La-Faujasite zeolite activated with boron trifluoride: synthesis and application as solid acid catalyst for isobutane–isobutene alkylation

The sodium form of Faujasite Y (Na-FAU) zeolite has been synthesized by the hydrothermal method, and it has been exchanged with ammonium sulphate and later with lanthanum (III) chloride solutions to obtain the La-FAU catalyst. The three zeolites Na-FAU, NH4+-FAU and La-FAU have been characterized by microcrystalline X-ray diffraction, X-ray fluorescence, surface area, pore volume and Brönsted acid sites. The La-FAU catalyst has been successfully activated with boron trifluoride etherate, and it has been tested in the alkylation reaction of isobutane with isobutene up to 112 h of time on stream, since the raw La-FAU catalyst showed a rapid deactivation.

Hybrid Pigments Based on Montmorillonite and Anionic Dyes for Leather Finishing

The work is focused on obtaining hybrid pigments by adsorption of anionic dyes on positively charged montmorillonite. Modification of the sodium form of montmorillonite by chromium hydroxocomplexes was provided to ensure effective adsorption of anionic dyes on the surface of mineral particles. A high level of adsorption of anionic dyes as a result of steric factor was revealed. It was shown that the adsorption of dyes depended on the pH of the medium and was characterized by a maximum level at pH 4.5 – 6.0. The scheme of obtaining hybrid pigments, which were characterized by good сovering ability, resistance to stratification, especially saturated and intense colour was proposed.

DEVELOPMENT OF EFFECTIVE CATALYSTS FOR PROCESSING C3-C4 HYDROCARBONS

The aim of the article is to study the effect of preparation and activation methods of a modified zeolite-containing catalyst on the activity and stability of catalytic properties displayed by it during the conversion of C3-C4 hydrocarbons. During the experiment, the industrial cracking catalyst OMNIKAT, which is a zeolite in the sodium form, was used as the initial one. Zinc, gallium, and REE (rare earth elements) were sequentially applied to decationized samples of this catalyst by ion exchange, impregnation, and dry mechanical mixing, and the effect of these methods on the catalytic properties of the zeolite-containing catalyst was observed. As a result of a comparative analysis of the regularities of aromatization of C3-C4 hydrocarbons, it was found that the mechanical mixing method is the most preferable, since it provides the best process performance. In order to improve the activity and stability of the catalysts, thermocouple and thermal activations were carried out during the preparation process. Further, differences were revealed for the thermocouple and thermal activation of the modified catalyst and their effect on the activity and selectivity of the zinc-galliumzeolite-containing catalyst with respect to ArH (aromatic hydrocarbons) in the process of conversion of C3-C4 hydrocarbons. The choice of these particular operations was dictated by the fact that preliminary thermal and thermal vapor treatment of the catalyst practically does not require significant capital expenditures, i.e., economically most acceptable. Regularities of reaction-regeneration cycles were established. Thus, the optimal technological parameters for the regeneration of catalytic compositions are: temperature - 600°C, atmospheric pressure, oxidizer - air feed rate - 2 h-1, which lead to the restoration of the activity and selectivity of the spent catalyst to the fresh level. Studies of the of oxidative regeneration process a zinc-gallium-zeolite-containing catalyst have shown that while maintaining a clearly regulated regeneration regime, the activity of the latter is restored. The main task of the research was the development of effective catalysts for the conversion of C3- C4 hydrocarbons. Therefore, in the first place, we compared the conversion rates and selectivity for ArH. The proposed catalyst is characterized by good operational properties (high activity and long service life), providing 59.2% by weight of the target product yield at 98.8% conversion of C3-C4 hydrocarbons.

Antimony recovery from recycled terminals of lead-acid batteries with Na2CO3 and SiC after firstly SsB2O3 formation

Terminals obtained from spent lead-acid batteries in Mexico contain around 2 wt% Sb. The terminals were melted in an electric furnace and then oxygen was injected to 750?C and a gas flow rate of 2 L/min to produce high purity Sb2O3. The antimony trioxide obtained was treated with a mixture of Na2CO3-SiC to 1000?C to obtain metallic antimony. The antimony trioxide is reduced by the C present in reagents while silicon and sodium form a slag phase. The amounts of Sb2O3 and SiC were held constant while the Na2CO3 was evaluated in the range from 30 to 42 wt%. The antimony and slag produced were characterized by X-ray diffraction and SEM-EDS techniques. The addition of 34 wt% Na2CO3 leading the recovery of antimony up to 90.16 wt% (99.57 wt% purity) and the lowest antimony losses in the slag (2 wt%). In addition, the compounds Na2SiO3 and Na2Si2O5 formed in the slag may indicate a more stable slag. Na2CO3 contents higher than 38 wt% decreased the antimony recovery since it promotes the Na2Sb4O7 compound in the slag. The oxidation and reduction process was modeled in FactSage 7.3 software for a better understanding of the Na2CO3 and SiC additions on the antimony recovery rates and compounds formed in the slag.

