WO3-CeO2-TiO2 catalysts for NO (nitrogen monoxide) reduction by ammonia were prepared by a sol-gel method. The catalysts were characterized by BET, XRD, Raman, NH3/NO adsorption and H2-TPR to investigate the relations...
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WO3-CeO2-TiO2 catalysts for NO (nitrogen monoxide) reduction by ammonia were prepared by a sol-gel method. The catalysts were characterized by BET, XRD, Raman, NH3/NO adsorption and H2-TPR to investigate the relationships among the catalyst composition, structure, redox property, acidity and deNOx activity. WO3-CeO2-TiO2 catalysts show a high activity in a broad temperature range of 200-480 ℃. The low-temperature activity of catalysts is sensitive to the catalyst composition especially under low-O2-content atmospheres. It may be related to the synergistic effect between CeOx and WOx in the catalysts. On one hand, the interaction between ceria and tungsten oxide promotes the activation of gaseous oxygen to compensate the lattice oxygen consumed in NH 3-SCR (selective catalytic reduction) reaction at low temperatures. Meanwhile, the Brnsted acid sites mainly arise from tungsten oxides, Lewis acid sites mainly arise from ceria. Both of the Brnsted and Lewis acid sites facilitate the adsorption of NH3 on catalysts and improve the stability of the adsorbed ammonia species, which are beneficial to the NH3-SCR reaction.
In this research work,three kinds of activated bentonite used as solid acid catalysts had been synthesized and studied on removal of olefins from the reformate *** bentonite samples were analyzed using the BET and pyr...
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In this research work,three kinds of activated bentonite used as solid acid catalysts had been synthesized and studied on removal of olefins from the reformate *** bentonite samples were analyzed using the BET and pyridine-FTIR measurements to investigate their physical and chemical *** results showed that both textural properties and surface acidity of the bentonite could affect the catalytic *** the catalyst samples,one kind of bentonite purchased from Hubei with high surface area,high pore volume and more acid sites revealed high activity in removing olefins from the reformate.
Solid-state NMR(ssNMR)spectroscopy is a powerful technique for characterizing the surface sites of solid acids and organic intermediates formed during the acid catalyzed *** a very useful probe molecule,ammonia is oft...
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Solid-state NMR(ssNMR)spectroscopy is a powerful technique for characterizing the surface sites of solid acids and organic intermediates formed during the acid catalyzed *** a very useful probe molecule,ammonia is often utilized to determine the density of solidacids’surface sites by ssNMR *** present mini-review summarizes some of the latest research developments on the quantitative characterization of the acid sites and carbenium ions during the zeolite catalytic reaction by ammonia probe-assisted ssNMR spectroscopy.
The recycling and stability of heterogeneous catalysts are very important for industrialization. The stability of tin based catalyst was low due to its catalytic oxidation in liquid phase. we use a simple method to di...
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The recycling and stability of heterogeneous catalysts are very important for industrialization. The stability of tin based catalyst was low due to its catalytic oxidation in liquid phase. we use a simple method to directly prepare tin oxide nanoparticles catalysts for deep oxidation desulfurization. The effects of catalysts on catalytic activity under different calcination temperatures were also investigated. During the oxidative desulfurization process, Sulfur removal of dibenzothiophene(DBT) in n-octane was 99.8% in 2 h at 60℃ under the conditions of HO/DBT molar ratio of ten and M(catalyst): V(oil) = 0.1 g:10 ml. And there was no significant catalytic performance decrease after 14 recycles. This excellent catalytic activity and recoverability of the catalyst was attributed to the change of specific surface area, acidic site strength of catalysts caused by different heat treatment temperatures, which may produce beneficial Lewis acid sites. The synthesized SnO catalyst was characterized via XPS, XRD, HRTEM, FT-IR, NH-TPD, and ICP-AES.
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