Immobilization of H<Subscript>3</Subscript>PMo<Subscript>12</Subscript>O<Subscript>40</Subscript> catalyst on the nitrogen-containing mesoporous carbon and its application to the vapor-phase 2-propanol conversion reaction

Nitrogen-containing mesoporous carbon (N-MC) with high surface area (=1,115 m²/g) and large pore volume (=1.18 cm³/g) was synthesized by a templating method. The surface of N-MC was then modified to form a positive charge, and thus, to provide sites for the immobilization of [PMo₁₂O₄₀]³⁻. By taking advantage of the overall negative charge of [PMo₁₂O₄₀]³⁻, H3PMo₁₂O₄₀ (PMo₁₂) was chemically immobilized on the N-MC support as a charge matching component. It was found that the PMo₁₂/N-MC still retained relatively high surface area (=687 m²/g) and large pore volume (=0.67 cm³/g) even after the immobilization of PMo₁₂. It was also revealed that PMo₁₂ species were finely and molecularly dispersed on the N-MC support via chemical immobilization. In the vapor-phase 2-propanol conversion reaction, the PMo₁₂/N-MC showed a higher conversion than the unsupported PMo₁₂. Furthermore, the PMo₁₂/N-MC showed an enhanced oxidation catalytic activity and a suppressed acid catalytic activity compared to the unsupported PMo₁₂. This catalytic behavior of PMo₁₂/N-MC was due to the molecular dispersion of PMo₁₂ on the N-MC support formed via chemical immobilization by sacrificing the proton.     

Preparation and Oxidation Catalysis of H5PMo10V2O40 Catalyst Immobilized on Nitrogen-Containing Spherical Carbon

Nitrogen-containing spherical carbon (N-SC) with a diameter of ca. 12 μm was synthesized by a hydrothermal method using melamine-formaldehyde resin as a carbon precursor. The N-SC was then modified to have a positive charge, and thus, to provide a site for the immobilization of H₅PMo₁₀V₂O₄₀ (PMo₁₀V₂) catalyst. The PMo₁₀V₂ catalyst was chemically immobilized on the surface-modified N-SC support by taking advantage of the overall negative charge of [PMo₁₀V₂O₄₀]^5?. Characterization results showed that nitrogen in the N-SC support played an important role in forming a nitrogen-derived functional group (amine group) and that PMo₁₀V₂ catalyst was chemically immobilized on the nitrogen-derived functional group of N-SC support. PMo₁₀V₂/N-SC catalyst showed a higher 2-propanol conversion than the unsupported PMo₁₀V₂ catalyst in the vapor-phase 2-propanol conversion reaction. Moreover, the PMo₁₀V₂/N-SC catalyst showed an enhanced oxidation catalytic activity (formation of acetone) and a suppressed acid catalytic activity (formation of propylene and isopropyl ether) than the unsupported PMo₁₀V₂ catalyst. The enhanced oxidation activity of PMo₁₀V₂/N-SC catalyst was due to fine dispersion of [PMo₁₀V₂O₄₀]^5? on the N-SC support formed via chemical immobilization.     

Preparation, characterization, and catalytic activity of H5PMo10V2O40 immobilized on nitrogen-containing mesoporous carbon (PMo10V2/N-MC) for selective conversion of methanol to dimethoxymethane

