The effects of Mg,La and Ca promoters on primary and secondary CO2 and H2O formation pathways during Fischer-Tropsch synthesis on precipitated Fe/Cu/SiO2 catalysts are investigated.The chemisorbed oxygen atoms in the ...The effects of Mg,La and Ca promoters on primary and secondary CO2 and H2O formation pathways during Fischer-Tropsch synthesis on precipitated Fe/Cu/SiO2 catalysts are investigated.The chemisorbed oxygen atoms in the primary pathway formed in the CO dissociation steps reacted with co-adsorbed hydrogen or carbon monoxide to produce H2O and CO2,respectively.The secondary pathway was the water-gas shift reaction.The results indicated that the CO2 production led to an increase in both primary and secondary pathways,and H2O production decreased when surface basicity of the catalyst increased in the order Ca 〉 Mg 〉 La.展开更多
CuZnAl catalysts with different La loadings were prepared by a complete liquid phase method and tested for higher alcohols（C_（2＋）OH） synthesis from syngas at the conditions of 250–290 ℃, 4.5 MPa, feed low rate ...CuZnAl catalysts with different La loadings were prepared by a complete liquid phase method and tested for higher alcohols（C_（2＋）OH） synthesis from syngas at the conditions of 250–290 ℃, 4.5 MPa, feed low rate = 150 mL/min and H_2/CO = 2. The catalysts were characterized by XRD, H_2-TPR, NH_3-TPD, N_2 adsorption, XPS, and TEM techniques. Characterization results showed that the incorporation of La into CuZnAl catalysts resulted in the decrease of crystallite size of Cu^0 and a strong interaction among copper and zinc or aluminum oxides. Especially, the incorporation of La increased the amount of weak acid and the Cu content on catalyst surface, which was speculated to contribute the formation of higher alcohols. Among these La-promoted CuZnAl catalysts, the La0.1 catalyst exhibited the best catalytic performance and the selectivity to higher alcohols reached above 60% when the reaction temperature was 290 ℃.展开更多
order to assess the promotional effects of La3+ on CO hydrogenation of Co/SiO2 catalyst, solvated metal atom impregnation (SMAI) method was used to prepare unpromoted 10% (mass fraction) Co/SiO2 and a series of La3+-p...order to assess the promotional effects of La3+ on CO hydrogenation of Co/SiO2 catalyst, solvated metal atom impregnation (SMAI) method was used to prepare unpromoted 10% (mass fraction) Co/SiO2 and a series of La3+-promoted 10% (mass fraction) Co/SiO2 catalyst with different La/Co atomic ratios (0.1, 0.3, 0.5). X-ray diffraction (XRD), and CO chemisorption measurements show that the cobalt particle size decreases as the La/Co ratios increase. X-ray photoelectron spectrescopy indicates that cobalt is in zero-valent state for all the samples. Catalytic test shows that the catalytic activity of La3+-promoted Co/SiO2 in CO hydrogenation is higher than that of unpromoted Co/SiO2, and enhances with the La/Co ratios increase. La3+ promotion also causes the enhanced selectivity of Co/SiO2 catalyst for higher hydrocarbon products.展开更多
文摘The effects of Mg,La and Ca promoters on primary and secondary CO2 and H2O formation pathways during Fischer-Tropsch synthesis on precipitated Fe/Cu/SiO2 catalysts are investigated.The chemisorbed oxygen atoms in the primary pathway formed in the CO dissociation steps reacted with co-adsorbed hydrogen or carbon monoxide to produce H2O and CO2,respectively.The secondary pathway was the water-gas shift reaction.The results indicated that the CO2 production led to an increase in both primary and secondary pathways,and H2O production decreased when surface basicity of the catalyst increased in the order Ca 〉 Mg 〉 La.
基金supported by the Key Program of the National Natural Science Foundation of China(No.21336006)the National Key Technology R&D Program(Grant No.2013BAC14B04)the National Natural Science Foundation of China(No.21176167)
文摘CuZnAl catalysts with different La loadings were prepared by a complete liquid phase method and tested for higher alcohols（C_（2＋）OH） synthesis from syngas at the conditions of 250–290 ℃, 4.5 MPa, feed low rate = 150 mL/min and H_2/CO = 2. The catalysts were characterized by XRD, H_2-TPR, NH_3-TPD, N_2 adsorption, XPS, and TEM techniques. Characterization results showed that the incorporation of La into CuZnAl catalysts resulted in the decrease of crystallite size of Cu^0 and a strong interaction among copper and zinc or aluminum oxides. Especially, the incorporation of La increased the amount of weak acid and the Cu content on catalyst surface, which was speculated to contribute the formation of higher alcohols. Among these La-promoted CuZnAl catalysts, the La0.1 catalyst exhibited the best catalytic performance and the selectivity to higher alcohols reached above 60% when the reaction temperature was 290 ℃.
文摘order to assess the promotional effects of La3+ on CO hydrogenation of Co/SiO2 catalyst, solvated metal atom impregnation (SMAI) method was used to prepare unpromoted 10% (mass fraction) Co/SiO2 and a series of La3+-promoted 10% (mass fraction) Co/SiO2 catalyst with different La/Co atomic ratios (0.1, 0.3, 0.5). X-ray diffraction (XRD), and CO chemisorption measurements show that the cobalt particle size decreases as the La/Co ratios increase. X-ray photoelectron spectrescopy indicates that cobalt is in zero-valent state for all the samples. Catalytic test shows that the catalytic activity of La3+-promoted Co/SiO2 in CO hydrogenation is higher than that of unpromoted Co/SiO2, and enhances with the La/Co ratios increase. La3+ promotion also causes the enhanced selectivity of Co/SiO2 catalyst for higher hydrocarbon products.
