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•Washcoated and packed-bed monoliths are compared as FTS reactors.•Washcoating led to lower pressure drops, but considerably lower catalyst inventory.•The washcoated monoliths ...performance were more efficient than the packed-bed ones.•Drainage of products through channels reduce extra-pellet diffusional limitations.
Washcoating and packing of Co-Re catalyst particles have been employed as structuring methods of parallel channel monoliths used in the low-temperature Fischer-Tropsch synthesis (FTS). These methods were compared with regard to catalyst hold-up, heat transfer properties and pressure drop. Reactors output was assessed in terms of CO conversion, CH4 selectivity and productivity of C5+ hydrocarbons. Washcoating led to much lower pressure drops, but also resulted in considerably lower catalyst inventory. As for the reactors performance (volumetric and per catalyst mass C5+ productivities), the washcoated monoliths were more effective than the packed-bed ones. This has been attributed to their more favorable hydrodynamic behavior that facilitates the drainage of the reaction products (liquids and waxes) through the central hollow of the channels thus reducing the extra-pellet diffusional limitations. For both catalyst configurations, it has been found that the productivity of C5+ per catalyst mass unit increases as the characteristic diffusion length increases within the range of values considered in this study (below 150 µm). This indicates that a moderate level of internal mass transport restrictions is beneficial for the low-temperature FTS, which has been explained in terms of the effects of diffusional limitations on the H2/CO molar ratio, and that of this ratio on the FTS kinetics. The possible influence of thermal effects on these results has been numerically and experimentally discarded.
•A new strategy named as post functionalization with B-N coordination complex was presented.•PGM-Pickering-0.10-BN possessed hierarchical porous structure and Wulff-type boronic ...acids.•PGM-Pickering-0.10-BN showed specific capture of flavone under neutral condition.•The results could be facilely adopted to predict and design optimal conditions in the scale-up.
An apparent disadvantage of boronate affinity is that it has to be performed in alkaline media and can lead to the oxidation of cis-diols in compounds. A new strategy named as post functionalization with B-N coordination complex was present to prepare boronic acid suspended macroporous polymeric monolith for the selective capture of cis-diol-containing luteolin (LTL) under neutral condition. In this work, a water-in-oil (W/O) Pickering (high internal phase emulsions) HIPE template stabilized by boronic acid suspended mesoporous silica nanoparticles (BA-MSNs) was applied to prepare macroporous poly(glycidyl methacrylate) monolith (PGM-Pickering-0.10), and then B-N coordination complex resulted from the reaction of 3-aminophenylboronic acid (APBA) and 1,6-hexamethylenediamine was integrated to the PGM-Pickering-0.10. As-prepared hierarchical porous PGM-Pickering-0.10-BN with “Wulff-type boronic acids” possessed special mesopore-in-macropore structure. In static adsorption, pH-dependent adsorption experiments demonstrated that PGM-Pickering-0.10-BN was able to capture LTL with expected high adsorption amount (158.5µmolg−1 at 298K) and fast binding kinetics (equilibrium in 2.0h) under neutral condition, while macroporous polymers without post functionalization or functionalized only with APBA display poor adsorption performance at pH=7.0. In addition, BA-MSNs as the stabilizers enhanced the mechanical property and specific adsorption ability of PGM-Pickering-0.10-BN simultaneously, and the integrated B-N coordination complex did play vital roles in the specific adsorption of LTL. By optimizing dynamic adsorption factors with response surface methodology (RSM), the maximum adsorption amount of 177.8µmolg−1 was also achieved under neutral condition.
Porogens are key components required for the preparation of porous polymer monoliths for application in separation science. Porogens determine the stability, selectivity, and permeability of polymer ...monoliths. This review summarizes the role of porogens in the preparation of porous polymer monoliths with a focus on clear understanding of effect of porogens on morphological properties, porosity, surface area, mechanical stability, and permeability of monoliths, particularly targeting the field of separation science. This review also includes the use of different types of porogens with the focus on various approaches used to set criteria for their systematic selection, including porogen‐free techniques recently used for synthesis of porous monoliths. It discusses the current state‐of‐the‐art applications of porogens in column preparation as well as where the future developments in this field may be directed.
