Tetrapropyl Ammonium Research Articles

Copper Oxide Nanoparticles Synthesis by Electrochemical Method

Copper oxide nanoparticles were prepared by electrochemical reduction method which is environmental benign. Tetra ethyl ammonium bromide (TEAB), tetra propyl ammonium bromide (TPAB), tetra butyl ammonium bromide (TBAB) were used as stabilizing agent in an organic medium viz . tetra hydro furan (THF) and acetonitrile (ACN) in 4:1 ratio by optimizing current density. The reduction process takes place under atmospheric condition over a period of 2 h. Such nanoparticles were prepared using simple electrolysis cell in which the sacrificial anode was a commercially available copper metal sheet and platinum (inert) sheet acted as a cathode. The stabilizers were used to control the size of a nanoparticles. The synthesized copper oxide nanoparticles were characterized by using UV-Visible, FT-IR, XRD, SEM-EDS and TEM analysis techniques. DOI: http://dx.doi.org/10.5755/j01.ms.22.2.7501

Synthesis and Characterization of SAPO-37 Molecular Sieve

Several synthesis parameters including silica precursor, alumina precursor and composition of reactant gel, during hydrothermal synthesis of SAPO-37, were studied. It was found that silica species is one indispensable component for the formation of SAPO-37. SAPO-37 could be synthesized only in a very narrow range within weak basic condition of pH = 8 ~ 9. In the use of no silica starting gel even SAPO-37 seeding, AlPO4-5 and SAPO-5 dominated the zeolite product without SAPO-37 formation. A new ion exchange procedure was developed for the removal of tetrapropyl ammonium (TPA) template from SAPO-37 with enhanced thermal stability by which the structure damage in SAPO-37 caused by the excessive steam during TPA burning could be avoided.

Hierarchical TS-1 synthesized effectively by post-modification with TPAOH and ammonium hydroxide

Hierarchical TS-1 with intracrystalline voids could be synthesized by post-modification with tetrapropyl ammonium hydroxide (TPAOH), however the process was supposed to be restrained by the charge balance effect.

Kinetics of Cu (II) Adsorption on Organo-Montmorillonite

Commercially available montmorillonite (Mt) was converted to organo-montmorillonite by grafting with tetramethylammonium (TMA) and tetrapropylammonium (TPA) cations to obtain potential adsorbents for metal cations. TMA-Mt and TPA-Mt showed IR bands at 1489 cm -1 and 1389 cm -1 attributed to C-N vibrations in tertiary amines and ơ as (C-H) bending vibrations due to CH 3 groups of the (CH 3 ) 4 N + cation, indicating intercalation of Mt with TMA and TPA. The basal spacings obtained from the XRD data showed marginal increase due to introduction of the quarternary ammonium ions. The CEC of Mt, TMA-Mt and TPA-Mt were 220, 294 and 257 cmol/g respectively showing an increasing order with modification of the clay. Cu(II) adsorption on the adsorbents showed that the interactions conformed to second order kinetics with the second order rate coefficient of 1.06 × 10 -2 , 9.00 × 10 -3 and 1.31 × 10 -2 L mg -1 min- 1 respectively for Mt, TMA-Mt and TPA-Mt.

Direct synthesis of Fe-ZSM-5 zeolite and its prospects as efficient electrode material in methanol fuel cell

New method of direct synthesis of Fe-ZSM-5 zeolite using tetrapropyl ammonium bromide (TPABr) as the template is reported in this study. The synthesis was based on one step procedure and did not involve the usual ion-exchange step to effect incorporation of the metal ion. The zeolite sample was characterized by XRD, FT-IR, TGA, SEM with EDX, and BET adsorption techniques. The average diameter of the porous particle of zeolite was about 10µm and it was a spherical cluster of crystals of about 141nm long along one of its axis. Zeolite-modified glassy carbon electrode (GCE) was prepared by using the mixture of the synthesized zeolite and carbon black (Vulcan X-72) and casting it as a thin layer. With modified GCE as the working electrode, the oxidation of methanol in alkaline medium was studied by cyclic voltammetry. The response of the electrode for methanol oxidation in alkaline medium is promising and it highlights the candidature of the synthesized material for methanol fuel cell. The electrochemical behavior of Fe-ZSM-5 in acidic medium reveals the oxidation state of iron in the zeolite. Cationic iron in the zeolite framework imparts electrocatalytic activity for methanol oxidation.

