硅溶胶粒径对沉淀铁催化剂费托合成性能的影响

Effects of particle size of silica sol on properties of precipitated iron catalysts for Fischer-Tropsch synthesis

在相同的制备条件下,采用相同SiO_2浓度、不同粒径的硅溶胶作为硅源制备费托合成沉淀铁Fe/Cu/K/SiO_2催化剂,考察了硅溶胶粒径对沉淀铁催化剂费托合成反应性能的影响。实验结果表明,硅溶胶的粒径在7~18 nm范围内时,硅溶胶粒径的不同会对沉淀铁催化剂的反应性能产生影响;随硅溶胶粒径的增加,催化剂的费托合成反应CO转化率明显下降。采用XRD、N_2吸附-脱附和H_2-TPR等方法表征了硅溶胶粒径对费托合成沉淀铁催化剂的织构和性能。表征结果显示,硅溶胶的粒径越小,催化剂主物相α-Fe_2O_3晶粒和比表面积越大,越有利于催化剂的还原和碳化,因而有利于催化剂CO反应性能的提高。

Fe/Cu/K/SiO_2 catalysts for the Fischer-Tropsch synthesis were prepared through precipitation from silica sol with alike silica concentration but different silica particle size. The effects of the silica sol particle size on the structure of the catalysts and their performances in the FischerTropsch synthesis were investigated by means of N_2 adsorption,XRD and H_2-TPR. It was found that the CO conversion over the catalysts was obviously decreased with increasing the silica sol particle size from 7 nm to 18 nm. It was showed that the crystal particle size and specific surface area of α-Fe_2O_3 increased with decreasing the silica sol particle size,which was beneficial to the reduction and carbonation of the catalysts,so the performances of the catalysts were improved.