Mesostructured Cellular Foam Silica Research Articles

Composite Membranes Based on Functionalized Mesostructured Cellular Foam Particles and Sulfonated Poly(Ether Ether Sulfone) with Potential Application in Fuel Cells.

Composite polymeric membranes were designed based on sulfonated poly(ether ether sulfone) (sPEES) and mesostructured cellular foam (MCF) silica nanoparticles functionalized with organic compounds. Parameters such as molecular weight (MW) of the polymer, nature of the functional group of the MCF silica, and percentage of silica charge were evaluated on the final properties of the membranes. Composite membrane characterization was carried out on their water retention capacity (high MW polymer between 20-46% and for the low MW between 20-60%), ion exchange capacity (IEC) (high MW polymer between 0.02 mmol/g-0.07 mmol/g and low MW between 0.03-0.09 mmol/g) and proton conductivity (high MW polymer molecular between 15-70 mS/cm and low MW between 0.1-150 mS/cm). Finally, the membrane prepared with the low molecular weight polymer and 3% wt. of functionalized silica with sulfonic groups exhibited results similar to Nafion® 117.

Mesostructured cellular foam silica supported Au–Pt nanoalloy: Enrichment of d-state electrons for promoting the catalytic synergy

A mesostructured cellular foam (MCF) silica was applied to support gold (Au) – platinum (Pt) alloy nanoparticles (NPs) for benzyl alcohol partial oxidation. A catalytic synergy on bimetallic gold (Au)-platinum (Pt) nanoparticle (NP) catalyst, referring to that introducing Au to Pt leading to a higher catalytic performance has been observed. However, the essence of this synergistic effect is still under debate. In this work, a series of MCF supported Au–Pt NP catalysts are designed to reveal the essence . Well-developed porous structure of MCF support eliminated the mass transfer limitation and intrinsic catalytic activity was obtained. The improved catalytic performance on bimetallic catalyst is attributed to the geometric and electronic changes of active sites after formation of Au–Pt alloy NPs. Compared with monometallic catalyst, the formation of Au–Pt alloy results in the changes of particle size and lattice structure. Electronic property analyses confirmed the increase of d state electrons on Au–Pt alloy NPs, which are calculated from s-p-d hybridization and intra-atomic charge redistribution, leading to the increased abundance of transferable d electrons near Fermi level and further enhancing the catalytic activity. These findings gain new insights into the catalytic synergy of bimetallic nanoparticles and shed light on the optimization of these catalysts. The catalytic synergy of mesostructured cellular foam silica supported bimetallic Au–Pt catalysts for benzyl alcohol oxidation is attributed to the increased abundance of transferable d electrons near Fermi level which are calculated from s-p-d hybridization and intra-atomic charge redistribution. • Mesostructured cellular foam silica support Au–Pt alloy nanoparticles were prepared by a facile one-pot method. • The formation of Au–Pt alloy nanoparticles results in particle size variation and lattice distortions. • Electron polarization leads to the increase of transferable d-orbital electrons on Au and Pt atoms. • The catalytic activity on Au–Pt alloy catalyst was enhanced through accelerating the O 2 activation.

Introduction of cross-linking agents to enhance the performance and chemical stability of polyethyleneimine-impregnated CO2 adsorbents: Effect of different alkyl chain lengths

Polyethyleneimine (PEI)-functionalized silica-based CO2 adsorbents are well known to irreversibly form urea during the regeneration process at high temperatures and under CO2-rich atmospheric conditions. The formation of urea is a critical drawback that substantially reduces the cyclic performance of PEI-functionalized adsorbents. In this study, epoxy cross-linkers were introduced to PEI to suppress the formation of urea. Pristine PEI and epoxy cross-linked PEI were impregnated into mesostructured cellular foam silica using a dry impregnation method. In particular, epoxy cross-linkers with different alkyl chain lengths were used, and the effect of the alkyl chain length of the cross-linkers on the chemical stability and CO2 adsorption performance of adsorbents was scrutinized. The suppression of urea formation improved as the alkyl chain length of the cross-linkers increased. The adsorbent functionalized with epoxy cross-linked PEI exhibited an approximately three times higher working capacity (0.71 mmol g−1) than the adsorbent functionalized with pristine PEI (0.23 mmol g−1) after 40 rapid cycles comprising adsorption at 100 °C with 15% CO2 balanced by N2 for 10 min and regeneration at 130 °C with 100% CO2 for 5 min. It is believed that the alkyl chain of the cross-linkers acted as a spacer that could hinder the urea formation, enhancing the chemical stability and CO2 adsorption performance of PEI-functionalized adsorbents.

