The effect of mixed oxide support on the performance of Ni/ZnO in the reactive adsorption desulfurization(RADS) reaction was investigated in a fixed bed reactor by using thiophene as the sulfur-containing compound in ...The effect of mixed oxide support on the performance of Ni/ZnO in the reactive adsorption desulfurization(RADS) reaction was investigated in a fixed bed reactor by using thiophene as the sulfur-containing compound in the model gasoline. A series of oxide supports for Ni/ZnO were synthesized by the co-precipitation method and characterized by XRD, N_2-adsorption, TPR and NH_3-TPD techniques. It was found that the desulfurization capacity of Ni/ZnO was enhanced greatly when active components were supported on the proper mixed oxide. Ni/ZnO supported on oxides exhibited much higher desulfurization efficiency and sulfur adsorption capacity than the unsupported Ni/ZnO and the synthesized Ni/ZnO-SA adsorbent exhibited the highest efficiency for thiophene removal. The higher desulfurization activity and sulfur capacity of Ni/ZnO supported on SiO_2-Al_2O_3 with small particle size, high specific surface area and large pore volume could promote the high dispersion of active metal phase and the transfer of sulfur to ZnO with lower mass transfer resistance. γ-Al_2O_3 species could weaken the interaction of active phases and SiO_2 as well as could increase greatly the amount of weak acids. Therefore, these oxides could impose a great influence on the structure and chemical properties of the catalyst.展开更多
In this work, the addition of praseodymium（Pr） into ceria as a mixed oxide support in a form of Ce（1-x）PrxO2（x = 0.01,0.025, 0.050, 0.075 and 0.10） was prepared using a co-precipitation method. The structural an...In this work, the addition of praseodymium（Pr） into ceria as a mixed oxide support in a form of Ce（1-x）PrxO2（x = 0.01,0.025, 0.050, 0.075 and 0.10） was prepared using a co-precipitation method. The structural and textural properties of the synthesized supports were characterized by X-ray diffraction（XRD）, N2 adsorption-desorption, Raman spectroscopy, H2-temperature programmed reduction（H2-TPR） and H2-chemisorption. Upon addition of Pr, XRD patterns and Raman spectra indicated an enlargement of ceria unit cell and the characteristics Raman broad peak at 570 cm^（-1） which was attributed to the existence of oxygen vacancies in the ceria lattice. This indicated that some Ce^（4＋） ions in ceria were replaced by larger Pr^（3＋） cations. To evidence the incorporation of Pr^（3＋） cations into ceria lattice,X-ray absorption near edge structure（XANES） was employed. The results showed that the oxidation states of Ce in mixed oxide supports were slightly lower than 4＋ while those of Pr were still the same as a precursor salt. Therefore, the incorporation of Pr^（3＋） into ceria lattice would lead to strain and unbalanced charge and result in oxygen vacancies. The reducibility of Ce（1-x）PrxO2 mixed oxide supports was investigated by H2-TPR and temperature-resolved X-ray absorption spectroscopy experiment under reduction conditions. XANES spectra of Ce L3 edges showed a lower surface reduction temperature（Ce^（4＋）to Ce^（3＋）） of Ce（0.925）Pr（0.075）O2 than that of CeO2 which agreed with H2-TPR results. H2-chemisorption indicated that Pr promoted the dispersion of the metal catalyst on the mixed oxide support and increased the adsorption site for CO. For WGS reaction, 1% Pd/mixed oxide support had higher WGS activity than 1%Pd/ceria. The increase of WGS activity was due to the increase of Pd dispersion on the support and the existence of oxygen vacancies produced from incorporation of Pr into the ceria lattice.展开更多
The Fe-modi fied sepiolite-supported Mn–Cu mixed oxide(Cux Mny/Fe-Sep) catalysts were prepared using the co-precipitation method.These materials were characterized by means of the XRD,N_2 adsorption–desorption,XPS,H...The Fe-modi fied sepiolite-supported Mn–Cu mixed oxide(Cux Mny/Fe-Sep) catalysts were prepared using the co-precipitation method.These materials were characterized by means of the XRD,N_2 adsorption–desorption,XPS,H_2-TPR,and O_2-TPD techniques,and their catalytic activities for CO and ethyl acetate oxidation were evaluated.The results show that catalytic activities of the Cux Mny/Fe-Sep samples were higher than those of the Cu1/Fe-Sep and Mn2/Fe-Sep samples,and the Mn/Cu molar ratio had a distinct in fluence on catalytic activity of the sample.Among the Cux Mny/Fe-Sep and Cu1Mn2/Sep samples,Cu1Mn2/Fe-Sep performed the best for CO and ethyl acetate oxidation,showing the highest reaction rate and the lowest T50 and T90 of 4.4×10^(-6) mmol·g-1·s-1,110,and 140 °C for CO oxidation,and 1.9×10^(-6) mmol·g-1·s-1,170,and210 °C for ethyl acetate oxidation,respectively.Moreover,the Cu1Mn2/Fe-Sep sample possessed the best lowtemperature reducibility and the lowest temperature of oxygen desorption as well as the highest surface Mn^(4+)/Mn^(3+) and Cu^(2+)/CuO atomic ratios.It is concluded that factors,such as the strong interaction between the Cu or Mn and the Fe-Sep support,good low-temperature reducibility,and good mobility of chemisorbed oxygen species,might account for the excellent catalytic activity of Cu1Mn2/Fe-Sep.展开更多
基金financially supported by the National Natural Science Foundation of China(No.21276086)
文摘The effect of mixed oxide support on the performance of Ni/ZnO in the reactive adsorption desulfurization(RADS) reaction was investigated in a fixed bed reactor by using thiophene as the sulfur-containing compound in the model gasoline. A series of oxide supports for Ni/ZnO were synthesized by the co-precipitation method and characterized by XRD, N_2-adsorption, TPR and NH_3-TPD techniques. It was found that the desulfurization capacity of Ni/ZnO was enhanced greatly when active components were supported on the proper mixed oxide. Ni/ZnO supported on oxides exhibited much higher desulfurization efficiency and sulfur adsorption capacity than the unsupported Ni/ZnO and the synthesized Ni/ZnO-SA adsorbent exhibited the highest efficiency for thiophene removal. The higher desulfurization activity and sulfur capacity of Ni/ZnO supported on SiO_2-Al_2O_3 with small particle size, high specific surface area and large pore volume could promote the high dispersion of active metal phase and the transfer of sulfur to ZnO with lower mass transfer resistance. γ-Al_2O_3 species could weaken the interaction of active phases and SiO_2 as well as could increase greatly the amount of weak acids. Therefore, these oxides could impose a great influence on the structure and chemical properties of the catalyst.
