The catalytic partial oxidation (CPOX) of methane is studied over staged palladium/alumina and rhodium/alumina coated monoliths by an in-situ sampling technique to resolve the axial species ...concentration and temperature profiles. A molar C/O ratio of unity, which is stoichiometric for the formation of synthesis gas (CO/H2), and short residence times are chosen for this autothermal process. The profiles of the staged monoliths are compared with profiles of single-sliced palladium/alumina and rhodium/alumina coated monoliths. The investigations clearly show two zones inside the catalytic channel. In the staged catalyst with the Pd stage being on the upstream side as well as in the single-sliced Pd catalyst, hydrogen is not formed before oxygen is almost completely consumed, i.e. a total oxidation zone is observed in front of a steam reforming zone. In the Rh catalyst, in the first 2 mm zone, total oxidation and steam reforming occur as prevalent reactions followed by a reforming zone with steam reforming as dominating reaction. The observations are interpreted in terms of the indirect and direct route towards hydrogen formation in CPOX of methane.
•Axial concentration and temperature profiles for partial oxidation over staged Pd–Rh catalyst.•Comparison of profiles for Pd and Rh reveals difference in H2 formation on Rh and Pd.•Results indicate indirect formation of hydrogen on Pd.
We report here a one-pot approach to achieve, for the first time, the simultaneous synthesis/anchorage of polymer monoliths in native PDMS channels. Monoliths consisting of ethylene glycol ...methacrylate phosphate (EGMP) and N,N′-methylene-bis-acrylamide (BAA) were synthesized within PDMS microchips through a photo-driven process. The EGMP monomer has never been employed for this purpose. To achieve this method, both the chemical nature of the photoinitiator and irradiation conditions were investigated. The main result was that the use of 2-methyl-4′-(methylthio)-2-morpholino-propiophenone, as photoinitiator, allowed simultaneous polymerization and anchorage of the resulting monolithic structure onto the PDMS channel. Morphology of the monolith revealed a compact structure composed of uniform nodules (135 ± 30 nm) and small pores (10–200 nm). The high specific surface area (66 m2/g) and the sufficient permeability (14.35 × 10−14 m2) obtained make the monolith particularly interesting for preconcentration. Such free radical-mediated method open new perspectives for preconcentration and electrophoretic separation in PDMS microsystems.
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•Efficient one-pot/one-step method for simultaneous synthesis and wall-anchoring of polymer monoliths in/to PDMS microchannel.•Polymer monoliths can be prepared in PDMS microchips without pre-treatment of the PDMS channel surface.•Dual role of 2-methyl-4′-(methylthio)-2-morpholino-propiophenone as H2 abstractor and free radical polymerization initiator.•Monolith morphology combined specific surface area and permeability optimized for separation and concentration purposes.
Green monoliths (GMs) were prepared from mixtures of KOH (5% by weight), carbon nanotubes (5%) and self-adhesive carbon grains (90%) from oil palm empty fruit bunch fibers. The GMs were carbonized up ...to 600, 700 and 800°C under an N2 gas environment, and activated by CO2 gas at 800°C for one hour to produce activated carbon monoliths (ACMs), designated as ACM6, ACM7 and ACM8, respectively. The characterization of the ACMs showed a notable effect of the carbonization temperature on the structure, microstructure, electrical conductivity and porosity of the ACMs. Consequently, three independent methods, galvanostatic charge-discharge, cyclic voltammetry and electrochemical impedance spectroscopy, used for the electrochemical characterization of supercapacitor cells fabricated using the ACMs as their electrodes, consistently found that the ACM7 and ACM8 cells have higher specific capacitance (77 Fg-1 and 85 Fg-1, respectively), specific energy (2.2 Wh kg-1 and 2.1 Wh kg-1, respectively) and specific power (156 W kg-1 and 161 W kg-1, respectively) compared to the ACM6 cell. These results suggest that carbonization should be performed at temperatures closer or equal to the activation temperature for the preparation of supercapacitor electrodes composed of biomass precursors.
The facile synthesis MOFs monolith adsorbent is highly imperative for the economically friendly development of water adsorption. Herein, metal-organic framework material MIL-160 monolith was ...synthesized by the dry-gel conversion method at low temperature. The effects of curing conditions, dry-gel composition and crystallization temperature on crystal structure, porosity, microstructure and water vapor adsorption/desorption properties were studied. XRD results showed that the MIL-160 powder and monolith adsorbent can be synthesized under the condition that the molar ratio of dry-gel was Al3+: FDCA: NaOH = 1:1:2 at 60 °C (FDCA is the abbreviation of 2,5-Furandicarboxylicacid). The water vapor saturation adsorption capacity and water vapor desorption activation energy of the powder and monolith adsorbent were 0.310, 0.231 g/g at 20 % RH and 72.3, 62.4 kJ/mol, respectively. The convenient dry-gel conversion synthesis of MIL-160 monolith may provide a guidance for the manufacture of high-performance water harvest device.
