2-propanol Solution Research Articles

Property estimation of water/alcohol/ionic liquid ternary system: Density

One of the most highly important applications of ionic liquids is for separation of the components of water/alcohol azeotropic mixture. The use of ionic liquids for this purpose creates a ternary system for which the determination of thermodynamic behavior and physical properties is highly matter of interest in design and operation of effective separation plants. In this work, the density of the aqueous ionic liquid ternary system is modelled based on three intelligent connectionist approaches. For the modelling, 1663 experimental density data points for ternary systems including 17 different ionic liquids in four aqueous alcohols (methanol, ethanol, propanol, and pentanol) solution were analyzed and taken into account at temperature range [288–343] K and pressure ranges [100–3000] kPa. The Shuffled complex evolution (SCE) algorithm was employed for optimization of the model parameters and constants. Four statistical parameters of R2, AARD, RMSE and STD were calculated for the connectionist models to compare their performance in the degree of comprehensiveness and accuracy. The highly matched results of the modelling with experimental demonstrate that the intelligent approach provides a suitable replacement for conventional thermodynamic models and equation of states which need too many fitting parameters.

Concentration Effects in the Hydrogenation of 4-Nitro-2′-Hydroxy-5′-Methylazobenzene over Skeletal Nickel in an Aqueous 2-Propanol Solution

The kinetics of hydrogenation of 4-nitro-2′-hydroxy-5′-methylazobenzene in aqueous 2-propanol solution over the skeletal nickel is investigated at different initial concentrations. It is established that the hydrogenation of 4-nitro-2′-hydroxy-5′-methylazobenzene over a skeletal nickel in azeotropic aqueous 2-propanol solution proceeds via two parallel pathways at both low and high initial concentrations. It is shown that increasing the initial concentration of the hydrogenated compound above its level of solubility raises the rate of azo group transformation in 4-nitro-2′-hydroxy-5′-methylazobenzene, while the content of 4-amino-2′- hydroxy-5′-methylazobenzene does not change in the hydrogenate and is not accumulated in the bulk of solution.

Radical Ions of 3-Styryl-quinoxalin-2-one Derivatives Studied by Pulse Radiolysis in Organic Solvents

The absorption-spectral and kinetic behaviors of radical ions and neutral hydrogenated radicals of seven 3-styryl-quinoxalin-2(1 H)-one (3-SQ) derivatives, one without substituents in the styryl moiety, four others with electron-donating (R = -CH3, -OCH3, and -N(CH3)2) or electron-withdrawing (R = -OCF3) substituents in the para position in their benzene ring, and remaining two with double methoxy substituents (-OCH3), however, at different positions (meta/para and ortho/meta) have been studied by UV-vis spectrophotometric pulse radiolysis in neat acetonitrile saturated with argon (Ar) and oxygen (O2) and in 2-propanol saturated with Ar, at room temperature. In acetonitrile solutions, the radical anions (4R-SQ•-) are characterized by two absorption maxima located at λmax = 470-490 nm and λmax = 510-540 nm, with the respective molar absorption coefficients ε470-490 = 8500-13 100 M-1 cm-1 and ε510-540 = 6100-10 300 M-1 cm-1, depending on the substituent (R). All 4R-SQ•- decay in acetonitrile via first-order kinetics, with the rate constants in the range (1.2-1.5) × 106 s-1. In 2-propanol solutions, they decay predominantly through protonation by the solvent, forming neutral hydrogenated radicals (4R-SQH•), which are characterized by weak absorption bands with λmax = 480-490 nm. Being oxygen-insensitive, the radical cations (4R-SQ•+) are characterized by a strong absorption with λmax = 450-630 nm, depending on the substituent (R). They are formed in a charge-transfer reaction between a radical cation derived from acetonitrile (ACN•+) and substituted 3-styryl-quinoxalin-2-one derivatives (4R-SQ) with a pseudo-first-order rate constant k = (2.7-4.7) × 105 s-1 measured in solutions containing 0.1 mM 4R-3-SQ. The Hammett equation plot gave a very small negative slope (ρ = -0.08), indicating a very weak influence of the substituents in the benzene ring on the rate of charge-transfer reaction. The decay of 4R-SQ•+ in Ar-saturated acetonitrile solutions occurs with a pseudo-first-order rate constant k = (1.6-6.2) × 104 s-1 and, in principle, is not affected by the presence of O2, suggesting charge-spin delocalization over the whole 3-SQ molecule. Most of the radiolytically generated transient spectra are reasonably well-reproduced by semiempirical PM3-ZINDO/S (for 4R-SQ•-) and density functional theory quantum mechanics calculations employing M06-2x hybrid functional together with the def2-TZVP basis set (for 4R-SQ•+).

