Microporous and Mesoporous Materials最新文献

In addressing eutrophication resulting from phosphate accumulation, multi-metallic oxides often outperform single-metallic oxides in phosphate adsorption capacity. While alumina is abundant, its stability in acidic or alkaline environments is limited. Contrastingly, zirconium and cerium oxides demonstrate superior acid and base resistance, alongside specific phosphate affinity. This study focuses on the synthesis of Zr-Al and Ce-Al binary oxide nanoparticles through a sol-gel approach for phosphate removal from aqueous solutions, evaluating their efficiency through batch experiments. By judiciously adjusting the Zr/Al and Ce/Al ratios, binary oxide nanoparticles with distinct structures, grain sizes, surface characteristics, and phosphate adsorption properties were fabricated. Results indicate that Zr(3)Al(10) and Ce(3)Al(10) nanoparticles exhibit optimal phosphate adsorption properties among Zr-Al binary oxide variants and Ce-Al binary oxide counterparts, respectively. Kinetic data conform to the pseudo-second-order model for phosphate adsorption on Zr(3)Al(10) and Ce(3)Al(10), while equilibrium adsorption isotherms align with the Langmuir model. Phosphate adsorption capacities reached 83 mg/g for Zr(3)Al(10) and 210 mg/g for Ce(3)Al(10), positioning them as potent adsorbents. Coexisting anions minimally influence phosphate adsorption on Zr(3)Al(10) and Ce(3)Al(10) nanoparticles, indicating high selectivity towards phosphate, whereas Ca²⁺ and Mg²⁺ ions notably enhance phosphate adsorption. Mechanistically, phosphate adsorption on both nanoparticles follows electrostatic attraction, ligand exchange, and inner-sphere complexation, with surface-OH groups playing a pivotal role. Leveraging the advantageous properties of their parent materials, Zr-Al and Ce-Al binary oxide adsorbents exhibit synergistic effects, enhancing their potential for phosphate removal.

Carbon dioxide (CO₂) emission causes global warming which has been the greatest challenge for humanity since last decade. Herein, we developed nitrogen and phosphorus rich hyper cross-linked polymers for CO₂ capture, designated as BDA-HCP-1 and BDA-HCP-2 (benzene-1,4-diamine based hyper cross-linked polymers) having BET surface area 294.5904 m²g^-1 and 519.6918 m²g^-1 respectively^. The pore width range of BDA-HCP-1 and BDA-HCP-2 is 0–25 nm and 0–15 nm and pore volume of BDA-HCP-1 and BDA-HCP-2 is 0.01–0.18cm³/g and 0.01–0.25 cm³/g, respectively.Total pore volume, studied using DFT, is 0.20100 cm³/g for BDA-HCP-1 and 0.27973 cm³/g for BDA-HCP-2. BJH cumulative pore volume of BDA-HCP-1 is 0.113023 cm³/g and BDA-HCP-2 is 0.284733 cm³/g. The BDA-HCP-1and BDA-HCP-2 were synthesized by replacement of chlorines of hexachlorocyclophosphazenes (HCCP) and phosphorousdichlorophosphazenes (PDCP) with bezene-1,4-diamine to form linear and cyclic polyphosphazenes, which are later cross-linked through Friedal crafts reaction to form hyper cross-linked polymers. The maximum CO₂ adsorption quantity of BDA-HCP-1 is 48.62 cm³/g (CO₂ weight adsorbed 9.070 % with equilibrium time 8.16 min) at 273K/1 bar and 37.96 cm³/g (weight adsorbed 7.15 % with equilibrium time 8.25 min) at 298K/1 bar that gives adsorption capacity of 2.14 mmol/g and 1.69 mmol/g, respectively. Adsorption capacity of BDA-HCP-2 is 2.30 mmol/g and 2.13 mmol/g at 273 K/1 bar and 298 K/1 bar respectively. It is calculated from maximum CO₂ adsorption quantity of 51.6 cm³/g (weight adsorbed 9.83 % with equilibrium time 11.4 min, at 273 K/1 bar) and 47.7 cm³/g (weight adsorbed 9.25 % with equilibrium time 8.45 min, at 298 K/1 bar) respectively. Both BDA-HCPs can be reused with minor loss in adsorption capacity (2 and 1 %), which makes them excellent candidates to use on industrial scale applications. Adsorption isotherm study (Langmuir, Freundlich, and Temkin) and Kinetics study (pseudo first order and pseudo second order) reveals that this study fit best for Freundlich isotherms and pseudo first order kinetic model for both BDA-HCPs. This research contributes valuable insights into the design of hyper cross-linked materials with high surface area, good pore volume, excellent thermal stability and promising gas adsorption capacities particularly for addressing environmental pollution challenges related to CO₂ emissions.

