Microporous and Mesoporous Materials最新文献

SBA-15 supported CuCl (CuCl/SBA-15) adsorbents were prepared with CuCl₂ as precursor via a facile ethylene reduction, where the reduction of CuCl₂ was carried out at temperatures ranging from 120 to 220 °C. The prepared adsorbents were characterized by X-ray diffraction, N₂ adsorption-desorption, Transmission electron microscopy, and X-ray photoelectron spectroscopy. The characterization reveals that the CuCl₂ supported on SBA-15 can be reduced to CuCl, and the ratio of Cu⁺ to the total copper amount increases with increasing the reduction temperature, reaching 85.7 % at 200 °C. The adsorption capacities of thiophene (TP), benzothiophene (BT) and dibenzothiophene (DBT) over the CuCl/SBA-15(x) were further tested at 30 °C, and the Langmuir equation was used to fit the adsorption isotherms. It shows that their adsorption capacities of desulfurization follow the order of CuCl/SBA-15(200) > CuCl/SBA-15(180) > CuCl/SBA-15(150) > CuCl/SBA-15(120) > CuCl/SBA-15(220). The CuCl/SBA-15 (200) outperforms the other samples, and its adsorption capacities are up to 40.83 mg S/g for TP, 56.10 mg S/g for BT, and 81.23 mg S/g for DBT, respectively. The regeneration experiments for CuCl/SBA-15(200) show that the desulfurization performance was still maintained after four adsorption-desorption cycles.

Due to the high surface area and facile functionalized or modified groups of polymers of intrinsic microporosity, and the hydrophilicity of sodium alginate (SA), a simple strategy was proposed for preparing porous composite hydrogel beads with excellent cationic dye adsorption capacity and selectivity. The porous composite hydrogel beads were prepared by introducing the amidoxime modified polymers of intrinsic microporosity (AOPIM-1) into SA polymer solution and then dropping the mixture into CaCl₂ aqueous solution at low temperature for crosslinking. The prepared porous SA/AOPIM-1 hydrogel beads performed excellent adsorption capacity on Rhodamine B (RhB) from aqueous solution and the Langmuir model was suitable for describing the adsorption behavior of RhB on porous SA/AOPIM-1 hydrogel beads. It is surprising that the maximum theoretical adsorption capacity obtained by fitting the Langmuir model was up to 1648.3 mg·g⁻¹. More importantly, porous SA/AOPIM-1 hydrogel beads showed outstanding selective adsorption capacity for cationic dyes in the mixed anionic and cationic dyes solution. Besides, the adsorption capacity of porous SA/AOPIM-1 hydrogel beads could maintain above 80 % of the initial adsorption capacity after 10 adsorption/desorption cycles. The above results indicate that porous SA/AOPIM-1 hydrogel beads can be used as a promising adsorbent with for effective removal of dyes from wastewater treatment.

In this work, we report that poly (acrylic acid) (PAA) and poly (ethylenimine) (PEI) capped Pd nanoparticles (NPs) encaged in hollow silica nanospheres (PAA/PEI-Pd@HSNs) function as highly efficient and selective catalysts for hydrogenations of a series of alkynes. We used the coordination of Pd⁴⁺ ions with PEI and PAA to build the micelles system in an ethanol-water system, which was employed as the templates for silica deposition and following NaBH₄ reduction to give PAA/PEI-Pd@HSNs. The materials feature polymer-coordinated small Pd NPs inside silica nanospheres with thin shells and large cavities. The PAA/PEI-Pd@HSNs exhibit extremely high catalytic efficiency and reusability with enhanced alkene selectivity of ∼90 % at near complete conversions for hydrogenation of a series of alkynes, and maintain high selectivity even with a significantly extended reaction time. The enhanced catalytic performance of PAA/PEI-Pd@HSNs is ascribed to their thin silica shells/large cavities to improve the catalytic activity, PEI/PAA ligands that inhibit the deep hydrogenation of alkenes to alkanes on Pd NPs, and the protection of silica shells for inner ligands and Pd NPs to improve the reusability.

