| Summary: | 碩士 === 義守大學 === 生物技術與化學工程研究所碩士班 === 98 === Room-temperature ionic liquids (RTILs) are now commonly defined as organic salts which melt below 373.15K. The RTILs, a reaction media with very low vapor pressure, peculiar physicochemical properties, and selective solubility towards many organic and inorganic substances, have attracted growing interest. Therefore, we do use it in this as solvent and catalyst.
The kinetics of CO2 fixation reaction with cyclohexylamine to produce 1,3- dicyclohexylurea was investigated. The reaction is conducted under catalysis of [BMIM][Br], [BMIM][Br]/KOH, KOH, KBr or [BMIM][OH], and found that [BMIM][Br]/KOH is the most active, while KOH and KBr have no activity. The influence of reaction parameters, reaction time (2~8 hr), temperature (130~160 ℃), pressure (10~50 Bar), on the fixation reaction was studied by using ionic liquid “[BMIM][Br] as solvent and catalyst, and KOH as cocatalyst. It was found that the conversion was increased with the increase of reaction time, temperature, and pressure. When the reaction time was 6 hrs, temperature at 150~160℃and 30 Bar, the conversion of urea reached as high as 63%. The kinetic data also show that it is a first order dependence of the rate with respect to the cyclohexylamine concentration; the rate are 0.0742 hr-1, 0.0984 hr-1, 0.1177 hr-1 at 120℃, 130℃, 150℃ with 20 Bar of CO2; the activation energy is 4.821 kcal/mol. A reaction mechanism is also proposed.
|
|---|
