7 results on '"Phyu Thin Wai"'
Search Results
2. Encapsulated ultrafine and highly dispersed molybdenum dioxide nanoparticles in hollow mesoporous silica spheres as an efficient epoxidation catalyst for alkenes
- Author
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Yuming Dong, Phyu Thin Wai, Pingbo Zhang, Pingping Jiang, and Yirui Shen
- Subjects
Materials science ,010405 organic chemistry ,Nanoparticle ,chemistry.chemical_element ,General Chemistry ,Mesoporous silica ,010402 general chemistry ,01 natural sciences ,Hydrothermal circulation ,0104 chemical sciences ,Catalysis ,lcsh:Chemistry ,chemistry.chemical_compound ,lcsh:QD1-999 ,Chemical engineering ,chemistry ,Molybdenum ,Selectivity ,Molybdenum dioxide ,Reusability - Abstract
A facile post-synthetic strategy was developed to functionalize the preformed hollow mesoporous silica spheres by encapsulating the molybdenum dioxide (MoO2) nanoparticles inside the interior cavity. Hollow mesoporous silica spheres were prepared and employed as carriers, and the encapsulation of MoO2 nanoparticles was achieved through a one-pot hydrothermal protocol. After characterization, the encapsulated MoO2 nanoparticles were certified to be ultrafine and highly dispersed, which greatly promoted the catalytic activity. The as-prepared catalysts were utilized in epoxidation of alkenes and exhibited as a promising catalyst in this reaction. After reacting for 10 h, the optimal catalyst MoO2@SiO2-1 achieved a conversion above 95% and selectivity above 95%, respectively. Moreover, the catalysts also exhibited good reusability, conversion of 78% and selectivity of 89% (reaction time 4 h) were still obtained after recycling for 5 times. Meanwhile, the employed facial and efficient hydrothermal approach could be expanded to other molybdenum modified heterogeneous catalysts in various applications. Keywords: Post-synthesis, Ultrafine, Molybdenum dioxide, Alkene, Epoxidation
- Published
- 2019
3. MoO 3 @SiO 2 nanoreactors: Synthesis with a thermal decomposition strategy and catalysis on alkenes epoxidation
- Author
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Pingping Jiang, Phyu Thin Wai, Wang Yingchun, Gang Bian, Yirui Shen, and Yuming Dong
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Thermogravimetric analysis ,Materials science ,Thermal decomposition ,02 engineering and technology ,Nanoreactor ,Mesoporous silica ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,law.invention ,Catalysis ,Inorganic Chemistry ,Adsorption ,Chemical engineering ,law ,Materials Chemistry ,Ceramics and Composites ,Calcination ,Physical and Theoretical Chemistry ,0210 nano-technology ,Thermal analysis - Abstract
A general thermal decomposition strategy is reported to fabricate MoO3@SiO2 nanoreactors, with a mesoporous silica shell and embedded MoO3 nanoparticles. The novel preparation procedure involves mixing certain mass ratio of (NH4)6Mo7O24·4H2O (AMM) and hollow mesoporous silica spheres (HMSS) by grinding, fusion and thermal decomposition of (NH4)6Mo7O24·4H2O under calcination and removing the residual via filtration. The as-prepared MoO3@SiO2 nanoreactors were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), N2 adsorption/desorption and X-ray photoelectron spectra (XPS). The nanoreactors were utilized in epoxidation of alkenes and displayed high catalytic activity and stability. The mass ratio of AMM and HMSS greatly affected the properties and catalytic performance of the nanoreactors. The optimal mass ratio of AMM: HMSS has been confirmed as 1/2. After reacting for 12 h with H2O2 (50 wt%) as oxidant, conversion and selectivity of optimal MoO3@SiO2-400-1/2 almost reached up to 98% and 99%, respectively. Furthermore, the catalyst still had high conversion (78%) and selectivity (95%) at 4 h epoxidation of cyclooctene after recycling for 6 runs. Kinetics study was also carried out and demonstrated the epoxidation of alkenes follows the first order model.
- Published
- 2018
4. A dual-templating strategy for synthesis of Bi2WO6 with oxygen vacancies for enhanced light-driven photocatalytic oxidation alcohol
- Author
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Yirui Shen, Pingbo Zhang, Kai Zhang, Qian Gu, Yan Leng, Phyu Thin Wai, and Pingping Jiang
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Band gap ,Process Chemistry and Technology ,Cationic polymerization ,chemistry.chemical_element ,Alcohol ,Photochemistry ,Oxygen ,Catalysis ,chemistry.chemical_compound ,chemistry ,Benzyl alcohol ,Light driven ,Photocatalysis ,Physical and Theoretical Chemistry - Abstract
In this study, the flower-like Bi2WO6 with oxygen vacancies were synthesized by using the anionic and cationic dual surfactants strategy. The study results indicate that the synergistic effect of dual surfactants provides more oxygen vacancies for Bi2WO6, which leads to a narrower band gap, an expanded light response range, and an improved separation efficiency of photogenerated charges in Bi2WO6. In the experiment of photocatalytic selective oxidation benzyl alcohol, Bi2WO6 with dual surfactants shows excellent photocatalytic activity. Especially when the molar rate of CTAB to SDS is 2, the conversion of benzyl alcohol overs 90%, which is 1.74-fold than that of pure Bi2WO6. Meanwhile, Bi2WO6 with dual surfactants also exhibits better photocatalytic efficiency for other aromatic alcohols. Furthermore, the free radical capture experiments show that superoxide radical (•O2−) and hole (h+) play a major role in the photocatalytic selective oxidation of benzyl alcohol.
