Aqueous-phase Reduction Research Articles

Ru-Sn/AC for the Aqueous-Phase Reduction of Succinic Acid to 1,4-Butanediol under Continuous Process Conditions

Succinic acid is a biomass-derived platform chemical that can be catalytically converted in the aqueous phase to 1,4-butanediol (BDO), a prevalent building block used in the polymer and chemical industries. Despite significant interest, limited work has been reported regarding sustained catalyst performance and stability under continuous aqueous-phase process conditions. As such, this work examines Ru-Sn on activated carbon (AC) for the aqueous-phase conversion of succinic acid to BDO under batch and flow reactor conditions. Initially, powder Ru-Sn catalysts were screened to determine the most effective bimetallic ratio and provide a comparison to other monometallic (Pd, Pt, Ru) and bimetallic (Pt-Sn, Pd-Re) catalysts. Batch reactor tests determined that a ∼1:1 metal weight ratio of Ru to Sn was effective for producing BDO in high yields, with complete conversion resulting in 82% molar yield. Characterization of the fresh Ru-Sn catalyst suggests that the sequential loading method results in Ru sites that ...

Silver nanoparticles supported over Al2O3@Fe2O3 core-shell nanoparticles as an efficient catalyst for one-pot synthesis of 1,2,3-triazoles and acylation of benzyl alcohol

Metallic nanoparticles supported over core-shell metal oxide nanostructures have huge scope in heterogeneous catalysis due to the scope for fine dispersion of the reactive NPs on high surface area material. Silver nanoparticles are supported over Al2O3@Fe2O3 core-shell nanostructured material through aqueous phase reduction method. Ag-Al2O3@Fe2O3 core-shell nanoparticles has been characterized through powder X-ray diffraction, ultra high resolution transmission electron microscopy, scanning electron microscopy, N2 adsorption/desorption isotherm, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy and thermogravimetric analysis. The N2 adsorption/desorption isotherms of Ag-Al2O3@Fe2O3 material are classified as typical type IV isotherm with a large H2 type hysteresis loop for the mesopores. This core-shell mesoporous nanocatalyst showed high catalytic efficiency for the synthesis of 1,4-disubstituted 1,2,3-triazoles in water and acylation of benzyl alcohol under solvent-free conditions. The catalyst is heterogeneous in nature and can be easily recovered and reused without appreciable decrease in its catalytic activity.

Surfactant-free Pd–Fe nanoparticles supported on reduced graphene oxide as nanocatalyst for formic acid oxidation

Herein, a novel surfactant-free nanocatalyst of Pd–Fe bimetallic nanoparticles (NPs) supported on the reduced graphene oxide (Pd–Fe/RGO) were synthesized using a two-step reduction in aqueous phase. Electrochemical studies demonstrate that the nanocatalyst exhibits superior catalytic activity towards the formic acid oxidation with high stability due to the synergic effect of Pd–Fe and RGO. The optimized Pd–Fe/RGO (Pd:Fe = 1:5) nanocatalyst possess an specific activity of 2.72 mA cm−2 and an mass activity of 1.0 A mg−1(Pd), which are significantly higher than those of Pd/RGO and commercial Pd/C catalysts.

Aqueous-Phase Synthesis of Metal Nanoparticles Using Phosphates As Stabilizers

In this paper, we describe a simple, aqueous-phase route to the synthesis of metal nanoparticles including Pt, Pd, Ru, and Au based on the aqueous-phase reduction of metal salts with NaBH4. In this approach, various phosphates were applied as new type of stabilizers for the synthesis of metal nanoparticles thanks to its negatively charged functional group (PO−).

