CATALYSIS SURVEYS FROM ASIA
·
2020
·Vol. 24
·期 2
·115-122
·
IF 2.194
Gao Meixiang,Jiang Haoxi,Zhang Minhua
This paper has systematically investigated the structures and properties of the ZrO 2 , Nano-SiO 2 and their composition. The catalysts were prepared by impregnation, characterized by N 2 adsorption–desorption, TEM, XRD, Raman, temperature-programmed desorption of NH 3 and CO 2 , FTIR spectroscopy of adsorbed pyridine and CO 2 , and UV–vis spectra. Compared with dry-mixed samples, these catalysts have larger average pore diameter, enabling ZrO 2 to be dispersed more uniformly on the surface of Nano-SiO 2 . With the Zr–O–Si bonds, ZrO 2 could interact intensely with Nano-SiO 2 . The catalyst prepared shows the best performance, with the selectivity of 93.18% and conversion of 58.52%. The preparation methods have a significant influence on the interaction between ZrO 2 and Nano-SiO 2, which then affects the acid–basic properties. This paper finds that weak acid–basic sites with moderate-intensity are more suitable for ethanol conversion to BD, with the amount of acid and basic sites as close as possible.
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APPLIED CATALYSIS A-GENERAL
·
2020
·
IF 5.006
Hui Huang,Jun Wang,Yafei Xu,Rui Xu,Wuke Li
In this paper, a luminescent and thermo-responsive catalyst based on SiO 2 @Pt@PABI-Tb@PNIPAM was prepared by incorporating Pt nanoparticles , luminescent material and mesoporous silica with thermo-responsive polymer. The obtained catalyst was characterized by IR, TGA, UV–vis, SEM, TEM, X-ray photoelectron spectroscopy and luminescence. The hybrid catalyst exhibits “on-off” green luminescence in solution under UV irradiation, which could be observed by eyes. The catalytic results indicate that the dehydrogenation of ammonia borane (AB) catalyzed by SiO 2 @Pt@PABI-Tb@PNIPAM is thermo-controllable and switchable. The SiO 2 @Pt@PABI-Tb@PNIPAM shows high catalytic activity for the generation of hydrogen at room temperature. However, it exhibits much lower catalytic activity at high temperature. The catalysts exhibit excellent durability because the support and polymer could prevent the aggregation and leaching of Pt nanoparticles during catalysis. The catalytic research offers a new approach to the thermo-controllable application in the generation of hydrogen from AB.
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JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2020
·
IF 6.155
Wenzhi Li,Lihong Gao,Zhuang Ma,Yanbo Liu,Fuchi Wang,Jiawei Wang,Lijun Wang,Hezhang Li
Faced with the challenge of high energy ablation problems, especially for laser ablation , effective energy dissipation protective materials fabricate by efficient preparation method is a feasible solution. The Ni-graphite/SiO 2 coatings with different Ni content were prepared by plasma spraying method with optimized plasma spraying parameters. All coatings are pure without oxidation and dense. Their ablation behaviors were investigated by high power continuous wave laser. The results indicate that the Ni-graphite/SiO 2 coating with appropriate Ni content could realize the purpose of energy consumption by endothermal reaction of graphite/SiO 2 and reflection improvement. High Ni content will block the occurrence of endothermal reaction of graphite/SiO 2 and increase the heat diffusion to interior part of coating, which can make the ablation situation of coating more serious.