Monolithic materials having 3D-network structure are now widely used for the separation such in liquid chromatography and solid-phase extraction. Additionally, monolithic materials showed several ...functionalities, we previously discovered that epoxy monoliths, which were prepared with epoxy compounds and amine curing agents using suitable porogens, showed antibacterial potency when quaternized by hydrogen halides and alkyl halides and immersed in coli suspension. Antibacterial activity was enhanced by lowering pH of the aqueous phase with the former and cell membrane disruption triggered by cell contact with the latter. As well as the epoxy monoliths with nitrogen (N) at the high content rate enhance antibacterial activity. We consider that these actions may be effective for molds. In this study, we synthesize epoxy monoliths, conducting quaternization with hydrochloric acid and butyl bromide. Alternaria alternate, one of the genera in sooty mold, is employed for an evaluation. We examine effects of the epoxy monoliths on spores and hyphal growth. With the effects on spores, unquaternized monoliths and ones quaternized with hydrochloric acid and/or butyl bromide were immersed in coli suspension, and after predetermined time, the suspension was cultured in potato dextrose agar. Consequently, the monoliths quaternized with butyl bromide inhibited the growth of the spores. With the effects on the hyphal growth, we observed mold growth by placing the fabricated epoxy monolith in PDA and injecting molds to the surface of the monolith. The monoliths quaternized with hydrochloric acid inhibited the hyphal growth most by lowering pH of the culture medium. The quaternized monoliths with butyl bromide could inhibit the hyphal growth due to the positively charged surface of the monolith. Besides, we successfully achieved antimold with inhibiting the fungal growth by raising the N content rate and increasing degree of quaternization.
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Removal of toxic effluents (like dyes and pesticides) by cost-effective and user-friendly method is needed to provide sustaining the environment for civilization. Here, low-cost ...mesoporous silica monolith (SiO2) and silica supported metal-oxide (ZnO@SiO2) monolith were synthesized to reduce the solemn impact of toxic effluents. Batch experiments were performed to remove Alizarin (AZ), Paradol (PD), Acid blue-113 (AB) and Rhodamine-B (RD) from aqueous solution via synthesized monoliths. The influence of various parameters (like pH, contact time, temperature and adsorbate concentration) has been optimized. The maximum adsorption capacity of ZnO@SiO2 monolith is 625, 500, 714 and 555mg/g for AZ, RD, AB, and PD respectively. The adsorption for AZ, PD, AB, and RD is spontaneous and exothermic. The adsorption process can be well described by the pseudo-second-order kinetic model (high regression coefficients) and the Freundlich isotherm model (R2=0.97–0.99).
This review summarizes the most-recently updated progress on fabrication strategies and applications of MOF-mediated devices. Enhanced mechanical stability and better recyclability are obtained due ...to 3D continuous bodies. The additional multi-scale pores and densely packed structure render higher both volumetric and gravimetric energy density or adsorption capacity. MOF-device acts as a versatile platform with designability and controllability in various fields.
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•Fabrication strategies and interesting applications of MOF-devices are critically summerized.•Improved mechanical stability, recyclability and volumetric capacity are achieved.•Significant advantages are highlighted compared to MOF powder.•Foreseeable challenges and perspectives for MOF-medicated 3D devices are proposed.
In the past two decades, considerable metal-organic frameworks (MOFs) have been identified and prepared, showing great promise in various fields. In general, the powdery MOFs have limited mechanical strength and poor processability and recyclability owing to the rigidity and fragility of MOFs. Moreover, the cost ease and large-scale production with good controllability and integrity are prerequisites to cross the gap from lab to market, especially for large-scale application. Most recently, the fabrication of MOF-based 3D monoliths is of greatest focus to tackle the aforementioned issues. Herein, we briefly summarize the representative fabrication strategies and features of 3D MOF-monoliths and their application in energy storage, separation, gas storage, bio-medical applications, catalysis and motors. The fabricated MOF-monoliths exhibit excellent advantages and even additional bonus to surpass MOF powder in different aspects, including: 1) improved robustness benefited from substrates and 3D structures; 2) enhanced reusability facilitated by integrity and large-salacity; 3) extra pores and active sites for accommodating more guest molecules; 4) ease in medical supplies preparation with enhanced processabilities. Thus, MOF-monoliths have promising advantages with good commercial-transnationality and clinical-transnationality.
