查看更多>>摘要：ATS-type zeolite is used to be known as aluminophosphate or borosilicate. Its aluminosilicate analog was supposed to be a promising solid acid material, which is still of great challenges to synthesize directly. Herein, we report a new zeolite, SCM-39, as the first directly synthesized ATS aluminosilicate, using commercially available 4-pyrrolidinopyridine as OSDA. SCM-39 exhibits great hydrothermal stability and possesses a large amount of acid sites. In comparison with MOR zeolite, it showed better catalytic performances in the disproportionation of toluene and self-condensation of cyclohexanone.
查看更多>>摘要：The development of non-previous-metal electrocatalyst with low cost, high activity and stability towards oxygen reduction reaction (ORR) remains a challenge. Covalent organic frameworks (COFs) have emerged as promising candidates for the preparation of porous metal/nitrogen co-doped carbon catalysts. In the present work, porous Fe-Nx nanoclusters/carbon catalysts are prepared by pyrolyzing iron-containing covalent-triazine organic frameworks. It is found that the synthesis conditions including pyrolysis temperature and pressure have great impacts on the surface area of micropores, mesopores and macropores, which in turn influences the ORR activity of catalysts by varying the mass diffusion and the contact of active centers with electrolytes. The optimized catalyst (denoted as Fe1.2NC-0.02-800), having the highest both BET and external surface areas, shows much higher kinetic current density and catalytic stability than commercial Pt/C catalyst in ORR process. When being assembled into Zn-air battery, it also exhibits excellent performances in terms of open circuit voltage (1.45 V), power density (210 mW cm-2 at 330 mA cm-2) and specific capacity (713.1 mA h g- 1 Zn ), which outperform the corresponding values of Pt/C-based Zn-air battery. Moreover, 15 light-emitting diodes can be powered by two series-connected Zn-air batteries with Fe1.2NC-0.02-800 as the air-cathode catalyst, implying its promising application in clean energy conversion field.
Hanif, Muhammad AdliIbrahim, NaimahIsa, Khairuddin MdRidwan, Fahmi Muhammad...
12页
查看更多>>摘要：Dry regenerative flue gas desulfurization (FGD) is a promising method to tackle industrial issues regarding SO2 emission into the atmosphere due to its sorbent being highly accessible, the lack of water dependency and reduction in waste management. This study examined the feasibility of using fibrous mesoporous silica KCC-1 which has been reported to possess better properties than several other predecessor mesoporous silica as alternative sorbents for dry FGD. Calcium metal was introduced to overcome the lack of active sites available on KCC-1 while simultaneously providing sufficient basicity to counter the increase in acidity brought by SO2 adsorption. Three sorbent modification parameters were analyzed: metal loading (5-15 wt %), calcination temperature (823-973 K) and calcination time (5.5-7 h), and the prepared samples were characterized using BET surface area and pore analyzer, FESEM-EDX, XRD and H-2-TPR. The breakthrough experiment was conducted using a lab scale fixed bed reactor system with 1500 ppm SO2/N-2 at 200 mL/min. SO2 removal was optimized by sorbent prepared with calcium loading of 5 wt %, calcination temperature of 923 K and calcination time of 6.5 h with adsorption capacity of 3241.94 mg SO2/g KCC-1. The optimized sorbent demonstrated highest surface area, good pore development, high dispersion of calcium metal, appropriate impregnation of calcium oxide which caused only minor distortion to the silica framework of KCC-1. Subjecting the optimized sample to five consecutive regeneration cycles by heating at 773 K while simultaneously flowing N-2 gas for an hour shows good regeneration performance with a total final reduction of only 25% from the initial adsorption capacity obtained from a fresh sample.