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CHEMICAL ENGINEERING SCIENCE
·
2021
·
IF 4.311
Zhongliang Huang,Yujia Yuan,Miaomiao Song,Zhimian Hao,Jingran Xiao,Dongren Cai,Abdul-Rauf Ibrahim,Guowu Zhan
Herein, we fabricated a series of bimetallic Pt-Ni catalysts supported on mesoporous silica nanorods ( m SNR, specific BET surface area of 1802 m 2 g −1 ) to study the effect of Ni/Pt ratio on the product selectivity in CO 2 hydrogenation. Both monometallic Pt/ m SNR and Ni 50 Pt 50 / m SNR catalysts revealed negligible methane selectivity. However, methane became the major product only when increasing the Ni/Pt ratio up to 9. X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma (ICP) characterizations showed that the Pt/Ni ratio on the catalyst surface was appreciably higher than the bulk composition, suggesting the enrichment of Pt on the surface ( e.g. , Pt/Ni of 61/39 for Ni 50 Pt 50 / m SNR catalyst). The Pt/Ni ratio was crucial in determining the CH 4 /CO selectivity, and the addition of a tiny amount of Pt could improve the catalytic performance and stability of Ni/ m SNR. Among the different catalysts, Ni 98 Pt 2 / m SNR showed the best CO 2 conversion (59%) and CH 4 selectivity (96%) at 400 °C, 0.1 MPa, 9600 mL h −1 g cat −1 , and H 2 /CO 2 of 3. In-situ DRIFTS and temperature-programmed surface experiments suggested that the dissociated adsorption of CO 2 on the Pt site led to CO*, but the strongly adsorbed CO* cannot be further hydrogenated to CH 4 over the Pt site. In contrast, CO* could be further hydrogenated into CH 4 via CH x O* intermediates on adjacent Ni sites.
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COMPOSITES PART B-ENGINEERING
·
2021
·
IF 9.078
Meng Yuan,Meng Zhou,Heqing Fu
Recently, thin, lightweight, wide and strong microwave absorption performance are the main targets for researchers to design high-performance absorbers. A new two-dimension MXene material has attracted significant attention because of its unique hierarchical structure, large specific surface area and special metallic features. However, its improperly high electrical conductivity of MXene causes the bad microwave absorption performance. To meet the needs of practical application, the sandwich-like NiFe 2 O 4 @SiO 2 @MXene nanocomposites were fabricated via multilayered MXene and core-shell NiFe 2 O 4 @SiO 2 nanoparticles. By the synergistic effects from the SiO 2 (transparent medium) improving impedance matching and the two-dimensional laminated MXene increasing conductive loss, the microwave absorption performance of NiFe 2 O 4 @SiO 2 @MXene can be effectively regulated and optimized. As a result, the minimum reflection loss of NiFe 2 O 4 @SiO 2 @MXene reaches −52.8 dB at 11.6 GHz with a thickness of 2 mm, and the maximum effective absorption bandwidth is 7.2 GHz (10.8–18 GHz) covering the whole Ku-band with only a 1.5 mm thickness. It has proved that microcosmic sandwich-like structure design is an efficient approach to achieving excellent microwave absorption performance. The multiple components and unique structure generate heterogeneous interfaces, multiple reflections, polarization features and well-matched impedance. This work provides an insight for rationally constructing hybrid materials with a complex structure in the application of microwave absorption field.
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INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
·
2021
·Vol. 22
·期 20
·11087
·
IF 5.924
Guangjie Hu,Yuxuan Xiao,Jie Ying
Coatings are of great significance for irons and steels in regards to the harsh marine environment. Graphene oxides (GO) have been considered as an ideal filler material of epoxy coating. However, the undesired dispersion in the epoxy together with easy agglomeration and stacking remain great problems for practical application of GO composited epoxy coatings. A method that can effectively solve both self-aggregation and poor dispersion of GO is highly desired. Herein, we present a high dispersion strategy of graphene oxides in epoxy by co-decoration of nano-SiO2and silane coupling agent. The co-decorated GO filled epoxy coating exhibits high anti-corrosion performance, including high electrochemical impedance, high self-corrosive potential, low self-corrosive current, and superior electrochemical impedance stability for ten days to Q235 carbon steel. This work displays new possibilities for designing novel coating materials with high performance toward practical marine anti-corrosion applications.Keywords:graphene oxide;epoxy coating;surface decoration;anti-corrosion
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2021
·
IF 7.312
Jiahao Wei,Jingtao Bi,Longfei Zhang,Dandan Han,Junbo Gong
Constructing a robust catalytic membrane with simultaneous fast liquid transport and efficient organic pollutant degradation is appealing for efficient organic wastewater treatment. Herein, Fe-doped CoTiO 3 grew uniformly on the SiO 2 fiber membrane to form a catalytic membrane (FCTSM). Benefiting from the great water wettability, FCTSM facilitated fast water transport with low energy consumption and exhibited high physical separation performance (98.4% rejection of oil in the emulsion). The catalytic active sites were fully exposed on membrane surface, which could easily react with peroxymonosulfate and target pollutants. Under the gravity-driven permeation, FCTSM performed decent catalytic degradation property (e.g., 96.3% removal of nimesulide with the flux of 300 L/m 2 ·h) in the presence of peroxymonosulfate. Electron paramagnetic resonance (EPR) spectra and quenching tests found that SO 4 •− and 1 O 2 were involved in pollutant degradation, and the possible degradation pathway of nimesulide was investigated. Besides, the toxicity analyses based on quantitative structure–activity relationship (QSAR) verified the reduced toxicity of degradation products. This work provides an insight into the design of multifunctional membranes and advances the potential applications of heterogeneous catalytic oxidation in environmental remediation.