Self-standing binderless FAU-X monoliths with hierarchical trimodal porosity have been synthesized for the first time by a double pseudomorphic transformation. Parent silica monoliths obtained by the ...combination of spinodal decomposition and sol-gel process have first been synthesized. The silica monoliths have been then transformed into silica-alumina monoliths (0.25 < Al/Si < 0.40) in low NaOH concentration (NaOH = 0.24 mol/L) at 40 °C for 24 h. Silica-alumina monoliths have been then transformed into FAU-X monoliths featuring nanocrystals in the struts at high NaOH concentration (NaOH = 2.2 mol/L) with an aging step at 40 °C for 4 days and a crystallization step at 100 °C for 24 h. The FAU-X monoliths feature macropores with diameters adjustable from 3 to 20 μm (similar to the parent silica monolith). The skeleton of the FAU-X monoliths is formed by an aggregation of two populations of FAU-X nanocrystals (100–200 nm/400–500 nm) generating a secondary porosity between the nanocrystals of 30–1000 nm in diameter, centered at 300 nm. The FAU-X monoliths present three levels of porosity with a macropore volume of ca. 1.0 mL/g, a secondary pore volume of ca. 0.40 mL/g and a micropore volume of 0.30 mL/g. These new FAU-X monoliths with hierarchical porous structure fulfill the requirements of high performance adsorbents for continuous flow process intensification.
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•FAU-X monoliths with hierarchical macro-/meso-/microporosity.•Adjustable macropore diameter from 3 to 20 μm.•FAU-X nanocrystals to improve diffusion.•Shaping FAU-X without binders.•A new family of FAU-X for adsorption processes intensification.
In this study, hierarchical porous structured CeO2/Al2O3 monolith was prepared through the combination of sol-gel and heating-drying-calcination methods. Subsequently, the Au-CeO2/Al2O3 monoliths of ...different Au loadings were prepared by the deposition-precipitation method. When the Au3.2%-CeO2/Al2O3 monolith was used for low- temperature CO oxidation, compared with Au3.2%-CeO2/Al2O3 powder particles, excellent activity (temperature of 34 °C for complete conversion) and stability (up to 100 h) for the CO oxidation were achieved. Such an excellent performance was attributed to the unique hierarchical porous structure of monolith, the good oxygen storage capacity of CeO2, as well as the excellent CO adsorption and catalytic properties of the monodisperse Au nanoparticles.
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•Hierarchical porous structured monolithic catalysts.•Al2O3 monolith supported CeO2.•The size and content of Au nanoparticles effect on the catalytic activity.
•Monolithic oxygen carriers were prepared by loading BaCoO3-δ powder perovskite onto cordierite ceramics for CLAS.•The oxygen release performance of the monolithic oxygen carriers was simulated using ...CFD numerical method.•The monolithic oxygen carrier primarily released O2 via the lattice oxygen of BaCoO3-δ perovskite.•The square was a more suitable cross-section shape for the loaded material.
This work is the second part of the application of BaCoO3-δ perovskite as an oxygen carrier for chemical looping air separation (CLAS). In this paper, monolithic oxygen carriers were prepared by loading BaCoO3-δ powder perovskite onto cordierite ceramics. The oxygen release performance of the monolithic oxygen carriers was evaluated through experimentation on a fixed-bed reactor and simulated using computational fluid dynamics (CFD) numerical methods. The surface temperature variation, oxygen release efficiency, and the effect of the cross-section shape of the loading material were investigated. The results showed that the monolithic oxygen carrier primarily released O2 via the lattice oxygen of BaCoO3-δ perovskite during the reaction process, and the kinetic model for oxygen release and the reaction mechanism of the monolithic oxygen carrier were essentially identical to those of powder BaCoO3-δ perovskite. CFD simulation showed that the surface temperature of the monolithic oxygen carrier decreased and then increased as the oxygen release reaction proceeded. And the temperature on the centerline of the inner surface of the monolithic oxygen carrier was the lowest. The hexagonal monolithic oxygen carrier demonstrated the highest maximum temperature difference along the centerline of its inner surface, reaching 7.26 °C, whereas both square and triangular monolithic oxygen carriers exhibited a maximum temperature difference of 6.73 °C. The monolithic oxygen carriers exhibited the highest conversion rate at the inlet and the lowest at an axial length of 19 mm. Among them, the square-shaped oxygen carrier showed higher surface temperatures and conversion rates, achieving values of 0.830 and 0.814 at the inlet and axial length of 19 mm after a duration of 600 s. These findings suggest that a square cross-section shape is more suitable for loading materials.
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