Carbon nanotube supported PdAg nanoparticles for electrocatalytic oxidation of glycerol in anion exchange membrane fuel cells

Electro-oxidation of alcohol is the key reaction occurring at the anode of a direct alcohol fuel cell (DAFC), in which both reaction kinetics (rate) and selectivity (to deep oxidation products) need improvement to obtain higher power density and fuel utilization for a more efficient DAFC. We recently found that a PdAg bimetallic nanoparticle catalyst is more efficient than Pd for alcohol oxidation: Pd can facilitate deprotonation of alcohol in a base electrolyte, while Ag can promote intermediate aldehyde oxidation and cleavage of CC bond of C3 species to C2 species. Therefore, a combination of the two active sites (Pd and Ag) with two different functions, can simultaneously improve the reaction rates and deeper oxidation products of alcohols (Applied Catalysis B, 2016, 199, 494). In this continuing work, Pd, Ag mono, and bimetallic nanoparticles supported on carbon nanotubes (Ag/CNT, Pd/CNT, Pd1Ag1/CNT, and Pd1Ag3/CNT) were prepared using an aqueous-phase reduction method; they served as working catalysts for studying electrocatalytic oxidation of glycerol in an anion-exchange membrane-based direct glycerol fuel cell. Combined XRD, TEM, and HAADF-STEM analyses performed to fully characterize as-prepared catalysts suggested that they have small particle sizes: 2.0nm for Pd/CNT, 2.3nm for PdAg/CNT, 2.4nm for PdAg3/CNT, and 13.9nm for Ag/CNT. XPS further shows that alloying with Ag results in more metal state Pd presented on the surface, and this may be related to their higher direct glycerol fuel cell (DGFC) performances. Single DGFC performance and product analysis results show that PdAg bimetallic nanoparticles can not only improve the glycerol reaction rate so that higher power output can be achieved, but also facilitate deep oxidation of glycerol so that a higher faradaic efficiency and fuel utilization can be achieved along with optimal reaction conditions (increased base-to-fuel ratio). Half-cell electrocatalytic activity measurement and single fuel cell product analysis of different glycerol oxidation intermediates, including C3: glycerate, tartronate, mesoxalate, and lactate; C2: glycolate and oxalate, over PdAg/CNT catalyst was further conducted and produced deeper insight into the synergistic effects and reaction pathways of bimetallic PdAg catalysts in glycerol electrocatalytic oxidation.

Direct glycerol fuel cell with polytetrafluoroethylene (PTFE) thin film separator

Anion-exchange membrane-based direct glycerol fuel cells (AEM-DGFCs) can yield high power density, however challenges exist in developing chemically stable AEMs. Here, we demonstrate a porous PTFE thin film, a well-known chemical, electro-chemical, and thermal robust material that can serve as a separator between anode and cathode, thus achieving high DGFC’s performance. A simple aqueous-phase reduction method was used to prepare carbon nanotube supported PdAg nanoparticles (PdAg/CNT) with an average particle size of 2.9 nm. A DGFC using a PTFE thin film without any further modification with PdAg/CNT anode catalyst exhibits a peak power density of 214.7 mW cm−2 at 80 °C, about 22.6% lower than a DGFC using a state-of-the-art AEM. We report a 5.8% decrease and 11.1% decrease in cell voltage for a PTFE thin film and AEM; similarly, the cell voltage degradation rate decreases from 1.2 to 0.8 mV h−1 for PTFE thin film, while for AEM, it decreases from 9.6 to 3.0 mV h−1 over an 80 h durability test period. Transmission electron microscopy results indicate that the average particle size of PdAg/CNT increases from 2.9 to 3.7 nm after 80 h discharge; this suggests that PdAg particle growth may be the main reason for the performance drop.

Aqueous-phase synthesis of metal nanoparticles using phosphates as stabilizers

We describe a simple, aqueous-phase route to the synthesis of metal nanoparticles including Pt, Pd, Ru, and Au based on the aqueous-phase reduction of metal salts with NaBH4. In this approach, various phosphates were applied as new type of stabilizers for the synthesis of metal nanoparticles thanks to its negatively charged functional group (PO−).

