与微反应器一体化的Fe系催化剂制备及其费托合成催化性能研究

Study on preparation of Fe-based catalysts integrated with microreactor and their catalytic performances in Fischer-Tropsch synthesis

通过正交试验设计,在优化条件制备的微结构钢管(Fe)基体上,浸渍共活性成分(Mn、Co或Ce)制备了Fe系双组分催化剂(Fe-Mn:D1~D3,Fe-Co:D4~D6,Fe-Ce:D7~D9),从而与基体形成一体化微反应器。对催化剂在费托合成中的催化性能进行了评价,结果表明,高温有利于提高CO和H_(2)转化率,而低温有利于降低CH_(4)选择性并提高C_(2)~C_(4)烃类选择性,C_(2)~C_(4)烃类收率几乎均在300℃达峰值,其中D3最高,达38.84%。以300℃的C_(2)~C_(4)烃类选择性为指标进行正交试验分析得最优制备条件:Fe-Mn活性组份、2.0 mol/L前驱体浓度、1 h浸渍时间和300℃焙烧温度。活性组份是影响C_(2)~C_(4)烃类选择性的主要因素,前驱体浓度和浸渍时间的影响次之,焙烧温度影响最小。催化剂表征结果表明,浸渍共活性组份后催化剂表面平滑,仅有少量不规则微坑和孔隙,相对均匀的表面活性组份分布可提升其对费托合成的催化性能;高前驱体浓度有利于获得晶化程度更高的催化剂。

Fe-based two-component catalysts(Fe-Mn:D1~D3,Fe-Co,D4~D6,Fe-Ce,D7~D9)were prepared through orthogonal design by impregnating the co-active ingredient(Mn,Co or Ce)on the microstructure steel tube(Fe)matrix prepared under optimized conditions,with which thus forming integrated microreactors.Catalytic performances of the catalysts were evaluated in Fischer-Tropsch synthesis.The results indicate that high temperature is beneficial to improve conversion rates of CO and H_(2),while low temperature is beneficial to reduce the selectivity of CH_(4) and improve C_(2)~C_(4) hydrocarbons selectivity.Almost all the yields of C_(2)~C_(4) hydrocarbons reached the peak value at 300℃,and D3 shows the highest(38.84%).The optimal preparation conditions were obtained by orthogonal analysis with C_(2)~C_(4) hydrocarbons selectivity at 300℃ as the index:Fe-Mn as active component,2.0 mol/L precursor concentration,1 h impregnation time and 300℃ calcination temperature.The active component is main factor affecting the selectivity of C_(2)~C_(4) hydrocarbons,followed by the precursor concentration and impregnation time,and the calcination temperature has the least effect.The characterization results of catalysts show that the catalysts surface are smooth with only a few irregular micro-pits and pores after impregnated with co-active components.The relative uniform surface distribution of active components can promote catalytic performance in Fischer-Tropsch synthesis,and high precursor concentration is beneficial to form the catalysts with higher crystallization.