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用草酸高铁铵浸渍NaY沸石,并在高温下焙烧,得到α-Fe_2O_3/NaY沸石体系。经XRD相定量外推法测定,α-Fe_2O_3在NaY沸石上的最大分散量为0.060gα-Fe_2O_3/gNaY,仅占α-Fe_2O_3在沸石表面密置单层量的5.5%。首次尝试用正电子寿命谱方法测定α-Fe_2O_3在沸石表面的最大分散量,所得结果与XRD方法完全吻合。由程序升温还原方法发现沸石上α-Fe_2O_3的还原分两步进行,α-Fe_2O_3先还原成Fe_3O_4,然后再还原成金属。α-Fe_2O_3分散相与沸石之间的强相互作用,使这两个还原反应受到阻抑。
NaY zeolite was impregnated with ammonium iron oxalate and calcined at high temperature to obtain α-Fe 2 O 3 / NaY zeolite system. The maximum dispersion of α-Fe_2O_3 on NaY zeolite was 0.060gα-Fe_2O_3 / gNaY by XRD phase quantitative extrapolation method, accounting for 5.5% of the single-layer density of α-Fe_2O_3 on zeolite surface. The first attempt to determine the maximum dispersion of α-Fe 2 O 3 on the surface of zeolite by positron lifetime spectroscopy is in good agreement with the XRD method. Reduction of α-Fe 2 O 3 on the zeolite was found in two steps by temperature-programmed reduction. The α-Fe 2 O 3 was first reduced to Fe 3 O 4 and then reduced to metal. The strong interaction between the α-Fe 2 O 3 disperse phase and the zeolite makes these two reductions to be suppressed.