乙酰丙酮盐催化甲苯液相氧化制苯甲醛的研究

Preparation of Benzaldehyde by Aerobic Liquid-Phase Oxidation of Toluene with Co(acac)_2

以Co(acac)2为催化剂,研究其对甲苯液相空气氧化制苯甲醛的催化性能;考察了反应时间、反应温度、催化剂用量、钴锰配比等对苯甲醛浓度和收率的影响。结果表明,甲苯液相氧化反应是一平行连串的复杂反应,在反应初期(低甲苯转化率时),苯甲醛生成速率快、反应液中苯甲醛浓度迅速升高,之后趋于一稳定值,浓度变化不大,但因苯甲醛易被深度氧化生成苯甲酸,苯甲醛收率随着转化率提高而下降。反应温度对苯甲醛浓度和收率影响甚微。与醋酸钴、环烷酸钴等催化剂相比,Co(acac)2催化剂具有催化剂用量较小和腐蚀作用较轻的优点,适当添加Mn(acac)2有利于提高苯甲醛的收率。

The preparation of benzaldehyde by aerobic liquid-phase oxidation of toluene using Co（acac）2 asthe catalyst was investigated. The effects of operation parameters, such as reaction time, reaction temperature,concentrations of Co, Co/Mn ratio were studied. The results show that the oxidation of toluene is a multiplereaction process with parallel and series reaction steps. The concentration of benzaldehyde increases fastly inthe initial reaction stage （low toluene conversion）, and then reaches a steady value. However, the yield ofbenzaldehyde decreases significantly with further toluene conversion because benzaldehyde is easier to befurther oxidized to benzoic acid. Reaction temperature change has little effect on the concentration and the yieldof benzaldehyde. Compared with cobalt acetate and cobalt naphthenate catalysts, cobalt acetylacetonateCo（acac）2 has a better catalytic effect with less amount needed. The addition of Mn（acac）2 as a co-catalyst isfavorable for enhancing the reaction yield.