Molecular simulations are performed to decipher the nanoscale processes associated with water sorption in tobermorite, a microporous phase that functions as the binder in autoclaved aerated cement composites. Merlino’s cross-linked tobermorite 11 Å is studied. We show that there is no hysteresis in bulk tobermorite at the molecular scale because the zeolitic cavities occupied by water are smaller than the critical pore size for hysteresis disappearance, and upon sorption, tobermorite 11 Å shows virtually no volume change. These effects combined explain why hysteresis under sorption in tobermorite is limited. Similar explanation could also explain absence of significant hysteresis in some layered double hydroxides present in cement systems.

In this work, inexpensive aluminum nitrate was used as the raw material and ammonium carbonate as the precipitant. Ordered mesoporous alumina (OMA) with a high surface area was synthesized using suitable template agents and auxiliary agents. The synthesized materials underwent characterization via X-ray powder diffraction (XRD), N₂ adsorption-desorption (BET), transmission electron microscopy (TEM), and other analytical techniques. The effects of various template agents, aging durations, calcination methods, and calcination temperatures on the structure of the synthesized OMA were investigated. Key factors influencing the formation of inorganic precursors, the self-assembly of template agents with inorganic precursors, and the pore formation process (involving template agent and water removal) during synthesis were analyzed. Using the synthesized OMA as the substrate and triethylenetetramine (TETA) as the modifier, the impact of modified materials on CO₂ adsorption performance was assessed. The results showed that OMA prepared with P123 as the template agent and ammonium dihydrogen phosphate as the auxiliary agent exhibited a specific surface area of 545.2 m²/g, an average pore diameter of 3.8 nm, and a pore volume of 1.01 cm³/g. The addition of auxiliary agents significantly increased the specific surface area of the synthesized material. The modified TETA-OMA, with a loading capacity of 50 %, achieved an adsorption capacity of 216.25 mg/g at an intake flow rate of 20 mL/min and an adsorption temperature of 40 °C. After six cycles of adsorption-desorption recycling, minimal changes were observed in the adsorption performance, indicating excellent regeneration capability. The synthesized high-surface-area ordered mesoporous alumina holds potential for industrial applications.

Cytochrome c (Cyt-c) was encapsulated in hollow mesoporous silica spheres as a support for immobilization. Cyt-c was denatured by an aqueous solution of guanidine hydrochloride to increase the flexibility of Cyt-c structure by unfolding and subsequently passed through the mesopores into the hollow spaces by diffusion. After incorporation, the refolding of Cyt-c was carried out by removing the guanidine hydrochloride using dialysis. Considering that the mesopore size was slightly smaller than the native Cyt-c size, Cyt-c was immobilized inside the hollow spheres. Modification of encapsulated Cyt-c with 18-crown-6 showed catalytic activity for the asymmetric oxidation of methyl 4-tolyl sulfoxide. The encapsulated catalyst could be reused to achieve almost the same catalytic activity.

TiO₂ was successfully synthesized within the internal pores of MIL-101(Cr), leading to the formation of a TiO₂-in-MIL-101(Cr) composite. This heterojunction structure significantly improved the photogenerated electron-hole separation within the metal-organic framework (MOF) composite. Subsequently, carbon dots (CDs) and silver nanoparticles (AgNPs) were introduced to further modify the TiO₂-in-MIL-101(Cr), resulting in a multimodified MIL-101(Cr) composite. The integration of CDs enhanced the light absorption capabilities of the composite, thereby boosting the photocurrent. Meanwhile, AgNPs not only enhanced the absorption of visible light through the local surface plasmon resonance effect (LSPR) but also facilitated efficient electron transport. This multimodal modification strategy led to a remarkable enhancement in the photoelectrochemical (PEC) performance of MIL-101(Cr), with the photocurrent density (J) increasing by approximately a factor of 19. To further expand the functionality of this composite, AβO capture DNA (cDNA) and CuS-binding aptamer were grafted onto the TiO₂-in-MIL-101(Cr)@CDs@AgNPs, creating a sandwich-like structure. Based on this multimodified MIL-101(Cr) composite, an "on-off-on" type PEC biosensor was constructed. The p-type semiconductor CuS served as a signal amplifier, capturing photogenerated electrons and effectively reducing the photocurrent. When cDNA hybridized with AβO, the Apt-CuS moiety detached from the MIL-101(Cr) composite, leading to the restoration of the photocurrent. The PEC biosensor for the detection of AβO exhibited optimal performance at a pH of 7.00, an incubation temperature of 37 °C, and an incubation time of 45 min. Under these conditions, the biosensor demonstrated a wide detection range of 5 fM to 1 μM, with an ultralow detection limit of 4.36 fM. This method exhibits high sensitivity, robust anti-interference capabilities, and holds great promise for applications in tracing the detection of AβO in human serum.

