In chemical production process, acetic acid is a kind of important organic rawmaterial, there are many kinds of production technology. It roughly experienced cobalt-iodine catalytic system to the rhodium-iodine catalytic system and then to the iridium-iodine catalytic system. Each catalytic system has its unique advantages and there arealso many shortages, the study of the reaction mechanism will enable to find theinsufficient place for the researchers, then we can improve the catalytic system which ismore conducive to the reaction system. Low-pressure carbonylation method (pressurefor3-6Mpa, temperature is150-200℃) mainly have rhodium-iodine catalytic systemand iridium-iodine catalytic system. After a large number of experimental andtheoretical researches, both of the two catalytic cycle mechanism of the methanolcarbonylation composed of the following elementary reactions: CH3I oxidative addition,carbonyl rearrangement, CO coordination and CH3COI reductive elimination, the onlydifference is the speed control step.Adding different additives in methanol carbonylation reaction is also a researchemphasis for this kind of reaction. Room temperature ionic liquids are widely used asreaction medium, catalyst, solvent separation and so on due to their a series ofadvantages such as low volatility, high thermal stability, low vapor pressure, goodsolubility for most inorganic or organic matter, and the adjustable acidity. Early researchhas shown that different ionic liquid have different effects in the reaction of producingacetic acid by methanol carbonylation which catalyzed by iridium-iodine catalyticsystems. By join the ionic liquid which contains Tf2N anion in the iridium-iodinecatalytic system can greatly improve the selectivity of acetic acid while other ionicliquids get the opposite result. For purpose of explaining the results of previous researchand get a better understanding of the catalytic mechanism within ionic liquids, thefollowing researches were done.①Firstly, we analyzed the catalytic role of the different kinds of ionic liquids fromthe physical properties aspect in the process of low-pressure liquid methanolcarbonylation to acetic acid. The result shows that the ionic liquid which contains Tf2Nanion can increase the solubility of carbon monoxide in it and the mutual contactionbetween the reactants.②After that we used the characterization methods like Infrared, Nuclear Magnetic, Ultraviolet and Fluorescence to study the interaction between Tf2N anion and theoriginal material in the iridium-iodine catalytic system and preliminarily determinesthe configuration of the new active intermediates which involved ionic liquid[Bmim]Tf2N in the methanol carbonylation.③Finally, we calculated the change of the reaction energy barrier of the fast stepthat is the methyl migration into step in the methanol carbonylation to acetic acid withinor without ionic liquid, the calculation results show that the energy barrier reducedgreatly in the new primitive reaction within Tf2N anion. And infer the whole mechanismof the catalytic cycle involved Tf2N anion by the calculated results.On the other hand, rare earth metal halide salts and rare earth metal complexes asmetal additives were added to the methanol carbonylation reaction to explore the effectof rare earth metal compounds on the product catalyzed by iridium or non-iridiumcatalytic system of liquid-phase methanol carbonylation reaction and simply expoundtheir role in the reaction mechanism. |