Morphology dependent effect of γ-Al2O3 for ethanol dehydration: nanorods and nanosheets

Boehmite (γ-AlOOH) nanorods and nanoplates were hydrothermally fabricated with the aid of tetrapropylammonium bromide by modifying the pH values of solutions. Under acidic conditions, the adsorption of anions like Br-...

Removal of Siloxanes from Model Biogas by Means of Deep Eutectic Solvents in Absorption Process

The paper presents the screening of 20 deep eutectic solvents (DESs) composed of tetrapropylammonium bromide (TPABr) and glycols in various molar ratios, and 6 conventional solvents as absorbents for removal of siloxanes from model biogas stream. The screening was achieved using the conductor-like screening model for real solvents (COSMO-RS) based on the comparison of siloxane solubility in DESs. For the DES which was characterized by the highest solubility of siloxanes, studies of physicochemical properties, i.e., viscosity, density, and melting point, were performed. DES composed of tetrapropylammonium bromide (TPABr) and tetraethylene glycol (TEG) in a 1:3 molar ratio was used as an absorbent in experimental studies in which several parameters were optimized, i.e., the temperature, absorbent volume, and model biogas flow rate. The mechanism of siloxanes removal was evaluated by means of an experimental FT-IR analysis as well as by theoretical studies based on σ-profile and σ-potential. On the basis of the obtained results, it can be concluded that TPABr:TEG (1:3) is a very effective absorption solvent for the removal of siloxanes from model biogas, and the main driving force of the absorption process is the formation of the hydrogen bonds between DES and siloxanes.

Silica Gel Impregnated by Deep Eutectic Solvents for Adsorptive Removal of BTEX from Gas Streams

The paper presents the preparation of new adsorbents based on silica gel (SiO2) impregnated with deep eutectic solvents (DESs) to increase benzene, toluene, ethylbenzene, and p-xylene (BTEX) adsorption efficiency from gas streams. The DESs were synthesized by means of choline chloride, tetrapropylammonium bromide, levulinic acid, lactic acid, and phenol. The physico-chemical properties of new sorbent materials, including surface morphology and structures, as well as porosity, were studied by means of thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and Brunauer–Emmett–Teller analysis. The effect of DESs type, flow rate, and initial concentration of BTEX were also investigated followed by regeneration and reusability of adsorbents. The results indicate that SiO2 impregnated with tetrapropylammonium bromide and lactic acid in a 1:2 molar ratio have great potential for the removal of BTEX from gas streams. Its adsorption capacity was higher than the pure SiO2 and other developed SiO2-DES adsorbents. This result can be explained by the specific interaction between DESs and BTEX, i.e., hydrogen bonds interaction.

Supported Ruthenium and Tetrapropylammonium Bromide Catalysts for Oxidative Carboxylation of 1-Decene

Cyclic carbonate compounds are valuable for a range of applications and can be synthesized by a one-pot reaction involving epoxidation of olefin followed by reaction of the epoxide with CO2. This study used supported ruthenium catalysts for the epoxidation step (first step), where a combination of tetrapropylammonium bromide and zinc bromide was used for the cycloaddition of carbon dioxide. The supported ruthenium catalyst, prepared by a sol-immobilization method, allowed the effective epoxidation of 1-decene in air (using oxygen as the main oxidant) at 90 ºC in the presence of a catalytic quantity of radical initiator. This approach was applied to the one-pot multi-step oxidative carboxylation of 1-decene in the presence of 1 % Ru/support-Pr4NBr/ZnBr2 catalyst

Synthesis of pyrazolopyridine and pyrazoloquinoline derivatives by one-pot, three-component reactions of arylglyoxals, 3-methyl-1-aryl-1H-pyrazol-5-amines and cyclic 1,3-dicarbonyl compounds in the presence of tetrapropylammonium bromide

Pyrazolopyridine and pyrazoloquinoline derivatives were obtained by a one-pot, three-component reaction of arylglyoxals, 3-methyl-1-aryl-1H-pyrazol-5-amines and cyclic 1,3-dicarbonyl compounds in the presence of tetrapropylammonium bromide at 80°C in water through Knoevenagel and Micheal reactions, followed by intramolecular condensation, unexpected dearoylation and oxidation. Mild reaction conditions, high yields, simplicity of work up procedure, starting materials availability and clean product formation are some of the main advantages of this synthetic strategy.

An Efficient One-Pot, Four-Component Synthesis of Pyrazolo[3,4-b]pyridines Catalyzed by Tetrapropylammonium Bromide (TPAB) in Water

A novel and one-pot pseudo-four-component reaction between a series of arylglyoxals, malononitrile, 3-methyl-1-phenyl-1H-pyrazol-5-amine, and acetone in the presence of tetrapropylammonium bromide (TPAB) has been developed to synthesize a series of new substituted pyrazolo[3,4-b]pyridines, using water as an environmentally friendly solvent, in high to excellent yields.

A neutron scattering and modelling study of aqueous solutions of tetramethylammonium and tetrapropylammonium bromide

Tetrapropylammonium ions cluster and have less structured water arrangements whereas tetramethylammonium ions occur as single molecules with tetrahedral water arrangements.