Synthesis of ZSM-5 zeolite from diatomite for fluid catalytic cracking (FCC) application

In this study, ZSM-5 zeolite was successfully synthesized hydrothermally from cheap and easily accessible natural mineral diatomite in the presence of tetrapropyl ammonium bromide. The pore structure, acidic sites and surface features of as-synthesized ZSM-5 zeolite were well characterized by X-ray diffraction, scanning electron microscopy, pyridine-adsorbed Fourier transform infrared spectroscopy, and N2 adsorption. The analysis results revealed that the as-synthesized ZSM-5 zeolite exhibited excellent hydrothermal stability, high specific surface area (223 m2 g−1) and more acidic cites than diatomite. After mixing ZSM-5 zeolite with a FCC base catalyst, the catalytic performance was evaluated in a micro-fixed bed reactor using vacuum gas oil (VGO) as feedstock. The high surface area and more acidic sites of as-synthesized ZSM-5 zeolite played an important role in the production of light olefins (propylene and butylene) during catalytic cracking of VGO.

Efficiency enhancement in dye-sensitized solar cells with a novel PAN-based gel polymer electrolyte with ternary iodides

The dye-sensitized solar cells (DSSCs) are promising, but their efficiency and stability require improvements. Quasi-solid-state DSSCs, based on gel polymer electrolytes, have exhibited reasonable performance with binary iodides. In this work, polyacrylonitrile-based gel polymer electrolytes were prepared using three iodide salts namely lithium iodide (LiI), 1-butyl-3-methylimidazolium iodide (BMII), and tetrapropyl ammonium iodide (Pr4NI) and investigated for their suitability for improving the performance of DSSCs. Hence, the LiI content was optimized for enhancement of both conductivity and DSSC performance employing fixed amounts of Pr4NI and BMII, and the compositions investigated had the chemical formula (PAN)10(EC)25(PC)20(BMII) (Pr4NI)0.75(LiI)n(I2)n/10. The highest room temperature ionic conductivity, 3.93 mS cm−1, was obtained for the electrolyte sample with LiI molar fraction n = 1.75, out of the prepared set of electrolytes. This electrolyte in a DSSC with a single mesoporous layer of TiO2 produced the best efficiency of 5.41 % with J sc of 20.6 mA cm−2. The changes in short circuit current density, open circuit voltage, and cell efficiency with the composition of the electrolyte are explained considering possible influences of cations in the electrolytes toward the electron injection from dye to TiO2, the electron diffusion through TiO2, shift of flat band potentials, and conductivity in the electrolyte. The incorporation of LiI into the electrolyte with the binary iodide system enhanced the efficiency by 30 % and the J sc by 62 % in the DSSCs fabricated with such electrolytes. This work uncovers the advantage of using ternary iodides in quasi-solid-state DSSCs rather than single or binary iodides.

Manufacture of b-Oriented ZSM-5/Silicalite-1 Core/Shell Structured Zeolite Catalyst

A b-oriented MFI shell was formed on the ZSM-5 crystal by pretreating the core using ammonia prior to the hydrothermal synthesis in tetrapropyl ammonium hydroxide medium. The effect of surface structure of the core material on synthesis of MFI/MFI zeolite was investigated. The surface Si-OH groups and amorphous aluminate may play an important role in forming the b-oriented coating. The shell composition changed from high-silica ZSM-5 to silicalite-1 after twice coating synthesis, while the shell coverage increased from 85% to 99%. In toluene methylation, the silicalite-1 shell not only prevented the deactivation of the catalyst, but also enhanced para-selectivity up to 61%.

Effect of Tetra Propyl Ammonium Bromide During Cobalt Electrodeposition from Acidic Sulfate Solutions

In the current study, the effect of an organic additive tetra propyl ammonium bromide (TPAB) on the structural, morphological characteristics of the cobalt metal produced from aqueous sulfate solutions has been investigated. The concentration of TPAB was varied over a range of 1 to 50 mg/L to evaluate its effect on current efficiency, energy consumption, and quality of electrodeposited cobalt. Smooth and bright electrodeposits of cobalt were obtained at low concentration of TPAB (10 mg/L) maintaining a current efficiency of 99.4 pct, with a low energy consumption of 2.42 kWh/kg. X-ray diffraction studies revealed that (100) plane is the most preferred plane of crystal growth during cobalt electrodeposition. However, at higher concentrations, the (101) plane became the most preferred one. Scanning electron micrographs indicated that smooth and uniform deposit of cobalt was obtained at 10 mg/L beyond which the deposit quality deteriorates. The presence of TPAB in the electrolytic bath polarizes the cathode and decreases the cathodic current considerably. AAS results indicated that the cobalt deposits were of high purity.