Perovskite LaNiO3 Nanocrystals inside Mesostructured Cellular Foam Silica: High Catalytic Activity and Stability for CO2 Methanation

To simultaneously obtain high catalytic activity and stability, LaNiO3‐based catalysts supported on mesostructured cellular foam (MCF) silica are prepared by a citric acid–assisted impregnation method and applied for a CO2 methanation reaction. These MCF‐supported perovskite LaNiO3 (LaNiO3/MCF) samples are characterized by nitrogen adsorption, X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, H2‐temperature‐programmed reduction, and X‐ray photoelectron spectroscopy. The results indicate that these catalysts offer highly dispersed La2O3 and metallic Ni nanoparticles with intimate contact inside the pores of MCF support after reduction in H2 flow. Compared with the catalyst prepared by the coimpregnation method (30LNOM‐Im‐650), the citric acid–assisted LaNiO3/MCF (30LNOM‐C‐650) catalyst exhibits a much higher catalytic activity due to its higher Ni dispersion and stronger interrelationship between La2O3 and Ni species. In the 100 h‐lifetime test under the conditions of 450 °C, 0.1 MPa, and a high weight hourly space velocity of 60 000 mL g−1 h−1, 30LNOM‐C‐650 also shows a high long‐term stability without Ni sintering, which is attributed to the formation of enhanced interaction between metallic Ni and La2O3 via La2O2CO3 species on their interface as well as the confinement effect of the MCF support.

Mesostructured cellular foam silica supported bimetallic LaNi1-xCoxO3 catalyst for CO2 methanation

To address the metal sintering problem over the transitional one-dimensional-channel materials supported metal catalyst at high loadings, the 3-dimensional mesostructured cellular foam silica (MCF) supported bimetallic LaNi1–xCoxO3 perovskite catalyst was prepared via a citric acid assisted impregnation method for CO2 methanation. Highly dispersed La2O3 and bimetallic Ni–Co alloy nanoparticles with size of around 5.1 nm were immobilized inside the pores of the MCF silica with intimate contact, resulting in high catalytic activity at low temperature and superior stability at high temperature for CO2 methanation. Among all catalysts, the LaNi0.95Co0.05O3/MCF catalyst exhibited the highest catalytic activity due to its smallest Ni–Co alloy nanoparticles as well as the synergistic effect between Ni and Co species. In addition, LaNi0.95Co0.05O3/MCF catalyst also showed high long-term stability without Ni sintering in a 100 h-lifetime test, which was attributed to the confinement effect of the MCF support as well as the physical barrier of La2O3 species nearby metallic Ni nanoparticles.

Review of large-pore mesostructured cellular foam (MCF) silica and its applications

AbstractThe unique properties of mesostructured cellular foam (MCF) silica such as, large pore size, continuous three-dimensional (3D) pore system and hydrothermal robust materialallow favorable conditions for incorporating active sites to produce modified MCF silica as catalysts, biocatalysts and adsorbents. Recently, the modified MCF silicas were reported to be efficient catalysts for the hydrogenation of phenylacetylene, heck coupling reaction of arylboronic acid, etc. Biocatalysts derived from modified MCF silicas were found to be a potential to convert glucose to gluconic acid, hydrolysis of N-benzoyl-DLarginine-p-nitroanilide (BAPNA) and casein, transesterification of racemic 1 phenyl- ethanol and hydrolytic, etc. Several separation processes such as CO2 capture and adsorption of L-tryptophan, lysozyme and bovine serum were sucessfully conducted using adsorbents derived from modified MCF silicas. This paper reviews the synthesis of the MCF silica material and the incorporation of active sites or immobilization of enzymes in the MCF silica material. Additionally, a detailed understanding of the characterization of the modified MCF silicas, which includes pore size, active sites/enzymes sizes, amount of active sites/enzymes bound with the MCF silica, was also discussed to obtain their potentialities as catalysts, biocatalysts and adsorbents. The review also describes recent progress on the applications of the MCF silica.