Schematic diagram of the preparation of MIL-160 adsorbent. Display omitted
•MIL-160 monolith was synthesized by the dry-gel conversion method at low temperature(60 °C).•The crystallization temperature of MIL-160 can be decreased by increasing the amount of NaOH appropriately.•The monolith adsorbent could reach adsorption saturation within 60 min and release 76.9 % of water at 80 °C.
•Mn-doped CsPbCl3-SAM possess excellent optical properties.•Mn-doped CsPbCl3-SAM not only maintain the PQDs remarkable optical properties, but also improve their stability.•Mn-doped CsPbCl3-SAM can ...used as red phosphor and stacked on the.•Ce-PiG with InGaN blue chip to achieve warm WLED.
Recently, more and more scholars synthesised the Mn-doped CsPbX3 (X = Cl, Br, I) inorganic perovskite quantum dots (PQDs), which exhibited a strong dopant luminescence characteristic of d-d transition of Mn2+ and dual-color emission. However, Mn-doped CsPbCl3 PQDs suffer from the instability, which hindered the application of PQDs in optoelectronic devices. Here, we resolve this problem with SiO2/Al2O3 monolith (SAM) through a simple sol-gel process and obtained a robust luminescent PQDs-SiO2/Al2O3 monolith (PQDs-SAM) with surprising high stability. This is an easy one-pot operation and can be done with large quantities. The composites not only maintain the PQDs remarkable optical properties, but also improve their stability, which is significantly. The Mn-doped CsPbCl3 PQDs-SAM in powder form is easily mixed into the resins and applied as color-converting layer with curing on blue light-emitting diodes (LED). And above all, the orange PQDs-SAM composite is used as red phosphor and stack on the Ce3+:YAG phosphor-in-glass (Ce-PiG) via screen-printing technology (Ce-PiG&R-PQDs-SAM). Whereafter, warm WLED is constructed by blending the Ce-PiG&R-PQDs-SAM materials with the InGaN blue chips. And the constructed WLEDs generate a warm white with an optimal luminous efficacy (LE) of 80.91 l m/W, a high CRI of 83.8, and a low CCT of 4082 K.
► Carbon coated monolith (CCM) was modified by nitric acid. ► Twofolds escalation in acidic sites was observed on modified compared with unmodified CCM. ► Comparatively 53% higher MO adsorption was ...observed on modified CCM than CCM. ► Optimum MO uptake was 132.7mg/g at equilibration time 4560min, agitation 200rpm and temperature 30°C. ► Optimum MO elution (73%) was achieved with 1N NaOH solution.
Carbon coated monolith (CCM) was chemically modified by treating with nitric acid. The acid modified carbon coated monolith (ACCM) was then characterized by using various techniques. Two folds increase in acidic sites was observed on ACCM compared to CCM. Surface studies showed mesoporous nature of ACCM. A decrease in ACCM surface area and an increase in pore volume observed after the modification. The ATR-FT-IR studies showed increase in carboxylic groups on ACCM confirming CCM oxidation by nitric acid. The pH studies showed optimum adsorption (88mg/g) at pH 6 which is very near to pHPZC of ACCM. Contact time studies showed equilibration time in between 4320 and 4560min for initial MO concentration range 0.05–0.6g/L. Comparatively 53% higher MO adsorption was observed on ACCM than CCM under similar experimental conditions. Freundlich model applicability confirms multilayer MO adsorption on ACCM surface. Pseudo-second-order kinetics model was fitted best to the experimental data revealing chemical nature of adsorption process. The adsorption process is endothermic and spontaneous in nature. Desorption studies showed optimum MO recovery (73%) when 1N NaOH was used as an eluent.
Mesoporous carbon monoliths (MCM) were prepared by using soluble salt as templates. During the synthesis, a freeze-drying process enables a surface coating of self-assembled Na2SiO3 salt particles ...with sucrose, which is further transformed into carbon by heat treatment. After removal of the salt templates by washing, MCM were obtained. MCM samples exhibit high specific surface area together with high mesoporous volume, whose pore sizes can be tuned from 10 to 30 nm by adjusting the ratio between salt and carbon sources. MCM materials were further used as electrodes in combination with ionogel electrolyte to assemble a solid-state supercapacitor. In this configuration, MCM electrodes show capacitance as high as 75 F g−1 and good rate performance thanks to the carbon monolith pore size selected.
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•Mesoporous carbon monoliths (MCM) were synthesized by using a simple salt-templated approach.•The mesopore sizes of MCM were controlled from 10 to 30 nm.•MCM achieved the capacitance of 75 F g−1 in an ionogel-based solid-state supercapacitor.
