Mesoporous Cellular Foams Research Articles

Developing highly stable and reusable WO3 on mesoporous cellular foam silica for dilute bioethanol dehydration to ethylene

This study developed a highly stable and reusable WO3 on mesoporous cellular foam silica catalyst (MCF-Si) for dilute bioethanol (70%v/v) dehydration to ethylene. WO3/MCF-Si exhibited exceptional performance during reaction, maintaining a high yield of ethylene ranging from 79.6% to 76.3% even in the final cycle over five consecutive cycles (20 h each), operating without requiring regeneration. Characterization of the spent catalyst revealed the preservation of key textural properties and a shift in the acidity profile. The strength of acidity transitioned from weak to strong acidity, while the type of acid sites evolved from Lewis to Bronsted acid sites. However, the remaining acidity remained sufficiently high to promote efficient ethylene production. Additionally, WO3/MCF-Si demonstrated outstanding resistance to coke formation, with a coke content measured below 0.9 wt%. In light of these findings, WO3/MCF-Si emerges as a promising candidate catalyst for developing sustainable processes for converting dilute ethanol to ethylene.

SUPPORTED COBALT OXIDE NANOPARTICLES: THE INFLUENCE OF MESOPOROUS MATERIALS AND THEIR ROLE IMETHYL PHENYL SULFIDE OXIDATION REACTIONS.

The effect of the support in the incorporation of cobalt oxide nanoparticles on mesoporous materials (SBA‐15) and mesoporous cellular foam (MCF) was investigated. The materials were characterized using various techniques. The XRD diffraction patterns showed that the porous structures remained after cobalt incorporation, while high‐angle XRD of the MCF showed CoO peaks, in contrast to Co‐SBA‐15 which exhibited Co3O4. This was confirmed by XPS technique. The SEM‐EDS and HRTEM‐STEM microscopy indicate a distribution of cobalt oxides uniform in the samples synthesized and the average size of the particles is 1.88 nm. H2‐TPR analysis highlighted the interaction between the support surfaces and the metal oxide (SMSI). It was observed that in the SBA‐15 structure, small clusters of cobalt oxide formed with a strong interaction with silica, leading to high reduction temperatures. The catalysts activity was characterized in oxidation reactions of Methyl Phenyl Sulfide and a correlation was observed between the characterization results and the enhanced selectivity and yield towards sulfone exhibited by Co‐MCF.

Evaluation of the Dye Extraction Using Designed Hydrogels for Further Applications towards Water Treatment.

In this work, novel chitosan-silica hydrogels were synthesized and investigated by various complementary techniques. The hydrogels were obtained via the immobilization of chitosan (Ch) on the surface of mesoporous cellular foams (MCFs). The latter silica materials were obtained by a sol-gel process, varying the composition of the reaction mixture (copolymer Pluronic 9400 or Pluronic 10500) and the ageing temperature conditions (80 °C or 100 °C). The role of the silica phase in the hydrogels was the formation of a scaffold for the biopolymeric chitosan component and providing chemical, mechanical, and thermal stability. In turn, the chitosan phase enabled the binding of anionic pollutions from aqueous solutions based on electrostatic interaction mechanisms and hydrogen bonds. To provide information on structural, morphological, and surface properties of the chitosan-silica hydrogels, analyses such as the low-temperature adsorption/desorption of nitrogen, small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and Fourier-transform infrared spectroscopy (FTIR) were performed. Moreover, the verification of the utility of the chitosan-silica hydrogels as adsorbents for water and wastewater treatment was carried out based on kinetic and equilibrium studies of the Acid Red 88 (AR88) adsorption. Adsorption data were analyzed by applying various equations and discussed in terms of the adsorption on heterogeneous solid-surfaces theory. The adsorption mechanism for the AR88 dye-chitosan-silica hydrogel systems was proposed.

Steam reforming of ethanol for hydrogen production: Efficacy of ceria promoted Cu–Co on mesoporous cellular foam silica

Mesoporous silica-supported metals are often used as catalysts in the steam reforming of hydrocarbons to produce hydrogen or syngas. In the current study, the steam reforming of ethanol was undertaken using mesoporous cellular foam silica (MCF) and SBA-15 as supports with bimetals Cu and Co in different proportions. Among these 20% Cu–Co (1:1)/MCF was found to be superior exhibiting good activity and stability for hydrogen production. Thereafter, Ce was introduced to reduce coke deposition on the said catalyst. Amongst all synthesized catalysts 5%Ce–10%Cu–10%Co/MCF led to higher hydrogen yield (82.1%) with 97.4% conversion of ethanol at a lower temperature (673 K) using steam to carbon (S/C) ratio of 6. The effect of temperature, GHSV, and S/C ratio on H2 production was systematically examined. Ce-promoted Cu–Co/MCF provided high stability for three cycles, indicating its multi-cycle durability and selectivity. 5%Ce–10%Cu–10%Co/MCF produces hydrogen from ethanol in a sustainable way.