Mesostructured cellular foam silica materials for laccase immobilization and tetracycline removal: A comprehensive study

Abstract Due to its exceptional textural, morphological and mechanical properties, mesostructured cellular foam (MCF) silica is a suitable support material for enzyme immobilization. However, the simple and efficient protocol of enzyme immobilization using MCF is often overlooked. Thus, in the presented study, we describe the synthesis, modification and characterization of mesostructured cellular foam silica for use in laccase immobilization. It has been established that the synthesized materials are characterized by high surface area equal to approx. 550 m2 g−1 and pores with diameters of approx. 20 nm, which makes them suitable for effective enzyme binding. Furthermore, immobilization of the laccase onto both, unmodified and Cu-modified MCF has been carried out, resulting in process yield of over 95% and 85%, respectively. Upon immobilization, irrespectively of the support used, laccase retained higher activity (over 80%) at a wider temperature (20–40 °C) and pH (4–7) range, as compared to the free enzyme, which exhibited such high activity only at pH 5 and 30 °C. In addition, the reusability of the laccase immobilized onto MCF + Cu material has also been improved as it still retained approx. 90% of its initial activity after 10 reaction cycles. Finally, the obtained biocatalytic systems have been applied for degradation of tetracycline from aqueous solutions resulting in 100% removal of the antibiotic by the MCF + Cu + lac system due to simultaneous adsorption and biocatalytic conversion.

Amino-functionalized mesostructured cellular foam silica: a highly efficient andrecyclable catalyst in the Knoevenagel condensation reaction

Amino-functionalized mesostructured cellular foam silica: a highly efficient andrecyclable catalyst in the Knoevenagel condensation reaction

The Optimised Statistical Model for Enzymatic Hydrolysis of Tapioca by Glucoamylase Immobilised on Mesostructured Cellular Foam Silica

Enzymatic hydrolysis of starches using free glucoamylase to reducing sugars have difficulties in recovering and recycling of the enzyme, hence immobilisation on inert supports were widely studied. However, effectiveness of the immobilised glucoamylase were merely observed only on soluble starches. It was considered a valuable thing to know performance of glucoamylase on Mesostructured Cellular Foam (MCF) silica in hydrolysing of tapioca. An optimised study on enzymatic hydrolysis of tapioca using glucoamylase on MCF silica (9.2T-3D) and its kinetics were described including justification of the predicted model as it was required to develop in large scale operations. Central Composite Design was used to model the process by studying effects of three factors on DE values after enzyme immobilisation. Immobilisation of glucoamylase on this support gave up to 82% efficiency with the specific activity of 1,856.78 U.g-1. Its used to hydrolysis of tapioca resulted DE values of 1.740-76.303% (w/w) where the highest DE was obtained at pH of 4.1, temperature of 70 ℃ and agitation speed of 140 rpm. The optimisation produced a polynomial quadratic model having insignificant lack-of-fit and low standard deviation, so that it was applicable and reliable in simulating the DE with only 0.80% of data were not described. Temperature affected the process highly, but the buffer pH, agitation speed and factorial interactions were considered not important. KM value for immobilised enzyme was better than the free glucoamylase, however, its reaction rate was slower than the free glucoamylase catalysis. Copyright © 2019 BCREC Group. All rights reserved

Three‐Component Mannich Reaction Catalyzed by Mesostructured Cellular Foam Silica Immobilized H3PW12O40

AbstractOne‐pot three‐component Mannich reaction was carried out at room temperature using mesocellular cellular foam (MCF) silica loaded H3PW12O40 as catalyst. The H3PW12O40/MCF catalyst was prepared by the traditional impregnation method and confirmed by a series of characterizations such as nitrogen adsorption, X‐ray diffraction (XRD), Fourier‐transform infrared spectra (FT‐IR), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The results showed that the H3PW12O40/MCF catalyst with 50 wt% loading of H3PW12O40 exhibited the highest catalytic activity for the Mannich reaction of benzaldehyde, aniline and acetophenone with the yield of 94% in 1.8 hours under the optimal condition. In addition, the H3PW12O40/MCF catalyst could be easily recycled and reused four times without significant decline of activity. This work provided an improved modification of the three‐component Mannich reaction in terms of efficient activity, mild reaction conditions, clean reaction profiles and a simple workup procedure.

