No abstract

Controls over the atomic dispersity and particle shape of noble metal catalysts are the major qualities determining their usability in industrial runs, but they are usually difficult to be simultaneously realized. Inspired from the Deacon catalyst in which RuO2 can form epitaxial layers on the surfaces of Rutile TiO2, here we have investigated the shape evolution process of RuO2 nanoparticles on the surface of P25 TiO2. It is found that size effects exist in this process and RuO2 nanoparticles with sizes ~sub-2 nm can be transformed into epitaxial layers while nanoparticles with bigger sizes are not apt to change their shapes. Based on a thermodynamic model, we infer such transformation process is jointly driven by the surface tension and interfacial lattice match between the nanoparticles and substrates, which may be suggestive for the design of noble metal catalysts integrating both active crystal planes and high atomic exposure ratios.

Chromium oxide supported on SBA-15 was modified with Ce species by an incipient method. The effect of Ce on the activity of Cr/SBA-15 catalyst in the dehydrogenation of ethane with CO 2 was investigated. The activity is enhanced for Ce modified Cr/SBA-15 catalyst for the dehydrogenation of ethane with CO 2 . The cycle between Cr 6+ and Cr 3+ species can be carried out viaing the dehydrogenation of ethane and oxidation of CO 2 processes.

Sulfonic acid functionalized mesoporous SBA-15 materials were prepared using the co-condensation and grafting methods, respectively, and their catalytic performance in the dehydration of xylose to furfural was examined. SBA-15-SO 3 H(C) prepared by the co-condensation method showed 92-95% xylose conversion and 74% furfural selectivity, and 68-70% furfural yield under the given reaction conditions. The deactivation and regeneration of the SBA-15-SO 3 H(C) catalyst for the dehydration of xylose was also investigated. The results indicate that the used and regeneration catalysts retained the SBA-15 mesoporous structure, and the S content of SBA-15-SO 3 H(C) almost did not change. The deactivation of the catalysts is proposed to be associated with the accumulation of byproducts, which is caused by the loss reaction of furfural. After regeneration by H 2 O 2 , the catalytic activity of the catalyst almost recovered.