Enhanced catalytic activity of CuPd alloy nanoparticles towards reduction of nitroaromatics and hexavalent chromium

The present work reports a surfactant-free, economically feasible chemical route to synthesize bimetallic CuPd alloy nanoparticles under hydrothermal condition. The structural and morphological characterizations of the nanoparticles are carried out by XRD, SEM/EDX, TEM, XPS and BET surface area analyses. The synthetic strategy comprises of 9:1 molar composition of Cu2+ and Pd2+ salt in the aqueous solution. The size of the nanoparticles isca. 3–4nmwith very notable specific surface area of 298m2g−1. The synthesized nanoparticles exhibit excellent catalytic performance towards the aqueous phase reduction of 4-nitrophenol and 4-nitroaniline in the presence of NaBH4 as a reducing agent. Furthermore the CuPd alloy nanoparticles also demonstrate remarkable activity towards reductive conversion of toxic Cr(VI) to less toxic Cr(III) at room temperature. Bimetallic CuPd alloy nanoparticles are catalytically more active and exhibit good recyclability in comparison to the monometallic Cu and Pd due to synergistic effect.

Hetero–nanostructured Ni/α‐Mn2O3 as Highly Active Catalyst for Aqueous Phase Reduction Reactions

AbstractIn this work, a simple strategy for the synthesis of hetero‐nanostructured Ni/α‐Mn2O3 via surfactant‐aided co‐reduction method is reported. The as synthesized Ni/α‐Mn2O3 is applied as catalytic material for the aqueous phase reduction of 4‐nitrophenol (4‐NP) and organic dye pollutants, namely Rhodamine B (RhB), Methylene blue (MB), Rose Bengal (RB), Congo red (CR), and Methyl orange (MO) in the presence of a mild reducing agent, NaBH4. This synthetic route provides homogeneous dispersion of Ni nanoparticles over α‐Mn2O3 surface. The nanoparticles and support are characterized using XRD, SEM/EDX, TEM, AAS and BET surface area analyses. The Ni particles are spherical, crystalline and size ranges < 5 nm. Further, hetero‐nanostructured Ni/α‐Mn2O3 is established as a highly efficient recyclable catalyst for the reduction of 4‐NP to 4‐aminophenol (4‐AP). The HPLC and FTIR analysis shows that 4‐AP is the sole product of the reduction of 4‐NP. The Ni/α‐Mn2O3 also exhibits high activity towards reduction of cationic and anionic dye pollutants. Thus, the as synthesized hetero‐nanostructured Ni/α‐Mn2O3 can be considered as the future contender for the wastewater treatment.

Electrochemical Reduction of CO2 on Copper Oxidized By Electrochemical Methods

The electrochemical oxidation of copper surface in alkaline solution results in the formation of different products, which are a function of scan rate and concentration of OH- ions. It has been found that, the electro-oxidation results in oxide film on copper surface consist of Cu2O, Cu(OH)2 and CuO. The scanning electron microscopy (SEM) images of copper foils oxidized by linear sweep voltammetry at different scan rate show a systematic growth of oxides on the copper surface. At low scan rate growth of oxide takes place resulting in needle like structures projecting outwards from copper surface. Further, the density of these needles of oxides decreases as the scan rate increases. A similar behaviour was also observed in the chronoamperometry experiments performed at different potential and for different time duration. The length and the density of needles increase with increase in time when the applied potential was in potential region of peak B. On the other hand, at more negative potential and low concentration OH- ions instead of needles, a layer of oxide particles were observed. The x-ray photoelectron spectroscopy (XPS) analysis of oxidized copper surface shows the presence of Cu2O, Cu(OH)2and CuO in the oxide layer and the percentage of CuO increases as the density of needles increases on the surface. It has found that the catalytic activity of the copper obtained by reducing it from its oxides is more than that of the original polycrystalline copper foil for CO2reduction. The oxidation of copper surface can be achieved either by annealing in air or oxygen, or by electrochemical oxidation. Further, electrochemical oxidation of copper foil can be performed either by potential sweep or potential step techniques. Here, the oxidation of copper surface was carried out by chronoamperometry (CA), linear sweep voltammetry (LSV) as well as cyclic voltammetry (successive oxidation and reduction cycles) in Ar saturated 0.5 M KOH solution. The copper foil was oxidized by CA at -0.1 V for 30 minutes and LSV at scan rate of 0.5 mV/s from -1.2 to 0.5 V in Ar saturated 0.5 M KOH. The five cycles of CVs were carried out at a scan rate of 0.5 mV/s in Ar saturated 0.5 M KOH between -1.2 to 0.5 V. The SEM images shows that the needle like growth of oxides gets reduced back to copper in first few minutes of the electrochemical reaction when applied potential is more negative than hydrogen evolution. These in turn have been used for electrochemical reduction of CO2. The main product of CO2 reduction in aqueous phase was found to HCOO- and the gas phase analysis revealed predominantly hydrogen molecule. Faradaic efficiency for formic acid on copper foil oxidized by CV was higher than that for copper foil oxidized by the CA and LSV. The reason this observation may be the amount of active copper produced on the polycrystalline copper from the reduction of the copper oxides. This has been verified from the amount of charge transferred during the oxidation of copper which is highest for the CVs as with each cycle the peak current of both the peaks observed during oxidation of copper increases. During oxidation of copper foil by CV in fifth cycle a total charge of ~0.70 C/cm2 charge was transferred, whereas, during LSV a total of ~0.45 C/cm2 and during CA at total of ~0.30 C/cm2 of charge was transferred. Thus indicating more oxidation during CV than LSV and CA, and hence more amount of active copper will be produced on the copper surface resulting in increased faradaic efficiency of formic acid. Figure 1