Capability of immobilised glucoamylase on mesostructured cellular foam silica to hydrolyse tapioca starch

Mesoporous size siliceous-based materials have been associated with immobilisation of free glucoamylase and soluble starches hydrolysis. As ethanol and other chemicals can be produced from insoluble feed such as tapioca, understanding of glucoamylase immobilised on mesostructured cellular foam (MCF) silica to hydrolyse the starch is required. To get the knowledge on this process for development of a large-scale operation, free glucoamylase SQzyme AGP was immobilised on MCF silica (9.2T-3D) by direct adsorption and used the product to hydrolyse tapioca. The free enzyme was able to be immobilised onto the carrier with the efficiencies of 39.20-84.84% where the operational factors of temperature, agitation speed and pH affected the immobilisation process highly. During the enzymatic hydrolysis, effects of temperature and agitation speed were high. The dextrose equivalent (DE) values of 1.21-81.70% were obtained. The optimum temperature and agitation speed were 70°C and 140 rpm. Other factors such as buffer pH, starch concentration and enzyme unit activity showed low effects on the hydrolysis process. Excellent DE were obtained at the conditions of pH, tapioca concentration and enzyme unit activity of 4.6, 3 mg mL−1 and 2351 U, respectively.

Preparation and Characterization of UiO-66-Supported Cu–Ce Bimetal Catalysts for Low-Temperature CO Oxidation

A series of Zr-based metal–organic frameworks (UiO-66) supported CuO–CeO2 catalysts with various total metal loadings and various Cu/Ce ratios were prepared by using a co-impregnation method. The catalytic activities of the catalysts for low temperature oxidation of carbon monoxide were compared with that supported on the ZrO2 and mesostructured cellular foam silica. The results show that the catalysts supported by UiO-66 are expected to give the best catalytic activity, which should be attributed to the special construction of UiO-66. The samples were further characterized by XRD, TEM, N2 adsorption–desorption, H2-TPR, XPS, and in situ DRIFT. And the catalyst with a bimetallic loading of 50 wt% and Cu/Ce ratio of 3:7 (wt/wt) has the highest catalytic activity, which can be attributed to the larger amount of finely dispersed Cu species strongly interacting with CeO2, the highest amounts of oxygen vacancies and Cu+ species on the catalyst surface.

Saccharification Kinetics at Optimised Conditions of Tapioca by Glucoamylase Immobilised on Mesostructured Cellular Foam Silica

As insoluble substrates such as tapioca can be used to make chemical compounds, saccharification of tapioca by glucoamylase immobilised on mesostructured cellular foam (MCF) silica using Box-Behnken Design of experiment was conducted to optimize this process so that the experimental results can be used to develop large-scale operations. The experiments gave dextrose equivalent (DE) values of 6.15–69.50% (w/w). Factors of pH and temperature affected the process highly. The suggested quadratic polynomial model is significant and considered acceptable (R2 = 99.78%). Justification of the model confirms its validity and adequacy where the predicted DE shows a good agreement with the experimental results. The kinetic constants (Vmax, KM) produced by the immobilised enzyme differed highly from the values yielded by free glucoamylase indicating reduction of substrate access to enzyme active sites had occurred.

Theoretical and experimental insight into zinc loading on mesoporous silica

Zinc oxide species grafted on mesostructured cellular foam (MCF) silica are investigated using a combination of experimental and theoretical techniques. MCF is modelled using a realistic amorphous silica surface model surface slab. The most energetically favorable complexes grafted on the silica surface were identified and characterized at the molecular level. The Zn metal center was found in tetrahedral coordination. Moreover, the Si-O-Zn-OH species is found to be stabilized in a 5 fold coordinated silicon with an unusual trigonal bipyramidal geometry. A mechanism for the grafting process of the metal species on the support is proposed.