ZnO/PDA/Mesoporous Cellular Foam Functionalized Thin-Film Nanocomposite Membrane towards Enhanced Nanofiltration Performance.

Thin-film nanocomposite (TFN) membranes are the third-generation membranes being explored for nanofiltration applications. Incorporating nanofillers in the dense selective polyamide (PA) layer improves the permeability-selectivity trade-off. The mesoporous cellular foam composite Zn-PDA-MCF-5 was used as a hydrophilic filler in this study to prepare TFN membranes. Incorporating the nanomaterial onto the TFN-2 membrane resulted in a decrease in the water contact angle and suppression of the membrane surface roughness. The pure water permeability of 6.40 LMH bar-1 at the optimal loading ratio of 0.25 wt.% obtained was higher than the TFN-0 (4.20 LMH bar-1). The optimal TFN-2 demonstrated a high rejection of small-sized organics (>95% rejection for 2,4-dichlorophenol over five cycles) and salts-Na2SO4 (≈95%) > MgCl2 (≈88%) > NaCl (86%) through size sieving and Donnan exclusion mechanisms. Furthermore, the flux recovery ratio for TFN-2 increased from 78.9 to 94.2% when challenged with a model protein foulant (bovine serum albumin), indicating improved anti-fouling abilities. Overall, these findings provided a concrete step forward in fabricating TFN membranes that are highly suitable for wastewater treatment and desalination applications.

Mesoporous Cellular Foam (MCF): an efficient and biocompatible nanomaterial for the controlled release of Chlorambucil

Mesoporous Cellular Foam (MCF): an efficient and biocompatible nanomaterial for the controlled release of Chlorambucil

Organic-solvent assisted synthesis of highly dispersed iron based Fischer-Tropsch catalysts with MCF support: The effect of organic-solvent

The development of efficient catalysts for Fischer-Tropsch synthesis has attracted much attention in recent years. Mesoporous cellular silica foams (MCFs) supported iron-based Fischer-Tropsch catalysts are prepared via the organic solvent-assisted impregnation methods. The organic solvents (ethanol, acetic acid, glucose, and citric acid) have a great impact on both the structure and performance of the catalysts. In the case of catalyst Fe/MCF-E, obtained by ethanol-assisted impregnation, forming a highly dispersed ɛ-iron phase supported on the supports during relevant industrial FTS process, exhibited excellent stability and activity for 100 h. The Fe/MCF-E catalyst showed C2-C4 olefin selectivity of 30.9% and FTY (iron-time-yield) of 4.68 mol/(gFe· s)·10−5 at 270 °C, and achieved a total olefin selectivity of 48.6% and FTY of 38.59 mol/(gFe· s)·10−5 at 300 °C. These results highlight a convenient strategy to prepare highly stable and active MCF-supported iron based catalysts for FTS.

Lipase Immobilized on MCFs as Biocatalysts for Kinetic and Dynamic Kinetic Resolution of sec-Alcohols

Dynamic kinetic resolution (DKR) is one of the most attractive methods for enantioselective synthesis. In the reported studies, lipase B from Candida antarctica (CALB) immobilized on siliceous mesoporous cellular foams (MCF) functionalized with different hydrophobic groups, and two ruthenium complexes with substituted cyclopentadienyl ligands were investigated as catalysts for the chemoenzymatic DKR of (rac)-1-phenylethanol, using Novozym 435 as a benchmark biocatalyst. Studies on the (rac)-1-phenylethanol transesterification reaction showed that CALB supported on MCFs grafted with methyl groups is a promising biocatalyst and isopropenyl acetate is a preferable acylation agent. Both Ru-complexes activated by K3PO4 or t-BuOK, proved to be effective catalysts of the racemization reaction. The final DKR experiments using all catalysts combinations singled out, gave 96% conversion, and (R)-1-phenylethyl acetate enantiomeric excess of 98% in 8 h using K3PO4 activator.