Mercury Removal from Aqueous Solution Using ETS-4 in the Presence of Cations of Distinct Sizes

The removal of the hazardous Hg2+ from aqueous solutions was studied by ion exchange using titanosilicate in sodium form (Na-ETS-4). Isothermal batch experiments at fixed pH were performed to measure equilibrium and kinetic data, considering two very distinct situations to assess the influence of competition effects: (i) the counter ions initially in solution are Na+ and Hg2+ (both are exchangeable); (ii) the initial counter ions in solution are tetrapropylammonium (TPA+) and Hg2+ (only Hg2+ is exchangeable, since TPA+ is larger than the ETS-4 micropores). The results confirmed that ETS-4 is highly selective for Hg2+, with more than 90% of the mercury being exchanged from the fluid phase. The final equilibrium attained under the presence of TPA+ or Na+ in solution was very similar, however, the Hg2+/Na+/ETS-4 system in the presence of Na+ required more 100 h to reach equilibrium than in the presence of TPA+. The Hg2+/Na+/ETS-4 system was modelled and analyzed in terms of equilibrium (mass action law) and mass transfer (Maxwell–Stefan (MS) formalism). Concerning equilibrium, no major deviations from ideality were found in the range of studied concentrations. On the other hand, the MS based model described successfully (average deviation of 5.81%) all kinetic curves of mercury removal.

Recovery of Lanthanum(III) and Nickel(II) Ions from Acidic Solutions by the Highly Effective Ion Exchanger

The recovery of La(III) and Ni(II) ions by a macroporous cation exchanger in sodium form (Lewatit Monoplus SP112) has been studied in batch experiments under varying HNO3 concentrations (0.2–2.0 mol/dm3), La(III) and Ni(II) concentrations (25–200 mg/dm3), phase contact time (1–360 min), temperature (293–333 K), and resin mass (0.1–0.5 g). The experimental data revealed that the sorption process was dependent on all parameters used. The maximum sorption capacities were found at CHNO3 = 0.2 mol/dm3, m = 0.1 g, and T = 333 K. The kinetic data indicate that the sorption followed the pseudo-second order and film diffusion models. The sorption equilibrium time was reached at approximately 30 and 60 min for La(III) and Ni(II) ions, respectively. The equilibrium isotherm data were best fitted with the Langmuir model. The maximum monolayer capacities of Lewatit Monoplus SP112 were equal to 95.34 and 60.81 mg/g for La(III) and Ni(II) ions, respectively. The thermodynamic parameters showed that the sorption process was endothermic and spontaneous. Moreover, dynamic experiments were performed using the columns set. The resin regeneration was made using HCl and HNO3 solutions, and the desorption results exhibited effective regeneration. The ATR/FT-IR and XPS spectroscopy results indicated that the La(III) and Ni(II) ions were coordinated with the sulfonate groups.

Infl uence of Na+-montmorillonite modifi ed with acrylamide on the structure and properties of polypropylene

Sodium form montmorillonite was obtained from natural clay from the Gerpegezh deposit (Kabardino-Balkarian Republic, Russia). A procedure has been developed for modifying the sodium form of montmorillonite using acrylamide. The structure of the organoclay was confi rmed by IR spectroscopy. Composites based on polypropylene and modifi ed montmorillonite are obtained by melt mixing on a twin-screw extruder from JiangsuXindaScience & Technology. The structure of the obtained composites was investigated using X-ray diff raction analysis and scanning electron microscopy. The results of testing the obtained composites, which were used to evaluate the physical and mechanical properties, are presented: the melt fl ow index, impact strength according to Izod, modulus of elasticity, ultimate strength and elongation at break. ICompared to unfi lled polypropylene, polymer composites with 3 wt.% organoclay are shown to increase: impact strength by 31.61% (without notch) and 12.8% (with notch of 5 mm); modulus of elasticity in bending by 8.3%; tensile modulus by 10,3%. When polypropylene is fi lled with 5 wt.% organoclay, the composites show increased: impact strength by 12.60% (without notch) and by 10.52% (with an notch of 5 mm); the modulus of elasticity in bending and tension are the same as in the previous case. A further increase in the content of organoclay to 7 wt.% leads to a slight decrease in mechanical properties. Acrylamide can be used as a modifi er of organic clay; it is easily accessible and cheap, used in large-scale production. The resulting composites can be used as structural materials.

CHANGE IN THERMODYNAMIC CHARACTERISTICS OF HYDRATION OF CARBOXYL FIBER SORBENT IN EXCHANGE OF MAGNESIUM AND CALCIUM CATION

The relationship between the characteristics of hydration and the selectivity of the fibrous carboxyl sorbent is established. Using the isopiestic method and thermal analysis, the hydration of the carboxyl fiber ion exchanger VION KN-1 in sodium, calcium and magnesium forms was studied. The quantity of absorbed water was determined, including the ratio of kinetically unequal water in the sorbent phase. The amount of water absorbed form of magnesium ion exchanger is greater than calcium, the molar proportion of water distribution varying in the degree of hydration of the magnesium and calcium forms fibers substantially equally. The changes in Gibbs energy of hydration and enthalpy of dehydration of ion-exchange fiber are calculated. The increase in Gibbs energy is due to the absorption of near- hydration water, and water farthest hydration is adsorbed at a constant value of the energy. Its highest values are determined for the magnesium form of the sorbent, and the least-for calcium, which corresponds to the ratio of the absorbed solvent of both forms in the first step of hydration. The exchange isotherms of calcium and magnesium ions on the sodium form of VION KN-1 fiber were obtained. The Gibbs energy of solvent interface transfer was calculated, which represents the difference between the Gibbs energies of ion exchange sorption and the direct exchange of cations, and describes the contribution of the change in sorbent hydration during the transition from one ionic form to another. It is found that the selectivity of extractable fiber ion exchanger to metal cations depending on the change in the sorbent during the hydration of ion exchange, which is energetically favorable process and promotes ion-exchange sorption. Carboxyl cation exchanger is more selective for magnesium ions than calcium ions, as confirmed by phase transfer energy high values solvent and less water released during the transition from the sodium form to the magnesium than during the transition to the calcium.