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POLYMER COMPOSITES
·
2019
·Vol. 41
·期 1
·381-390
·
IF 2.268
Dongna Li,Jirui Fu,Xiaojun Ma
A biocomposite of poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH)/nano-SiO 2 modified with silane coupling agent KH570 (KH570-SiO 2 /PHBH) were prepared by solution-casting method. SiO 2 modified with KH570 exhibited improved uniform dispersion than that of pure nano-SiO 2 , and maximum thermal decomposition temperature range and crystallinity ( X c ) of KH570-SiO 2 /PHBH are 8.6°C and 119.7% higher than that of neat PHBH. Compared to the neat PHBH, a 75.4% and 70.8% improvement in Young's modulus and tensile strength were obtained. The water-vapor transmission and oxygen permeance of KH570-SiO 2 /PHBH decreased by 46.2% and 618.6%, respectively. The oxygen barrier property is equivalent to that of polyvinylidene chloride. Simultaneous enhancements on the thermal stability, mechanical, crystallizing, and barrier properties were mainly caused by uniform dispersion of modified nano-SiO 2 and solid interfacial bonding between filler and matrix.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2019
·
IF 4.175
Yao Fu,Jian Li,Pengzhen Li,Huajie Tao,Xianfu Luo,Dongjian Wang,Yiting Shan,Hongqing Zhou
In this work, the titanate coupling agent KR-TTS was used in tape casting of CaO–B 2 O 3 –SiO 2 (CBS) glass-ceramics to obtain a high-performance dielectric tape. The functional group ((RO) m ) of KR-TTS could directly react with the hydroxyl (–OH) of the CBS powders, which made the feature of powders from hydrophilicity into hydrophobicity . The modification mechanism of the modifier KR-TTS was illuminated by infrared absorption spectrum and contact angle of powders with modifier KR-TTS. The optimum amount of KR-TTS was determined by the rheological properties of suspensions, the density and the tensile strength of the green samples, the density and dielectric properties of the sintering samples sintered at 835 °C. The surface modification of CBS glass-ceramic by KR-TTS has made a substantial breakthrough in improving the densification and the mechanical performance of the green tapes. When the amount of KR-TTS was 1.0 wt%, the stability of slurry and the properties of the green samples had been greatly improved. The density of the green samples with 1.0 wt% KR-TTS reached 1.59 g/cm 3 and the tensile strength of the green samples reached 2.43 MPa. The sintering sample with 1.0 wt% KR-TTS realized sintering densification and performed better dielectric properties. The sintering density reached to 2.51 g/cm 3 . The permittivity and dielectric loss were ε r = 5.92 and tanδ = 13 × 10 −4 at 10 GHz.