KINETIC OF HYDROGENATION OF 4-NITRO-2'-HYDROXY-5'-METHYLAZOBENZEN ON SKELETAL NICKEL IN AQUEOUS SOLUTION OF 2-PROPANOL

The article is devoted to the kinetics of hydrogenation of 4-nitro-2'-hydroxy-5'-methylazobenzene on skeletal nickel in an aqueous solution of 2-propanol with the azeotropic composition at various initial concentrations of the starting compound. According to the obtained dependences of hydrogen absorption during the process, the changes in the amounts of the initial 4-nitro-2'-hydroxy-5'-methylazobenzene, the processing of the kinetic curves in linear coordinates of different orders, the data on the material balance of reaction products, the conlusion is drawn that at low concentrations the hydrogen addition is carried out through the nitro and azo groups to the starting 4-nitro-2'-hydroxy-5'-methylazobenzene molecule. An increase in the initial amount of 4-nitro-2'-hydroxy-5'-methylazobenzene introduced into the reactor leads to a marked decrease in the content of 4-amino-2'-hydroxy-5'-methylazobenzene. It was experimentally established that at the low initial concentrations, hydrogenation of 4-nitro-2'-hydroxy-5'-methylazobenzene on skeletal nickel in aqueous solution of 2-propanol with the azeotropic composition proceeds on the first order and zero one for hydrogen. An increase in the initial concentration of hydrogenated compound above the solubility limit leads to a sharp increase in a value of excessive adsorption of 4-nitro-2'-hydroxy-5'-methylazobenzene, to an increase in diffusion inhibition on hydrogen and to a change in the order for reducing agent. At the initial amounts of 4-nitro-2'-hydroxy-5'-methylazobenzene studied the transformation proceeds in two parallel directions. One of the directions is due to the addition of hydrogen on nitro groups to form 4-amino-2'-hydroxy-5'-methylazobenzene, and the second one on azo groups to form 2-amino-4-cresol and 4-nitroaniline.Forcitation:Hoang Anh, Kalashnikova V.A., Lefedova O.V. Kinetic of hydrogenation of 4-nitro-2'-hydroxy-5'-methylazobenzen on skeletal nickel in aqueous solution of 2-propanol. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 3. P. 10-15

Ether bond effects in quaternary ammonium and phosphonium ionic liquid-propanol solutions

The liquid-liquid equilibria (LLE) of quaternary ammonium and phosphonium ionic liquid (IL)-propanol solutions were examined. The ILs contained cations with or without ether bonds; the anion in all the ILs was bis(trifluoromethanesulfonyl)imide (TFSI−). The cations without ether groups are tributylmethyl ammonium (N4441+), triethylpentyl phosphonium (P2225+), triethyloctyl phosphonium (P2228+), and tributylmethyl phosphonium (P4441+). The cations containing ether groups are N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium, (N122(2O1)+), triethyl(methoxymethyl) phosphonium (P222(1O1)+), and triethyl(2-methoxyethyl) phosphonium, (P222(2O1)+). Propanol isomer effect was observed to affect the LLEs, reflecting the geometrical factors and hydrophobicities of 1-propanol and 2-propanol. According to Raman spectroscopy, the TFSI− anion conformers in the mixtures were altered in the presence of ether bonds in the cations. The universal quasichemical (UNIQUAC) interaction parameters are consistent with significant factors affecting IL-propanol solutions, such as the type of cation (ammonium or phosphonium), ether bonds, TFSI− conformers, and propanol isomer effects.