查看更多>>摘要：ABSTR A C T Porous carbon with abundant nitrogen doping (C-PCTF) was obtained by using porphyrin-based covalent triazine framework (PCTF) as the carbonization precursor. As expected, C-PCTF inherits the porous structure and the chemical composition of the PCTF. Due to the high surface area and accessible nitrogen sites, the carbon material can be employed as a superior supporting substrate to immobilize Au and Ag nanoparticles. Both the Au@C-PCTF and Ag@C-PCTF nanocatalysts show good catalytic activity in the reduction of 4-nitrophenol. Especially for Ag@C-PCTF, the catalytic activity is higher than most of other metal-catalysts reported previously. This study would provide a new strategy to use various porous organic polymers in fabricating carbon-supported hetero-geneous catalysts.
Hoseini, S. JafarBahrami, MehrangizFath, Roghayeh HashemiMontazerozohori, Morteza...
17页
查看更多>>摘要：Melamine-based porous network was prepared by the strong binding ability of amino functional groups of melamine with Pd(0) surface and pre-polymerization at the oil-water interface that confirmed by X-ray diffraction analysis. Palladium nanoparticles not only stimulate the pre-polymerization, but also stabilize themselves by this porous structure. Fourier-transform infrared spectroscopy, transmission electron microscopy, field-emission scanning electron microscopy, energy dispersive analysis of X-ray and thermal gravimetric analysis were applied for the catalyst characterization. The as-prepared catalyst forms an inclusion complex according to the host-guest chemistry in the presence of nitrophenols or different dyes. An efficient catalytic activity of this catalyst is due to the entrapment of the guest molecule in the cavity of the mesoporous structure and reaction progress on the Pd(0) nanoparticles surfaces which was approved by Brunauer-Emmett-Teller (BET) analysis. Simple preparation, unique structure and high catalytic reaction rate are some of the considerable advantages of this catalyst that can play key roles in the industrial processes.
查看更多>>摘要：High density graphite is widely used in friction and sealing area. The pore structure inside, which were mainly affected by molding method, has a great effect on its thermophysical properties and friction performance. Herein, isostatic pressing, compression molding and hot molding method were utilized in our work to prepare high density graphite with different pore structure in order to study the relationship between pore structure and the comprehensive property. The results showed that the properties of graphite vary significantly in different directions, which was mainly affected by porosity, pore size distribution, the specific surface area, pore shape and fractal dimension. The influence mechanism of three graphite materials with different pore structures on thermophysical properties was delved, and the correlation between the comprehensive properties of graphite materials and their pore structures was verified. The in-plane comprehensive properties of hot molding graphite were the best, the graphitization degree was the highest (75.4%) and the total porosity was the lowest (15.08%). Especially, according to the pore structure analysis of the graphite, we found a positive correlation between the fractal dimension and the friction and wear properties of the graphite materials. Furthermore, research of pore structure explained the properties of graphite materials and proved the potential application of graphite in friction and sealing fields.
查看更多>>摘要：High internal phase emulsion (HIPE) templating is a versatile strategy to prepare porous polymers and carbons. However, the prepared porous carbon materials usually show low specific surface area (SSA) due to the feature of macropores, which hampered their wider applications. This work developed a novel strategy, namely internal phase-external phase coefficient HIPE (IP-EP coHIPE) templating, to prepare polymer-derived hierarchically porous carbons (HPCs) with high SSA. In the strategy, sodium alginate (SA) aqueous solution was selected as the internal phase and emulsified in external oil phase containing divinylbenzene (DVB). HPCs were obtained by sequentially polymerizing the external phase, crosslinking the internal phase and carbonization. The testing results indicated that this strategy provided HPCs with notably enhanced porosity and increased SSA when compared with conventional HIPE method via the further utilization of the void space of polyHIPE-based HPCs via a facile way. The porous architectures of HPCs can be adjusted by changing the volume fraction and/or the concentration of the internal phase, respectively. The potential applications of the obtained HPCs were evaluated as the electrode material of supercapacitor. The specific capacitance of optimized HPC-based supercapacitor is 306 F/g, much higher than that based on general polyHIPE-derived HPC (145 F/g) at 1 A/g, which can be attributed to its enhanced porosity, hierarchically porous architecture and high SSA (2289 m(2)/g).
