碳六烃气相氧化裂解制低碳烯烃

对不同链结构的碳六烃(苯、正己烷、环己烷)的气相氧化裂解(GOC)制烯烃过程进行了研究。研究结果表明,氧气的存在降低了碳六烃GOC反应的活化能,GOC反应在较低的反应温度下具有高的反应性能;氧气同时起到消除积碳的作用。苯的GOC反应更容易发生生成CO的部分氧化反应,而不易发生生成低碳烯烃的裂解反应。环己烷的GOC反应具有高的开环裂解活性,在较低的反应温度下具有高的烯烃收率;其裂解机理与正己烷相似,氧气不仅参与六元环脱氢的链引发过程,也参与开环裂解的链传递过程。在正己烷和环己烷的GOC反应中,氧气低温下主要参与氧化脱氢反应,高温下则更多地参与COx的生成反应;在苯的GOC反应中,氧气主要参与烃的部分氧化反应生成CO。

Production of Lower Alkenes by Gas Phase Oxidative Cracking of C6 Hydrocarbons

Gas phase oxidative cracking(GOC)of benzene had higher reactivity and decoking ability than those of relevant pyrolysis.Benzene GOC produced more CO than lower alkenes.Oxygen showed high ability in ring opening of cycloalkane.High yield of lower alkene could be obtained at lower temperature in GOC of cycloalkane.Oxygen played an important role not only in initiation of cyclohexane dehydrogenation but also in its subsequent cracking to low alkenes(or alkanes),which was similar to cracking of n-hexane in mechanism.For GOC of n-hexane or cyclohexane,oxygen primarily participated in oxydehydrogenation at lower temperature,while it mostly participated partial oxidation reaction at higher temperatures and produced CO_x(x=1,2).Benzene was largely partially oxidized by oxygen into CO in GOC.