Nitrogen-containing mesoporous carbon (N-MC) was synthesized by a templating method using SBA-15 and polypyrrole as a templating agent and a carbon precursor, respectively. The N-MC was then modified to have a positive charge, and thus, to provide a site for the immobilization of [PMo₁₀V₂O₄₀]⁵⁻. By taking advantage of the overall negative charge of [PMo₁₀V₂O₄₀]⁵⁻, H₅PMo₁₀V₂O₄₀ (PMo₁₀V₂) catalyst was chemically immobilized on the N-MC support as a charge-matching component. Characterization results showed that nitrogen in the N-MC played an important role in forming a nitrogen-derived functional group (amine group), and PMo₁₀V₂ catalyst was finely and chemically immobilized on the nitrogen-derived functional group of N-MC support. In the vapor-phase selective conversion of methanol, the PMo₁₀V₂/N-MC catalyst showed a higher conversion of methanol than the bulk PMo₁₀V₂ catalyst. Furthermore, the PMo₁₀V₂/N-MC catalyst showed a higher selectivity for dimethoxymethane (a product formed by bifunctional oxidation-acid-acid catalysis) and a higher selectivity for methylformate (a product formed by bifunctional oxidation-acid-oxidation catalysis) than the PMo₁₀V₂ catalyst. Reaction pathway for selective conversion of methanol to dimethoxymethane over PMo₁₀V₂/N-MC catalyst could be controlled by changing the methanol feed rate.     

Preparation, characterization, and oxidation catalysis of H3PMo12O40 heteropolyacid catalyst immobilized on carbon aerogel

Carbon aerogel (CA) with high surface area and large pore volume was prepared by polycondensation of resorcinol with formaldehyde. The surface of CA was then modified to have a positive charge, and thus to provide a site for the immobilization of H₃PMo₁₂O₄₀ (PMo₁₂) catalyst. By taking advantage of the overall negative charge of [PMo₁₂O₄₀]^3?, PMo₁₂ catalyst was chemically immobilized on the surface-modified CA as a charge matching component. It was found that PMo₁₂ catalyst was finely dispersed on the CA support via chemical interaction. In the vaporphase 2-propanol conversion reaction, the PMo₁₂/CA catalyst showed a higher 2-propanol conversion than the unsupported PMo₁₂ catalyst. Furthermore, the PMo₁₂/CA catalyst showed an enhanced oxidation catalytic activity (formation of acetone) and a suppressed acid catalytic activity (formation of propylene and isopropyl ether) compared to the unsupported PMo₁₂ catalyst. The enhanced oxidation activity of PMo₁₂/CA catalyst was due to fine dispersion of [PMo₁₂O₄₀]_3? on the CA support formed via chemical immobilization.     

Chemical Immobilization of H5PMo10V2O40 (PMo10V2) Catalyst on Nitrogen-rich Macroporous Carbon (N-MC) for Use as an Oxidation Catalyst

Nitrogen-rich macroporous carbon (N-MC) was prepared using melamine-formaldehyde resin as a carbon precursor. The surface of N-MC was then modified to have a nitrogen-derived functional group (amine group), and thus, to provide an anchoring site for heteropolyacid (HPA) catalyst. By taking advantage of the overall negative charge of [PMo₁₀V₂O₄₀]^5?, H₅PMo₁₀V₂O₄₀ (PMo₁₀V₂) HPA catalyst was chemically immobilized on the N-MC support as a charge matching component. It was found that PMo₁₀V₂ was finely dispersed on the N-MC support. In the model vapor-phase 2-propanol conversion reaction, the PMo₁₀V₂/N-MC catalyst showed a remarkably enhanced oxidation catalytic activity and a suppressed acid catalytic activity compared to the mother catalyst. The PMo₁₀V₂/N-MC catalyst served as an efficient oxidation catalyst in the reaction where both acid and oxidation reactions occurred simultaneously.     

The enhancement effect of phosphomolybdic acid (H<Subscript>3</Subscript>PMo<Subscript>12</Subscript>O<Subscript>40</Subscript>) on Pd/C catalyst for the electroreduction of hydrogen peroxide

A Pd/C electrode modified by H₃PMo₁₂O₄₀ was prepared and its catalytic performance for H₂O₂ electroreduction in acidic medium was investigated by cyclic voltammograms. Pd nanoparticles supported on Vulcan XC-72 carbon were prepared by chemical reduction of PdCl₂ in aqueous solution using NaBH₄ as the reducing agent. X-ray diffraction analysis indicated that the particle size of Pd is around 9.7 nm. The modified electrode was prepared by cyclic voltammograms in H₂SO₄ solution containing H₃PMo₁₂O₄₀. The results showed that H₃PMo₁₂O₄₀ can efficiently enhance the electrocatalytic activity for H₂O₂ electroreduction on Pd/C. The effect of H₃PMo₁₂O₄₀ content on the electrocatalytic activity of the catalyst was also investigated by CV. The best results appeared at the concentration of H₃PMo₁₂O₄₀ = 0.5 mmol L⁻¹.     

