醋酸对环己烷气相氧化脱氢产物选择性影响的研究

Effects of Acetic Acid on Product Selectivity in Gas Phase Oxidative Dehydrogenation of Cyclohexane

以α1-VOPO4相为催化剂,在环己烷气相氧化脱氢反应中,通过在原料中加入醋酸可控制反应产物的分布.研究了不同醋酸量对目标产物选择性的影响,醋酸在反应体系中优于环己烷吸附在α1-VOPO4催化剂的表面上,使催化剂表面形成孤立的活性中心,避免了产物环己烯的深度氧化.反应温度为450℃,醋酸与环己烷的摩尔比为12.9∶1时,环己烷的转化率为6.9%,环己烯的选择性为100%.

The effect of adding acetic acid on the product distribution in gas phase oxidative dehydrogenation of cyclohexane over α1-VOPO4 catalyst was investigated. The role of acetic acid in the reaction process was put forward. The proposed mechanism is that acetic acid take precedence of cyclohexane adsorbing on the active sites of α1-VOPO4 catalyst to form isolated active site. Thus, cyclohexene species can desorb quickly from the active sites, avoiding its deep oxidation dehydrogenation. Almost 100% selectivity to cyclohexene could be obtained when the molar ratio of acetic acid to cyclohexane was 12. 9： 1 at 450 ℃, the conversion of cyclohexane was 6. 9%.