Synthesis of CIGS(Cu(In,Ga)Se2) Photovoltaic Materials in an Aqueous Solution for the Printable Solar Cell Application

Cu(In,Ga)Se2(CIGS) is one of the most effective photovoltaic devices for developing low cost and high efficiency solar cell. Bandgap of CIGS can be adjusted in the range from 1.04eV(Cu1.0In1.0Ga0.0Se2.0) to 1.67eV(Cu1.0In0.0Ga1.0Se2.0) by controlling the ratio of Ga in CIGS, while ideal band gap for solar cell is 1.40eV [1]. Moreover, CIGS solar cell needs only 1-2µm thickness, since it has a large optical absorption coefficient (105cm-1) [2]. Until now, CIGS solar cell, synthesized by utilizing gas phase method, achieved high conversion efficiency above 20% [3]. It is well known that gas phase evaporation process produces high quality films, however, this process needs high energy consumption and large amount loss of natural resources. Therefore, we reported completely new approach to synthesis low cost CIGS solar cell [4]. This process consists of three steps; 1) fabrication of CI and/or CIG nanoparticles by utilizing aqueous phase reduction method (low energy and resources consumption method), 2) print of these nanoparticles on a substrate, 3) selenization to form CIS/CIGS solar cell. As a result, CIS solar cell with the conversion efficiency of c.a. 3% was successfully synthesized. To increase the conversion efficiency, CIGS with the bandgap of 1.40eV should be developed. Thus, Ga should be incorporated into nanoparticles during aqueous phase CI synthesis procedure. However, co-reduction of Ga with Cu and/or In cannot be achieved until now, because of the reduction potential difference between Ga and Cu-In, and of low melting point of Ga (29.76℃). Therefore, in this study, to synthesize Cu-In-Ga nanoparticles in an aqueous solution, relationship between the condition of Ga complexes in an aqueous phase and its reduction potentials was evaluated. Results of calculation shows that Ga complexes in the Ga-Cl-OH-aspartic acid system can be restricted to homogenized species, [(Ga3+)(Asp2-)] (pH5) and [(Ga3+)(OH-)4] (pH9), by controlling the pH and concentration of complex reagent. Reduction potential of these species became apparent from cyclic voltammetry (CV) measurement. However, it also became clear that Ga complexes cannot be reduced by reducing agent (NaBH4), under Ga unary system. On the other hand, in a Cu-In-Ga ternary system, it became apparent that Ga can be co-reduced with Cu and/or In, and Ga incorporation ratio was varied by controlling pH and reaction temperature. SEM-EDX, XRD and TEM-EDX results expected that Ga was incorporated in Cu2In to form Cu2In0.95Ga0.25. In order to produce CIGS solar cells, it is necessary to synthesize CIG nanoparticles with the Ga/In+Ga ratio over 30%, while synthesized CIG nanoparticles (Cu2.0In0.95Ga0.25 phase and/or Cu1.0In1.1Ga0.022 phase) has the Ga/In+Ga ratio under 12%. So it is needed to increase the Ga incorporation ratio. To increase the Ga incorporation ratio, concentration of reducing agent (NaBH4) and Ga complex were selected as parameters, because these parameters have a potential of accelerating the reaction of Ga reduction process. The ratio of Ga/In+Ga in CIG particles increased to 14% with decreasing the concentration of Cu,In,Ga ion to 0.059M and with increasing the concentration of NaBH4 to 0.91M (i.e. the ratio of (NaBH4 [M]) /(Cu,In,Ga ion [M]) was 40 times larger than the method mentioned). On the other hand, the ratio of Ga/In+Ga in CIG particles increased to 18% with increasing the concentration of Ga ion to 0.68mM and decreasing the concentration of In ion to 0.80mM (i.e. the ratio of (Ga ion [mM])/(In+Ga ion [mM]) in aqueous solution was 2.9 times larger than above method). From these results, it became clear that the ratio of (Ga ion [mM])/(In+Ga ion [mM]) in aqueous solution was seriously affected to the ratio of Ga/In+Ga ratio in CIG particles. Another results will be released in our session. [1] Appl. Phys. A, 74 (2002), pp. 659–664, [2] basic technic of CIGS solar cell, Nakata, Nikkankougyoshinbunsha, 2010, [3] Phys. Status Solidi RRL, 9 (2015), pp. 28–31, [4] For example, 228th ECS meetings, Z01-1846 (2015) This work has been supported by the Grant-in-Aid for Scientific Research (B) (No. 26281054).

