Journal of Porous Materials最新文献

Foamed silicone rubber was prepared by mixing 45% vinyl silicone oil (Base), Karstedt platinum catalyst (Cata), and hydrogenated silicone oil (SiH) and the resulting material was subjected to secondary vulcanization, which led to its performance requirements. Vinyl silicone oil and hydrogenated silicone oil underwent an addition reaction under the action of a platinum catalyst to form an elastomer with a cross-linked network structure. The results showed that by increasing the content of hydrogenated silicone oil in the formulation, the elongation at break of the foamed silicone gel material decreased but the tensile strength increased. When the content of hydrogenated silicone oil in the formulation decreased, the elongation at break of the foamed silicone material increased. When the content of Karstedt catalyst in the formulation increased, the formation time of the reaction gel was greatly shortened, and the cell structure tended to be dense but delicate. When the proportion of vinyl silicone oil in the formulation increased, the elongation at break of the foamed, molded silicone rubber increased. However, the elastic modulus decreased, and the thermal stability improved. Finally, a more suitable formulation of V_Base:V_Cata:V_SiH = 32:1:2 was obtained, which showed a tear resistance of 5.52 KN/m, ductility of 133%, and limiting oxygen index of 26 with a stability temperature of 346.8 °C when the thermal mass loss reached 95%.

The development of advanced carbon materials is indispensable for high-performance supercapacitors. Herein, we report the direct pyrolysis of waste coal-tar pitch (CTP) with ZnO nanoparticles (Zn NPs) to produce hierarchical porous carbon materials (HPCs). The CTP served as a carbon source, and the embedded ZnO NPs as a simultaneous templating and activating agent for HPCs. At an optimum temperature of 800 °C, the produced HPCs (HPC-800) realized an optimal specific surface area (1267 m² g^-1) and pore volume of 1.71 cm³ g^-1, enabling the devised capacitor to exhibit a specific capacitance of 172 F g^-1 at a current density of 0.1 A g^-1 in 6 M KOH electrolyte and a capacitance retention of 81% (0.1–30 A g^-1). The as-symmetrical device could deliver an energy density of 8.3 Wh∙kg^-1 at a high-power density of 50.0 W∙kg^-1 and retained energy density of 4.9 Wh∙kg^-1 at a power density of 11.9 kW∙kg^-1.

To study the behavior of Mn²⁺ ions and water molecules in Mn²⁺-exchanged zeolite Y (Si/Al = 1.67) at different temperatures during dehydration, single crystals of Mn²⁺-exchanged zeolite Y were prepared by batch method at room temperature. Five single crystals of Mn²⁺-exchanged zeolite Y were dehydrated at 297 K (crystal 1), 523 K (crystal 2), 573 K (crystal 3), 623 K (crystal 4), and 673 K (crystal 5), respectively, under dynamic vacuum for 48 h. Their crystal structures were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group Fd (overline{3 }) m at 100(1) K. They were refined to the final error indices R₁/wR₂ = 0.0594/0.1615, 0.0450/0.1229, 0.0445/0.1108, 0.0447/0.1145, and 0.0418/0.1084 (for F_o > 4σ(F_o)) for crystals 1, 2, 3, 4, and 5, respectively. In all five crystals, about 36 Mn²⁺ ions occupy five crystallographic sites. Mn²⁺ ions are energetically preferentially located at site I in all structures. The Mn²⁺ ions migrated from one site (sites I’ or II’) to another available site (sites I or II) to better satisfy their coordination requirements upon dehydration. Finally, in the completely dehydrated crystal 5, 36 Mn²⁺ ions occupy the sites I, I’, II’, IIa, and IIb with the fractional occupancies 15, 2, 2, 12, and 5, respectively. All water molecules associated with Mn²⁺ ions in the incompletely dehydrated crystals 1 ~ 4 were located in the sodalite cavities. In the structure of crystal 1, about 10.5 water molecules were found per unit cell, each coordinating to Mn²⁺ ions at Mn(1’b). These water molecules formed clusters as [Mn₄(H₂O)₄]⁸⁺. Only 5, 3, and 2 water molecules were found in the structures of crystals 2 ~ 4, respectively, with increasing temperature. Each of these water molecules was bonded to one Mn²⁺ ion at Mn(2’), forming [MnH₂O]²⁺. The unit cell constant of the zeolite framework decreased, as the number of water molecules decreased with the increasing dehydration temperature.