Rapid preparation of high-silica CHA-type zeolite membranes and their separation properties

Abstract High-silica CHA-type zeolite membranes (HS-CHA membranes) have attracted considerable attention as zeolite membranes with high permeability, separation performance, and stability. However, long hydrothermal reaction times are required to form HS-CHA membranes. Therefore, in this study we investigated more rapid preparation methods to produce high performance HS-CHA membranes for practical applications. In our preparation process, FAU-type zeolite and N,N,N-trimethtyl-1-adamantammonium hydroxide were used as a raw material and structure-directing agent, respectively, through the secondary growth of seed crystals. As a result, the HS-CHA membranes could be prepared in a 5-h hydrothermal reaction. The permeation properties of the membranes were determined for pervaporation for either ethanol (EtOH), 2-propanol (IPA), or acetic acid (AcOH) solution containing water at 348 K. The permeation flux and separation factor of 80 wt% IPA solution with the use of the HS-CHA zeolite membrane with a Si/Al ratio of 11 were 20 kg m−2 h−1 and 1128, respectively. Furthermore, the gas separation performances of the HS-CHA membranes for binary mixtures of CO2 and CH4 were evaluated. For an equimolar mixture of the gases at 313 K, the CO2 permeance and the selectivity were 1.5 × 10−6 mol m−2 s−1 Pa−1 and 115, respectively.

1-Propanol Causes Reentrant Transition on DNA whereas 2-Propanol does not: Experimental Verification through Single Molecular Observation

Nowadays, structural characterization of genomic DNA is one of the most important trends in medicine, biology and agricultural sciences. The indispensable procedure for the analysis of DNA in living cells is to isolate DNA molecules as precipitates from the crude mixture in rich variety of cellular components. According to the standard experimental protocol in molecular biology and medicinal chemistry, usage of 2-propanol is recommended, seemingly without any reasonable physic-chemical explanation why 2-propanol is desirable. In the present study, we have measured the change of the higher-order structure of genomic DNA molecules in the presence of alcohols by use of single DNA observation with fluorescence microscopy, by focusing our attention to unveil the different effect between 1-propanol and 2-propanol. We found that, with 1-propanol, the long-axis length exhibits minimum at 60% and then tends to increase with the increase of alcohol content. On the other hand, with 2-propanol the long-axis length exhibits almost monotonous decrease with the increase of alcohol content. These results indicate that DNA undergoes reentrant transition of coil-globule-coil with 1-propanol, whereas such reentrance phenomenon does not appear with 2-propanol. As a related phenomenon, we have recently reported that ethanol causes reentrant transition on DNA accompanied by the increase of its concentration.[1] We will discuss the mechanism of the reentrant transition in terms of the effect of none-sized clusters on the ethanol and 1-propanol solutions with high concentrations. [1] Y. Oda, et al., “Highly Concentrated Ethanol Solution Behaves as a Good Solvent for DNA as Revealed by Single-Molecule Observation”, ChemPhysChem, 17, 471(2016).

Molecular structure of octadecylphosphonic acids during their self-assembly on α-Al2O3(0001).

The formation of octadecylphosphonic acid (ODPA) self-assembled monolayers (SAMs) from 2-propanol solutions on hydroxylated α-Al2O3(0001) surfaces was studied in situ and in real time at the solid/liquid interface. Time-resolved vibrational spectra from sum-frequency generation (SFG) of C-H stretching modes revealed contributions from ODPA's alkyl backbone and the terminal methyl group as well as vibrational bands that originated from the presence of 2-propanol molecules at the α-Al2O3 surface. 2-Propanol signatures in SFG spectra decreased during SAM formation. This is due to adsorption of ODPA molecules which trigger desorption of 2-propanol from the α-Al2O3(0001) surface, so that these sites can be occupied by ODPA molecules. SAM formation was studied for different bulk concentrations of ODPA which changed substantially both the quality and the coverage of the final SAM. At initial stages of SAM growth, SFG spectra are dominated by methylene contributions and are indicative for a low molecular order and coverage of ODPA molecules. For concentrations of ODPA ≤2 mM this situation did not change within reasonable adsorption times (∼16 h) while for 5 and 30 mM concentrations a dramatic increase in molecular order and coverage within the first 2 h of adsorption is observed. Thermodynamic analysis using Langmuir adsorption kinetics provided equilibrium constants and the Gibbs free energy of adsorption between -24 and -28 kJ mol-1.