Preparation and characterization of mesostructured cellular foam silica supported Cu–Ce mixed oxide catalysts for CO oxidation

A series of mesostructured cellular foam (MCF) silica supported CuO–CeO2 catalysts with various total metal loadings (10–40 wt%) and various Cu/Ce ratios (Cu/Ce = 1/9, 2/8, and 3/7 wt/wt) were prepared and tested for CO oxidation.

MCFs的碳化对其葡萄糖氧化酶吸附性能的影响

本文以三嵌段共聚物聚氧乙烯–聚氧丙烯–聚氧乙烯(Pluronic P123)及三甲苯(TMB)为模板剂及扩孔剂，制备出介孔硅泡沫分子筛。以糠醇为碳源，运用硬模板法对介孔硅泡沫分子筛进行碳化，得到介孔碳泡沫分子筛。采用SEM观察、TEM观察及氮气吸附等手段对碳化后的介孔碳泡沫分子筛及之前的硅模板的外部形貌、粒径及孔道结构进行表征。结果表明，经过碳化后的介孔泡沫分子筛较好地保持了之前模板剂的颗粒尺寸和外部形貌。碳化后的介孔泡沫分子筛其窗口孔径、胞体孔径和孔容都有所下降，但比表面积却有所增大。将所制备的介孔碳泡沫分子筛和硅基模板剂分别用于葡萄糖氧化酶的负载，碳化后的介孔材料对葡萄糖氧化酶的吸附量大于硅基模板，表明拥有较小窗口粒径、较小胞体孔径和孔容的介孔碳泡沫分子筛表现出更优异的葡萄糖氧化酶负载性能，有望成为优良的酶载体材料。 The mesostructured cellular foams (MCFs) were synthesized using microemulsion templating, in which the nonionic triblock copolymer surfactant Pluronic P123 was served as template and 1,3,5-trimethylbenzene (TMB) as organic swelling agent. Then, by using mesostructured cellular foam silica as templates, furfuryl alcohol as carbon precursors, the carbon-based mesostructured cellular foam was prepared. The exterior morphologies and pore structures of the samples were characterized by Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM) and nitrogen adsorption. It was found that mesostructured cellular foams kept its original particle size and external morphology after carbonization, and possessed the smaller windows and cell diameters and the smaller pore volumes, but had larger specific surface area. Both carbon-based and silicon-based mesocellular foams were used as the carriers for immobilization of glucose oxi-dase. The loading amounts on carbonaceous mesocellular foams were much higher than on the corresponding silicon templates. We can conclude that carbon-based mesocellular foam with smaller particle size, smaller window size and smaller pore volume had a better glucose oxidase adsorption performance. It might be served as the prospective enzyme carrier material.

Preparation and retention mechanism exploration of mesostructured cellular foam silica as stationary phase for high performance liquid chromatography

Siliceous mesostructured cellular foam (MCF) with highly interconnected porous structure, ultralarge pore size and relatively uniform particle size (3–5μm) was prepared to achieve the mixed-mode and efficient separation of intact proteins. And molecular sieving effect for the first time played an important role in protein separation using mesoporous silica materials as HPLC stationary phase. The spherical silica particles were synthesized via hydrothermal method and the pore size was easily regulated by adding NH4F as well as altering the aging time. After aminopropyl derivatization, the chromatographic performance of functionalized mesoporous silica particles was investigated in comparison with those without modification and commercial NH2 column, and their mixed-mode retention mechanisms were investigated in detail. The superior separation performance for the retention of proteins was obtained on our home-made column in comparison with commercial NH2 column. The influences of aminopropyl derivatization and mobile phase composition on the column property were also investigated. Moreover, the home-made column showed similar performance for separation of polar anilines and neutral PAHs with the commercial column, owing to mixed-mode retention mechanisms including p–π stacking, electron interaction, hydrophobic effect, π–π EDA interaction and hydrogen bonding. All these results indicated that the aminopropyl modified MCF would be promising in the mixed-mode and efficient separation of biomolecules in addition with small molecules.

Synthesis of large-pore mesostructured cellular foam silica spheres for the adsorption of biomolecules.