Direct fast pyrolysis bio-oil fuel cell

Bio-oil derived from the pyrolysis of lignocellulosic biomass shows a great promise, however, needs further upgrading to potentially serve as an alternative to fossil fuels. Herein, we demonstrate that crude fast pyrolysis bio-oil can be directly used as a fuel for anion exchange membrane fuel cells (AEMFCs) to generate high power density electrical energy at low temperature (⩽80°C). A simple aqueous-phase reduction method was used to prepare carbon nanotube (CNT) supported noble metal (Pt, Pd, Au, and Ag) nanoparticles with average particle sizes: 1.4nm, 2.0nm, 3.8nm, and 12.9nm for Pt/CNT, Pd/CNT, Au/CNT, and Ag/CNT, respectively. Direct fast pyrolysis bio-oil AEMFCs with the Pd/CNT anode catalyst and a commercial Fe-based cathode catalyst exhibit a remarkable peak power density of 42.7mWcm−2 at 80°C using 30wt% bio-oil+6.0M KOH electrolyte. Levoglucosan was identified as the major sugar compound with 11.1wt% of the bio-oil composition, along with disaccharides, pyrolytic lignin, and oligomer of lignin-derived phenolic compounds. Cyclic voltammetry (CV) studies investigated the electrocatalytic oxidation of high purity levoglucosan over the four noble metal catalysts in half cell, as levoglucosan is the dominant sugar component in bio-oil. Pd/CNT, compared to other catalysts, displayed the highest activity and lowest onset potential of electrocatalytic oxidation of levoglucosan. AEMFC with high purity sugars shows ∼1.2 to 3 times higher power density than that with fast pyrolysis bio-oil fuel.