Synthesis and crystal structure of copper (I) sulfamate π-complex with 5-methyl-N-(Allyl)-1,3,4-thiadiazol-2-amine of [Cu2(C6H10N3S2)2(NH2SO3)2] composition

[Cu 2 ( Mepeta ) 2 (NH 2 SO 3 ) 2 ] compound has been obtained by means of alternating current electrochemical technique starting from the mixture of propanolic solution of 5-methyl- N -(allyl)-1,3,4-thiadiazol-2-amine ( Mepeta ) and water solution of Cu(NH 2 SO 3 ) 2 ·xH 2 Oand later X-ray structurally characterized by single crystal method. High-quality crystals of the compound appeared in three days. The compound crystallizes in the triclinic system: Sp. gr. – P -1, a = 7.799(2), b = 8.054(3), c = 10.165(2) Å, α = 96.003(7), β = 109.17 (3), γ = 112.95(3)°, V = 535.2 (3) Å 3 ,Z = 1, D х = 1.954(3) g/sm 3 , R ( F ) = 0.056 for 2052 independent reflections with F ≥ 4 σ ( F ). In the structure 1 , organic molecule Mepeta acts as chelate-bridging tridentate ligand being connected to copper (I) by two N atoms of thiadiazo leringand (C=C)-bond fromallyl-group, resulting in a formation of stable cationic dimers [Cu 2 ( Mepeta ) 2 ] 2+ . In the structure 1 , N atom from sulfamate-anion occupies an apical position of the metal coordination polyhedron. The efficiency of Cu(I)-(C=C) interaction is confirmed by the fact that allylic C=C bond is slightly elongated to 1.355(7) Å. Selected bond length (in Å) and angle (in deg) values: Cu1–N3 2.092(3), Cu1–N4 i 1.998(4), Cu1–N1 2.267(4), Cu–m 1.965(4) (m –middle point of C7=C8 bond), C8–C9 1.355(7), N4 i –Cu1–N3 112.8(3), N4 i –Cu1–N1 95.5(4), N4 i –Cu1– m 130.5(2), N3–Cu1–N1 86.5(3), N3–Cu1– m 109.6(3). Despite the presence of sulfamate anion NH 2 SO 3 – N-atom, thiadiazole ligand participates in the formation of stable tectone [Cu 2 ( L ) 2 ] 2+ previously found in the structures of other Сu(I) π-complexes with allyl derivatives of 1,3,4-thiadiazole. Hydrogen bonds N-H···O play an additional stabilizing role in the formation of hydrogen-bonded chains. Keywords : copper (I), sulfamate anion, π-complex, 1,3,4-thiadiazole, crystal structure.

KINETICS OF 2-CHLORO-4-NITROANILINE HYDROGENATION OVER SUPPORTED PLATINUM AND PALLADIUM CATALYSTS IN WATER SOLUTION OF 2-PROPANOL

The kinetics of liquid-phase hydrogenation of 2-chloro-4-nitroaniline over supported platinum and palladium catalysts in the aqueous solution of 2-propanol (0.68 mole fraction) was studied. Dependences of changes in concentration of participants vs the reaction time was obtained. The orders of reaction with respect to hydrogen and initial reagent were zero and the first. The palladium catalysts in comparison with platinum catalysts absorbed more amount of hydrogen. The products of dehalogenation reaction are main by-products. The platinum catalysts, as rules, more active in the conversion of the nitro group and selective with respect to chloroamine. The chloroaniline hydrogenation over the studied catalysts proceeded on sequential scheme. So, the chloroamine was dehalogenated. The values of the rate constants for all catalyst samples were varied depending on the total metal content. It was found that low-percentage platinum catalysts allow to achieve high selectivity of hydrogenation of HNC with respect to CFDA while maintaining the values of the observed rates of hydrogen absorption the similar as palladium catalysts. It is known that the kinetic regularities of catalytic reactions are associated with the structural and physicochemical characteristics of the catalysts. In particular, palladium and platinum have different electronic structures and behave is different in the catalytic reaction. Structure characteristics have value for the reaction kinetics also. The obtained data are consistent with these facts. However, some assumption appeared, that when the nature of the solvent varies, the same catalyst can behave differently. So, determination the relationship between the structure and activity of the catalyst only is not sufficiently correct for liquid-phase systems, without including the effect of the nature of the solvent.Forcitation:Latypova A.R., Krasnov A.I., Sharonov N.Yu., Safarov I.M., Lefedova O.V. Kinetics of 2-chloro-4-nitroaniline hydrogenation over supported platinum and palladium catalysts in water solution of 2-propanol. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 1. P. 42-48