Mesostructured cellular foam (MCF) silica spheres with different textual parameters were synthesized using a triblock copolymer as a template. The effects of acid concentration and aging time on the window size and morphology were discussed. Besides, the adsorption performances of lysozyme and bovine serum albumin on the blank MCF with different window size and aminopropyl-modified MCFs were studied. The adsorption capacity and rates were shown to be dependent on the window size and surface chemical properties of the adsorbents. In particular, the MCF with window size of 15.2 nm showed fast adsorption for lysozyme with an adsorption capacity of 500 mg/g in 10 min. Furthermore, it has been shown that MCF spheres are potential materials in the separation of biomolecules because of their chemical tunable surface and molecular sieve properties.

介孔碳泡沫分子筛的制备及其对葡萄糖氧化酶的吸附行为

以添加氟化铵改性的介孔二氧化硅泡沫分子筛为模板，糠醇为碳源，运用硬模板法制备不同孔结构的介孔碳泡沫分子筛。采用SEM观察、TEM观察及氮气吸附等手段对介孔碳泡沫分子筛的粒径及孔结构进行了表征。结果表明，经氟离子改性的介孔泡沫分子筛具有较小的颗粒粒径及较大的窗口孔径、胞体孔径和孔容，但比表面积较小。将所制备的介孔碳泡沫分子筛和介孔二氧化硅泡沫分子筛分别用于葡萄糖氧化酶的负载，介孔碳泡沫分子筛对葡萄糖氧化酶的吸附量远远大于相应的硅模板，表明酶分子和载体表面间的静电作用对负载过程有很大影响；同时，拥有较小粒径、较大胞体孔径和孔容的介孔碳泡沫分子筛表现出更大的葡萄糖氧化酶负载量，有望成为优良的酶载体材料。 By using fluorine-modified and original mesostructured cellular foam silica as templates, furfuryl alcohol as carbon precursors, carbonaceous mesocellular foams with different pore sizes were prepared, and then the grain sizes and pore structures of the samples were characterized by scanning electron microscope (SEM), Transmission Electron Microscopy (TEM) and nitrogen adsorption. It was found that fluorine-modified mesostructured cellular foams possessed the smaller particle sizes and specific surface area, but the larger windows and cell diameters and the larger pore volumes. All prepared samples were used as the carriers for immobilization of glucose oxidase. The loading amounts on carbonaceous mesocellular foams were much higher than on corresponding silicon templates, indicating that the immobilization process might be affected strongly by the electrostatic repulsion between the glucose oxidase molecules and carrier surface. Furthermore, carbonaceous mesocellular foam with smaller particle size, larger window size and pore volume showed the highest glucose oxidase loading amounts. It might be served as the prospective enzyme carrier material.

Mechanical properties and crystallization of high-density polyethylene composites with mesostructured cellular silica foam

In this study, composites of high-density polyethylene (HDPE) with mesostructured cellular foam (MCF) silicas have been prepared by melt mixing and studied for the first time. Two different MCF silica analogues having different pore size were used, i.e., 12 nm (MCF-12) and 50 nm (MCF-50). The MCF content in the mesocomposites was 1, 2.5, 5, and 10 mass%. All HDPE/MCF-50 mesocomposites exhibited improved mechanical properties compared with neat HDPE, indicating that the mesocellular silica foam particles with the large mesopore size can act as efficient reinforcing agents. On the other hand, the MCF-12 silica with the smaller size mesopores induced inferior mechanical properties, mainly due to the poorer dispersion of the silica particles and the formation of large aggregates. The mesocellular silica foam particles also affected the thermal properties and the crystallization characteristics of HDPE. Crystallization of mesocomposites was faster than that of neat HDPE. Crystallization kinetics was analyzed with the Avrami equation for both isothermal and non-isothermal conditions. For isothermal crystallization, the Avrami exponent increased with increasing crystallization temperature from 2 to 3. In non-isothermal crystallization, the values of the Avrami exponent increased from 3 to 6.3 with decreasing cooling rate. Lower activation energy values of non-isothermal crystallization were calculated using the isoconversional method of Friedman, as well as using the Kissinger’s equation. Finally, the nucleation efficiency of the mesocellular silica foam particles was estimated from data associated with non-isothermal crystallization, according to the method of Dobreva.