂时相似,而酸性较弱的离子液体催化乙醇脱水反应的效果较差。在120～220℃范围内,HSO3-BMIM]HSO4催化乙醇脱水反应时乙醇转化率及乙烯选择性随反应温度的升高而增加;在一定的乙醇流量范围(1.0～8.0mL/h)内,反应温度为180℃时乙醇转化率及乙烯选择性随乙醇流量的增大而降低,而在220℃时,乙醇转化率及乙烯选择性则变化不大,反应200h内乙醇转化率及乙烯选择性都保持在96%以上。

Dehydration of Ethanol Catalyzed by Acidic Ionic Liquid

Dehydration of ethanol was carried out with H2SO4 and several acidic ionic liquids as catalysts separately. Effects of catalyst type,reaction temperature and feed flow rate on the reaction were studied. The catalytic activity of Brnsted acid ionic liquid 1-(4-sulfonic acid) butyl-3-methylimidazolium hydrogen sulfate(HSO3-BMIM]HSO4) is similar to H2SO4. Conversion of ethanol and selectivity to ethylene were 73.8% and 86.6% respectively at 180 ℃. However,acidic ionic liquids with weaker acidities are lower in catalytic activity. By using HSO3-BMIM]HSO4 as catalyst,conversion of ethanol and selectivity to ethylene increase with rising of reaction temperature within the range of 120-220 ℃. At 180 ℃ when flow rate of ethanol increases from 1.0 mL/h to 8.0 mL/h,both conversion of ethanol and selectivity to ethylene decrease,but at 220 ℃ the change of them are not so obvious,so reaction temperature is the dominant factor. Catalytic activity of ionic liquid HSO3-BMIM]HSO4 can keep steady for a long period at 220 ℃. Conversion of ethanol and selectivity to ethylene both stand at 96% or above after reaction for 200 h.