制备邻苯基苯酚的Cu-MgO催化剂失活研究

目的]探讨引起Cu-MgO催化剂失活的微观因素。方法]采用共沉淀法制备Cu-MgO催化剂,并采用XRD、BET、NH3-TPD、CO2-TPD、H2-TPD、失重等手段对失活前后的Cu-MgO催化剂进行了表征。结果]Cu-MgO催化剂对环己烯基环己酮脱氢制备邻苯基苯酚(OPP)有较高的活性,双聚的初始转化率达到99%以上,OPP的选择性达到95%以上,但其催化性能随运转时间的延长呈逐渐下降趋势。表征结果显示,在反应条件下催化剂上Cu原子和MgO随运转时间的延长明显聚集长大,导致Cu与MgO之间作用力减弱,氢吸附能力和碱量降低;催化剂表面积炭,改变了催化剂比表面积和孔结构,从而使催化剂活性和选择性下降。结论]为抑制催化剂失活的研究奠定了基础。

Studies on Deactivation of Cu-MgO Catalyst for Preparing O-phenylphenol

Objective] The aim was to study micro-factors to cause the deactivation of Cu-MgO catalysts.Method] Cu/MgO catalysts used for the synthesis of O-phenylphenol(OPP) were prepared by the precipitation method,furthermore the catalysts were characterized by XRD,BET,H2-TPD,NH3-TPD,CO2-TPD techniques and thermo-gravimetric.Result] The Cu/MgO catalysts showed high activity for the synthesis of OPP.The conversion of o-cyclohexenyl cyclohexanone and yield of OPP reached its maximum of 99% and 95%,but Cu/MgO catalysts was deactivated with the reaction carried through.Characterization results showed that the deactivation may contribute to the growth of crystalline sizes of Cu and MgO,the decrease of interaction between Cu and MgO,the decrease of adsorption capacity to H2 and the change of surface acid-base properties.On the other hand,the surface carbon deposition lead to the decrease of surface area and the increase of average pore size,which may also cause the deactivation of Cu/MgO catalysts.Conclusion] The research result lays the foundation for studies on inhibiting the deactivation of Cu-MgO catalysts.