Methanol selective oxidation to dimethoxymethane on H<Subscript>3</Subscript>PMo<Subscript>12</Subscript>O<Subscript>40</Subscript>/SBA-15 supported catalysts

A series of SBA-15 supported H₃PMo₁₂O₄₀ catalysts were prepared for the one-step oxidation of methanol to dimethoxymethane (DMM). The evaluation and characterization revealed that higher DMM selectivity obtained on the incipient wetness impregnation (IM) catalyst was related to the instability of H₃PMo₁₂O₄₀ on it. Raman spectra showed that 12-molybdophosphoric acid was more stable on the direct synthesis (DS) catalyst than on the IM catalyst and the existence of SBA-15 support enhanced the stability of H₃PMo₁₂O₄₀. Moreover, higher H₃PMo₁₂O₄₀ loading resulted in more acid sites and low DMM selectivity, furthermore the thermal pretreatment on H₃PMo₁₂O₄₀ influenced its structure and thus affected DMM selectivity. This paper was presented at the 7 ^th Korea-China Workshop on Clean Energy Technology held at Taiyuan, China, June 26–28, 2008.     

Preparation and electrochemical performance of Li-rich layered cathode material,Li[Ni<Subscript>0.2</Subscript>Li<Subscript>0.2</Subscript>Mn<Subscript>0.6</Subscript>]O<Subscript>2</Subscript>, for lithium-ion batteries

The Li-rich layered cathode material, Li[Ni_0.2Li_0.2Mn_0.6]O₂, was synthesized via a “mixed oxalate” method, and its structural and electrochemical properties were compared with the same material synthesized by the sol–gel method. X-ray diffraction (XRD) shows that the synthesized powders have a layered O₃–LiCoO₂-type structure with the R-3m symmetry. X-ray photoelectron spectroscopy (XPS) indicates that in the above material, Ni and Mn exist in the oxidation states of +2 and +4, respectively. The layered material exhibits an excellent electrochemical performance. Its discharge capacity increases gradually from the initial value of 228 mA hg⁻¹ to a stable capacity of over 260 mA hg⁻¹ after the 10th cycle. It delivers a larger capacity of 258 mA hg⁻¹ at the 30th cycle. The dQ/dV curves suggest that the increasing capacity results from the redox-reaction of Mn⁴⁺/Mn³⁺.     

Properties of unsupported MoS<Subscript>2</Subscript> species produced in the preparation of MoS<Subscript>2</Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> using a sonochemical method

Unsupported MoS₂ particles, which were produced in the preparation of MoS₂/Al₂O₃ using a sonochemical method, were successfully separated from the prepared sample catalyst by adding oleylamine as an agent for dispersing the unsupported particles. The fraction of the unsupported MoS₂, which was estimated based on Mo balance, varied between 0.03 and 0.4, independent of the Mo loading levels investigated (6–54 wt% of Mo). The activity of the unsupported MoS₂ for the hydrodesulfurization of dibenzothiophene was nearly the same as that of the Al₂O₃-supported MoS₂, indicating that the activity of the prepared catalyst was not affected by the presence of the unsupported MoS₂ particles.     