PdAg/CNT catalyzed alcohol oxidation reaction for high-performance anion exchange membrane direct alcohol fuel cell (alcohol = methanol, ethanol, ethylene glycol and glycerol)

Abstracts PdAg supported on carbon nanotubes (PdAg/CNT) with an average particle size of 2.7 nm is prepared by an aqueous phase reduction method for alcohol oxidation reaction in direct alcohol fuel cells. In a half-cell system with three electrodes, the peak mass activity of PdAg/CNT reaches 0.105 mA μgPd−1, 0.305 mA μgPd−1, 2.105 mA μgPd−1, and 8.53 mA μgPd−1 for methanol oxidation reaction, ethanol oxidation reaction, ethylene glycol oxidation reaction, and glycerol oxidation reaction, respectively, in 1 M KOH 0.1 M alcohol electrolyte. These values are higher than the mass activity of Pd/CNT at the same applied potential. With PdAg/CNT (0.5 mgPdperMEA−1) as an anode catalyst, a direct methanol fuel cell, a direct ethanol fuel cell, a direct ethylene glycol fuel cell and a direct glycerol fuel cell achieve peak power densities of 135.1 mW cm−2, 202.3 mW cm−2, 245.2 mW cm−2, and 276.2 mW cm−2, with corresponding peak mass activities of 270.2 mW mgPdperMEA−1, 404.6 mW mgPdperMEA−1, 490.4 mW mgPdperMEA−1, and 552.4 mW mgPdperMEA−1, respectively, at 80 °C and ambient pressure. Ag has shown excellent activity towards aldehyde (formaldehyde, acetaldehyde, and glyoxylate) oxidation, thus, the enhancement in alcohol oxidation on PdAg/CNT is proposed due to Ag’s promotion of intermediate aldehyde oxidation. PdAg/CNT also improves the fuel efficiency of glycerol oxidation by contributing to the C C bond cleavage of C3 glycerol to C2 oxalate.

Cu nanoparticles: a highly efficient non-noble metal catalyst for rapid reduction of nitro compounds to amines with NaBH4 in water

The purely aqueous-phase reduction of a wide range of nitro compounds to the corresponding amines has been carried out with NaBH4 in the presence of inexpensive Cu nanoparticles as catalyst. The reactions were taken place in water (80 °C) within 4–15 min to give amines in high to excellent yields.

Versatile (Pentamethylcyclopentadienyl)rhodium‐2,2′‐Bipyridine (Cp*Rh‐bpy) Catalyst for Transfer Hydrogenation of N‐Heterocycles in Water

AbstractAn investigation employing the catalytic system consisting of (pentamethylcyclopentadienyl)rhodium dichloride dimer [Cp*RhCl2]2 and 2,2′‐bipyridine (bpy) for transfer hydrogenation of a variety of quinoxalines, quinoxalinones, quinolines and indoles under aqueous conditions with formate as the hydrogen source is reported. This approach provides various tetrahydroquinoxalines, dihydroquinoxalinones, tetrahydroquinolines and indolines in good to excellent yields. The activity of the catalyst towards quinoxalines and quinoxalinones is excellent, with a substrate to catalyst ratio (S/C) of 10000 being feasible. The choice of ligand is critical to the catalysis, and the aqueous phase reduction is shown to be highly pH‐dependent, with acidic pH values needed for optimal reduction. The catalyst is easy to access, and the reaction is operationally simple without requiring an inert atmosphere.magnified image

Biogenic Synthesis of Silver Nanoparticles Using Cnidium officinale Extract and Their Catalytic Reduction of 4-Nitroaniline

Silver nanoparticles (AgNPs) with two different morphologies were synthesized using aqueous extract of Cnidium officinale rhizomes under different reaction conditions and applied to the facile aqueous phase reduction of 4-nitroaniline (4-NA) as catalysts. The synthesized AgNPs are characterized by UV–Visible spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) method and high resolution transmission electron microscopy (HR-TEM) with energy dispersive X-ray spectroscopy (EDS) analysis. HR-TEM showed that the synthesized AgNPs had two different morphological forms; truncated triangular prism shapes with a mean size of ~35 nm and spherical shapes with a mean size of ~9 nm. The HR-TEM and XRD results are consistent with the standard values. The catalytic activities of both AgNPs were compared on the reduction of 4-NA in water by NaBH4 as a reducing agent. The reduction of 4-NA was monitored using UV–Visible spectroscopy. The ~9 nm (spherical) sized AgNPs showed superior catalytic activity than the larger AgNPs. The calculated rate constant (k) for the catalytic reduction of 4-nitroanilie by spherical AgNPs was 11.16 × 10−3 s−1.