Bottom-Up Development of Nanoimprinted PLLA Composite Films with Enhanced Antibacterial Properties for Smart Packaging Applications

In this work, polymer nanocomposite films based on poly(L-lactic acid) (PLLA) were reinforced with mesoporous silica nanoparticles, mesoporous cellular foam (MCF) and Santa Barbara amorphous-15 (SBA). PLLA is a biobased aliphatic polyester, that possesses excellent thermomechanical properties, and has already been commercialized for packaging applications. The aim was to utilize nanoparticles that have already been established as nanocarriers to enhance the mechanical and thermal properties of PLLA. Since the introduction of antibacterial properties has become an emerging trend in packaging applications, to achieve an effective antimicrobial activity, micro/nano 3D micropillars decorated with cone- and needle-shaped nanostructures were implemented on the surface of the films by means of thermal nanoimprint lithography (t-NIL), a novel and feasible fabrication technique with multiple industrial applications. The materials were characterized regarding their composition and crystallinity using Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD), respectively, and their thermal properties using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Their mechanical properties were examined by the nanoindentation technique, while the films’ antimicrobial activity against the bacteria Escherichia coli and Staphylococcus aureus strains was tested in vitro. The results demonstrated the successful production of nanocomposite PLLA films, which exhibited improved mechanical and thermal properties compared to the pristine material, as well as notable antibacterial activity, setting new groundwork for the potential development of biobased smart packaging materials.

Application of Immobilized Cholest-4-en-3-one Δ1-Dehydrogenase from Sterolibacterium Denitrificans for Dehydrogenation of Steroids

Cholest-4-en-3-one Δ1-dehydrogenase (AcmB) from Sterolibacterium denitrificans was successfully immobilized on 3-aminopropyltrimethoysilane functionalized mesoporous cellular foam (MCF) and Santa Barbara Amorphous (SBA-15) silica supports using adsorption or covalently with glutaraldehyde or divinyl sulfone linkers. The best catalyst, AcmB on MCF linked covalently with glutaraldehyde, retained the specific activity of the homogenous enzyme while exhibiting a substantial increase of the operational stability. The immobilized enzyme was used continuously in the fed-batch reactor for 27 days, catalyzing 1,2-dehydrogenation of androst-4-en-3-one to androst-1,4-dien-3-one with a final yield of 29.9 mM (8.56 g/L) and 99% conversion. The possibility of reuse of the immobilized catalyst was also demonstrated and resulted in a doubling of the product amount compared to that in the reference homogenous reactor. Finally, it was shown that molecular oxygen from the air can efficiently be used as an electron acceptor either reoxidizing directly the enzyme or the reduced 2,4-dichlorophenolindophenol (DCPIPH2).

Selectivity Engineering in One-Pot Selective Synthesis of Drug Nabumetone over Novel Ni-Promoted La-Mg Oxide/Mesoporous Cellular Foam as Catalyst and Kinetic Modeling

One-pot synthesis of one of the popular non-steroidal anti-inflammatory drugs nabumetone (NBM) was achieved by using a novel catalyst. A series of mesoporous cellular foam (MCF) supported lanthanum...

Development of a method for the synthesis of basic catalysts with high number of active species

Abstract Mesoporous silica MCF and metalosilicates Nb/MCF-14 and Ce/MCF-14 were modified with anchoring of melamine followed by (3-chloropropyl)trimethoxysilane functionalization. The texture/structure parameters, chemical composition and surface properties of synthesized samples were investigated by XRD, N2 adsorption/desorption, XPS, UV–vis, TG, elemental analysis and 2-propanol dehydration and dehydrogenation, whereas the activity of obtained catalysts was tested in the Knoevenagel condensation between benzaldehyde and malononitrile. The Knoevenagel reaction required the presence of basic active sites or a pair of acid-base active centers. The novelty of the presented work was the use of mesoporous cellular foam (MCF) also modified with niobium (Nb/MCF-14) or cerium species (Ce/MCF-14) as supports for melamine anchoring. The use of the mentioned supports allowed the investigation of the role of open structure of MCF and metal dopant on melamine loading, its stability and reactivity in the Knoevenagel condensation. The obtained results clearly demonstrate that cerium and niobium species loaded into MCF increase significantly the efficiency of melamine loading as well as its stability. The anchoring of melamine to silica and metalosilicates increase the activity of this modifier as a result of formation of secondary amine species. The presence of defected ceria in Mel/Ce/MCF-14 raises the basicity of anchored melamine due to the electron donating effect of ceria. Consequently, the amine species in melamine are more active in the Knoevenagel condensation than those in Mel/Nb/MCF-14 because niobium species do not change oxidation state as easily as defected ceria.

