Volume 92, Issue 6

In the current paper, the possibility of the use of magnetically separable catalysts containing ruthenium oxide species in the supercritical deoxygenation of stearic acid for producing of the second generation of biodiesel is reported. Three different supports (silica, ceria, and hypercrosslinked polystyrene) were used for the stabilization of magnetic nanoparticles (MNPs) and Ru-containing particles. The effect of support on the magnetic properties as well as the catalytic activity of the obtained systems was studied. All synthesized catalysts were shown to provide high stearic acid conversion (up to 95 %). The highest yield of C 17+ hydrocarbons (up to 86 %) was observed while using the Ru–Fe 3 O 4 -HPS system. Ru–Fe 3 O 4 -HPS was characterized by the high values of the specific surface area (364 m 2 /g) and saturation magnetization (4.5 emu/g). The chosen catalytic system was found to maintain its catalytic activity for a minimum of 10 consecutive cycles.

Melamine based polymer (MT) was prepared and then reacted with a mixture of glucose (Glu) and β-cyclodextrin (CD) under hydrothermal conditions to afford, MT/Glu-CD. Then, the adsorption of Pd salt was realized on MT/Glu-CD. The resulting compound was subsequently carbonized to furnish Pd/MT/C that exhibited high catalytic activity for the hydrogenation of nitroarenes in aqueous media. To elucidate the roles of CD, Glu, the molar ratio of Glu:CD and the carbonization in the catalytic activity, several control catalysts have been prepared and their performances for a model hydrogenation reaction were compared with that of Pd/MT/C. The results confirmed the importance of the carbonization as well as the presence of CD for achieving high catalytic activity. Moreover, it was found that the molar ratio of Glu:CD could affect the catalytic activity of the final catalyst and the optimum molar ratio of Glu:CD was 30:70. The recycling test as well as measurement of Pd leaching demonstrated high recyclability and low Pd leaching of Pd/MT/C.

The macromolecular complexes of random, regular, graft, block and dendritic polyampholytes with respect to transition metal ions, surfactants, dyes, polyelectrolytes, and proteins are discussed in this review. Application aspects of macromolecular complexes of polyampholytes in biotechnology, medicine, nanotechnology, catalysis are demonstrated.

Metal-organic frameworks (MOFs) are promising sacrificial templates for synthesis of carbon functional materials with a relatively high concentration of stabilized metallic species. In this work coordination polymers based on trans , trans -muconic acid and transition metals (Cu, Zn, Ni, Co) were prepared and selected as the precursors for supramolecular organization of nanocomposites. The coordination polymers and metal-containing thermolysis products obtained were characterized using a number of analytical techniques including powder X-ray diffraction, elemental analysis, thermal gravimetric analysis, scanning electron microscopy and volumetric nitrogen adsorption/desorption. This study extends the application of coordination polymers as precursors for designing of carbon materials incorporating metal nanoparticles. It is shown that appropriate choice of metal-organic precursors in solid-phase thermolysis allowed to get materials with determined morphologies.

Macromolecular metal complexes provide a molecular-based synergy function of organic polymers and combined metal complexes. A new category of macromolecular complexes includes catalytically active metal complexes immobilized by organic polymers containing reactive substrate moieties in their repeating units. Here, we describe the extremely efficient oxidation of allylic hydrocarbon polymers with the attached iron complex catalyst, as well as the efficient oxygen-consumption or oxygen-scavenging function of the matrix polymer film. The less toxic N , N ´-di(salicylaldehyde)ethylenediiminatoiron(II) complex was combined with or fixed onto a series of allylic hydrocarbon polymers as both the oxidative substrate and the film matrix, i.e. poly(1,2-butadiene), polynorbornene, poly(5-vinyl-2-norbornene), poly(2,5-norboenadiene), poly(dicyclopentadiene), and poly(5-ethylidene-2-norbornene). Ultra-high oxygen-scavenging capacity up to 300 mL (oxygen gas at STP)/g(film) was achieved, based on the oxidative consumption of the allylic bond (particularly of poly(5-ethylidene-2-norbornene)), which was more than three times that of the previously reported highest oxygen-scavenging polymers. These oxygen-scavenging films are based on the high reactivity of polymer-metal complexes that provides an innovative development in the area of active packaging polymer films that facilitate cost-effective performance, safety, and sustainability.

