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TiO <sub/>2</sub> /zeolite Bifunctional (Photo)catalysts for a Selective Conversion of Methanol to Dimethoxymethane: On the Role of Br?nsted Acidity
摘要： In the present work, we report the first example of one-step selective methanol photooxidation to dimethoxymethane (DMM) at room temperature over TiO2/zeolite bifunctional catalysts. The effects of the porosity, basicity/acidity of the zeolites on the selectivity of the reaction are discussed. The role of TiO2 active sites and zeolitic Br?nsted acid sites on the DMM production is reported. As the photocatalytic reaction occurs at room temperature, the influence of the reaction temperature is also investigated to extrapolate the results to thermal catalysis. This study demonstrates a clear synergetic effect of the zeolites on the selectivity of the reaction. They can display an important impact on the selectivity of the photocatalytic reaction even at a low temperature (e.g. room temperature). Based on the obtained results, the reaction mechanism of methanol conversion to DMM is elucidated.
关键词： Br?nsted acidity,dimethoxymethane (DMM),selective conversion,methanol photooxidation,TiO2/zeolite bifunctional catalysts
更新于2025-09-09 09:28:46
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Impact of molecular structure on secondary organic aerosol formation from aromatic hydrocarbon photooxidation under low NO<sub><i>x</i></sub> conditions
摘要： The molecular structure of volatile organic compounds (VOC) determines their oxidation pathway, directly impacting secondary organic aerosol (SOA) formation. This study comprehensively investigates the impact of molecular structure on SOA formation from the photooxidation of twelve different eight to nine carbon aromatic hydrocarbons under low NOx conditions. The effects of the alkyl substitute number, location, carbon chain length and branching structure on the photooxidation of aromatic hydrocarbons are demonstrated by analyzing SOA yield, chemical composition and physical properties. Aromatic hydrocarbons, categorized into five groups, show a yield order of ortho (o-xylene and o-ethyltoluene) > one substitute (ethylbenzene, propylbenzene and isopropylbenzene) > meta (m-xylene and m-ethyltoluene) > three substitute (trimethylbenzenes) > para (p-xylene and p-ethyltoluene). SOA yields of aromatic hydrocarbon photooxidation do not monotonically decrease when increasing alkyl substitute number. The ortho position promotes SOA formation while the para position suppresses aromatic oxidation and SOA formation. Observed SOA chemical composition and volatility confirm that higher yield is associated with further oxidation. SOA chemical composition also suggests that aromatic oxidation increases with increasing alkyl substitute chain length and branching structure. Further, carbon dilution theory developed by Li et al. (2015a) is extended in this study to serve as a standard method to determine the extent of oxidation of an alkyl substituted aromatic hydrocarbon.
关键词： photooxidation,low NOx conditions,molecular structure,secondary organic aerosol,aromatic hydrocarbons
更新于2025-09-04 15:30:14
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Synthesis, structural characterization and photophysical properties of 7-cyanohexahelicene
摘要： 7-Cyanoexahelicene has been prepared in racemic form through a short photochemical synthetic approach and its enantiomeric separation was studied and allowed to obtain (P)- and (M)-enantiomers in 100% ee and > 98.5% ee, respectively. The optical rotatory dispersion and electronic circular dichroism (ECD) spectra of the resolved ones were measured. Other optical properties such as UV and photoluminescence as well as the electrochemical behavior were also examined in solutions.
关键词： Optical resolution,Chirality,Couplings,Photophysical properties,gap energy,Helicenes,Photooxidation
更新于2025-09-04 15:30:14
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A Cross‐linked Conjugated Polymer Photosensitizer Enables Efficient Sunlight‐induced Photooxidation
摘要： Photooxidation under sunlight has great potentials in organic synthesis, bacterial killing, organic waste treatment, etc. Photosensitizers (PSs) often play a very important role in this process. High 1O2 generation efficiency and excellent photostability under sunlight, as well as easy recyclability are ideal properties for PSs used for photooxidation, which are not easy to achieve simultaneously. Herein, a pure organic porous conjugated polymer PS of CPTF was designed and synthesized to show great photostability, large specific surface area and high 1O2 generation efficiency under sunlight for photooxidation in different applications. Taking the oxidation of aromatic aldehyde to aromatic acid as an example, the PS catalyst shows excellent recyclability, which enables solvent-free reactions in high yields both under direct sunlight and simulated AM1.5G irradiation. In addition, the successful application of CPTF in bacterial killing and organic waste decomposition under simulated AM1.5G irradiation indicates the potential of CPTF in sunlight-induced waste water treatment.
关键词： singlet oxygen,sunlight-induced organic synthesis,photooxidation,photosensitizers,sunlight-induced wastewater treatment
更新于2025-09-04 15:30:14
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A Cross-linked Conjugated Polymer Photosensitizer Enables Efficient Sunlight-induced Photooxidation
摘要： Photooxidation under sunlight has great potentials in organic synthesis, bacterial killing, organic waste treatment, etc. Photosensitizers (PSs) often play a very important role in this process. High 1O2 generation efficiency and excellent photostability under sunlight, as well as easy recyclability are ideal properties for PSs used for photooxidation, which are not easy to achieve simultaneously. Herein, a pure organic porous conjugated polymer PS of CPTF was designed and synthesized to show great photostability, large specific surface area and high 1O2 generation efficiency under sunlight for photooxidation in different applications. Taking the oxidation of aromatic aldehyde to aromatic acid as an example, the PS catalyst shows excellent recyclability, which enables solvent-free reactions in high yields both under direct sunlight and simulated AM1.5G irradiation. In addition, the successful application of CPTF in bacterial killing and organic waste decomposition under simulated AM1.5G irradiation indicates the potential of CPTF in sunlight-induced waste water treatment.
关键词： photooxidation,singlet oxygen,photosensitizers,sunlight-induced organic synthesis,sunlight-induced wastewater treatment
更新于2025-09-04 15:30:14
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Effect of Zn Content on the physicochemical Characteristics and Photoactivity of ZnO supported Activated Carbon
摘要： In the present work, synthesis of ZnO dispersed onto activated carbon (ZnO/AC) is reported. Synthesis was conducted by using impregnation method by zinc acetate as precursor at varied Zn content. A systematic characterization of ZnO/C materials was performed using XRD, SEM, gas sorption analyzer and diffuse reflectance UV-Visible spectrophotometer. Photoactivity of the materials was studied in phenol removal via photooxidation mechanism. From the study it is confirmed that ZnO dispersion give acceleration of phenol removal refer to surface area contribution. It is no linear correlation of each physical character to the photocatalytic activity.
关键词： ZnO,Activated Carbon,Photocatalyst,Photooxidation
更新于2025-09-04 15:30:14