To understand the dispersion behavior of metal oxides on composite oxide supports and with the expectation of developing more feasible catalysts for soot oxidation,CuO/La_(2)Sn_(2)O_(7)samples containing varied CuO lo...To understand the dispersion behavior of metal oxides on composite oxide supports and with the expectation of developing more feasible catalysts for soot oxidation,CuO/La_(2)Sn_(2)O_(7)samples containing varied CuO loadings were fabricated and characterized by different techniques and density functional theory calculations.In these catalysts,a spontaneous dispersion of CuO on the La_(2)Sn_(2)O_(7)pyrochlore support formed,having a monolayer dispersion capacity of 1.90 mmol CuO/100 m^(2) La_(2)Sn_(2)O_(7)surface.When loaded below this capacity,CuO exists in a sub-monolayer or monolayer state.X-ray photoelectron spectroscopy(XPS),Raman spectroscopy,and Bader charge and density of states analyses indicate that there are strong interactions between the sub-monolayer/monolayer CuO and the La_(2)Sn_(2)O_(7)support,mainly through the donation of electrons from Cu to Sn at the B-sites of the structure.In contrast,Cu has negligible interactions with La at the A-sites.This suggests that,in composite oxide supports containing multiple metals,the supported metal oxide interacts preferentially with one kind of metal cation in the support.The Raman,in situ diffuse reflectance infrared Fourier transform spectroscopy,and XPS results confirmed the formation of both O2^(-)and O2^(2-)as the active sites on the surfaces of the CuO/La_(2)Sn_(2)O_(7)catalysts,and the concentration of these active species determines the soot combustion activity.The number of active oxygen anions increased with increase in CuO loading until the monolayer dispersion capacity was reached.Above the monolayer dispersion capacity,microsized CuO crystallites formed,and these had a negative effect on the generation of active surface oxygen sites.In summary,a highly active catalyst can be prepared by covering the surface of the La_(2)Sn_(2)O_(7)support with a CuO monolayer.展开更多
采用溶胶-凝胶法制备了SiO_2-CuO复合氧化物,通过X射线衍射（XRD）、扫描电镜（SEM）、N2吸附（BET）等表征手段对试样进行了表征。以石油醚为溶剂,配制500 mg/L（以S计）的苯并噻吩（BT）模拟原料油,以SiO_2-CuO复合氧化物为催化剂,考...采用溶胶-凝胶法制备了SiO_2-CuO复合氧化物,通过X射线衍射（XRD）、扫描电镜（SEM）、N2吸附（BET）等表征手段对试样进行了表征。以石油醚为溶剂,配制500 mg/L（以S计）的苯并噻吩（BT）模拟原料油,以SiO_2-CuO复合氧化物为催化剂,考察了催化剂用量、氧化剂H_2O_2用量、溶剂用量、反应温度、反应时间等因素对脱硫率的影响。研究结果表明,SiO_2-CuO复合氧化物呈片状,粒径在0.5~7.0μm,复合氧化物中的Cu以CuO形式存在,其比表面积低于SiO_2。在原料油10 m L,催化剂0.05 g,氧化剂H2O20.1 m L,乙腈与原料油体积比0.3∶1,反应温度65℃,反应时间60 min等最佳反应条件下,BT脱除率达到64.6%。展开更多
文摘To understand the dispersion behavior of metal oxides on composite oxide supports and with the expectation of developing more feasible catalysts for soot oxidation,CuO/La_(2)Sn_(2)O_(7)samples containing varied CuO loadings were fabricated and characterized by different techniques and density functional theory calculations.In these catalysts,a spontaneous dispersion of CuO on the La_(2)Sn_(2)O_(7)pyrochlore support formed,having a monolayer dispersion capacity of 1.90 mmol CuO/100 m^(2) La_(2)Sn_(2)O_(7)surface.When loaded below this capacity,CuO exists in a sub-monolayer or monolayer state.X-ray photoelectron spectroscopy(XPS),Raman spectroscopy,and Bader charge and density of states analyses indicate that there are strong interactions between the sub-monolayer/monolayer CuO and the La_(2)Sn_(2)O_(7)support,mainly through the donation of electrons from Cu to Sn at the B-sites of the structure.In contrast,Cu has negligible interactions with La at the A-sites.This suggests that,in composite oxide supports containing multiple metals,the supported metal oxide interacts preferentially with one kind of metal cation in the support.The Raman,in situ diffuse reflectance infrared Fourier transform spectroscopy,and XPS results confirmed the formation of both O2^(-)and O2^(2-)as the active sites on the surfaces of the CuO/La_(2)Sn_(2)O_(7)catalysts,and the concentration of these active species determines the soot combustion activity.The number of active oxygen anions increased with increase in CuO loading until the monolayer dispersion capacity was reached.Above the monolayer dispersion capacity,microsized CuO crystallites formed,and these had a negative effect on the generation of active surface oxygen sites.In summary,a highly active catalyst can be prepared by covering the surface of the La_(2)Sn_(2)O_(7)support with a CuO monolayer.
文摘采用溶胶-凝胶法制备了SiO_2-CuO复合氧化物,通过X射线衍射（XRD）、扫描电镜（SEM）、N2吸附（BET）等表征手段对试样进行了表征。以石油醚为溶剂,配制500 mg/L（以S计）的苯并噻吩（BT）模拟原料油,以SiO_2-CuO复合氧化物为催化剂,考察了催化剂用量、氧化剂H_2O_2用量、溶剂用量、反应温度、反应时间等因素对脱硫率的影响。研究结果表明,SiO_2-CuO复合氧化物呈片状,粒径在0.5~7.0μm,复合氧化物中的Cu以CuO形式存在,其比表面积低于SiO_2。在原料油10 m L,催化剂0.05 g,氧化剂H2O20.1 m L,乙腈与原料油体积比0.3∶1,反应温度65℃,反应时间60 min等最佳反应条件下,BT脱除率达到64.6%。