A 2<Superscript>7-3</Superscript> fractional factorial optimization of polybenzimidazole based membrane electrode assemblies for H<Subscript>2</Subscript>/O<Subscript>2</Subscript> fuel cells

We describe the usefulness of a statistical fractional factorial design to obtain consistent and reproducible behavior of a membrane-electrode-assembly (MEA) based on a phosphoric acid (PA) doped polybenzimidazole (PBI) membrane, which allows a H₂/O₂ fuel cell to operate above 150 °C. Different parameters involved during the MEA fabrication including the catalyst loading, amount of binder, processing conditions like temperature and compaction load and also the amount of carbon in the gas diffusion layers (GDL) have been systematically varied according to a 2^7-3 fractional factorial design and the data thus obtained have been analyzed using Yates’s algorithm. The mean effects estimated in this way suggest the crucial role played by carbon loading in the gas diffusion layer, hot compaction temperature and the binder to catalyst ratio in the catalyst layer for enabling continuous performance. These statistically designed electrodes provide a maximum current density and power density of 1,800 mA cm⁻² and 280 mW cm⁻², respectively, at 160 °C using hydrogen and oxygen under ambient pressure.     

Determination of cadmium (II) using H<Subscript>2</Subscript>O<Subscript>2</Subscript>-oxidized activated carbon modified electrode

Pristine activated carbon (AcC) was oxidized by H₂O₂ under ultrasonic conditions. Compared with pristine AcC, the H₂O₂-oxidized AC possesses higher accumulation ability to trace levels of Cd²⁺. Based on this, a highly sensitive, simple and rapid electrochemical method was developed for the determination of Cd²⁺. In 0.01 mol L⁻¹ HClO₄ solution, Cd²⁺ was effectively accumulated at the surface of H₂O₂-oxidized AcC modified paste electrode, and then reduced to Cd under −1.10 V. During the following potential sweep from −1.10 to −0.50 V, reduced Cd was oxidized and a sensitive stripping peak appears at −0.77 V. The stripping peak current of Cd²⁺ changes linearly with concentration over the range 5.0 × 10⁻⁸ to 5.0 × 10⁻⁶ mol L⁻¹. The limit of detection was found to be 3.0 × 10⁻⁸ mol L⁻¹ for 2-min accumulation. Finally, this new sensing method was successfully used to detect Cd²⁺ in waste water samples.     

Pd/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalysts on cellular supports for VOC vapor neutralization

The results from investigating the influence of temperature, concentration, and flow rate on the catalytic oxidation of vapors of volatile organic compounds (VOCs) in the presence of Pd/γ-Al₂O₃ catalyst on cellular supports are presented. The activity of Pd/γ-Al₂O₃ catalysts on ceramic and metal monolith supports with a cellular structure during the catalytic neutralization of VOC (ethanol, ethyl acetate) vapors under laboratory conditions was determined, and the most stable catalyst for the preliminary study of a large batch was chosen. A pilot unit was created to test a large batch of cellular monolith catalyst in neutralizing VOC vapors under conditions of flexographic production. It was established that a high rate of conversion (> 99 %) was achieved for VOC concentrations of 0.5 g/m³ at space velocities of up to ∼10⁴ h⁻¹, and for VOC concentrations of 5.0 g/m³ at space velocities of up to ∼5 × 10⁵ h⁻¹. The change in the activity of the catalysts on metal (nickel alloyed by aluminum) and ceramic cellular supports in service was investigated. After 300–500 min of operation, virtually complete deactivation of catalyst on a metal support was observed, accompanied by the formation of nickel oxide and acetate. Pilot unit tests with catalyst on cellular supports having a volume of 14.5 l in neutralizing the ventilation exhausts of flexographic production confirmed the possibility of more than 90% conversion at VOC concentrations of ∼0.1 g/m³ and more than 97% at VOC concentrations of over 1 g/m³. A consistently high conversion of VOC was observed during a 100 h test of the pilot unit. A system for recovering the heat released during VOC oxidation lowers the operating costs of the pilot unit.     

