B_2O_3/TiO_2-ZrO_2催化环己酮肟气相Beckmann重排反应的研究 Ⅲ.反应条件的影响

Study on Vapor-Phase Beckmann Rearrangement of Cyclohexanone Oxime over B_2O_3/TiO_2-ZrO_2 Catalyst Ⅲ. Effect of Reaction Conditions

对B2 O3 /TiO2 ZrO2 催化环己酮肟气相Beckmann重排制己内酰胺的反应条件进行了优化研究 ,系统考察了反应温度、原料空速、载气及其流速和稀释剂等对催化剂催化性能的影响 .结果表明 ,当反应温度为 30 0℃、环己酮肟的重时空速(WHSV)为 0 33h-1、氮气为载气 (流速 30ml/min)及乙腈为稀释剂时 ,B2 O3 /TiO2 ZrO2 催化剂的催化性能最佳 ,连续反应 6h ,环己酮肟的转化率为 10 0 % ,己内酰胺的选择性高达 98 6 % .

The effects of reaction conditions such as reaction temperature, weight hourly space velocity (WHSV), carrier gas and its flow rate, and diluting solvent on the catalytic performance of the B 2O 3/TiO 2-ZrO 2 catalyst in the vapor-phase Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam were studied. With increasing reaction temperature the oxime conversion increased. The maximum caprolactam selectivity and yield were obtained at a reaction temperature of 300 ℃. A decrease in oxime conversion and an increase in caprolactam selectivity were observed with the increase in WHSV of the feed and the flow rate of the carrier gas. Polar diluting solvents gave higher selectivity and yield of caprolactam and lower deactivation rate than nonpolar diluting solvents. The optimal operating conditions were as follows: reaction temperature 300 ℃, WHSV 0.33 h -1, nitrogen as carrier gas (flow rate 30 ml/min), and acetonitrile as diluting solvent. Under these conditions, the B 2O 3/TiO 2-ZrO 2 catalyst showed very high catalytic efficiency for the vapor-phase Beckmann rearrangement of cyclohexanone oxime. The complete oxime conversion was achieved with a caprolactam selectivity of 98.6% after reaction for 6 h.