In the current research water-soluble functional polymers (WSFP) were prepared via radical polymerization and purified by fractionation through ultrafiltration membranes with different molecular weights cut off (MWCO) of 30 and 100 kDa. The WSFPs were poly(3-acrylamide propyl) trimethyl ammonium chloride, P(ClAPTA), poly(2-acrylamido-2-methyl-1-propane sodium sulfonate, P(AMPSNa), and poly(3-methacrylamino propyl) dimethyl 3-sulfopropyl ammonium hydroxide, P(HMPDSPA). These polymers were characterized by Fourier transformed infrared spectroscopy (FT-IR) and thermogravimetry analysis (TGA). Using liquid-phase polymer-based retention technique (LPR), chromium [Cr(III) and Cr(VI)] retention was studied as a function of pH, polymer and chromium concentration, selectivity, maximum retention capacity, chromium elution capacity, and polymer regeneration through sorption and desorption studies. Results of FT-IR showed the characteristic absorption bands of the synthesized polymers. The decomposition temperatures of P(ClAPTA) were at 303.1 °C, and for P(AMPSNa) three decompositions temperatures were registered at 190.5 °C, 223.2 °C, and 304.8 °C. P(HMPDSPA) presented two important decomposition temperatures at 292.4 °C and 391.7 °C, respectively. Concerning to the retention of Cr(VI), it was maximal (100 %) when P(ClAPTA) was studied at pH 6. The maximum retention of Cr(III) (100 %) was achieved by P(AMPSNa) at pH 3. The optimum polymer:Cr mole ratio obtained was 10:1 for both Cr(VI) and Cr(III). The retention of Cr(VI) decreased due to the presence of interfering ions, and the hydrodynamic flow was almost constant during the ultrafiltration of polymer-Cr macromolecule.

Following spinal cord injury, the use of electrodes for neurostimulation in animal models has been shown to stimulate muscle movement, however, the efficacy of such treatment is impaired by increased interfacial impedance caused by fibrous encapsulation of the electrode. Sputter-deposited gold-on-polyimide electrodes were modified by potentiostatic electrodeposition of poly(pyrrole- co -3-pyrrolylbutyrate- conj -aminoethylmethacrylate): sulfopropyl methacrylate [P(Py- co -PyBA- conj -AEMA):SPMA] to various charge densities (0–100 mC/cm 2 ) to address interfacial impedance and coated with a phosphoryl choline containing bioactive hydrogel to address biocompatibility at the ABIO-BIO interface. Electrodes were characterized with scanning electron microscopy (surface morphology), multiple-scan rate cyclic voltammetry (peak current and electroactive area), and electrochemical impedance spectroscopy (charge transfer resistance and membrane resistance). SEM analysis and electroactive area calculations identified films fabricated with a charge density of 50 mC/cm 2 as well suited for neurostimulation electrodes. Charge transfer resistance demonstrated a strong inverse correlation (−0.83) with charge density of electrodeposition. On average, the addition of polypyrrole and hydrogel to neurostimulation electrodes decreased charge transfer resistance by 82 %. These results support the use of interfacial engineering techniques to mitigate high interfacial impedance and combat the foreign body response towards epidurally implanted neurostimulation electrodes.

Ruthenium particles with size from 1 to 7 nm were formed by reduction of ruthenium complexes with urea, ethylenediaminetetraacetic acid, acetone azine, 1,2-Bis(2-furylmethylene)hydrazine) inside halloysite nanotubes. Catalysts of different morphology with Ru content from 0.75 to 0.93 %wt. were obtained using NaBH 4 or H 2 as reducing agents and tested in benzene hydrogenation as a model reaction. NaBH 4 reduced catalysts showed similar catalytic activity with 100 % benzene conversion after 1.5 h. Reduction with H 2 resulted in a decrease of catalytic activity for all samples. High benzene conversion was achieved only in the case of 1,2-Bis(2-furylmethylene)hydrazine and ethylenediaminetetraacetic acid. It was concluded that the thermal stability of complexing agents plays a key role in activity of catalysts reduced with H 2 .

In the review we describe a method for concentration of anionic liposomes with encapsulated water-soluble substances within a small volume via electrostatic liposome adsorption on the surface of polymer particles with grafted cationic chains (spherical polycationic brushes), or cationic microgel particles. Dozens of intact liposomes can be bound to each polymer particle, the resulting polymer/liposome complex does not dissociate into the original components in a physiological solution. This allows fabrication of multi-liposomal complexes (MLCs) with a required ratio of encapsulated substances. Two approaches are discussed for the synthesis of stimuli-sensitive MLCs. The first is to incorporate the conformation switch, morpholinocyclohexanol-based lipid, into the liposomal membrane thus forming pH-sensitive liposomes capable of releasing their cargo when acidifying the surrounding solution. These liposomes complexed with the brushes release encapsulated substances much faster than the uncomplexed liposomes. The second is to adsorb liposomes on cationic thermo-responsive microgels. The resulting MLCs contracts upon heating over a volume phase transition temperature from the swollen to the collapsed state of microgel, thus causing the adsorbed liposomes to change drastically their morphology and release an encapsulated substance. Complexation of anionic liposomes with chitosan microgels and polylactide micelles gives MLCs which degrade in the presence of enzymes down to small particles, 10–15 nm in diameter. A novel promising approach suggests that immobilized liposomes can act as a capacious depot for biologically active compounds and ensure their controllable leakage to surrounding solution.