Trace Element Analysis of Fusel Oil by Microwave-Induced Plasma Optical Emission Spectrometry

Background: Fusel oil is a mixture of higher alcohols produced as a minor fraction of the fermentation-distillation process in sugar and ethanol industries. It can be used as a fixating agent in cosmetics products, as solvent in the food industry, or recycled as fertilizer. Considering the effects of toxic elements contamination on the quality and safety of these products, and on the environment, an efficient method for elemental fusel oil analysis may find applications in many fields. In this work, we evaluate the application of microwave-induced plasma optical emission spectrometry (MIP OES) for trace element determinations in the fusel oil matrix. Methods: Simple external calibration with standard solutions prepared in either water or 1-propanol is evaluated. Undiluted fusel oil, and 1-propanol solutions containing 5 or 50% v v-1 sample matrix are analyzed. The introduction of air into the plasma prevented potential carbon deposition on the torch and the optics, and contributed to minimizing background signals. Results: No matrix effects were observed for calibration with 1-propanol solutions even for determinations in the undiluted sample (recoveries between 90-109% for a 1.0 mg L-1 spiking level). The MIP stability requires no sample preparation, which allows for lower limits of detection (LODs) and higher sample throughput. The LODs for Cd, Cr, Cu, Ni and Pb in 1-propanol are 0.03, 0.009, 0.01, 0.007 and 0.04 mg L-1, respectively. Conclusion: The MIP OES procedure described here is a simple, accurate and precise approach to trace element analysis of fusel oil. Keywords: Nitrogen plasma, organic solvent effects, matrix effects, higher alcohols, fusel oil, copper accumulation.

Experimental and modeling study of the surface tension and interface of aqueous solutions of alcohols, cetyltrimethylammonium bromide (CTAB) and their mixtures

In this study, the experimental surface tensions were measured for aqueous solutions of cetyltrimethyl ammonium bromide, 1-propanol, 2-propanol, and 1-butanol with a pendant drop apparatus. The temperature and pressure of all experiments were 298.15K and 1bar, respectively. Subsequently, a model based on the equality of the chemical potential of components at the interface and the bulk liquid was used. The results of this part showed that the surface tensions were reproduced well. The average absolute deviation percent of surface tension was 1.11. Then the surface tensions of (cetyltrimethylammonium bromide+alcohols) aqueous mixtures were measured at different concentrations. Moreover, the critical micelle concentrations of the applied systems were determined. The present model was used for aqueous mixtures of (cetyltrimethylammonium bromide+alcohols). The average absolute deviation percent of surface tension was 2.72, so the model successfully predicted the surface tension for aqueous solutions of (cetyltrimethylammonium bromide+alcohols). Furthermore, the results of the model proved that the presence of alcohols decreased the surface coverage of cetyltrimethylammonium bromide and increased the values of the critical micelle concentration.

