摘要: Bimetallic Co/Fe catalysts supported on carbon nanotubes (CNTs) were prepared, and niobium (Nb) was added as promoter to the 70Co:30Fe/CNT catalyst. The physicochemical properties of the catalysts were characterized, and the catalytic performances were analyzed at the same operation conditions (H2:CO (volume ratio)=2:1, p=1 MPa, and t=260 ℃) in a tubular fixed-bed microreactor system. The addition of Nb to the bimetallic catalyst decreases the average size of the oxide nanoparticles and improves the reducibility of the bimetallic catalyst. Evaluation of the catalyst performance in a Fischer-Tropsch reaction shows that the catalyst results in high selectivity to methane, and the selectivity to C5+ increased slightly in the bimetallic catalyst unlike that in the monometallic catalysts. The addition of 1% Nb to the bimetallic catalyst increases CO conversion and selectivity to C5+. Meanwhile, a decrease in methane selectivity is observed.
摘要: The Fischer-Tropsch synthesis has offered an alternative way to convert coal and biomass into chemicals such as α-olefins via sygas comprised of H2 and CO. A pulse process switching between Fischer-Tropsch synthesis and N2 purging was carried out when the Fischer-Tropsch synthesis became stable in the fixed bed reactor. The activity and selectivity over Fe-Co catalyst for α-olefins in Fischer-Tropsch synthesis reaction were measured under the normal conditions of 2.0 MPa, 497 K, 2 000 h-1 and H2/CO volume ratio of 2.0. It was found that the olefin to paraffin ratio of C3 for Fe-Co catalyst purged at 517 K and 0.2 MPa was almost nine times higher than that of the fresh one without purging under the same reaction conditions, and the CH4 selectivity and CO conversion decreased after purging. Two possible reasons were proposed to explain these phenomena. Moreover, a batch experiment by the pulse process in fixed bed reactor was performed. Notably, a high olefins yield was obtained via the pulse process during the Fischer-Tropsch synthesis.
摘要: Glucose and cellobiose were used as model compounds to investigate the effect of retro-aldol condensation and hydrogenation rates on the product distribution of cellulose conversion. It was shown that the product distribution obtained over the physical mixture of Ni/SBA-15 and WO3/SBA-15 in the glucose and cellobiose conversions were different from that attained on the Ni-WO3/SBA-15 prepared by the co-impregnation method. The ethylene glycol (EG) yield depended on the structures of tungstic compounds, and it increased in the order of WO3 < WO3/SBA-15 < (NH4)6W7O24·6H2O (AMT), while the particle sizes of them decreased in such an order. Regardless of the types of tungstic compounds, the EG yield obtained in the glucose conversion is lower than that attained in the cellobiose conversion at the same amount of catalyst.
摘要: The catalytic activity of CoMoS/CNT towards the Egyptian heavy vacuum gas oil hydrotreating was studied. The delivered CNT was functionalized with 6 mol/L HNO3. The CNT were loaded with 12% MoO3 (by weight) and 0.7 Co/Mo atomic ratio with impregnation methods. The γ-Al2O3catalyst was also prepared by impregnation method to compare both catalysts activities. The analysis tools such XRD, Raman spectroscopy, TEM, and BET were used to characterize the catalysts. The autoclave reactor was used to operate the hydrotreating experiments. The hydrotreating reactions were tested at various operating conditions of temperature 325-375 ℃, pressure 2-6 MPa, time 2-6 h, and catalyst/oil ratio (by weight) of 1:75, 1:33 and 1:10. The results revealed that the CoMoS/CNT was highly efficient for the hydrotreating more than the CoMoS/γ-Al2O3. Also, the hydrodesulfurization (HDS) increased with increasing catalyst/oil ratio. Additionally, results showed that the optimum condition was temperature 350 ℃, pressure 4 MPa, catalyst/oil ratio of 1:75 for 2 h. Furthermore, even at low CoMoS/CNT catalyst/oil ratio of 1:75, an acceptable HDS of 77.1% was achieved.