A novel plasmonic photocatalyst, Au/Pt/g-C3N4, was prepared by a facile calcination-photodeposition technique. The samples were characterized by X-ray diffraction, energy-dispersive spectroscopy, transmission electron microscopy, and UV-vis diffuse reflectance spectroscopy, and the results demonstrated that the Au and Pt nanoparticles (7-15 nm) were well-dispersed on the surfaces of g-C3N4. The Au/Pt codecorated g-C3N4 heterostructure displayed enhanced photocatalytic activity for antibiotic tetracycline hydrochloride (TC-HCl) degradation, and the degradation rate was 3.4 times higher than that of pure g-C3N4 under visible light irradiation. The enhancement of photocatalytic activity could be attributed to the surface plasmon resonance effect of Au and electron-sink function of Pt nanoparticles, which improve the optical absorption property and photogenerated charge carriers separation of g-C3N4, synergistically facilitating the photocatalysis process. Finally, a possible photocatalytic mechanism for degrading TC-HCl by Au/Pt/g-C3N4 heterostructure was tentatively proposed.

ZnO/Ag2O heterostructures were successfully synthesized via a simple one-step photochemical route.

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The influence of alumina binder on the catalytic performance of PtSnNa/ZSM-5 catalyst for propane dehydrogenation was studied. Solid-state 27Al MAS NMR spectroscopy, temperature-programmed desorption of ammonia (TPDA), temperature-programmed oxidation (TPO), catalytic grain intensity, hydrogen chemisorption, BET surface area, and pore size distribution measurements were used to characterize the catalysts. It was found that the addition of binder results in a decrease in the surface area of the catalyst but an obvious improvement in its particle intensity. Some soluble Al species from the binder might migrate into the ZSM-5 zeolite framework during calcination so as to produce some acid sites of moderate intensity, which consequently increases the acid amount of the catalyst. When propane dehydrogenation is carried out under the same space velocity by changing the weight of the corresponding catalyst, the acid amount is the dominant factor influencing the catalytic properties. When this reaction is performed under the same catalyst weight, a small amount of binder is seen to have a positive effect, increasing the catalytic activity as a result of the enhanced metal dispersion and acid amount. However, a negative effect is observed when the binder amount continues to increase. The function of stabilizing the tin species can be strengthened by alumina addition, which might facilitate the transport of the carbon deposits from the active sites to the carrier. TPO profiles of the corresponding catalysts under different reaction conditions represent dissimilar behaviors, which is attributed to an increase in acid amount and change in metal dispersion in the presence of binder. Finally, a model for the influence of the alumina binder on the catalytic performance of PtSnNa/ZSM-5 catalyst for propane dehydrogenation is proposed.

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Sn modified ZSM-5 was hydrothermally synthesized and this kind of zeolite was used as the support for platinum catalyst in propane dehydrogenation. In this tin-doped material, XRD results established the presence of highly crystalline and the analysis of SEM showed the deterioration in crystal quality. The incorporation of Sn into the framework of ZSM-5 zeolite introduced the strong interactions between Sn species and the support, thus more amounts of tin could exist in oxidized form. Moreover, on the Sn-containing PtNa/Sn-ZSM-5 catalyst, the substitution of Sn changed the interfacial character between Pt and the support, which in consequence promoted the occurrence of spillover hydrogen and facilitated the reduction of Pt species. Compared with the conventional impregnated PtNa/HZSM-5 and PtSnNa/HZSM-5 catalysts, the Sn-modified ZSM-5-based Pt catalyst exhibited higher reaction activity and stability. It showed the lowest deactivation parameter (6.2%) and exhibited a selectivity to propene higher than 98% with the corresponding propane conversion of about 39.0% after the reaction for 9 h.

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