Macroscopic SiO2 spheres with a homogeneous amine distribution were synthesized by a one-step emulsion based synthesis approach in a flow column reactor. The CO2 adsorption capacity of the nanostructured amine-functio...Macroscopic SiO2 spheres with a homogeneous amine distribution were synthesized by a one-step emulsion based synthesis approach in a flow column reactor. The CO2 adsorption capacity of the nanostructured amine-functionalized silica spheres was studied in absence and presence of H2O. The structural properties were adjusted by varying solvents and surfactants during the synthesis and, at constant amine loadings, were found to be the main factor for influencing the CO2 sorption capacities. Under water-free conditions CO2 is bound to the amino groups via the formation of carbamates, which require two neighboring amino groups to adsorb one CO2 molecule. At constant amine concentrations sorbents with lower surface area allow to establish a higher amine density on the surface, which enhances the CO2 uptake capacities under dry conditions. In presence of H2O the CO2 adsorption changes to 1：1 stoichiometry due to stabilization of carbamates by protonation of H2O and formation of further species such as bicarbonates, which should in principle double the adsorption capacities. Low concentrations of physisorbed H2O（0.3 mmol/g） did not impair the adsorption capacity of the adsorbents for CO2, while at higher water uptakes（0.6 and 1.1 mmol/g） the CO2 uptake is reduced, which could be attributed to capillary condensation of H2O or formation of bulky reaction products blocking inner pores and access to active sites.展开更多
The effects of H2O2 pretreatment on the surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy(SMA)were investigated by scanning electron microscopy,X-ray diffraction,X-ray photoelectron spect...The effects of H2O2 pretreatment on the surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy(SMA)were investigated by scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,Raman spectra,Fourier transform infrared spectroscopy as well as a simulated body fluid(SBF)soaking test.It is found that the H2O2 pretreatment can lead to the direct creation of more Ti—OH groups and the decrease in the amount of Ni2O3,Na2TiO3 and remnant NiTi phases on the surfaces of bioactive NiTi SMA prepared by NaOH treatment.As a result,the induction period of apatite formation is shortened by dispensing with the slow kinetic formation process of Ti—OH groups via an exchange of Na+ ions from Na2TiO3 phase with H3O+ ions in SBF,which indicates that the bioactivity of NaOH-treated NiTi SMA can be further improved by the H2O2 pretreatment.展开更多
The toluene oxidative bromination reaction catalyzed by hollow titanium silicalite(HTS)zeolite in aqueous medium was investigated by employing H2O2 and HBr under mild conditions without the need for organic solvent.A ...The toluene oxidative bromination reaction catalyzed by hollow titanium silicalite(HTS)zeolite in aqueous medium was investigated by employing H2O2 and HBr under mild conditions without the need for organic solvent.A high toluene conversion(90.7%)and high selectivity of mono-bromotoluene(99.0%)was achieved under the optimal reaction conditions.The UV-Raman spectroscopy was applied for the mechanism study and the result reveals that HTS is efficient for catalyzing the oxidation reaction of HBr with H2O2 to produce abundant active bromine species,which can further facilitate the toluene electrophilic bromination reaction.A two-step toluene bromination reaction mechanism involving the HTS catalyzed active bromine species“generation-conversion-utilization”process is proposed based on the UV-Raman spectroscopy analysis.展开更多
Rice husk ash was used as a new, green, and cheap adsorbent for FeCl3. Characterization of the obtained reagent showed that rice husk ash supported FeCl2·2H2O was formed. This reagent is efficient at catalyzing t...Rice husk ash was used as a new, green, and cheap adsorbent for FeCl3. Characterization of the obtained reagent showed that rice husk ash supported FeCl2·2H2O was formed. This reagent is efficient at catalyzing the synthesis of multisubstituted quinolines by the Friedl鋘der heteroannulation of o‐aminoaryl ketones with ketones or β‐diketones under mild reaction conditions. This methodology allows for the synthesis of a broad range of substituted quinolines in high yields and with excellent regioselectivity in the absence of a solvent.展开更多
