Baoshan Wu

Effect of A12O3 Binder on the Precipitated Iron-Based Catalysts for Fischer-Tropsch Synthesis

Abstract A series of iron-based Fischer-Tropsch synthesis (FTS) catalysts incorporated with Al 2 O 3 binder were prepared by the combination of co-precipitation and spray drying technology. The catalyst samples were characterized by using N 2 physical adsorption, temperature-programmed reduc-tion/desorption (TPR/TPD) and Mossbauer effect spectroscopy (MES) methods. The characterization results indicated that the BET surface area increases with increasing Al 2 O 3 content and passes through a maximum at the Al 2 O 3 /Fe ratio of 10/100 (weight basis). After the point, it decreases with further increase in Al 2 O 3 content. The incorporation of Al 2 O 3 binder was found to weaken the surface basicity and suppress the reduction and carburization of iron-based catalysts probably due to the strong K-Al 2 O 3 and interactions. Furthermore, the H2 adsorption ability of the catalysts is enhanced with increasing content. The FTS performances of the catalysts were tested in a slurry-phase continuously stirred tank reactor (CSTR) under the reaction conditions of 260 °C, 1.5 MPa, 1000 h −1 and molar ratio of H2/CO 0.67 for 200 h. The results showed that the addition of small amounts of Al 2 O 3 affects the activity of iron-based catalysts to a little extent. However, with further increase of Al 2 O 3 content, the FTS activity and water gas shift reaction (WGS) activity are decreased severely. The addition of appropriate Al 2 O 3 do not affect the product selectivity, but the catalysts incorporated with large amounts of Al 2 O 3 have higher selectivity for light hydrocarbons and lower selectivity for heavy hydrocarbons.

Structural Properties, Reduction and Carburization Behaviors of Fe/Cu/K/Al2O3 Catalyst for Fischer-Tropsch Synthesis

Abstract An Fe/Cu/K/Al 2 O 3 catalyst for Fischer-Tropsch synthesis (FTS) was prepared by using a combination of co-precipitation and spray-drying method. Thermal gravity (TG), N 2 physisorption, X-ray diffraction (XRD), H 2 temperature programmed reduction (H 2 -TPR), CO temperature programmed reduction (CO-TPR), and Mossbauer effect spectroscopy (MES), were used to investigate the effects of different calcination temperatures on the structural properties, reduction, and carburization behaviors of the iron-based catalyst. The results indicated that an increase in calcination temperature facilitated the carbonate decomposition and H 2 O removal and promoted the reduction of the catalyst. With further increasing the calcination temperature, the BET surface area of the catalyst decreased, and the size of the catalyst crystallite and the average pore diameter increased. Furthermore, high calcination temperature enhanced the metal-support interaction, which weakened the promotional effect of CuO and K 2 O, and therefore, severely suppressed the reduction and carburization behaviors of the catalyst.采用连续共沉淀与喷雾干燥成型技术相结合的方法制备了微球状Fe/Cu/K/Al2O3催化剂,结合TG、N2物理吸附、XRD、H2-TPR、CO-TPR、Mssbauer谱等表征手段,研究焙烧温度对Fischer-Tropshc（F-T）合成铁基催化剂的结构性质、还原行为和碳化行为的影响.结果表明,较高的焙烧温度有利于碳酸盐的分解和结晶水的脱除,促进了催化剂的还原.随着焙烧温度的进一步升高,催化剂的比表面积减小,平均孔径增大,α-Fe2O3晶粒的粒径增大,催化剂中金属与载体的相互作用增强,从而削弱了CuO、K2O助剂的作用,严重抑制了催化剂的还原和碳化.

Controllable deposition of Pt nanoparticles into a KL zeolite by atomic layer deposition for highly efficient reforming of n-heptane to aromatics

Atomic layer deposition (ALD) was applied to deposit Pt into KL zeolite channels. The location of Pt deposition and the interaction between Pt and the KL zeolite have been investigated by various characterization methods as well as DFT simulations. It has been demonstrated that Pt nanoparticles (NPs) with precisely controlled size (∼0.8 nm) and high dispersion have been successfully deposited into the micropores of the KL zeolite. The produced Pt/KL catalysts exhibited highly efficient performance for n-heptane reforming to aromatics with a high toluene selectivity up to 67.3% (toluene/total aromatics = 97.8%) and a low methane selectivity (0.9%), in spite of an ultralow Pt loading (0.21 wt%). It was revealed that the strong interaction between Pt and the KL zeolite resulting in the electron-enriched state of Pt and the confinement of Pt in the micropores of the KL zeolite facilitated the aromatization of n-heptane. The small size and high dispersion of Pt NPs contributed to inhibition of the hydrogenolysis reaction. Prevention of agglomeration of Pt NPs due to confinement inside the micropores of the KL zeolite and the strong interaction led to the high stability of the Pt/KL catalysts.

Synthesis of nano-sized LTL zeolite by addition of a Ba precursor with superior n-octane aromatization performance

A nano-sized LTL-type zeolite was successfully synthesized using a facile and commercially viable hydrothermal method by the addition of a small amount of Ba precursor to the conventional synthesis mixture regardless of the types of Ba precursors used. The results showed that the Ba added can be used to finely tune LTL particle sizes in the range of 0.1–1 μm and shorten the synthesis time, indicating that Ba had a significant effect on the crystallization process of LTL-type zeolite. By comprehensively tracing the evolution of two systems, namely KL and BaKL, it was found that the crystallization of KL zeolite took place by a chain of processes including the appearance of worm-like particles (WLPs), their random aggregation/coalescence and crystallization of these aggregates. On the other hand, the Ba added can accelerate the coordination between monosilicate and alumina species. Therefore, LTL zeolites with small crystal sizes were quickly produced by rapid crystallization of the amorphous phase to the final products. The Pt/LTL catalysts were obtained by impregnating the obtained zeolites with Pt and then evaluated in n-octane aromatization reactions. Compared with conventional LTL zeolite, the nano-sized LTL zeolite-supported Pt catalyst exhibited superior catalytic performance with an about 3-fold prolonged catalytic lifetime and higher selectivity for aromatics due to the shorter diffusion path of the primary aromatic products in nano-sized zeolites, which inhibited the secondary undesirable reactions (coke formation and hydrogenolysis).