COORDINATION COMPOUNDS OF TIN(IV) WITH HYDAZEPAM AND PRODUCTS OF ITS CONDENSATION WITH ARYLALDEHYDES

Reaction of tin tetrachloride in a 2-propanol solution and 2-(7-bromo-2-oxo-5-phenyl-3H- 1,4-benzodiazepin-1-yl)acetohydrazide (“gidazepam”, hydazepam – HHy) made it possible to obtain for the first time the corresponding tin coordination compound [Sn(HHy)Cl4] (I). A synthetic technique of the template synthesis has been developed and a novel coordination compounds [Sn(HHySl)Cl3] (II), [Sn(HHySlNO2)Cl3] (III), [Sn(HHy2Nf)Cl3] (IV), [Sn(HHy2NfBr)Cl3] (V) in the systems HHy–(HSl, HSlNO2, H2Nf, H2NfBr)–SnCl4–2-propanol, where HSl is 2-hydroxybenz-, HSlNO2 – 2-hydroxy-5-nitrobenz-, H2Nf – 1-hydroxy- 2-naphth-, H2NfBr – 4-bromo-1-hydroxy-2-naphth-aldehydes, have been synthesized. They are crystalline substances readily soluble in DMF and acetonitrile and moderately soluble in ethanol. The composition and structure of the complexes were confirmed by a number of physicochemical methods: elemental analysis, electrical conductivity, mass spectrometry, IR spectroscopy and thermogravimetry. The measurement of the electrical conductivity of solutions of the I−V in DMF has shown that they all are non-electrolytes. It was found by the thermogravimetric method that the thermolysis of complexes I−V proceeds uniformly and is stepwise in nature. The presence of peaks of molecular ions of the corresponding hydrazones in the mass spectra of complexes II−V obtained by template synthesis confirmed the formation of these hydrazones and the participation in coordination to the Sn4+ ion in the reaction course. Tin(IV) coordination polyhedron in all complexes is the octahedron formed by: four chlorine atoms, the nitrogen atom of the hydrazide amino group and the oxygen atom of the ligand carbonyl group in I; three chlorine atoms, azomethine nitrogen atom and two oxygen atoms of the carbonyl and deprotonated hydroxy group of the ligand in II−V.

A potential method for comparing instrumental analysis of volatile organic compounds using standards calibrated for the gas phase

In this paper we report a method for the comparative analysis of volatile organic compounds (VOCs) at physiologically representative concentrations by different analytical methods Standard aqueous solutions of acetone, ethanol, methanol, 1-propanol, 2-propanol and acetaldehyde were prepared by adding a specific mass of compound to a known volume of water, calculated using published Henry’s law constants for individual compounds. Headspace concentrations are thus known from established partitioning from dilute aqueous phase in accordance with Henry’s law. Selected Ion Flow Tube Mass Spectrometry (SIFT-MS), Proton Transfer Reaction Mass Spectrometry (PTR-MS), and Gas Chromatography–Mass Spectrometry (GC–MS) coupled to thermal desorption have been used to study and evaluate the performance of the instruments in the analysis of these VOCs. These analytical techniques have been widely used in the identification and quantification of trace concentrations of VOCs in biological samples. Quantitative determination of VOC concentration was achieved and the performance of the instruments compared with one another. Calibration curves are given within the range 101–103ppbv.

Correlation between viscosity, diffusion coefficient and spin-spin relaxation rate in 1H NMR of water-alcohols solutions

In this paper we investigate correlations between viscosity (ηs), 1H spin-spin relaxation times (T2) and diffusion coefficients (Ds) of protons obtained in a low field 1H NMR (20MHz) of solutions of methanol, ethanol, 1-propanol, 2-propanol and tert-butanol with water in all range of concentrations. As each of these three properties are associated with different dynamics of the molecules (ηs: transportation across planes of flow; Ds: translational diffusion; T2: rotational diffusion), we investigate their correlations with the micro-heterogeneity of the different alcohol-water mixtures.

Investigation of the electrical performance of hfo2 dielectrics deposited on passivated germanium substrates

Propanethiol solution (0.1 M) in 2-propanol, octanethiol solution (0.1 M) in 2-propanol and 20% (NH4)2S solution in water were used to passivate the germanium substrates. HfO2 thin films of 150 ALD cycles were then deposited on the passivated germanium substrates. The morphology of the thin films was investigated by X-ray diffraction and it was found that the morphology of the thin films was not affected by the chemical treatments. A lower leakage current density was observed in the passivated samples compared with the witness one. In addition, the interface quality and long-time stress reliability of the passivated samples were improved when the samples were annealed in forming gas ambient.