Due to its serious hazards to human health and the environment, the deep removal of sulfur dioxide (SO₂) has been of great significance. Thus, it is critical to develop high efficient SO₂ capture and sequestration materials in gas purification process. Herein, we reported two novel prophyrin-based nitrogen-rich porous organic polymers (POPs), PrPOA-BP and PrPSN-BP, constructed through the simple catalyst-free condensation reaction. Owing to the strong affinity to SO₂ from the conjugate-electron macrocycles structure of prophyrin and nitrogen-rich porous networks, also the high porous structure, these two POPs demonstrated excellent SO₂ capture and separation performance with the adsorption uptakes up to 18.2 mmol g⁻¹ (273 K, 1 bar), 13.3 mmol g⁻¹ (298 K, 1 bar), 1.68 mmol g⁻¹ (298 K, 0.01 bar). This very competitive performance has far exceeded most of the prior reported nanoporous materials. Meanwhile, the IAST selectivities of SO₂/CO₂ (10/90, v/v) could reach 107.8 and 72.0 at 273 and 298 K, 1 bar. This study represents a new type prophyrin-based POPs materials and confirms the intrinsic potential for high efficiency SO₂ capture and sequestration.

The development of catalysts and processes with high activity, good selectivity and easy reproducibility and regeneration is the core of the solution for the oxidation of ethylbenzene to acetophenone. In this paper, the catalyst of cobalt metal oxide supported on TS-1 zeolite co-modified by alkali treatment and titanium silicon composite oxide was prepared. The catalysts were characterized by XRD, Raman, N₂ adsorption-desorption, SEM, TEM, XPS, FT-IR and UV–vis techniques to establish the correlation between physical and chemical properties and catalytic performance. Among the prepared catalysts, SiO₂ and TiO₂ co-coated TS-1 supported 3.75 wt % Co₃O₄ catalyst showed better oxidation activity. Under the optimized reaction conditions: T = 80 °C, t = 8 h, m_cat = 0.03 g, nEB: nHAC: nKBr: nH₂O₂ = 1 : 21: 0.1 : 16, the conversion of ethylbenzene was as high as 86.7 % and the selectivity of acetophenone was 85.6 %. After repeated tests, it showed good cycle and regeneration reaction performance. The high activity of this catalyst is attributed to the synergistic effect of cobalt oxide and TS-1 zeolite, and the mesoporous structure of titanium-silicon composite oxide is conducive to the adsorption and diffusion of reactants, intermediates and products.

An efficient catalytic chemical vapor deposition method utilizing an Fe-Mo/MgO-supported catalyst was developed, allowing the highly selective synthesis of double-walled carbon nanotubes (DWCNTs) in high yield, exceeding 89 %. The carbon yield, tube diameter, and crystallinity of the synthesized DWCNTs were characterized using high-resolution transmission electron microscopy, field-emission scanning electron microscopy, thermogravimetric analysis, and Raman spectroscopy. The nanopore structure and adsorption characteristics of the DWCNTs purified by removing the support and catalyst (i.e., Fe-Mo/MgO) were analyzed via N₂ adsorption–desorption measurements at 77 K. A remarkable advantage of the highly enriched DWCNTs with small bundle network structures is that guest molecules can easily access the outer (i.e., external) surface of the DWCNTs, resulting in a large specific surface area (SSA) of >691 m² g⁻¹ and pore volume of 2.70 mL g⁻¹ in the double-walled structures. Thus, highly enriched DWCNTs with large pore volumes and SSAs prepared via facile solution-based processes can yield CNT-based structures for applications in high-performance energy storage.

For chlorinated volatile organic compounds (CVOCs), it is critical to design and fabricate applicable noble metal catalysts to exhibit superior catalytic performance in catalytic oxidation under both dry air and 5.0 vol% H₂O conditions. In pursuit of this goal, a facile strategy was developed to prepare a series of Pt-supported catalysts for the elimination of o-dichlorobenzene (o-DCB). Among these catalysts, Pt/CeAlZrO_x possessed excellent activity (T₉₀ = 285 °C) and Pt/LaAlO_x showed outstanding selectivity within/without 5.0 vol% H₂O, attributed to the strong interaction of multi-components, abundance of adsorbed oxygen, prominent redox properties, and suitable acidity. According to the analysis results of density functional theory (DFT), the introduction of Pt can significantly improve the adsorption and activation of o-DCB molecules on the catalysts. Specifically, the action of Marse-van Krevelen (MvK) combining with Langmuir-Hinshelwood (L-H) mechanism was proposed. In general, this work provides promising candidates and valuable insights into the comprehensive improvement of o-DCB catalytic degradation for industrial application.

