scholarly journals Pyrrole-Based Conjugated Microporous Polymers as Efficient Heterogeneous Catalysts for Knoevenagel Condensation

2021 ◽  
Vol 9 ◽  
Author(s):  
Ruidong Gao ◽  
Guang Zhang ◽  
Fanli Lu ◽  
Long Chen ◽  
Yang Li
Keyword(s):  
Specific Surface ◽  
High Performance ◽  
Heterogeneous Catalysts ◽  
Knoevenagel Condensation ◽  
Condensation Reaction ◽  
High Catalytic Activity ◽  
Microporous Polymers ◽  
Surface Areas ◽  
Specific Surface Areas ◽  
Conjugated Microporous Polymers

Conjugated microporous polymers (CMPs) with robust architectures, facilely tunable pore sizes and large specific surface areas have emerged as an important class of porous materials due to their demonstrated prospects in various fields, e.g. gas storage/separation and heterogeneous catalysis. Herein, two new pyrrole-based CMPs with large specific surface areas and good stabilities were successfully prepared by one-step oxidative self-polycondensation of 1,2,4,5-tetra (pyrrol-2-ly)benzene or 1,3,5-tri (pyrrol-2-ly)benzene, respectively. Interestingly, both CMPs showed very high catalytic activity toward Knoevenagel condensation reaction, which was attributed to the inherent pore channels, high specific surface areas and abundant nitrogen sites within CMPs. Additionally, both CMPs displayed excellent recyclability with negligible degradation after 10 cycles. This work provides new possibilities into designing novel nitrogen-rich high-performance heterogeneous catalysts.

N-doped carbon nanocages with high catalytic activity and durability for oxygen reduction

2015 ◽  
Vol 3 (23) ◽  
pp. 12427-12435 ◽  
Author(s):  
Xiao Xia Wang ◽  
Biao Zou ◽  
Xin Xin Du ◽  
Jian Nong Wang
Keyword(s):  
Catalytic Activity ◽  
Oxygen Reduction Reaction ◽  
Specific Surface ◽  
Oxygen Reduction ◽  
Reduction Reaction ◽  
High Catalytic Activity ◽  
Surface Areas ◽  
Excellent Activity ◽  
Specific Surface Areas

N-doped carbon nanocages with high specific surface areas exhibited excellent activity and durability for oxygen reduction reaction in acidic electrolytes.

A strategy for the synthesis of VN@C and VC@C core–shell composites with hierarchically porous structures and large specific surface areas for high performance symmetric supercapacitors

2018 ◽  
Vol 47 (24) ◽  
pp. 8052-8062 ◽  
Author(s):  
Yifu Zhang ◽  
Jiqi Zheng ◽  
Xuyang Jing ◽  
Changgong Meng
Keyword(s):  
Thermal Treatment ◽  
Electrochemical Performance ◽  
Specific Surface ◽  
High Performance ◽  
Core Shell ◽  
Porous Structures ◽  
Hierarchically Porous ◽  
Surface Areas ◽  
Specific Surface Areas ◽  
Novel Strategy

A novel strategy for the fabrication of VN@C and VC@C was developed by the thermal treatment with H2V3O8@C under N2 and Ar atmospheres. VN@C SSC device exhibited better electrochemical performance than VC@C SSC device.

scholarly journals Role of pulping process as synergistic treatment on performance of agro-based activated carbons

2019 ◽  
Vol 6 (7) ◽  
pp. 190579 ◽  
Author(s):  
Altaf H. Basta ◽  
Vivian F. Lotfy ◽  
Philippe Trens
Keyword(s):  
Specific Surface ◽  
High Performance ◽  
Activated Carbons ◽  
Sorption Properties ◽  
Surface Areas ◽  
Pseudo Second Order ◽  
Specific Surface Areas ◽  
The One ◽  
Reported Data ◽  
The Impact

To recommend the beneficial effect of the pulping process on enhancing agro-wastes as precursors for the production of high-performance activated carbons (ACs), different pulping methods (alkali, sulfite and neutral sulfite) were applied on two available Egyptian agriculture by-products (rice straw and sugar cane bagasse), using the one-step pyrolysis method and H 3 PO 4 activating agent. The adsorption performance of the different prepared ACs was evaluated in terms of Iodine Numbers and their sorption properties for removing the methylene blue (MB) from aqueous solutions. The corresponding sorption processes were also analysed using Lagergren first order, pseudo-second order and intraparticle diffusion models. Data revealed that the applied pulping conditions were effective for removing the non-cellulosic constituents of agro-residues. This was demonstrated by the hydrogen/carbon and oxygen/carbon ratios, thermal stability and IR-measurements of the final pulps. These data were effective on the particular sorption properties of RS and SCB-based ACs. Interestingly, the pulping process is a profound modification of the SCB-based fibres, on which it induced a clear increase of the specific surface areas of the corresponding ACs even though they had an impact on the sorption of MB and iodine. These values are superior to the reported data on agro-based ACs with H 3 PO 4 activators. Pulping processes therefore play a dual role in the sorption properties of ACs. The first important role is the impact on the specific surface areas and the second impact is a profound modification of the surface chemistry of the ACs. Therefore, SCB-based ACs can be seen as an economical breakthrough product, and an alternative to the high-cost commercial ACs for the purification of industrial wastewaters.

