Xia An

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.

Effect of Sulfate on an Iron Manganese Catalyst for Fischer-Tropsch Synthesis

Abstract The effect of sulfate on Fischer-Tropsch synthesis performance was investigated in a slurry- phase continuously stirred tank reactor (CSTR) over a Fe-Mn catalyst. The physiochemical properties of the catalyst impregnated with different levels of sulfate were characterized by N 2 physisorption, X-ray photoelectron spectroscopy (XPS), H 2 (or CO) temperature-programmed reduction (TPR), Mossbauer spectroscopy, and CO 2 temperature-programmed desorption (TPD). The characterization results indicated that the impregnated sulfate slightly decreased the BET surface area and pore volume of the catalyst, suppressed the catalyst reduction and carburization in CO and syngas, and decreased the catalyst surface basicity. At the same time, the addition of small amounts of sulfate improved the activities of Fischer- Tropsch synthesis (FTS) and water gas shift (WGS), shifted the product to light hydrocarbons (C 1 –C 11 ) and suppressed the formation of heavy products (C 12+ ). Addition of SO 2 − 4 to the catalyst improved the FTS activity at a sulfur loading of 0.05–0.80 g per 100 g Fe, and S-05 catalyst gave the highest CO conversion (62.3%), and beyond this sulfur level the activity of the catalyst decreased.

Effect of Manganese Incorporation Manner on an Iron-Based Catalyst for Fischer-Tropsch Synthesis

Abstract A systematic study was undertaken to investigate the effects of the manganese incorporation manner on the textural properties, bulk and surface phase compositions, reduction/carburization behaviors, and surface basicity of an iron-based Fischer-Tropsch synthesis (FTS) catalyst. The catalyst samples were characterized by N2 physisorption, X-ray photoelectron spectroscopy (XPS), H2 (or CO) temperature-programmed reduction (TPR), CO2 temperature-programmed desorption (TPD), and Mossbauer spectroscopy. The FTS performance of the catalysts was studied in a slurry-phase continuously stirred tank reactor (CSTR). The characterization results indicated that the manganese promoter incorporated by using the coprecipitation method could improve the dispersion of iron oxide, and decrease the size of the iron oxide crystallite. The manganese incorporated with the impregnation method is enriched on the catalysts surface. The manganese promoter added with the impregnation method suppresses the reduction and carburization of the catalyst in H2, CO, and syngas because of the excessive enrichment of manganese on the catalyst surface. The catalyst added manganese using the coprecipitation method has the highest CO conversion (51.9%) and the lowest selectivity for heavy hydrocarbons (C12+).

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.