Cu-Fe基双孔载体催化剂结构和低碳醇合成反应性能

采用超声浸渍法制备了Cu、Fe 双活性组元改性的双孔载体(M)催化剂, 采用N₂物理吸附、H₂程序升温 还原/脱附(H₂-TPR/TPD)、X射线衍射(XRD)等表征手段考察了催化剂中Cu-Fe的相互作用, 并在固定床反应器 中评价了Cu/Fe摩尔比的改变对低碳醇合成反应性能的影响. 结果表明: 小孔硅溶胶浸渍在大孔硅凝胶中可形 成具有不同纳米孔径结构的双孔载体, 增加小孔硅溶胶的含量可促使双孔载体中小孔纳米结构尺寸变小. Fe/ Cu摩尔比的增加有利于铜物种在载体表面的分散, 促进了表层CuO和Fe₂O₃的还原, 加强了双孔载体内孔道 与铜铁氧化物之间的相互作用, 促使了单质铜的分散和铁碳化物的生成. CO加氢反应活性和低碳醇时空收率 随着Fe/Cu 摩尔比的逐渐增加呈现增加的变化趋势. 当Fe/Cu 摩尔比增加到30/20 时, Cu-Fe 基双孔载体催化 剂的CO转化率增加到46%, 低碳醇的时空收率增加到0.21 g·mL^-1·h^-1, C₂₊OH/CH₃OH质量比达到1.96.

Structure and Performance of Cu-Fe Bimodal Support for Higher Alcohol Syntheses

Copper-iron modified bimodal support(M) with different mass fractions of Cu and Fe elements were prepared by an ultrasonic impregnation method.The catalytic performance for higher alcohol syntheses(HAS) was investigated in a fixed-bed flow reactor.Several techniques,including N2 physical adsorption,temperature-programmed reduction/desorption of hydrogen,(H2-TPR/TPD) and X-ray diffraction(XRD) were used to characterize the catalysts.The results indicated that the bimodal pore support was formed by the addition of small-pore silica sol into the macroporous silica gel.Increased amounts of small pore silica sol caused a decrease in pore size in the bimodal carrier.An increase in the Fe/Cu molar ratio facilitated the dispersion of CuO,promoted the reduction of CuO and Fe2O3 on the surface layers,and enhanced the interaction between the copper and iron species as well as the bimodal support inside the large pores.The copper was well-dispersed on the catalyst and the amount of iron carbides formed was high in catalysts with a high Fe/Cu molar ratio.Increasing the Fe/Cu mass ratio promoted the catalytic activity and thus facilitated the synthesis of higher alcohols.When the Fe/Cu molar ratio was increased to 30/20,the CO conversion and the yield of higher alcohols increased to 46% and 0.21g · mL-1 · h-1,respectively.At the same time,the mass ratio of C2+OH/CH3OH reached 1.96.