The effect of post-treatment of TS-1 zeolite by tetrapropyl ammonium hydroxide aqueous solution under hydrothermal condition was studied in this work. The characterizations of structure, morphology and composition demonstrated that an open and hierarchical porous structure was generated in TS-1 zeolite after the post-treatment. With increasing the alkalinity of TPAOH solution, the hierarchical porosity and hydrophobicity increased and the framework Ti content decreased in the post-treated TS-1 zeolite. Both the pristine and post-treated TS-1 zeolites were employed as the catalysts for the reaction of phenol hydroxylation. It was found that the post-treated TS-1 zeolite possessed a higher catalytic performance than the pristine TS-1 zeolite. The larger the alkalinity of the post-treatment solution was, the higher the catalytic performance of the post-treated TS-1 zeolite was; however, a too high alkalinity of the post-treatment solution also led to the decline in the catalytic performance. This could be a result of the combined influences of the hierarchical porosity, hydrophobicity and framework Ti content on the catalytic performance. The higher levels of hierarchical porosity and hydrophobicity promoted but the lower level of framework Ti content inhibited the catalytic performance of TS-1 zeolite. Accordingly, the controlling to the alkalinity of TPAOH solution for the post-treatment was very important in respect of the catalytic performance of TS-1 zeolite.

Spherical AlPO₄ supported WO₃ catalysts were synthesized and characterized by XRD, N₂ sorption isotherm, SEM, TEM and NH₃-TPD, and used as a catalyst for the production of Euro 95 standard gasoline fuel additives from biomass-derived furfural via reductive etherification. Compared with the AlPO₄ catalyst, the surface acidity increased after the impregnation of tungsten oxide. The activity and stability of the catalysts also improved with the impregnation of tungsten oxide on AlPO₄. However, the existing catalytic system cannot provide high conversion to furfural and selectivity to ether due to the formation of side reactions. To optimize the reaction conditions, the effect of temperature, catalyst amount, furfural/isopropanol molar ratio, and choice of hydrogen donor were studied. Under these optimized conditions, a high conversion of furfural (92%) and a yield of isopropyl furfuryl ether (IPFE) (83%) were obtained with the byproducts of furfuryl alcohol and acetal. The WO₃/AlPO₄ catalyst also achieved a high yield of ether with various aldehydes and alcohols via reductive etherification.

The discharge of dye industry wastewater without any proper treatments has raised tremendous concerns due to its hazardous nature and potential risks. Photocatalytic degradation is a promising technology for environmentally friendly and sustainable treatment of dye pollutants. Nanomaterial-based photocatalysts have been successfully applied to treat industrial dye wastewater. Among them, titanium dioxide (TiO₂) with diverse nanostructure and numerous advantages has garnered significant attentions. However, the morphological difference of TiO₂ is of paramount importance for enhancing its degradation performance. This review provides an overview of recent advances in various forms of multidimensional TiO₂, including 0D nanoparticles, 1D nanowires, nanotubes, nanofibers, and nanorods, 2D nanosheets and nanoplates, as well as assembled 3D micro-nano structures, for photocatalytic dye wastewater treatment. The article could briefly elaborate the conventional synthesis routes, advantages, challenges, and application areas of TiO₂ in different dimensions, and compares their photocatalytic degradation performance and mechanisms. Simultaneously, these approaches of modified performances by doping metal ions and non-metal ions have emphatically involved over here. Noteworthily, the insights into the future trends, challenges, and prospects of multidimensional TiO₂ materials have been also proposed.