Mesostructured cellular foam solid-phase microextraction coating for the highly sensitive recognition of polychlorinated biphenyls in water samples.

We herein presented a mesoporous cellular foam solid-phase microextraction coating that showed highly sensitive recognition for weakly polarity polychlorinated biphenyls in water samples. The mesoporous cellular foam coater fiber was for the first time prepared by a simple sol-gel method. The main experimental parameters including extraction temperature, extraction time, desorption time, stirring rate, and ionic strength were investigated by high-efficiency orthogonal array design, a L16 (44 ) matrix was applied for the identification of optimized extraction parameters, and the optimized method was successfully applied to the analysis of environmental water sample. The novel mesoporous cellular foam coated fibers exhibited sensitive limits of detection (0.07-0.28 µg/L), wide linearity (5-3000 µg/L), and good reproducibility (3.5-8.3% for single fiber, and 4.9-8.7% for fiber-to-fiber) for polychlorinated biphenyls. The home-made coating was successfully used in the analysis of polychlorinated biphenyls in real environmental water samples. These results indicate that the synthesized mesoporous cellular foams are promising materials for adsorption and separation applications in sample pretreatment.

Al-Doped Mesoporous Cellular Foam Modified Electrode as Sensor for the Detection of Parathion Pesticide

Al-Doped Mesoporous Cellular Foam Modified Electrode as Sensor for the Detection of Parathion Pesticide

UV–vis spectroscopy combined with azastilbene probe as a tool for testing basicity of mesoporous silica modified with nitrogen compounds

N-bromobenzyl substituted (E)-4′-hydroxy-4-stilbazolium bromide (NBSB), a representative of azastilbene compounds which reveals strong solvatochromism, was used as a probe molecule for testing basicity of nitrogen organic compounds grafted on mesoporous cellular foam silica (MCF). Easy deprotonation of this compound in contact with basic species was the reason for its use for probing the basicity of AP/MCF (AP - (3aminopropyl)trimethoxysilane), Im/MCF (Im - N-trimethoxysililpropylimidazole) and Az/MCF (Az - (3-azidopropyl)(triethoxy)silane). NBSB and its deprotonated form were analyzed by UV–vis spectroscopy measurements in solutions and UV–vis in solid materials. Ab-initio calculation allowed distinction between the preference of NBSB for interactions with SiOH on the support surface and with nitrogen species of the modifier. The NBSB protonation - deprotonation equilibrium dependence on pH was indicated. The role of solvent was considered. In water indirect probing of basicity by NBSB was observed via abstraction of proton from solvent by the modifier and deprotonation of NBSB due to the increased pH of the solution. In acetonitrile direct basicity probing took place in which NBSB was adsorbed in MCF pores. AP/MCF and Im/MCF caused deprotonation of NBSB, as monitored by UV–vis reflectance spectra. This effect was stronger for AP/MCF, which showed higher basicity. Az/MCF could not deprotonate NBSB in either water or acetonitrile.

Surface Charge and Morphological Characterization of Mesoporous Cellular Foam Silica/Nafion Composite Membrane by Using EFM

Surface Charge and Morphological Characterization of Mesoporous Cellular Foam Silica/Nafion Composite Membrane by Using EFM

The role of gold dopant in AP-Nb/MCF and AP-MCF on the Knoevenagel condensation of ethyl cyanoacetate with benzaldehyde and 2,4-dichlorobenzaldehyde

The Knoevenagel condensation with chlorine substituted benzaldehyde is difficult because of deactivation of aldehyde group. In this work we have shown that the activity of mesoporous cellular foams (MCF and Nb/MCF), modified with 3-aminopropyl-trimethoxysilane (AP) as a source of basicity, can be enhanced for this reaction by the anchoring of gold species. Gold species were loaded on amine modified materials towards Au/AP-MCF and Au/AP-Nb/MCF. Moreover, copper was used as a dopant for the latter sample giving rise to AuCu/AP/MCF. All these materials were characterized in details by different complementary techniques (N2 adsorption isotherms, TEM, UV–vis, TG/DTA, XPS, DFT calculations) which allowed the evaluation of states of all components of the catalysts. The interaction between niobium species and AP was evidenced to increase the stability of the basic modifier. This interaction was weakened by the introduction of gold and copper. The presence of both, negatively charged gold nanoparticles (NPs) and gold cations was crucial for the activation of 2,4-dichlorobenzaldehyde via the interaction with chlorine substituent atoms and aldehyde oxygen atoms as well as breaking of the “pseudo hydrogen bond” between aldehyde hydrogen atom and chlorine substituent, which destabilized the structure making it more active. Gold dopants did not influence significantly the condensation of ethyl cyanoacetate with benzaldehyde.