基金supported by the German Research Council(DFG)within the priority program(Schwerpunktprogramm),“Poröse Medien mit definierter Porenstruktur in der Verfahrenstechnik–Modellierung,Anwendngen,Synthese”(SPP 1570)under the projects LE 1187/10 and SP 648/4the framework of the DFG Excellence Initiative the Cluster of Excellence“Engineering of Advanced Materials”(DFG EXC 415)funding via the DFG research training group GRK 1896
文摘Macroscopic SiO2 spheres with a homogeneous amine distribution were synthesized by a one-step emulsion based synthesis approach in a flow column reactor. The CO2 adsorption capacity of the nanostructured amine-functionalized silica spheres was studied in absence and presence of H2O. The structural properties were adjusted by varying solvents and surfactants during the synthesis and, at constant amine loadings, were found to be the main factor for influencing the CO2 sorption capacities. Under water-free conditions CO2 is bound to the amino groups via the formation of carbamates, which require two neighboring amino groups to adsorb one CO2 molecule. At constant amine concentrations sorbents with lower surface area allow to establish a higher amine density on the surface, which enhances the CO2 uptake capacities under dry conditions. In presence of H2O the CO2 adsorption changes to 1：1 stoichiometry due to stabilization of carbamates by protonation of H2O and formation of further species such as bicarbonates, which should in principle double the adsorption capacities. Low concentrations of physisorbed H2O（0.3 mmol/g） did not impair the adsorption capacity of the adsorbents for CO2, while at higher water uptakes（0.6 and 1.1 mmol/g） the CO2 uptake is reduced, which could be attributed to capillary condensation of H2O or formation of bulky reaction products blocking inner pores and access to active sites.
基金Project(50501007) supported by the National Natural Science Foundation of ChinaProject(BK2003062) supported by the Natural Science Foundation of Jiangsu Province,China+2 种基金Project(CityU 1/04C) supported by Hong Kong Research Grants Countil(RGC) Central Allocation Group ResearchProject(4012001007) supported by Teaching and Research Award Program for Outstanding Young Teachers of Southeast UniversityProject(9212001352) supported by Pre-research Project for National Natural Science Foundation in Southeast University,China
文摘The effects of H2O2 pretreatment on the surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy(SMA)were investigated by scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,Raman spectra,Fourier transform infrared spectroscopy as well as a simulated body fluid(SBF)soaking test.It is found that the H2O2 pretreatment can lead to the direct creation of more Ti—OH groups and the decrease in the amount of Ni2O3,Na2TiO3 and remnant NiTi phases on the surfaces of bioactive NiTi SMA prepared by NaOH treatment.As a result,the induction period of apatite formation is shortened by dispensing with the slow kinetic formation process of Ti—OH groups via an exchange of Na+ ions from Na2TiO3 phase with H3O+ ions in SBF,which indicates that the bioactivity of NaOH-treated NiTi SMA can be further improved by the H2O2 pretreatment.
基金The author thanks for the financial support of SINOPEC Corporation(S413108).
文摘The toluene oxidative bromination reaction catalyzed by hollow titanium silicalite(HTS)zeolite in aqueous medium was investigated by employing H2O2 and HBr under mild conditions without the need for organic solvent.A high toluene conversion(90.7%)and high selectivity of mono-bromotoluene(99.0%)was achieved under the optimal reaction conditions.The UV-Raman spectroscopy was applied for the mechanism study and the result reveals that HTS is efficient for catalyzing the oxidation reaction of HBr with H2O2 to produce abundant active bromine species,which can further facilitate the toluene electrophilic bromination reaction.A two-step toluene bromination reaction mechanism involving the HTS catalyzed active bromine species“generation-conversion-utilization”process is proposed based on the UV-Raman spectroscopy analysis.
文摘Rice husk ash was used as a new, green, and cheap adsorbent for FeCl3. Characterization of the obtained reagent showed that rice husk ash supported FeCl2·2H2O was formed. This reagent is efficient at catalyzing the synthesis of multisubstituted quinolines by the Friedl鋘der heteroannulation of o‐aminoaryl ketones with ketones or β‐diketones under mild reaction conditions. This methodology allows for the synthesis of a broad range of substituted quinolines in high yields and with excellent regioselectivity in the absence of a solvent.