Improvement of the electrochemical performance of an NCA positive-electrode material of lithium ion battery by forming an Al-rich surface layer

A positive-electrode material of LiNi0.80Co0.15Al0.05O2 (NCA) having an Al-rich surface layer was synthesized, and its characteristics and electrochemical performance were investigated and compared with those of pristine NCA prepared by a conventional solid-state reaction. The Al-rich surface layer with its compositional gradient was formed by a wet-coating method using a fluidized bed coating technique and a subsequent heat treatment: fluidized NCA powder and a mist of 2-propanol solution containing an aluminium oxide sol were mixed in a chamber, followed by heat treatment at 600 °C in an oxygen atmosphere. For the electrochemical measurement, the positive electrode fabricated using the positive-electrode material was assembled into a 2032-type coin cell with lithium metal as an anode and LiClO4 in ethylene carbonate-diethyl carbonate as an electrolyte. The measurement revealed that the Al-rich surface layer effectively contributed to the improvement of charge-discharge cycle life performance; NCA with the Al-rich surface layer retained 96% of the initial capacity after 100 cycles, compared to the 90% retained by pristine NCA. For a better understanding of the improvement, the structure of the positive-electrode materials after 100 cycles was examined by scanning transmission electron microscopy (STEM) and scanning electron microscopy (SEM). High-angle annular dark-field signal images obtained from STEM showed no clear difference between these materials in terms of the growth of inactive rock-salt-like structure layer near the surface of the primary particles. On the other hand, low-magnification SEM observation revealed that the pristine NCA had widened microcracks among the primary particles in the secondary particles, while the NCA with the Al-rich surface layer did not. Therefore, the Al-rich surface layer improved the fracture strength of the secondary particles during the charge-discharge cycling, thus preventing the formation of isolated primary particles, which do not contribute to the charge-discharge behaviour.

Kinetics of nitrobenzene hydrogenation on spongy nickel and catalyst with supported palladium in 2-propanol aqueous solutions with acid or base additives

The effect acetic acid and sodium hydroxide additives in a 2-propanol aqueous solution of azeotrope composition have on the rate of nitrobenzene (NB) hydrogenation over spongy nickel and supported palladium catalysts is studied. Analysis of the experimental data indicates that adding acid slows the rate more than adding a base during NB hydrogenation on spongy nickel. The observed rate for spongy nickel falls in a series of solvents: 2-propanol–water (0.68 mole fraction) > 2-propanol–water (0.68 mole fraction) + NaOH (0.01M) > 2-propanol–water (0.68 mole fraction) + CH3COOH (0.01 M). When a palladium catalyst is used, the addition of acid has less of an effect on slowing the rate of the reaction than that of the base: 2-propanol–water (0.68 mole fraction) > 2-propanol–water (0.68 mole fraction) + CH3COOH (0.01 M) > 2-propanol–water (0.68 mole fraction) + NaOH (0.01 M).

Substrate material dependant structural, morphological and electrochemical behavior of spray pyrolysed titanium oxide thin films via partially aqueous route

By using 0.04 M partially aqueous solution of 1-propanol in double distilled water, thin films of TiO2 has been prepared on different conducting substrates such as stainless steel (SS), copper (Cu) and fluorine doped tin oxide (FTO) by using ultrasonic spray pyrolysis. Decomposition was carried out at 723 K, 10 cc/min spray rate. The structural, morphological and electrochemical properties of the thin films have been studied. Sample show tetragonal crystal structure with rutile as prominent phase. The novel nano-bricks like morphology was observed by scanning electron microscopy and transmission electron microscopy for the sample deposited on SS substrate. In electrochemical study, all deposited samples show pseudocapacitive behavior as observed from cyclic voltametry. The highest specific capacitance values observed from cyclic voltammetery, in 1 M KOH for the electrode deposited on SS, Cu and FTO substrates are 706.87, 5150.00 and 90.22 F/g respectively. From the charge discharge behavior, the observed highest values of electrochemical parameters such as specific energy 82.77 Wh/kg, specific power 41.25 kW/kg and efficiency (η) 93.17% respectively. Impedance study was carried out for the optimized electrode in the frequency range 1 mHz–1 MHz exhibits moderate internal resistance 3.896 Ω.

Kinetics of the hydrogenation of 2-chloro-4-nitroaniline over skeletal nickel and supported palladium catalysts in an aqueous solution of 2-propanol

The kinetics of the liquid-phase hydrogenation of 2-chloro-4-nitroaniline in an aqueous solution of 2-propanol over skeletal nickel and supported palladium catalysts is studied. The selectivity of the reaction with respect to 2-chloro-1,4-phenylenediamine is determined. It is found that samples of supported palladium catalysts differ with respect to the amount of the active component and the nature of the support. Some of their structural characteristics are provided.