查看更多>>摘要：Maya blue is an ancient hybrid pigment composed of indigo and microporous palygorskite, with a fantastic hue and outstanding stability. Its color-causing and stabilization mechanism are unsolved problems. In this work, different palygorskite materials were obtained by heating at 180, 300 and 570 degrees C, with raw palygorskite as a reference. Maya blue-like pigments were prepared from these palygorskite materials and solid indigo. The microporous structure of palygorskite and the status of inside water molecules were investigated by thermal analysis, X-ray diffraction, Fourier transform infrared and microporous analysis. The color properties, chemical resistance and photostability of pigments were characterized by reflectance spectra, CIE color parameters and color differences after the attack of concentrated nitric acid, dimethyl sulfoxide, and visible light exposure equaling to about 100 years. It was confirmed that the greenish-blue and stable hybrid pigment could only be prepared when indigo molecules were inserted into the micropores of palygorskite. Zeolitic water molecules inside the micropores should be removed because they hindered the insertion of indigo molecules. The key to immobilizing indigo molecules inside micropores was hydrogen bonds between indigo and coordinated water (C=O center dot center dot center dot center dot center dot center dot H-OH). This study emphasized the important role of micropores and hydrogen bonds in the synthesis of organic-inorganic hybrid pigments.
查看更多>>摘要：The vanadium-doped mesoporous silica nanospheres (nV-MSNs) with worm-like porous structure were successfully synthesized by simple sol-gel method and applied to propane dehydrogenation (PDH) reaction. The moderate introduction of vanadium species didn't affect the self-assembly of the worm-like porous structure of support. The prepared samples were characterized by X-ray diffraction (XRD), Raman, X-ray photoelectron spectra (XPS), temperature-programmed desorption (TPD) of NH3 and temperature-programmed reduction (TPR) with H-2 to investigate the influence of the chemical states of VOX on the catalytic properties in PDH reaction. It is found that the appropriate amount and high dispersion degree of VOX species of the nV-MSNs catalyst is the key to obtain excellent catalytic performance in PDH. It is shown that 9V-MSNs catalyst exhibits optimum reaction activity with an initial propane conversion of 50.6% at 600 degrees C. The catalyst obtains the maximum percentage of active V-V species, and has better vanadium dispersion than others, which is demonstrated by Raman and XPS analysis. 9V-MSNs catalyst also exhibits outstanding activity and stability in reaction-regeneration for six cycles. Hence, the prepared nV-MSNs catalysts hold immense potential to further development in application of PDH.
查看更多>>摘要：Effectively controlling the release behavior of silver bactericide to promote its antibacterial ability is highly important in the fields of chemical, biomedical and biotechnology industry. In this study, ultrasmall Ag clusters were successfully encapsulated into silicalite-1 zeolite through in situ hydrothermal approach, and the key to this success was choosing 3-mercaptopropyltriethoxysilane as ligand to facilitate Ag precursor involved into zeolite initial sol-gel system. The structure of prepared silicalite-1 zeolite encapsulation of Ag clusters (denoted as Ag@Silicalite-1) has been well defined with various characterizations and probe reactions. Benefiting from confinement effect and shape-selectivity of silicalite-1 zeolite, Ag@Silicalite-1 sample showed much better Ag+ controlled release performance than that of sample with Ag nanoparticles impregnated onto silicalite-1 zeolite (denoted as Ag/Silicalite-1). The release behavior of Ag+ in Ag@Silicalite-1 can be well described with ritger-peppas model. Taking killing Escherichia coli as an example, in comparison with Ag/Silicalite-1, Ag@Silicalite-1 sample displayed more efficient and sustainable antibacterial activity for its controlled release character.
NSTL
Elsevier