Synthesis of TiO2 nanoparticles by electrochemical method and their antibacterial application

Titanium dioxide nanoparticles were successfully prepared by electrochemical method. The tetra propyl ammonium bromide salt was used as stabilizing agent in an organic medium viz. tetra hydro furan (THF) and acetonitrile (ACN) in 4:1 ratio by optimizing current density. The parameters such as current density, solvent polarity, distance between electrodes and concentration of stabilizers were used to control the size of nanoparticles. The synthesized titanium dioxide nanoparticles were characterized by using UV–Visible spectroscopy, X-ray diffraction, scanning electron microscopy (SEM), energy dispersive spectrophotometer (EDS) and transmission electron microscopy (TEM) analysis techniques. TEM analysis proved a nearly tetragonal structure with size of 25–30nm which was in agreement with the result calculated from the XRD analysis. EDS analysis revealed the presence of Ti and O element. The nanoparticles were screened for their in vitro antibacterial activity against human pathogens such as gram negative Escherichia coli (E. coli), and gram positive Staphylococcus aureus strains and which proved excellent results.

Na+/K+ Pump Ion Binding Site Interactions Regulate the Proton Leak Pathway

The Na+/K+ pump (NKA) is a membrane bound transporter located in animal cells which transports three Na+ ions out for two K+ ions into the cell for every one ATP molecule hydrolyzed. Two out-of-three ion-binding sites within the protein reciprocally bind two K+ or two Na+ ions (shared sites), while the remaining site exclusively binds Na+. Without these two ions present the NKA passively transports H+, likely through the Na-exclusive site. In order to understand the proton transport mechanism voltage-clamp was used to study the effect of tetrapropylammonium (TPA) and Beryllium Fluoride (BeFx) on inward proton current (IH) transport by NKA expressed in Xenopus oocytes. TPA (a shared site blocker) had a dual effect on IH; between pH 7.6-6.0 TPA partially inhibited IH, and at pH 5.0 (where an inhibitory effect on the steady state IH is present), TPA partially activated IH. When the phosphate analogue BeFx was injected into oocytes, stabilizing an externally open conformation of the ion binding sites, K+ still inhibited inward current at pH 7.6. At pH 5.0 K+ activated IH resembling the effect of TPA on fully functional NKA. These results illustrate the complex interaction between the occupancy of shared sites and proton permeation. Blocking access at the shared sites with TPA activated IH by relieving the inhibition normally observed at high [H+]. Partial inhibition by TPA at pH 5.0 may reflect incomplete block of H+ access or a reduced rate of the conformational changes needed for H+ translocation. After BeFx inhibition NKA was still capable of interacting with K+. The mixed occupancy of K+ and H+ at low pH activated the leak, likely relieving the H+ inhibition due to K+ occlusion. Supported by NIH GM 061583 to CG and NSF MCB-1243842 to PA.

Effect of Different Templates on the Synthesis of Mesoporous Sodalite

Sodalite is a type of zeolite having ultramicropore size and high thermal stability with strong basic sites. However, sodalite has several drawbacks in the catalyst application due to its smallest pore size (2.8 Å) and low surface area. To overcome these disadvantages, microporous sodalite can be modified to have mesoporous structure but maintain its active sites suitable for catalyst applications. This study was focused on the synthesis of mesoporous sodalite using various organic templates as structure directing molecules. A hierarchical mesoporous sodalite has been synthesized hydrothermally at 150°C for crystallization by using several mesotemplate and fumed silica as a silica source. The synthesized samples were characterized using XRD, FTIR, BET surface area, and FESEM. XRD and FTIR showed that all templates being used in the synthesis produced sodalite phase. The sodalite synthesized using organosilane (trimethoxysilyl-propyldimethyloctadecyl ammonium chloride) and mixture of tetrapropyl ammonium hydroxide and cetyltrimethylammonium bromide with ratio of 1 : 1 showed mesoporosity as proven by higher BET surface area as compared to microporous sodalite with different pore structure as proven by pore distribution.