Effect of H<Subscript>2</Subscript>O<Subscript>2</Subscript> modification of H<Subscript>3</Subscript>PW<Subscript>12</Subscript>O<Subscript>40</Subscript>@carbon for m-xylene oxidation to isophthalic acid

The production of isophthalic acid (IPA) from the oxidation of m-xylene (MX) by air is catalyzed by H₃PW₁₂O₄₀ (HPW) loaded on carbon and cobalt. We used H₂O₂ solution to oxidize the carbon to improve the catalytic activity of HPW@C catalyst. Experiments reveal that the best carbon sample is obtained by calcining the carbon at 700 °C for 4 h after being impregnated in the 3.75% H₂O₂ solution at 40 °C for 7 h. The surface characterization displays that the H₂O₂ modification leads to an increase in the acidic groups and a reduction in the basic groups on the carbon surface. The catalytic capability of the HPW@C catalyst depends on its surface chemical characteristics and physical property. The acidic groups play a more important part than the physical property. The MX conversion after 180 min reaction acquired by the HPW@C catalysts prepared from the activated carbon modified in the best condition is 3.81% over that obtained by the HPW@C catalysts prepared from the original carbon. The IPA produced by the former is 46.2% over that produced by the latter.     

V<Subscript>2</Subscript><Emphasis Type="Italic">O</Emphasis><Subscript>5</Subscript>/SiO<Subscript>2</Subscript> as a Heterogeneous Catalyst in the Synthesis of bis(indolyl)methanes Under Solvent Free Condition

The heterogeneous catalyst of V₂ O ₅/SiO₂ was prepared and characterized with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy. XRD of the silicon dioxide used reveals the amorphous nature while the spectrum of the prepared catalyst shows sharp intense peaks at about (20.2, 26.1, 31.0 and 47.3^°) and less intense sharp peaks at about (51.1, 55.2, 57.1 and 60.4^°) indicating formation of a crystalline phase with orthorhombic geometry. The FTIR spectra of the catalyst showed characteristic vibration stretching bands of V ?O at their specified position. An efficient and facile approach for the synthesis of bis(indolyl)methanes through a catalytic one pot reaction. Indole and aromatic aldehydes were stirred in the presence of a catalytic amount of the prepared and characterized heterogeneous catalyst V₂ O ₅/SiO₂ at 50^°C under solvent free condition. This procedure has advantages in competition with the previously reported methods, in terms of high yield, green catalyst, mild reaction condition, simple procedure, lack of toxicity, low cost, and simplicity of workup.     

Chemical and electrochemical characterization of TiO<Subscript>2</Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> atomic layer depositions on AZ-31 magnesium alloy

In this study, innovative TiO₂/Al₂O₃ mono/multilayers were applied by atomic layer depositions (ALD) on ASTM-AZ-31 magnesium/aluminum alloy to enhance its well-known scarce corrosion resistance. Four different configurations of ALD layers were tested: single TiO₂ layer, single Al₂O₃ layer, Al₂O₃/TiO₂ bilayer and Al₂O₃/TiO₂/Al₂O₃/TiO₂ multilayer deposited using Al[(CH₃)]₃ (trimethylaluminum, TMA), and TiCl₄ and H₂O precursors. All depositions were performed at 120°C to obtain an amorphous-like structure of both oxide layers. The four coatings were then investigated using different techniques, such as scanning electron microscope (SEM), stylus profilometer, glow discharge optical emission spectrometry (GDOES) and polarization curves in 0.05-M NaCl solution. The thickness of all the coatings was around 100 nm. The layers compositions were successfully investigated by the GDOES technique, although obtained data seem to be affected by substrate roughness and differences in sputtering rates between ceramic oxides and metallic magnesium alloy. Corrosion resistance showed to be strongly enhanced by the nanometric coatings, giving lower corrosion current densities in 0.05-M NaCl media with respect to the uncoated substrate (from 10⁻⁴ to 10⁻⁶ A/cm² for the single layers and from 10⁻⁴ to 10⁻⁸ A/cm² for the bi- and multilayers). All polarization curves on coated samples also showed a passive region, wider for the bi-layer (from −0.58 to −0.43 V with respect to Ag/AgCl) and multilayer (from −0.53 to −0.38 V with respect to Ag/AgCl) structures.     