The urgent need for effective SO₂ capture materials has driven research into the development of novel nanoporous organic polymers (NOPs). Herein, we developed a triphenylamine-based nanoporous organic polymer, designated as ANOP-5, through the self-condensation of an AB₂ triphenylamine monomer. The adsorption/separation properties of SO₂ and CO₂ are comparatively evaluated through the investigation of static gas adsorption isotherms. At 273 K and 100 kPa, ANOP-5 displays a high SO₂ adsorption capacity of 399 cm³ g⁻¹ and a high selectivity of 388 for SO₂/CO₂, with a molar ratio of SO₂ to CO₂ at 10/90. The exceptional performance of desulfurization is attributed to the strong interaction between ANOP-5 and SO₂, in addition to the ultramicroporous structure. These findings are further supported by the dispersion-corrected density functional theory calculations. This study contributes valuable insights into the design and preparation of NOPs with high gas adsorption properties, particularly for addressing environmental pollution challenges related to SO₂ emissions.

Cryoporometry (or thermoporometry) offers a way of pore structural characterisation for mesoporous materials that often needs little sample preparation, is relatively quick, and is statistically-representative for macroscopic samples. While it is well-known that freezing is controlled by pore-blocking, and is thus an invasion percolation process, the percolative nature of pore-to-pore co-operative advanced melting effects has been much less studied. In this work, PFG NMR studies, of diffusivity within the molten phase, have shown that the early melting process follows the scaling law, expected from percolation theory, below the percolation threshold. The percolation threshold thereby obtained was that for a 3D isotropic Poisson polyhedral lattice, consistent with the observation of patchwise macroscopic heterogeneities in the spatial distribution of local average pore size seen in MR relaxation time-weighted images. MRI has shown that once advanced melting effects kicked-in, around the percolation threshold, they occurred to different degrees in different slices along the length of the extrudate pellet. The macroscopic banding in pore-blocking, during freezing, and advanced melting effects, along the axis of the extrudate was consistent with anisotropic diffusional properties observed with MRI. Hence, it has been shown how the pore-pore co-operative effects can be utilised to improve structural characterisation of mesoporous solids.

Palladium (Pd)-based catalysts supported by silicaluminate materials are potential as the efficient non-mercury catalyst for acetylene hydrochlorination, which is a necessary industrial reaction for producing vinyl chloride monomer. A new strategy was employed to improve Pd/USY zeolite catalysts taking advantage of 4-carboxybutyl triphenylphosphonium bromide ((4-CB)TPPB) for acetylene hydrochlorination. The most active catalyst (Pd@20(4-CB)TPPB/USY) with the 0.5 wt% Pd loadings and the 20 wt% (4-CB)TPPB additives could achieve a stable acetylene conversion of 99.9 % and the vinyl chloride selectivity of 99.7 % during more than 50 h, outperforming the Pd/USY catalyst. The additive of (4-CB)TPPB was preferential to stabilize the catalytic active Pd species, inhibit the Pd (II) reduction and change the surface acidic properties during the preparation process and reaction, hence restraining the carbon deposition. Density functional theory (DFT) calculations further indicate that (4-CB)TPPB additives could effectively enhance the adsorption energy of catalyst for reactants and the desorption energy of vinyl chloride monomer (VCM) products, thus inhibiting the carbon deposition for improving the catalytic performance of Pd/USY catalysts. These findings provide guidance for designing efficient Pd-based catalysts as well as their utilization for acetylene hydrochlorination.