In this study, two oil fractions – straight-run diesel and light cycle oil (LCO) – and the products of their hydrotreatment with sulfide catalysts, synthesized in the pores of porous aromatic frameworks, were analyzed by comprehensive two-dimensional gas chromatography (GC) with time of flight mass spectrometry (GC × GC–TOFMS). Effective separation of numerous compounds in the analyzed multicomponent mixtures and high resolution of mass spectra of reaction products made it possible to study the features of the activity of sulfide catalysts.

The unsupported catalysts were obtained during hydrogenation by in situ high-temperature decomposition (above 300 °C) of water-soluble metal precursors (ammonium molybdate and nickel nitrate) in water-in-oil (W/O) emulsions stabilized by surfactant (SPAN-80) using elemental sulfur as sulfiding agent. These self-assembly Ni–Mo sulfide nanosized catalysts were tested in hydrogenation of aromatics under CO pressure in water-containing media for hydrogen generation through a water gas shift reaction (WGSR). The composition of the catalysts was determined by XRF and active sulfide phase was revealed by XRD, TEM and XPS techniques. The calculations based on TEM and XPS data showed that the catalysts are highly dispersed. The surfactant was found to affect both dispersion and metal distribution for Ni and Mo species, providing shorter slab length in terms of sulfide particle formation and stacking within high content of NiMoS phase. Catalytic evaluation in hydrogenation of aromatics was performed in a high-pressure batch reactor at T  = 380–420 °С, p(CO) = 5 MPa with water content of 20 wt.% and CO/H 2 O molar ratio of 1.8 for 4–8 h. As shown experimentally with unsupported Ni–Mo sulfide catalysts, the activity of aromatic rings depends on the substituent therein and decreases as follows: anthracene>>1-methylnaphthalene≈2-methylnaphthalene>1,8-dimethylnaphthale-ne>>1,3-di-methylnaphthalene>2,6-dimethylnaphthalene≈2,3-dimethylnaphthalene>2-ethyl-naphthalene. The anthracene conversion reaches up to 97–100% for 4 h over the whole temperature range, while for 1MN and 2MN it doesn’t exceed 92 and 86% respectively even at 420 °С for 8 h. Among dimethyl-substituted aromatics the higher conversion of 45% was achieved for 1,8-dimethylnaphthalene with 100% selectivity to tetralines at 400 °С for 6 h. Similar to 1- and 2-methylnaphtalenes, the hydrogenation of asymmetric dimethyl-substituted substrate carries out through the unsubstituted aromatic ring indicating that steric factors influence on the sorption mechanism over active metal sites. The catalysts were found to be reused for at least six cycles when the hydrogenation is sulfur-assisted preventing metal oxide formation. It was established, that at the first 2–3 h known as the induction period, the oxide catalyst precursors formed slowly by metal salt decomposition, which reveals that it is the rate-determining step. The sulfidation is rather fast based on high catalytic activity data on 2MN conversion retaining at 93–95% upon recycling.

Carbon nanotubes (CNTs) are usually very expensive, but inexpensive CNTs have been mass-produced by a super-growth (SG) method. The SG-CNTs, however, have many defects resulting in a low conductivity, which is a disadvantage of the SG-CNTs. We discovered that even the defective SG-CNTs can provide a good thermoelectric performance by forming ternary hybrid films made of the SG-CNTs, nanoparticles (NPs) of a conducting polymer complex, poly(nickel 1,1,2,2-ethenetetrathiolate) (PETT) and poly(vinyl chloride) (PVC). The good thermoelectric performance of the ternary film (PETT-NP/SG-CNT/PVC) was possibly attributed to the defect repair effect in addition to the bridging effect of the PETT-NPs among the CNTs. In order to confirm this new concept, we attempted the deposition of metal NPs at the defects of the SG-CNTs. We initially made a physical mixture of palladium (Pd) NPs and the SG-CNTs in dispersions to cover the SG-CNT defects with the Pd-NPs. The obtained films showed only a slight improvement in electrical conductivity. Chemical reduction of the Pd ions in the dispersion of the SG-CNTs, on the other hand, provided hybrids with an enhanced electrical conductivity, thus, use as thermoelectric materials. The thermoelectric figure-of-merit was estimated to be ∼0.3, which is a relatively high value for organic hybrid materials.

For previously studied Fischer–Tropsch nanosized Fe catalyst slurries, polymer compounds with or without polyconjugating structures are used as precursors to form the catalyst nanomatrix in situ, and several catalytic experiments and X-ray diffraction and atomic force microscopy measurements are performed. The important and different roles of the paraffin molecules in the slurry medium in the formation and function of composite catalysts with the two types of aforementioned polymer matrices are revealed. In the case of the polyconjugated polymers, the alkanes in the medium are “weakly” coordinated with the metal-polymer composites, which does not affect the effectiveness of the polyconjugated polymers. Otherwise, alkane molecules form a “tight” surface layer around the composite particles, which create transport complications for the reagents and products of Fischer-Tropsch synthesis and, in some cases, can change the course of the in situ catalyst formation.