工业条件下铁钼氧化物催化剂上甲醇氧化反应的复杂振荡

在工业条件下，观察到甲醇在Ｆｅ２（ＭｏＯ４）３－ＭｏＯ３催化剂上的氧化反应发生强烈的自振荡，反应温度及尾气成分呈现周期性变化。振荡参数与反应温度、进料流速以及原料气中甲醇浓度有关，但不受原料气中氧浓度的影响，用原位红外技术检测到ＭｏＯ３及Ｆｅ２（ＭｏＯ４）３中Ｍｏ＝Ｏ双键的振荡有着不同的相位，说明振荡过程伴随着晶格氧的转移及金属离子价态的变化。这些变化造成反应速度的负反馈，从而产生振荡。用多种手段研究了铁和铂之间的协同效应，并提出了协同作用机理及避免振荡的措施。

Complicated Oscillation in the Oxidation Reaction of Methanol over MoO_3-Fe_2(MoO_4)_3 Catalyst under Commercial Working Conditions

Strong self-oscillation phenomena were observed in methanol oxidation over a MoO3-Fe2(MoO4)3 catalyst under the commercial working conditions. The periodical variations of the effluent composition as well as the reaction temperature were monitored. Experimental results indicated that the oscillation parameters were related to the reaction temperature, the flow rate of the feed mixture and the methanol content in feed, but were not affected by the oxygen content in feed. The oscillation of the Mo=O double bonds of MoO3 and Fe2(MoO4)3 was also observed by in-situ IR. The oscillation phases of the bonds in the two compounds were different. which means that the oscillation is accompanied by a reciprocating transfer of lattice oxygen and a fluctuating variation of the valent state of Mo and Fe. These changes taking place within the catalyst cause a feedback to the reaction rate and result in the oscillation. The synergetic effect between Mo and Fe was also studied by means of laser Raman spectroscopy. XRD, SEM and IR, and a mechanism concerning this effect has been proposed. Finally. the measures to prevent the oscillation are discussed.