Optimization of the CeO2/CeCl3 cycle by cerium IV oxide reductive dissolution catalysis

While thermochemical cycles can be a way to produce hydrogen, physiochemical studies show that implementing them is often difficult for reactivity reasons. Most of the cycles actually involve solid–gas type systems with limited reactivity due to interface passivation processes. To overcome this difficulty, studies have shown that using the CeO2/CeCl3 pair, in which the cerium undergoes a reversible oxidation–reduction cycle, has enormous potential since it may partially be carried out in aqueous phase by reductive dissolution from cerium oxides (IV) to cerium chloride (III).If the first reaction of the cycle is well known for industrial application, its second and its third reaction still need some investigation. Thus, this article primarily describes the work done on the second reaction to assess the possibility of carrying out cerium reduction in aqueous phase. The extremely positive results have highlighted the possibility of achieving 100% reaction efficiency in systems catalyzed by fluoride ions. Conducting the reaction with in-line distillation of the excess water also helps significantly reduce reaction time which offers good potential for the next stage. A ratio of 8 ml of a 20 w% HCl solution per gram of CeO2 containing 6w% of CaF2 leads to ensure a total reaction in a few minutes at 108.6 °C (boiling temperature of the H2O–HCl azeotrope).The work presented herein also describes a brief feasibility study for the third reaction cycle which could be carried out by spraying the solution from the second reaction, in a hot column whose temperature will be determined by further work. These results have allowed upgrading the first flowsheet proposed in a previous publication.

UV-induced polymerization of size-controlled platinum/poly[styrene-divinylbenzene-tri(propylene glycol) diacrylate] hydrophobic catalyst beads in microfluidics

Abstract The catalytic exchange of hydrogen isotopes between hydrogen and water has been known to be a very useful process for the separation of tritium from tritiated water. For the process, a highly active hydrophobic catalyst is needed. This study provides an effective fabrication method of size-controlled platinum/poly[styrene-divinylbenzene-tri(propylene glycol) diacrylate] [Pt/poly(SDB-TPGDA)] hydrophobic catalyst beads with a narrow size distribution. Platinum nanoparticles were prepared by γ-ray-induced reduction in the aqueous phase first, and then uniformly dispersed in SDB-TPGDA comonomer after the hydrophobization of platinum nanoparticles with alkylamine stabilizers. The porous Pt/poly(SDB-TPGDA) hydrophobic catalyst beads were synthesized by the UV-initiated polymerization of the mixture droplets prepared in a capillary-based microfluidic system. The size of as-prepared catalyst beads can be controlled in the range of 200–1,000 μm by adjusting the flow rate of dispersed and continuous phases, as well as the viscosity of the continuous phase. Sorbitan monooleate and cyclohexanol were used as coporogens to control the porosities of the catalyst beads.

Effect of the Surfactant on the Growth and Oxidation of Iron Nanoparticles

Fe nanoparticles and branched nanostructures of iron oxide were synthesized by chemical reduction in aqueous phase. The mechanism of formation of iron oxides as a function of the amount of surfactant employed during the synthesis process was studied. Specifically Fe, Fe2O3, and Fe3O4 nanoparticles were obtained. The oxidation of Fe to Fe3O4 and finally to Fe2O3 was carried out by oxidative etching process, decreasing the amount of stabilizer agent. The structures obtained were characterized by high resolution (HRTEM) and scanning/transmission (STEM) electron microcopies, energy dispersive spectroscopy (EDS), and optical spectroscopy (UV‐Vis and IR).

Poly(diallyldimethylammonium chloride)-functionalized reduced graphene oxide supported palladium nanoparticles for enhanced methanol oxidation

PDDA-functionalized rGO supported nano-size Pd particles show superior MOR activity in alkaline medium.