ZSM-5 Zeolite with Micro-Mesoporous Structures Synthesized Using Different Templates for Methanol to Propylene Reaction

ZSM-5 zeolites with different pore structures were synthesized using different templates(tetrapropyl ammonium hydroxide(TPAOH), cetyltrimethylammonium bromide(CTAB) and C18-6-6Br2). The obtained nanosized(NZ), mesoporous(MZ), and nanosheets(NSZ) ZSM-5 samples were compared with conventional microporous ZSM-5 zeolite(CZ). The physicochemical properties of these samples were characterized using X-ray diffraction(XRD), scanning electron microscopy(SEM), N2 adsorption-desorption,and temperature-programmed desorption of ammonia(NH3-TPD). The results showed that the mesopore volumes and surface areas of the four samples increased in the order NSZ MZ NZ CZ, and the ratio of strong/weak acidity increased in the order CZ MZ NZ NSZ. In the methanol to propylene(MTP) reaction,the catalyst porosity played an important role on the product selectivity and catalytic stability. The selectivities for propylene and total olefins improved with increasing mesoporosity; NSZ, with the largest mesopore volume, gave the highest propylene selectivity, i.e., 47.5%, and 78.4% total olefins. Meanwhile, the introduction of mesopores into the ZSM-5 zeolite extended the catalytic lifetime. The NZ sample displayed reliable MTP catalytic activity for 200 h, which was predominately attributed to its optimal combination of acidity and porosity.

Conventional hydrothermal synthesis of nanostructured H-ZSM-5 catalysts using various templates for light olefins production from methanol

High-silica H-ZSM-5 catalysts (Si/Al = 200) were successfully synthesized using the conventional hydrothermal method under a static condition in the presence of tetrapropyl ammonium hydroxide (TPAOH), tetrapropyl ammonium bromide (TPABr), n-butyl amine (NBA) and morpholine (MOR) as the structure-directing agents. The influence of the templates on the crystal size, surface area, pore volume, morphology and surface acidity of H-ZSM-5 catalysts was characterized by XRD, FE–SEM, BET, FT–IR and NH3-TPD techniques. The catalytic performance of the H-ZSM-5 samples in the methanol to olefins (MTO) reaction was conducted in a fixed-bed reactor at 480 °C, atmospheric pressure and methanol WHSV of 0.9 h−1 using methanol to water weight ratio of unity in the feed. The FE–SEM micrographs revealed that only ZSM-5 samples prepared with TPAOH and TPABr exhibited the MFI-typical hexagonal and spherical-shaped morphologies. The XRD patterns indicated higher crystallinity for the catalyst synthesized using TPABr. Also, this catalyst exhibited the highest acidity and acceptable surface area. All the samples illustrated activity in the MTO reaction but the products selectivity especially for the propylene and other light olefins was extremely different. The prepared sample with TPABr as the template displayed the highest methanol conversion (99.37%) and propylene selectivity (37.59%).

Study of template interactions in MFI and MEL zeolites using quantum methods

The interactions between zeolites and templates in MFI and MEL (MEL1 and MEL2) structures combined with different conformations of tetrapropylammonium (TPA) and tetrabutylammonium (TBA) templates were investigated using DFT type methods. Molecular dynamics (MD) simulations were carried out with a tight binding code with London dispersion (DFTB-LD) approach to investigate the conformational space of templates before zeolite formation. Conformational preferences are in agreement with experimental results observed in zeolite using TPA and TBA templates when the temperature of synthesis changes. Zeolite–templates interactions were calculated by using both DFT-D and DFTB-LD methods. Analysis of intrinsic zeolite–template interactions and energy changes in zeolites and templates may explain experimental findings. Template distortion energies were evaluated at channel interception distances and anion–cation electrostatic effects were also included to account for template aggregation. A model of cation and anion distribution for MFI zeolite is presented.

Determination of bismuth in pharmaceutical products by resonance light scattering using quaternary ammonium salts as molecular probe

Resonance light scattering (RLS) of bismuth-iodide-quaternary ammonium salts and their analytical application have been studied. Bismuth can react with a large excess of I− to form [BiI4]− in the presence of Tween-20; [BiI4]− further reacts with quaternary ammonium salts such as tetramethyl ammonium bromide (TMAB), tetrapropyl ammonium bromide (TPAB) and tetrabutyl ammonium bromide (TBAB) to form an ion-association compound. Moreover, the characteristics of RLS spectra of the complexes, the optimum conditions and the influencing factors have been investigated. The method has been applied to determine Bi(III) in pharmaceutical products with satisfactory results which are in agreement with that of atomic absorbance spectrometry (AAS).