- Published
- 2021
5. Lamellar porous mo-modified carbon nitride polymers photocatalytic epoxidation of olefins
- Author
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Phyu Thin Wai, Qian Gu, Agus Haryono, Pingping Jiang, Yirui Shen, and Kai Zhang
- Subjects
Materials science ,Scanning electron microscope ,Process Chemistry and Technology ,Nitride ,Catalysis ,Styrene ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Styrene oxide ,Photocatalysis ,Lamellar structure ,Physical and Theoretical Chemistry ,Melamine ,Carbon nitride - Abstract
A lamellar porous Mo-modified carbon nitride polymers (CN-Mo) was successfully prepared by a simple bottom-up method, which involves molecule self-assembly by hydrogen bonding between uracil and melamine. Analysis Results of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectra (XPS) show that Mo element has been doped in the skeleton of carbon nitride. The optical characterization results of the as-prepared photocatalysts show that, CN-Mo has a suitable band structure that can promote the separation of carriers and expands the absorption of light. Compared with CN, CN-Mo has better photocatalytic activity for epoxidation of olefins. When the mass value (relative to melamine) of ammonium molybdate tetrahydrate is 2 %, the photocatalytic efficiency is the best for the epoxidation of styrene. And the conversion rate of styrene reaches 38.4 % and the selectivity of styrene oxide is up to 83.2 %. In addition, it can maintain the better photocatalytic performance for the epoxidation of styrene after five reaction-regeneration cycles. This finding provides an effective development direction for photocatalytic olefins epoxidation under mild conditions.
- Published
- 2021
6. An efficient cold-resistant strategy: Synthesis and application of green cold-resistant bio-based plasticizer for poly(vinyl chloride)
- Author
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Huihang Zhao, Pingping Jiang, Zheming Zhang, Yirui Shen, Nie Zhixin, Liu Dekai, Pingbo Zhang, Minzhong Zhao, Haryono Agus, and Phyu Thin Wai
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Materials science ,Polymers and Plastics ,Organic Chemistry ,Plasticizer ,Strategy synthesis ,General Physics and Astronomy ,Bio based ,02 engineering and technology ,Raw material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Poly vinyl chloride ,Oleic acid ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Adipate ,Materials Chemistry ,Degradation (geology) ,0210 nano-technology - Abstract
Nowadays, the most commonly used cold-resistant plasticizer, bis(2-ethylhexyl)adipate (DOA), not only has the poor migration resistance so that it can only be used as auxiliary plasticizer, but also causes huge pollution to the environment, especially water. Here, using renewable and green oleic acid as raw material, we had synthesized a series of oleate plasticizers. By means of capability tests, we detected that the Ti (initial degradation temperature) of PVC films plasticized with oleate plasticizers was 40 °C higher than that of DOA/PVC and 20 °C higher than that of DOTP/PVC. More importantly, in addition to illustrious migration resistance, they could maintain remarkable flexibility in cold environments as well. The low-temperature efficiency value of these oleate plasticizers exceeded 70 °C, which was much higher than DOTP and DOA. These results demonstrated that they possessed the potential to replace toxic DOP and poorly stable DOA, which provided an effective and green approach to solve the harm of plastic products to human health and the threat to the environment. In addition, these plasticizers broadened the application of PVC in cold environments, which was a boon for the application of PVC industry in the cold-resistant field, and contributed to sustainability of the hackneyed and oft-maligned PVC industry.
- Published
- 2021
7. Entrapment of peroxophosphotungstate in SBA-15 by silylation and its catalytic efficiency in the epoxidation of soybean oil
- Author
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Phyu Thin Wai, Pingbo Zhang, Pingping Jiang, Qian Gu, and Yirui Shen
- Subjects
food.ingredient ,Silylation ,010405 organic chemistry ,Chemistry ,Process Chemistry and Technology ,010402 general chemistry ,01 natural sciences ,Catalysis ,Soybean oil ,0104 chemical sciences ,Solvent ,Epoxidized soybean oil ,chemistry.chemical_compound ,Adsorption ,food ,Chemical engineering ,Desorption ,Mesoporous material - Abstract
The efficient catalysts were designed to allow the entry and release of reactants and products into the mesoporous SBA-15 in which the active sites, peroxophosphotungstate, were entrapped by silylation with three different silylating agents (C3, C5, and C8 arm). The as-prepared catalysts were characterized by elemental analysis, ICP analysis, TGA, XRD, N2 adsorption/desorption, SEM, TEM, and FT-IR spectra. Their catalytic performances were tested for the epoxidation of soybean oil using different parameters such as temperature, H2O2 to unsaturation molar ratio, catalyst loading and stirring speed. The resulting epoxidized soybean oil was analyzed qualitatively and quantitatively by FT-IR and 1HNMR. The results confirmed that the catalyst silylated with C8 arm is promising for the synthesis of epoxides of long-chain carbon and reusable at least three times without obvious decrease in activity. Moreover, use of H2O2 oxidant and free of solvent in the epoxidation reaction are the main advantages of these catalysts.
- Published
- 2020
Catalog
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