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JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
·
2019
·
IF 2.683
Zigui Luo,Xi'an Fan,Wentao Hu,Fan Luo,Jian Wang,Zhaoyang Wu,Xin Liu,Guangqiang Li,Yawei Li
In this work, Fe 2 SiO 4 /SiO 2 coated Fe-Si soft magnetic composites (SMCs) have been prepared successfully via ball milling Fe-6.5wt%Si/Fe 3 O 4 composite particles combined with subsequent spark plasma sintering (SPS) process. The formation mechanism of Fe 2 SiO 4 /SiO 2 insulating layer and effect of Fe 3 O 4 coating content on the microstructure and properties for the Fe-Si SMCs were investigated in detail. It is interesting that high temperature SPS process would lead to the occurrence of redox reactions between Fe 3 O 4 and Si from Fe-Si alloy cores, and resulted in the transformation from Fe 3 O 4 coating layer to Fe 2 SiO 4 /SiO 2 insulating layer. As a consequence, the novel Fe-Si SMCs exhibited superior performances including high saturation magnetization (190.4 emu/g) and low core loss (9.02 mW/cm 3 at 10 kHz) decreased by 89.1% compared to that of the uncoated Fe-Si SMCs (83.08 mW/cm 3 at 10 kHz). The results indicated that the method of preparing insulating layer by the redox reactions is a simple and effective way to synthesize new SMCs with high performance for electro-magnetic energy conversion equipments.
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JOURNAL OF MOLECULAR LIQUIDS
·
2019
·
IF 4.561
Yang Wang,Si Sun,Lin Shi,Pengcheng Gao,Yingying Wei,Chuan Zhang,Yong Jiang
A facile and energy-efficient synthesis of Fe 3 O 4 @SiO 2 -PHEMA complex and its application as adsorbent for removal of Cu 2+ from aqueous solution were investigated. Fe 3 O 4 @SiO 2 -PHEMA was synthesized by mixing Fe 3 O 4 @SiO 2 and HEMA monomer and then initiating the polymerization of HEMA monomer by H 2 O 2 under Fe 2+ catalyzing at room temperature . As adsorbent, the maximum sorption capacity of Fe 3 O 4 @SiO 2 -PHEMA for Cu 2+ was calculated to be 20.7 mg/g at pH 6.0. And the efficient enrichment of Cu 2+ on Fe 3 O 4 @SiO 2 -PHEMA depended on its multiple carbonyl groups and the electrostatic interaction between carboxyl groups and Cu 2+ . The carboxyl groups were from slow hydrolysis of partial ester bonds of PHEMA under acidic conditions. The possible hydrolysis process of ester bonds was facilitated to avoid sorption capacity of Cu 2+ decreasing caused by other ions sorption (like Fe 2+ ) during the synthesis of the adsorbent. The adsorption of Cu 2+ on Fe 3 O 4 @SiO 2 -PHEMA coincided with Langmuir model. The Fe 3 O 4 @SiO 2 -PHEMA had good dispersity in water and it could be easily collected from wastewaters by a magnet. The results showed that Fe 3 O 4 @SiO 2 -PHEMA was a promising adsorbent in wastewater treatment.
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JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY
·
2019
·Vol. 19
·期 12
·7799-7809
·
IF 1.093
Xu Li-Hui,Wang Li-Ming,Pan Hong,Shen Yong,Ding Ying,Zhang Xuan-Yu,Sheng Yu
Superhydrophobic cotton fabrics were prepared by simultaneous incorporation of SiO2 aerogel particles and polydimethylsiloxane (PDMS). The SiO2 aerogels were synthesized via acid-base catalyzed sol–gel reaction with methyl trimethoxy silane (MTMS) as the
single precursor and oxalic acid and ammonium hydroxide as the catalyst in methanol (MeOH) solution by drying under ambient pressure. The preparation parameters (e.g., MTMS/MeOH molar ratio, oxalic acid/MTMS molar ratio, gelation pH value, and gelation temperature) had great influences on
the density and porosity of the SiO2 aerogel. The obtained SiO2 aerogel had low density, high porosity and high specific surface area, showing the typical rough mesoporous structure. The prepared bulk SiO2 aerogel displayed excellent superhydrophobicity with
a water contact angle (WCA) of 151.0 ± 0.8°. Superhydrophobic cotton fabric with a WCA of 155.6 ± 0.9° for a 5 μL water droplet was successfully obtained by simply coating the PDMS/SiO2 aerogel composite solution via dip-pad-cure process. This could
be attributed to the combination of SiO2 aerogel particles with porous rough microstructure, high specific surface area and PDMS adhesive layer with low surface energy. The effect of PDMS/SiO2 aerogel coating treatment on the mechanical strength properties of the cotton
fabrics was negligible. This simple approach may pave the potential way for practical applications.
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