基金Project supported by Center of Excellence for Innovation in Chemistry(PERCH-CIC)Commission on Higher Education,Ministry of Education and the Center of Alternative Energy Research and Development,Khon Kaen University
文摘In this work, the addition of praseodymium（Pr） into ceria as a mixed oxide support in a form of Ce（1-x）PrxO2（x = 0.01,0.025, 0.050, 0.075 and 0.10） was prepared using a co-precipitation method. The structural and textural properties of the synthesized supports were characterized by X-ray diffraction（XRD）, N2 adsorption-desorption, Raman spectroscopy, H2-temperature programmed reduction（H2-TPR） and H2-chemisorption. Upon addition of Pr, XRD patterns and Raman spectra indicated an enlargement of ceria unit cell and the characteristics Raman broad peak at 570 cm^（-1） which was attributed to the existence of oxygen vacancies in the ceria lattice. This indicated that some Ce^（4＋） ions in ceria were replaced by larger Pr^（3＋） cations. To evidence the incorporation of Pr^（3＋） cations into ceria lattice,X-ray absorption near edge structure（XANES） was employed. The results showed that the oxidation states of Ce in mixed oxide supports were slightly lower than 4＋ while those of Pr were still the same as a precursor salt. Therefore, the incorporation of Pr^（3＋） into ceria lattice would lead to strain and unbalanced charge and result in oxygen vacancies. The reducibility of Ce（1-x）PrxO2 mixed oxide supports was investigated by H2-TPR and temperature-resolved X-ray absorption spectroscopy experiment under reduction conditions. XANES spectra of Ce L3 edges showed a lower surface reduction temperature（Ce^（4＋）to Ce^（3＋）） of Ce（0.925）Pr（0.075）O2 than that of CeO2 which agreed with H2-TPR results. H2-chemisorption indicated that Pr promoted the dispersion of the metal catalyst on the mixed oxide support and increased the adsorption site for CO. For WGS reaction, 1% Pd/mixed oxide support had higher WGS activity than 1%Pd/ceria. The increase of WGS activity was due to the increase of Pd dispersion on the support and the existence of oxygen vacancies produced from incorporation of Pr into the ceria lattice.
基金Supported by the National Natural Science Foundation of China(21277008,20777005)the Natural Science Foundation of Beijing(8082008)
文摘The Fe-modi fied sepiolite-supported Mn–Cu mixed oxide(Cux Mny/Fe-Sep) catalysts were prepared using the co-precipitation method.These materials were characterized by means of the XRD,N_2 adsorption–desorption,XPS,H_2-TPR,and O_2-TPD techniques,and their catalytic activities for CO and ethyl acetate oxidation were evaluated.The results show that catalytic activities of the Cux Mny/Fe-Sep samples were higher than those of the Cu1/Fe-Sep and Mn2/Fe-Sep samples,and the Mn/Cu molar ratio had a distinct in fluence on catalytic activity of the sample.Among the Cux Mny/Fe-Sep and Cu1Mn2/Sep samples,Cu1Mn2/Fe-Sep performed the best for CO and ethyl acetate oxidation,showing the highest reaction rate and the lowest T50 and T90 of 4.4×10^(-6) mmol·g-1·s-1,110,and 140 °C for CO oxidation,and 1.9×10^(-6) mmol·g-1·s-1,170,and210 °C for ethyl acetate oxidation,respectively.Moreover,the Cu1Mn2/Fe-Sep sample possessed the best lowtemperature reducibility and the lowest temperature of oxygen desorption as well as the highest surface Mn^(4+)/Mn^(3+) and Cu^(2+)/CuO atomic ratios.It is concluded that factors,such as the strong interaction between the Cu or Mn and the Fe-Sep support,good low-temperature reducibility,and good mobility of chemisorbed oxygen species,might account for the excellent catalytic activity of Cu1Mn2/Fe-Sep.