Direct Synthesis of Dimethyl Carbonate from Methanol and Carbon Dioxide over Ga<Subscript>2</Subscript>O<Subscript>3</Subscript>/Ce<Subscript>0.6</Subscript>Zr<Subscript>0.4</Subscript>O<Subscript>2</Subscript> Catalysts: Effect of Acidity and Basicity of the Catalysts

Abstract  

Ce _X Zr_1−X O₂ catalysts with different cerium content (X) (X = 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1.0) were prepared by a sol–gel method for use in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Among these catalysts, Ce_0.6Zr_0.4O₂ was found to show the best catalytic performance. In order to enhance the acidity and basicity of Ce_0.6Zr_0.4O₂ catalyst, Ga₂O₃ was supported on Ce_0.6Zr_0.4O₂ (XGa₂O₃/Ce_0.6Zr_0.4O₂ (X = 1, 5, 10, and 15)) by an incipient wetness impregnation method with a variation of Ga₂O₃ content (X, wt%). Effect of acidity and basicity of Ga₂O₃/Ce_0.6Zr_0.4O₂ on the catalytic performance in the direct synthesis of dimethyl carbonate was investigated using NH₃-TPD and CO₂-TPD experiments. Experimental results revealed that both acidity and basicity of the catalysts played a key role in determining the catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Large acidity and basicity of the catalyst facilitated the formation of dimethyl carbonate. The amount of dimethyl carbonate produced over XGa₂O₃/Ce_0.6Zr_0.4O₂ catalysts increased with increasing both acidity and basicity of the catalysts. Among the catalysts tested, 5Ga₂O₃/Ce_0.6Zr_0.4O₂, which retained the largest acidity and basicity, showed the best catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide.     

Synthesis,structural, and electrochemical performance of V<Subscript>2</Subscript>O<Subscript>5</Subscript> nanotubes as cathode material for lithium battery

Various vanadium oxide nanostructures are currently drawn interest for the potential applications of Li batteries, super capacitors, and electrochromic display devices. In this article, the synthesis of V₂O₅ nanotubes by hydrothermal method using 1-hexadecylamine (HDA) and PEO as a template and surface reactant were reported, respectively. The structural properties and electrochemical performances of these nanostructures were investigated for the application of Li batteries. Structure and morphology of the samples were investigated by XRD, FTIR, SEM, and TEM analysis. The battery with V₂O₅ nanotubes electrode showed initial specific capacity of 185 mAhg⁻¹, whereas the PEO surfactant V₂O₅ nanotubes exhibited 142 mAhg⁻¹. It was found that PEO surfactant V₂O₅ nanotubes material showed less specific capacity at initial stages but better stability was exhibited at higher cycle numbers when compared to that of V₂O₅ nanotubes. The cyclic performance of the PEO surfactant material seems to be improved with the role of polymeric component due to its surface reaction with V₂O₅ nanotubes during the hydrothermal process.     

The role of TiO<Subscript>2</Subscript> layers deposited on YSZ on the electrochemical promotion of C<Subscript>2</Subscript>H<Subscript>4</Subscript> oxidation on Pt

The electrochemical promotion of Pt/YSZ and Pt/TiO₂/YSZ catalyst-electrodes has been investigated for the model reaction of C₂H₄ oxidation in an atmospheric pressure single chamber reactor, under oxygen excess between 280 and 375 °C. It has been found that the presence of a dispersed TiO₂ thin layer between the catalyst electrode and the solid electrolyte (YSZ), results in a significant increase of the magnitude of the electrochemical promotion of catalysis (EPOC) effect. The rate enhancement ratio upon current application and the faradaic efficiency values, were found to be a factor of 2.5 and 4 respectively, higher than those in absence of TiO₂. This significantly enhanced EPOC effect via the addition of TiO₂ suggests that the presence of the porous TiO₂ layer enhances the transport of promoting O²⁻ species onto the Pt catalyst surface. This enhancement may be partly due to morphological factors, such as increased Pt dispersion and three-phase-boundary length in presence of the TiO₂ porous layer, but appears to be mainly caused by the mixed ionic-electronic conductivity of the TiO₂ layer which results to enhanced O²⁻ transport to the Pt surface via a self-driven electrochemical promotion O²⁻ transport mechanism.     