Nitroxyl radical based conjugated microporous polymers as heterogeneous catalysts for selective aerobic alcohol oxidation

2018 ◽  
Vol 6 (21) ◽  
pp. 9860-9865 ◽  
Author(s):  
Mingxuan Liu ◽  
Baolong Zhou ◽  
Lei Zhou ◽  
Zhen Xie ◽  
Shen Li ◽  
...  
Keyword(s):  
Heterogeneous Catalysts ◽  
Nitroxyl Radical ◽  
Aerobic Oxidation ◽  
Oxidative Polymerization ◽  
Cost Effective ◽  
Alcohol Oxidation ◽  
Porous Polymers ◽  
High Catalytic Activity ◽  
Microporous Polymers ◽  
Conjugated Microporous Polymers

Porous radical polymers were constructed via cost-effective FeCl3-catalyzed oxidative polymerization of dicarbazole functionalized TEMPO. These porous polymers exhibit high catalytic activity and excellent recycling performance for the aerobic oxidation of a wide variety of alcohols.

scholarly journals Ultrafine porous boron nitride nanofibers synthesized via a freeze-drying and pyrolysis process and their adsorption properties

RSC Advances ◽  
2016 ◽  
Vol 6 (2) ◽  
pp. 1253-1259 ◽  
Author(s):  
Jing Lin ◽  
Lulu Xu ◽  
Yang Huang ◽  
Jie Li ◽  
Weijia Wang ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Specific Surface ◽  
Freeze Drying ◽  
Adsorption Properties ◽  
Pyrolysis Process ◽  
Surface Areas ◽  
Aspect Ratios ◽  
Large Pore ◽  
Specific Surface Areas

Ultrafine porous boron nitride nanofibers with high aspect ratios, high specific surface areas and large pore volumes has been synthesized in large quantity via a freeze-drying and post pyrolysis process.

scholarly journals Experimental Investigation of Coal Dust Wettability Based on Surface Contact Angle

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Gang Zhou ◽  
Han Qiu ◽  
Qi Zhang ◽  
Mao Xu ◽  
Jiayuan Wang ◽  
...  
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Specific Surface ◽  
Coal Dust ◽  
Single Point ◽  
Contact Angles ◽  
Critical Surface ◽  
Volume Percentage ◽  
Surface Areas ◽  
Specific Surface Areas

Wettability is one of the key chemical properties of coal dust, which is very important to dedusting. In this paper, the theory of liquid wetting solid was presented firstly; then, taking the gas coal of Xinglongzhuang coal mine in China as an example, by determination of critical surface tension of coal piece, it can be concluded that only when the surface tension of surfactant solution is less than 45 mN/m can the coal sample be fully wetted. Due to the effect of particle dispersity, compared with the contact angle of milled coal particle, not all the contact angles of screened coal powder with different sizes have a tendency to increase. Furthermore, by the experiments of coal samples’ specific surface areas and porosities, it can be achieved that the volume of single-point total pore decreases with the gradual decreasing of coal’s porosity, while the ultramicropores’ dispersities and multipoint BET specific surface areas increase. Besides, by a series of contact angle experiments with different surfactants, it can be found that with the increasing of porosity and the decreasing of volume percentage of ultramicropore, the contact angle tends to reduce gradually and the coal dust is much easier to get wetted.

Facile Method To Synthesize Mesoporous Multimetal Oxides (ATiO3, A = Sr, Ba) with Large Specific Surface Areas and Crystalline Pore walls

2010 ◽  
Vol 22 (4) ◽  
pp. 1276-1278 ◽  
Author(s):  
Xiaoxing Fan ◽  
Ying Wang ◽  
Xinyi Chen ◽  
Ling Gao ◽  
Wenjun Luo ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Areas ◽  
Specific Surface Areas

Carbon Microspheres Prepared by High Internal Phase Emulsion Polymerization

2011 ◽  
Vol 239-242 ◽  
pp. 3105-3108
Author(s):  
Ming Xian Liu ◽  
Li Hua Gan ◽  
Jun Hu ◽  
Hong Lai Liu ◽  
Long Wu Chen
Keyword(s):  
Electron Microscopy ◽  
Specific Surface ◽  
Aqueous Phase ◽  
Apparent Density ◽  
Tween 80 ◽  
Carbon Microspheres ◽  
High Internal Phase Emulsion ◽  
Surface Areas ◽  
Internal Phase ◽  
Specific Surface Areas

In this paper, we present a novel approach for the synthesis of carbon microspheres via the polymerization of a high internal phase emulsion (HIPE). By using Span 80 and Tween 80 as emulsifiers, 1iquid paraffin as oil phase, and the mixture of resorcinol/formaldehyde (R/F) solution as aqueous phase, an O/W emulsion was obtained. This emulsion phase inverted to a W/O HIPE induced by ammonia which served as the polymerization catalyst. Carbon microspheres (CMs) were prepared by polymerization of the HIPE, followed by drying and carbonization. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) analyzer were used to characterize as-prepared CMs. The results indicate that, in case of 0.25 wt% ammonia of the HIPE, the diameters of CMs decreased from about 2 to 1 μm when the mass fraction of aqueous R/F decreased from 0.714 to 0.357; the apparent density and the specific surface areas of the CMs, however, did not change obviously, which are about 0.6 g/cm3and 200 m2/g, respectively. The dosage of ammonia has a significant influence on the morphology and properties of CMs. With increasing of the ammonia mass to 1 wt% of the HIPE, the resultant carbon materials comprise not only CMs, but also some carbon sheets; the apparent density of which increased to 0.9 g/cm3and the specific surface areas of which decreased to below 100 m2/g. In addition, the other parameters for CMs preparation were also investigated. It was found that the proper conditions were controlling the temperature of 303-333 K and the oil/aqueous phase mass ratio of 2.5:7.

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