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本文系统考察了镧系14种稀土氧化物对烯烃歧化催化剂MoO_3/SiO_2的影响,发现其中多数均可使催化剂的寿命延长,并以Tb及Pr的效果最佳,其稳定时间可达未改性时的1.6倍。主要原因是稀土添加剂有抑制积炭的能力和缩短催化剂的增活期(为未改性的40％～75％)。通过ESR表征,从本质上阐明了Tb_4O_7的作用在于促进了歧化活性中心——挠动四棱锥结构的Mo~(5+)值的增长。在增活期过程中,活性物种前体的减少服从一级反应力学规律。
In this paper, we systematically investigated the influence of lanthanum series 14 rare earth oxides on the olefin disproportionation catalyst MoO_3 / SiO_2 and found that most of them can prolong the life of the catalyst, and the best effect of Tb and Pr, the stabilization time up to unmodified When 1.6 times. The main reason is the rare earth additives have the ability to inhibit carbon deposition and shorten the catalyst activation period (40% to 75% unmodified). Through the ESR characterization, it is clarified that the role of Tb_4O_7 is to promote the growth of the Mo 5+ value of the disproportionation active center-flexible tetrapod structure. During the period of increase, the reduction of active species precursors obeys the first-order reaction mechanics law.