Study on the properties of Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>-B<Subscript>2</Subscript>O<Subscript>3</Subscript>-BaO lead-free glass using in the electronic pastes

The Sb₂O₃ doping lead-free glass in Bi₂O₃-B₂O₃-BaO ternary system were prepared in the composition of several different subsystem, and the glass powder was produced through the process of water quenching. Glass transition temperatures (T _g ), glass soften temperatures(T _s ), the volume resistivity (ρ) in the temperature range of 80–200°C, and linear thermal coefficients of expansion in the temperatures range of 25–300°C (α_25–300) were measured for subsystems along with the different ratio of Bi₂O₃, B₂O₃ and BaO. For these subsystems, T _g ranged from 458 to 481°C, and T _s ranged from 490 to 512°C, both decreasing with the increasing of Bi₂O₃/B₂O₃ ratio, and increasing with the increasing of BaO/B₂O₃ ratio. The measured α_25–300 ranged from 65.3 to 76.3 × 10⁻⁷ K⁻¹, with values increasing with increasing Bi₂O₃/B₂O₃ and BaO/B₂O₃ ratio. The volume resistivity remains at a high standards, which may caused by it’s non-alkali composition, and it fluctuated from 10¹³ to 10¹¹ Ω cm with the temperature varied from 80–200°C. The structure of Bi₂O₃-B₂O₃-BaO ternary leadfree glass system was mearsured by FT-IR. The IR studies indicate that these glasses are made up of [BiO₆], [BO₃], and [BO₄] basic structural units, and it appears that Ba²⁺ acts as a glass-modifier in this ternary system, but the Bi³⁺ has entered the glass network when it is in relative high content so as to change the α_25–300, T _s and T _g .     

Investigating active centers of industrial catalysts for the oxidative chlorination of ethylene on a γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> surface

Selecting the best catalyst for large-scale industrial processes of the oxychlorination of ethylene (OCE) is a practical task of great importance. In such processes, even a slight reduction in selectivity results in considerable losses of raw materials. The enhancement of selectivity requires knowledge of the structure of the catalysts’ surfaces and the mechanism of the process of oxidative chlorination of ethylene into 1,2-dichloroethane (1,2-DCE). The structure of active sites of copper chloride catalysts on the surface of alumina was studied by physicochemical methods of IR spectroscopy and DTA. The structure was described for the active sites of catalysts for the oxidative chlorination of ethylene into (1,2-DCE) of two types, CuCl₂ and CuCl on γ-Al₂O₃: H1 (Harshow, United States) and OXYMAX-B (MEDC-B) (Sǜd-Chemie Catalysts, Germany). It was ascertained that complex compounds with [CuCl₄]⁻² and [CuCl₂]⁻¹ are formed upon interaction between the active phase of the catalyst (copper chlorides CuCl₂ or CuCl), and the surface groups of the support γ-Al₂O₃ (≡Al-OH) (this observation does not fall into the known theory of their structure). In accordance with the results from our study, a method was elaborated for synthesizing a catalyst with the optimum properties for OCE, and a pilot setup for the detailed investigation of this process was built. The possibility of cutting ethylene losses in half during deep oxidation and eliminating the formation of side products by a factor of 1.5–2 was demonstrated by the industrial production of 1,2-DCE and vinyl chloride at OOO Karpatnaftokhim in Kalush. The method for producing 1,2-DCE is protected by a Ukranian patent.