Ni/AC催化剂上甲醇羰化制醋酸反应机理热力学分析

在研究Ni/AC催化剂上甲醇常压气相羰基化制醋酸的基础上 ,结合甲醇液相羰基化和加压情况下气相羰基化的反应情况 ,对常压气相羰基化制醋酸体系进行热力学分析 ,探讨该体系的反应途径和机理。结果表明 ,反应体系中可能存在的中间态CH3 CO -Ni2 + -I不会被直接还原为零价Ni而释放出乙酰碘 ,所有的羰基化反应都通过该中间态进行 ;除醋酸甲酯水解途径外 ,也存在由甲醇与CH3 CO -Ni2 + -I直接作用生成醋酸的可能性 ;二甲醚的产生并非通过甲醇与碘甲烷直接发生反应 ,而主要是在碘甲烷和活性炭的共同催化作用下在活性炭载体上通过甲醇脱水反应实现 ,Ni也起到一部分催化作用。体系的热力学分析表明 ,进料中加入水蒸气有望促进目的产物醋酸的生成

Thermodynamic analysis on vapor-phase carbonylation of methanol to acetic acid over Ni/AC catalyst

On the basis of experiments, thermodynamic analysis for vapor phase carbonylation of methanol to acetic acid over Ni/AC catalyst at atmospheric pressure, with referring to the liquid phase and pressurized vapor phase carbonylation path and mechanism, was carried out, and the path and mechanism of the system were discussed. It is shown that the possible intermediate CH 3CO-Ni 2+ -I species can not be reduced directly to zero valent nickel to release acetyl iodide, and all carbonylation steps may be implemented through CH 3CO-Ni 2+ -I species. Besides methyl acetate hydrolysis,the direct reaction between methanol and CH 3CO-Ni 2+ -I species may also play a role in the formation of acetic. Dimethyl ether is mainly produced over the activated carbon carrier through the dehydation of methanol which is catalyzed by both activated carbon and methyl iodide with catalytic step of nickel, but not through the direct reaction between methanol and methyl iodide. The thermodynamic analysis of the system suggests that the productivity of acetic acid would be improved when water steam is added into the feed flow of the system.