In the presented work, changes in the surface morphology and crystal structure of the coatings obtained by adding Zr, Si, Nb, ZrSi and ZrNb elements added to the TiCN base matrix after thermal annealing at high temperature were studied. The novelty of the current study lies in the comprehensive investigation of the structural and compositional changes of carbonitride coatings, their behavior under thermal conditions, and the implications for their practical applications. The goal of the proposed experiment was to evaluate the influence of composition and structure on the oxygen adsorption tendencies at both high (2000 –1500 K) and low temperatures (0–100 K), through molecular dynamics. The formation mechanism of the gas and oxide phase on the surface of the coatings during the thermal annealing was simulated by the molecular dynamics code. The formation of gas products before the formation of the oxide layer on the surface of the coatings was shown by molecular dynamics simulation. Based on the structural analysis conducted by scattering X-rays from small angles, it was determined that a new phase is formed on the surface of the coatings. Formation of free cubic TiC phase was observed in both TiZrSiCN and TiZrNbCN coatings under the influence of temperature. Degradation of surface morphology and formation of pinholes were found after thermal annealing. The experimental formation of the oxide phase on the surface of the sample up to a temperature of 1270 K expands the application possibilities of the coatings in various industrial fields including catalysis.

In this research, we have synthesized and characterized new magnetic, stable and reusable nanocatalyst Fe₃O₄/MWCNT@SⁿPr-DPhG-Ni. The new ligand of diphenylglyoxime was use for the gapping nickel ion on the nanocatalyst. This nanocatalyst was analyzed by FT IR, EDX, XRD, VSM, SEM, TEM and TGA-DTA spectroscopic techniques. This nanocatalyst was used for the one-pot synthesis of spiro furo[2,3-d]pyrimidines in the reaction with various aldehydes, (1,3-dimethyl)barbituric acid, cyanogen bromide and triethylamine in excellent yield at room temperature.

Mesoporous solids possessing open framework, tunable pores, high surface area, and considerable thermal stability provide an ideal environment to be employed as solid catalysts, host material, adsorbent, etc. Herein, we report the study about the insertion of iron into the mesoporous silicate framework of SBA-1 and utilize the material as a potential heterogeneous catalyst for the selective oxidation of lignin model non-phenolic monomer, i.e. veratryl alcohol under mild reaction conditions. Veratraldehyde and veratric acid were obtained as the oxidation products. FeSBA-1 in combination with hydrogen peroxide was selective towards veratraldehyde, on the other hand, veratric acid was selectively obtained when tert-butyl hydroperoxide was used as the oxidant under identical reaction conditions. X-ray diffraction pattern of FeSBA-1 revealed the formation of a cubic, three-dimensional SBA-1 structure. HRTEM shows uniform and ordered pore structure having dimensions of ∽ 2.3 ̶ 3.4 nm and wall thickness of ∽ 3.5 nm. FESEM showed regular-shaped FeSBA-1 with spherical morphology having a dimension of ∽ 1.6 μm. BET surface area of 1337 m² g⁻¹ and pore diameter of ∽ 19 Å was determined by N₂ adsorption-desorption measurements. The mesoporous nature of FeSBA-1 was further supported by TGA studies. EPR studies indicated the presence of Fe(III) both in tetrahedral and octahedral coordination within the framework of FeSBA-1. DRUV-VIS studies revealed the presence of Fe(III) in both framework and extra-framework locations of the SBA-1 silicate network. IR studies supported the linkage of Fe–O–Si within FeSBA-1. The absence of the Fe₂O₃ phase was evidenced by Raman studies.

Pure Mg foams stabilized by ex-situ added CaO particles were developed in this study. Mg/xCaO foams (x = 5, 7 and 10 wt.%) exhibited uniform pore distribution, thinner yet stable pore wall cross-sections. Mg-Ca-O transition phase and MgO particles were formed at the interface of Mg-CaO, which improved the wetting of CaO particles in the Mg melt. The CaO particles, Mg-Ca-O transition phase and blocky MgO particles collectively stabilized the foam. Mg-Ca-O and MgO phases disperse along the gas-liquid interface of foams thereby preventing from wrinkling of interfaces during solidification. TEM analysis of Mg/10wt.% CaO foam powder also confirmed the formation of nano-sized (~ 200 nm) MgO particles of different morphologies. TG-DSC analysis confirmed the exothermic Mg-CaO reaction at 610 ºC, resulting in formation of Mg₂Ca and MgO phases, as identified using XRD analysis. 7 wt.% CaO addition exhibited the best foam structure in terms of mean pore diameter (2.19 mm) and circularity (0.75). The lowest foam density of 0.38 g/cm³ and relative density of 21 % was achieved in case of Mg/10wt.% CaO foams.