助催化剂对Fe1-xO基费托合成催化剂性能的影响

考察了助催化剂对Fe_1-xO基合成熔铁催化剂反应性能的影响，并通过XRD和TPD对催化剂进行表征。结果表明，MnO可以使产物中甲烷选择性降低，低碳烯烃的选择性增加，（CO＋H₂）转化率下降。稀土氧化物M₂O₃(M=La、Nd、Pu等)的加入，产物中甲烷的选择性降低，低碳烯烃的选择性增加，C₅^＋选择性增加。对于熔铁催化剂，较少量M₂O₃(质量分数为0.5％～1.0％)的加入可以使甲烷选择性由21.1％降到14.84％，低碳烯烃收率由31.20 g·m^-3升高到40.91 g·m^-3，C₅^＋收率由45.52 g·m^-3升高到59.61 g·m^-3，但是较多量M₂O₃(质量分数为1.5％)的加入，（CO^＋H₂）转化率大幅下降，（CO＋H₂）转化率仅为30.29％。XRD结果表明，加入MnO，Mn²⁺部分取代了较大离子半径的Fe²⁺的位置，晶胞参数变大；M₂O₃的加入，形成了新的晶相。TPD结果表明，低温脱附峰的面积在添加MnO或M₂O₃后明显减少，催化剂表面活性中心数目减少。

Effect of promoters on reaction performance of Fischer-Tropsch synthesis over Fe1-xO-based fused iron catalyst

The effects of MnO and M₂O₃ promoters on Fischer Tropsch synthesis behaviors over Fe_1-xO Based fused iron catalyst was investigated by means of CO hydrogenation, XRD and CO TPD techniques. The results showed that selectivity tomethane decreased，CO+H₂ conversion decreased, and selectivity to light olefins increased with the addition of MnO. Selectivity to methane decreased from 21.18% to 18.84%,light olefins yield remarkably increased from 31.20 g·mm^-3 to 40.91 g·mm^-3, and CC₅^＋ yield increased from 45.52 gmm to 59.61 g·mm^-3 with the addition of 0.5%-1.0wt％ rare earth oxide of M₂O₃(M=La,Nd,Pu,etc).However, CO+H₂ conversion declined to 30.29％with the addition of 1.5wt％M₂O₃. XRD results indicated that, with the addition of MnO, Mn²⁺ replaced Fe²⁺ in the lattice of Fe_1-xO, and lattice parameter of Fe_1-xO increased. New crystalline phase formed with the addition of M₂O₃. CO TPD results indicated that the area of desorption peak observably decreased with the addition of M₂O₃ or MnO.