摘要
用原位穆斯堡尔谱和微型固定床反应器考察了Fe-Mo/SiO_2催化剂在还原、碳化和反应中的物相及费-托合成(F-T)反应性。富钼的Fe-Mo/SiO_2催化剂在550℃H_2中还原生成Fe-Mo合金,该合金在300℃合成气中碳化转化为Fe-Mo碳化物,是F-T反应中的主要物相。该催化剂的活性较高,其选择性体现了铁和钼的平均性质。富铁的Fe-Mo/SiO_2催化剂在550℃H_2中还原主要生成Fe^(2+),还有Fe-Mo合金和α-Fe,碳化时大部分转化为Fe^(3+),在F-T反应中的主要物相为Fe^(2+)及碳化铁,该催化剂的活性很低,其选择性类似于Fe-Mo/SiO_2。
The performance of Fe-Mo/SiO2 catalysts for F-T synthesis was studied. The catalysts were prepared by impregnation of SiO2 with aqueous Fe(NO3)3 and HgCPMo12O40). The iron species after reduction, carburi-zation and F-T reaction were determined by in-situ Mcssbauer speclroscopy. The reactivity of the catalysts were evaluated with a fixed bed microrea-ctor at 320℃ and 2.5 MPa in syngas. Fe-Mo alloy was formed for Mo-rich Fe-Mo/SiO2 during reduction at 550℃ in H2 and converted into Fe-Mo carbide during the carburization at 300℃in syngas. In the reaction, Fe-Mo carbide was the main phase of Mo-ricb catalyst, showing high activity and an average selectivity of Fe and Mo supported on SiO2. For Fe-rich Fe-Mo/SiO2, the reduction at 550℃in H2 resulted in the formation of mainly Fe2+, as well as Fe-Mo alloy and α-Fe, which in turn were converted into Fe3+ and iron carbide during carburization. and in the reaction, Fe2+ and a small amount of iron carbide were the main phase showing very low activity and a selectivity similar to that of Fe/SiO2.
基金
国家自然科学基金
关键词
铁
钼
双金属催化剂
费-托合成
Iron,molybdenum,bimetallic catalyst,Fiscber-Tropscb synthesis,catalytic property,Mossbauer spectroscopy
