Demand for environmentally friendly plastic materials which are obtained from renewable resources such as biomass-based polyesters is of concern. Herein, the enhanced characteristic performances of poly(butylene succinate) (PBS) by employing the fabrication of PBS-based composites with the nanosilver-coated carbon black (AgCB) using an injection-molding method are reported. The preformed AgCB additives are priorly prepared by the benzoxazine oxidation method. Phase characterization of the obtained composite materials examined by X-ray diffraction (XRD) reveals the crystalline PBS matrix and the presence of metallic silver particles, confirming the successful fabrication of the composite materials. Detailed analyses on thermal, mechanical, electrical, and antimicrobial properties of the composite materials are reported. The AgCB-PBS composite materials provide such potential features by an enhancement of electrical conductivity and the antimicrobial activity by an inhibition against E. coli and C. albicans. These AgCB-PBS composite materials show the possibility to be an option for antielectrostatic and antimicrobial applications such as for the production of smart, environmentally friendly keyboards.
The precalcined and calcined silica supported cobalt catalysts at 15, 20, and 25%Co were investigated by X-ray Absorption Spectroscopy (XAS) including the X-ray absorption near edge structure (XANES) and the extended X-ray absorption fine structure (EXAFS). The results showed the phase of Co(NO3)2.6H2O in all precalcined catalysts, which corresponded to the XRD measurement. When increasing the amount of cobalt in the precalcined catalysts, there was the presence of ordered Co(NO3)2.6H2O phase. After calcination in Ar at 600°C for 6 h, the Co3O4phase was presented in all calcined catalysts. For the catalytic performance testing, the selected 20%Co/Aerosil_wi_calcined catalyst was reduced at 450°C in H2and operated at 190°C with a total pressure of 10 bar and H2/CO flow rate of 20:10 ml/min for Fischer-Tropsch synthesis. After reaction testing, the used 20%Co/Aerosil_wi catalyst showed the main phase of Co3O4. The result showed high methane selectivity at the beginning of reaction. By increasing of reaction time, the methane selectivity tended to decrease, whereas the C2-C4and C5+selectivity was increased.
The redox reactions of supported metal species have been investigated by means of in-situ and time-resolved XAFS technique for the Co, Ni, and Cu catalysts supported on silica. The in-situ XAFS experiments revealed the chemical state conversions of supported metal species during the temperature-programmed reduction and oxidation processes. The small metal particles tend to be oxidized at lower temperature and reduced at higher temperature than the corresponding larger particles for the Co and Ni catalysts. The temperature shift is ascribed by the strong interaction of the divalent metal oxide with silica. The time-resolved XAFS measurements revealed the detail dynamic processes of redox reactions for the supported metal specie. The chemical state conversions of the supported Ni species under the mixed gas environment of CO and NO were studied by means of the time-resolved XAFS technique at 873 K. The faster oxidation of metallic Ni than the reduction of NiO were directly demonstrated, and the dynamic conversion of the Ni species thus indicated that the oxidation of CO and the reduction of NO were simultaneously achieved on the supported Ni particles.
The performance of ZrO2-La promoted silica supported cobalt catalyst (100Co/15ZrO2/ 100Aerosil/0.66La) was compared to the ZrO2-Ru promoted one, 100Co/15ZrO2/100Aerosil/0.66Ru, in Fischer-Tropsch synthesis (FTS). These catalysts were prepared by co-precipitation and incipient wetness impregnation methods. The characterization by XRD confirmed the cobalt phase of Co3O4 in both catalysts. For their catalytic activity on FTS reaction, the results preliminarily showed the higher methane fraction (60-80%) and lower C2-C4(10-20%) and C5+(10-20%) fractions in ZrO2-La promoted catalyst compared to the fractions of methane (20-40%), C2-C4(20-50%), and C5+(10-60%) from the ZrO2-Ru promoted catalyst. During reaction, the maximum n-paraffin selectivity of 40% was at C3and the hydrocarbon chain was up to C6for the ZrO2-La promoted catalyst. For the ZrO2-Ru promoted catalyst, the result showed the maximum n-paraffin of C3at 30 min of reaction time. When the reaction time increased, the maximum n-paraffin selectivity shifted toward higher C number but levelled off (15%) and the hydrocarbon chain was up to C16.
Abstract. In order to investigate the phases of used Co/SiO2 catalysts, one of the most commonly used catalysts for Fischer-Tropsch synthesis, time-resolved X-ray absorption near edge structure (TR-XANES) technique was introduced. The catalysts were prepared by incipient wetness impregnation method with %Co loading of 15% and 20% and used for Fischer-Tropsch synthesis at the reaction temperature of 190 o C and the pressure of 10 and 20 bar, called 15%Co/Aerosil_wi_used_10_bar, 15%Co/Aerosil_wi_used_20_bar, and 20%Co/Aerosil_wi_used_20_bar. TR-XANES showed the edge energy of 7721 eV for all used catalysts and by looking at the feature of their spectra, the results implied that the major phase was CoO. To further investigate their ability of being oxidized at elevated temperatures, the catalysts were oxidized by heating from ambient to 450 o C with the heating rate of 8 o C/min at the pressure of 1 bar with the O2:N2 flow rate of 70:30 ml/min. Once reaching 450 o C, the temperature was held at 450 o C for 90 min before cooling down to room temperature. During heating, holding, and cooling, the catalyst properties were measured by TR-XANES. When all catalysts heating up from 300 to 400 o C, the edge energy of 15%Co/Aerosil_wi_used_10_bar, 15%Co/Aerosil_wi_used_20_bar, and 20%Co/Aerosil_wi_used_20_bar at 7719, 7717, and 7718 eV, respectively, showed the main phase of CoO mixed with Co3O4. There were no significant changes in phase while holding the temperature at 450 o C. Once cooling from 450 o C to room temperature, the edge energy of 15%Co/Aerosil_wi_used_10_bar at 7724 eV showed the main Co3O4 phase, the ones of 15%Co/Aerosil_wi_used_20_bar and 20%Co/Aerosil_wi_used_20_bar at 7717 and 7718 eV showed the mixed phase of Co3O4 and CoO. All results would be confirmed by further studies on temperature programmed oxidation (TPO).
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