Ding Mingyue

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 N-2 physical adsorption, temperature-programmed reduction/desorption of hydrogen, (H-2-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 0.21 g . mL(-1) . h(-1), respectively. At the same time, the mass ratio of C2+OH/CH3OH reached 1.96.

Hβ改性Co/SiO 2 对费托合成航空燃油类烃的影响

在中孔SiO 2 (SG)和微孔Hβ分子筛(Si/Al=25、60、80)组成的复合载体上, 制备了多功能Co基费托合成催化剂, 考察了其合成航空燃油类烃(C 8 ~C 18 )的性能。XRD、FTIR、H 2 -TPR、N 2 -物理吸附研究表明: Hβ 的引入, 使得Co/SG/Hβ催化剂具有一定酸性和微孔结构。随分子筛硅铝比的降低, 催化剂红外图谱的特征波数向低波数移动, 酸性有所提高, 中孔SiO 2 消弱了其酸性及载体与金属粒子相互作用, 提高了Co分散和还原度及加氢活性。Hβ的微孔结构和酸性促进了初级产物裂解及异构化反应, 提高了异构烃类选择性。Co/SG/Hβ(80)催化剂较大的比表面积和微孔体积及适当的酸性中心是其高活性(CO转化率95.7%)及高航空燃油类烃选择性(42.3%, 其中异构烃为27.6%)的关键因素。Bi-functional catalysts were prepared using hybrid supports, mesoporous SiO2(SG) and microporous HP zeolites with different Si/Al ratios of 25, 60 and 80 for direct jet fuel-range hydrocarbon synthesis (C-8-C-18). The textual and structural properties of the catalysts were studied by Fourier transform infrared (FTIR), X-ray diffraction(XRD), H-2-temperature-programmed desorption(H-2-TPR) and N-2 physisorption. The results showed that catalysts supported on tailor-made SiO2 and H beta hybrid maintained both meso- and micro-pores with acid centers. With the decrease of Si/Al ratio, the bands corresponding to the characteristic adsorptions of Co/SG/H beta catalysts shifted to the lower wave numbers, which accompanied by increased acidity. SiO2 decreased the acidity of H beta and the interaction between Co and support, resulting in high Co dispersion, reduction and CO conversion for Co/SG/H beta. The microporous structure and acidity of H beta accelerated the hydrocracking/hydroisomerizaion reaction, which contributed to the high selectivity to jet fuel-range isoparaffins. The increased BET surface area and microporous volume with moderate acidity of Co/SG/H beta(80) were essential for its high CO conversion (95.7%) and selectivity to jet fuel-range hydrocarbons (42.3%, including 27.6% of isoparaffins).在中孔SiO 2 (SG)和微孔Hβ分子筛(Si/Al=25、60、80)组成的复合载体上, 制备了多功能Co基费托合成催化剂, 考察了其合成航空燃油类烃(C 8 ~C 18 )的性能。XRD、FTIR、H 2 -TPR、N 2 -物理吸附研究表明: Hβ 的引入, 使得Co/SG/Hβ催化剂具有一定酸性和微孔结构。随分子筛硅铝比的降低, 催化剂红外图谱的特征波数向低波数移动, 酸性有所提高, 中孔SiO 2 消弱了其酸性及载体与金属粒子相互作用, 提高了Co分散和还原度及加氢活性。Hβ的微孔结构和酸性促进了初级产物裂解及异构化反应, 提高了异构烃类选择性。Co/SG/Hβ(80)催化剂较大的比表面积和微孔体积及适当的酸性中心是其高活性(CO转化率95.7%)及高航空燃油类烃选择性(42.3%, 其中异构烃为27.6%)的关键因素。