Dehydration of glucose into 5-hydroxymethylfurfural (5-HMF) is an effective approach for generating bio-based chemicals. Metal-organic frameworks (MOFs) are notable catalysts for this process due to their unsaturated metal centers. Functionalized MOFs further enhance these catalytic properties. This study investigates the catalytic abilities of MIL-101(Cr) and MIL-101(Cr)-NH₂ for glucose dehydration into 5-HMF using an H₂O + DMSO solvent system. Using Response Surface Methodology (RSM), the reaction parameters (temperature, time, and catalyst amount) were optimized to maximize 5-HMF yield. Results showed that at 180 °C, MIL-101(Cr) achieved a 5-HMF yield of 21 % with a selectivity of 22 %, while MIL-101(Cr)-NH₂ achieved a 5-HMF yield of 55 % with a selectivity of 56 %. MIL-101(Cr) demonstrated a glucose conversion rate of 92 %, and MIL-101(Cr)-NH₂ achieved a conversion rate of 99 % after 3 h at 180 °C. The optimized 5-HMF yield predicted by RSM for MIL-101(Cr) was 53.8 %, whereas the experimentally obtained value was 24.23 %. For MIL-101(Cr)-NH₂, the predicted 5-HMF yield was 35.46 %, with an experimental value of 47.51 %. The Lewis acidic nature of MIL-101(Cr) arises from the Cr sites, while MIL-101(Cr)-NH₂ exhibits both Lewis acidic characteristics from the Cr sites and Brønsted basic characteristics from the non-coordinated primary amine groups. The experimental results highlight the potential of MIL-101(Cr)-NH₂, which produced a higher 5-HMF yield compared to MIL-101(Cr). The dual nature of MIL-101(Cr)-NH₂ enhances glucose dehydration to 5-HMF, resulting in significantly higher yields. This study underscores the effectiveness of MIL-101(Cr)-NH₂ in converting glucose to 5-HMF, advancing biomass utilization efficiency.

The prevailing Zn/AC catalysts was plagued by limited lifetime and difficulties in regeneration for acetylene acetoxylation. In order to exploring renewable catalyst for acetylene acetoxylation, Zn/S-1 catalyst was synthesized using Silicalite-1(S-1) as support. The catalytic performance of Zn/S-1 was compared with Zn/AC catalyst using active carbon as support. The CH₃COOH conversion of Zn/S-1 catalyst only decreased 15 % after running 225 h, much better than the 66 % of Zn/AC after 154 h. TG analysis revealed that the improved stability of Zn/S-1 catalyst was attributed to its better resistance for carbon deposition with the presence of S-1 support. A series of characterizations and DFT results elucidated that the Lewis acid sites of S-1 support and Zn component serve as dual active sites, which enhanced the adsorption of CH₃COOH and inhibited the carbon deposition. In addition, the deactivated Zn/S-1 catalyst could be regenerated by calcination in air atmosphere due to the thermal stability of S-1, and the regenerated Zn/S-1 catalyst showed similar catalytic activity with the fresh catalyst.

Pervaporation (PV) is considered a promising energy-efficient process for recovering ethanol from fermentation liquids. In this study, ethanol separation characteristics were elucidated using mixed-matrix pervaporation membranes composed of hydrophobic polymers (PDMS) and high-silica ZSM-5 (HSZ). The selectivity and flux of ethanol/water were both improved when HSZ content in PDMS matrices was increased — at 50 wt% HSZ content the selectivity reached 15 and the flux of ethanol was improved to 0.05 kg/m²/hr. A new method was demonstrated to quantify the local thickness of the PDMS matrices by cross-sectional SEM binarization and inscribed circle analysis. PDMS matrices became more uniform with an increase in the HSZ content. The uniform presence of the PDMS matrices can be interpreted as more uniform dispersion of HSZ particles. An increase in total length of PDMS-HSZ interface resulted in improved ethanol permeability. NMR analysis showed that the molecular mobility of PDMS was restricted. Those results suggest an increase in the physical interaction between PDMS and HSZ. This study demonstrated a new analytical method for understanding the local thickness of the PDMS matrices and the interfacial state of mixed-matrix pervaporation membranes.