Comparative study of acid-basic properties of MCF impregnated with niobium and cerium species

Niobium and cerium dopants of mesoporous cellular foams, MCF, have been recently considered as promoters enhancing the basicity of amino-organosilanes anchored to the supports. Thus, the knowledge of acid-basic properties of niobium and cerium containing MCFs is important. Therefore, in this work monometallic (Ce and Nb) and bimetallic (Ce + Nb) materials based on MCF were investigated by means of NO and pyridine adsorption combined with infrared (FTIR) and electron spin resonance (ESR) spectroscopies as well as test reactions. The properties of bimetallic materials strongly depended on the method of impregnation (one-pot vs. step-by-step procedure). If niobium was included in step-by-step method (first niobium and next cerium sources – Ce/Nb/MCF) the Nb species were incorporated to silica skeleton and ceria surrounded some of the framework niobium species (NbO−) enhancing the acidic strength of tetra-coordinated niobium cations playing the role of Lewis acid sites (LAS). One-pot modification (simultaneous impregnation with Nb and Ce sources – CeNb/MCF) resulted in the formation of niobium and cerium oxides showing synergistic interaction. In this system ceria was more defected than in Ce/Nb/MCF sample and acidic strength of niobium species (LAS) was lower.

Efficient visible-light-driven depolymerization of oxidized lignin to aromatics catalyzed by an iridium complex immobilized on mesocellular silica foams

A novel Ir(ppy)2(bpy) complex-containing mesoporous cellular silica foams (Ir(ppy)2(bpy)-MCFs) was prepared by a facile thiol-ene click reaction between the prefabricated thiol-functionalized mesoporous cellular silica foams and vinyl-tagged [Ir(ppy)2(bpy)]PF6 complex. The elaborate Ir(ppy)2(bpy)-MCFs material possessed the large surface area (355 cm2/g), open foam-like mesoporous structure with 30 nm cell pore size and 3.0 nm window pore size. Importantly, it had the well-defined molecular configuration of Ir(ppy)2(bpy) active species. As expected, it exhibited excellent catalytic reactivity and selectivity in the visible-light-driven reductive depolymerization of oxidized lignin β-O-4 model compounds including p-hydroxyphenyl (H)-, guaiacyl (G)- and syringyl (S)-type units under the mild conditions. Meanwhile, it showed the comparable catalytic efficiency with the corresponding homogeneous [Ir(ppy)2(bpy)]PF6 catalyst. These high catalytic performances could be attributed to aerogel-like three-dimensional pore structure and high visible-light transparency, which efficiently decreased the mass transfer resistance and the photon propagation hindrance. Furthermore, it could be easily recycled and reused at least six times without the remarkable loss of catalytic activity.

A novel electrochemical sensor for chlorophenols based on the enhancement effect of Al-doped mesoporous cellular foam

Al-doped mesoporous cellular foam (Al-MCF) was prepared and characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, nitrogen adsorption-desorption isotherms and pore size distribution plots. An Al-MCF modified carbon paste electrode (Al-MCF/CPE) was developed, and both cyclic voltammetry and electrochemical impedance spectroscopy were employed to study the electrochemical properties of the Al-MCF/CPE. The electrochemical behaviors of pentachlorophenol (PCP) at different electrodes were investigated by cyclic voltammetry. Compared to bare CPE and mesoporous cellular foam (MCF) modified CPE (MCF/CPE), the Al-MCF/CPE showed a stronger enhancement effect on the electrochemical oxidation of PCP. Consequently, the determination of PCP was achieved via a convenient electrochemical method. Under optimal conditions, the oxidation peak current was linearly proportional to PCP concentration in the range of 0.10–5.0mgL−1, while the detection limit was 0.080mgL−1 (signal-to-noise ratio=3). The proposed method was found to be a convenient way for the determination of the total amount of chlorophenols (CPs).