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制备了一系列不同La2O3含量(100Fe/2.8Si/nLa,n=0,0.5,1,2,4,原子比)的沉淀铁费-托合成催化剂,通过原位X射线衍射、一氧化碳程序升温还原和N2吸附-脱附等手段对催化剂进行了表征.催化剂费-托反应评价在固定床反应器中进行.结果表明,少量La2O3助剂(La/Fe≤0.01,原子比)的加入显著降低了Fe2O3颗粒大小,增加了催化剂的比表面积和分散度,有利于碳化铁的形成,从而导致费-托合成催化活性的提高.随着La2O3含量的进一步增加(La/Fe≥0.02),催化剂表面大量La2O3的覆盖和LaFeO3化合物的形成降低了铁碳化物的形成,反应活性反而降低.因此,最适宜的La2O3含量为La/Fe=0.01.La2O3的加入提高了甲烷的选择性,抑制了C5+碳氢化合物的形成.
A series of precipitated Fe-Fischer-Tropsch catalysts with different La 2 O 3 loadings (100Fe / 2.8Si / nLa, n = 0,0.5,1,2,4, atomic ratio) were prepared and characterized by in situ XRD and CO temperature programmed reduction And N2 adsorption-desorption, etc. The catalyst Fischer-Tropsch reaction was evaluated in a fixed bed reactor.The results showed that the addition of a small amount of La2O3 (La / Fe≤0.01, atomic ratio) was significantly reduced Fe2O3 particle size increased the specific surface area and dispersion of the catalyst, which was in favor of the formation of iron carbide, resulting in the improvement of the catalytic activity of the Fischer-Tropsch synthesis. With the further increase of La2O3 content (La / Fe≥0.02), a large amount of catalyst surface The formation of La2O3 and LaFeO3 compounds reduced the formation of FeCr and decreased the reaction activity, so La2O3 was the most suitable La2O3 = 0.01.The addition of La2O3 enhanced the methane selectivity and inhibited the formation of C5 + hydrocarbons Formation of compounds.