Time-consuming or tedious operation in multiple-step process might is the obstacle for efficiently preparing aptamer-affinity monolithic column. Here, a new and facile strategy to prepare ...aptamer-based hybrid affinity monolith in “one-pot” at room temperature was exploited, in which UV light-initiated free-radical polymerization and “thiol-ene” click reaction were implemented simultaneously. Only 7 min was cost for finishing the polymerization reaction, which was only 1/100 of that for the traditional thermal polymerization. Using ochratoxin A (OTA) as the model analyte, the recipe for photo-initiated polymerization was optimized, and SEM morphology, FTIR, EDS, pore size distribution and specific recognition performance were also studied. Compared with traditional thermal polymerization, the resultant monolith was achieved more facilely and displayed better results such as more homogeneous skeleton structure, higher reaction efficiency of aptamer (>88.2%) and better specific selectivity to OTA. Besides, an extremely low nonspecific adsorption of analogues was obtained and showed a level at only 1/25 of that in the similar aptamer-affinity monolith prepared by thermal polymerization. Applied to beer and red wine samples, good recovery yields about 99.7 ± 4.0% –101.2 ± 2.3% (n = 3)was achieved with the acceptable RSDs. It would open up a rapid and promising access to efficiently preparing high-performance aptamer-based affinity monolithic columns for online specific recognition.
A facile UV light-initiated polymerization strategy was exploited for ultrafast preparing aptamer-affinity monolith in 7 min with high specific recognition performance. Display omitted
•Fast preparation of aptamer-affinity monolith using photopolymerization in 7 min.•Short reaction time is only 1/100 of that for traditional thermal polymerization.•Facile manipulation was carried out via “one-pot” approach at room temperature.•Nonspecific adsorption could be only 1/25 of traditional aptamer-affinity monoliths.•Excellent stability and accurate measure of target mycotoxin were achieved.
•Developed a multi-scale Computational Fluid Dynamics (CFD) model for analysing catalytic heterogeneous reactions within porous monoliths.•Conducted pore-scale simulations to study flow and ...concentration profiles for optimized design.
In this research work, a multi-scale CFD model is developed for a catalytic heterogeneous reaction under continuous flow in a porous monolith. For this purpose, the Knoevenagel condensation was chosen as a model reaction. The model is based on a homogenization approach as well as pore scale modelling by coupling convection, diffusion and reaction within macro-meso porous hierarchical monoliths. The model's accuracy was determined through successful validation against previously available experimental data in the literature. Subsequently, the model was employed to examine the influence on reaction rates of structural and key process parameters like temperature, flow rates and macro/meso porosity. To analyze flow patterns and concentration profiles at the macro pore level, pore-scale simulations were conducted through image processing and CFD modeling of 25x25 µm Scanning Electron Microscopy (SEM) images of the monoliths. These simulations yielded an in-depth comprehension of pore flow and concentration behavior at the macro-meso level, offering valuable insights for optimizing pores in hierarchical structures.
A novel N-glycan enrichment strategy is presented using unexpected but strong interactions between the sulfonate groups brought by the fluorescent dye of glycans and the Zr4+ modified poly(ethylene ...glycol methacrylate phosphate (EGMP)-co-acrylamide (AM)-co-bis-acrylamide (BAA)) monolith. The poly (EGMP-co-AM-co-BAA) monolith was synthesized via ultraviolet (UV) irradiation and then functionalized with Zr4+. The obtained monolith was characterized with scanning electron microscopy and mercury intrusion porosimetry. Large through-pores and a continuous skeleton with high permeability were observed. The N-glycans were labeled with the 1-aminopyrene-3, 6, 8-trisulfonic acid (APTS) and enriched by the Zr4+ modified monolith through IMAC interaction. This enrichment step was then coupled off-line to capillary electrophoresis (CE) separation with laser induced fluorescence (LIF) detection. Successful preconcentration of the APTS labeled maltooligosaccharide ladder was achieved under optimized conditions. Enrichment factors obtained for the maltooligosaccharides ranged from 9 to 24 with RSDs from 2.0% to 9.2% (n = 3). Moreover, very good repeatabilities (<6.7%) were obtained for glucose oligomers (4–15 glucose units) corresponding to sizes expected for N-glycans, demonstrating the great potential of this Zr4+ modified monolith to enrich APTS labeled glycans from N-glycoproteins. The proposed method was then successfully applied for the enrichment of N-glycans released from Ribonuclease B, in which case all five expected oligomannose glycans (Man 5 to Man 9) were successfully enriched. Thanks to the advantage of the method to enrich selectively APTS-glycans compared to the commercial SPE columns composed of HILIC or PGC materials, the first proof of concept of on-line enrichment coupled to CE-LIF separation was demonstrated for maltooligosaccharides as well.
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•A novel N-glycan enrichment method is presented using a capillary affinity monolith.•Fluorescent labeled N-glycans are efficiently enriched by Zr4+ modified monolith.•All five expected oligomannoses from Ribonuclease B were successfully enriched.•It is the first online affinity-based glycan enrichment to capillary electrophoresis.
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