One-step dual template synthesis of hybrid lamellar-bulk MFI zeolite

A one-step dual template strategy was employed to achieve the facile synthesis of hybrid lamellar-bulk MFI (HLBM) zeolite, consisting of a lamellar zeolite structure on the surface of the bulk zeolite core. Tetrapropyl ammonium hydroxide (TPAOH) and diquarternary ammonium surfactant ([C22H45–N+(CH3)2–C6H12–N+(CH3)2–C6H13]Br2, C22-6-6) with a composition of 100SiO2/xC22-6-6/36TPAOH/4000H2O was used as the template in the HLBM zeolite synthesis. The influences of several parameters on the HLBM zeolite formation were investigated, including concentration of C22-6-6, hydrothermal synthesis time, and ageing temperature and time prior to hydrothermal crystallization. The sizes of lamellar and bulk domains of the HLBM zeolite and thus its meso- and micro-porosity can be modulated by simply tuning these parameters. A possible growth scheme of the HLBM zeolite is discussed. The ability to form hybrid zeolite particles with tunable meso-/micro-porosity is important to keep their potential application as broad as possible for specific zeolite structures. The dual template synthesis approach presented is potentially applicable to form other types of hybrid lamellar-bulk zeolite materials.

Effect of TS-1 treatment by tetrapropyl ammonium hydroxide on cyclohexanone ammoximation

TS-1 has been treated with different concentrations of tetrapropyl ammonium hydroxide (TPAOH), characterized by a series of techniques, and studied in cyclohexanone ammoximation. The results show that the MFI structure of TS-1 is not destroyed, while mesopores are formed in TS-1 crystals and the pore diameters increase with the TPAOH concentrations; the amount of the framework Ti species decreases slightly at low concentrations of TPAOH, but decreases appreciably at the concentrations of TPAOH above 0.0125mol/L; the activity and the selectivity of TS-1 are not affected by the treatment, but the catalyst stability is markedly increased after the TPAOH treatment. The increase of the stability is attributed to the mesopore formation. But when the pore diameters are larger than 6.51nm, the catalyst stability begins decreasing due to the appreciable damage of the framework titanium by TPAOH.

AMMONIA AS A MODIFIER IN ION MOBILITY SPECTROMETRY: EFFECTS ON ION MOBILITIES AND POTENTIAL AS A SEPARATION TOOL

A commercial ammonia solution was introduced in the buffer gas of an ion mobility spectrometer and the mobilities of tetramethylammonium (TMA), tetraethylammonium (TEA), tetrapropylammonium (TPA), and tetrabutylammonium (TBA) ions, tribenzylamine (TBzA), tributylamine (TBtA), 2,4-dimethyl pyridine (2,4-lutidine), 2,6-di-tert-butyl pyridine (DTBP), serine, atenolol, and valinol decreased depending on their structures. Electrospray ionization-ion mobility spectrometry-quadrupole mass spectrometry was used in these experiments. Analyte ion mobilities decreased to different extents with the amount of ammonia introduced in the mobility spectrometer. When the amount of ammonia increased from 0.0 to 22 mmol m-3 (with a concomitant concentration of water of 106 mmol m-3), percentage reductions in mobilities were: -4.8% (serine), -1.9% (reactant ions), -1.1% (TBtA), -0.9% (TBzA), -0.5% (TEA), -0.4% (valinol and TBA), -0.3% (TEA, TMA, and 2,4-lutidine), and 0% (atenolol and DTBP). These selective variations in mobilities were due to formation of large analyte ion-ammonia-water clusters. The small change in mobility of tetraalkylammonium ions, TBzA, TBtA, atenolol, and DTBP with the introduction of ammonia into the buffer gas was explained by steric hindrance of bulky substituents which shielded the positive charge of the ion from the attachment of ammonia and water molecules, and delocalized the positive charge. Ammonia in the buffer gas produced ion clusters with one or two ammonia molecules in compounds with little steric hindrance such as serine. At concentrations of ammonia of 4.4 mmol m-3 or higher (at 150°C), ligand-saturation with ammonia and water molecules occurred on the positive charge of some ions; when the positive charge saturated, no significant reductions in ion mobility occurred when increasing the concentration of ammonia in the buffer gas.

Green synthesis of nano‐silicalite‐1: Biomass fly ash as a silica source and mother liquid recycling

This study investigated the effect of silica from biomass fly ash, template (tetrapropyl ammonium hydroxide; TPAOH) reduction, and mother liquid recycling on the synthesis of nano‐silicalite‐1 by the clear gel solution method. The results showed that nano‐silicalite‐1 was synthesized by using silica from the biomass fly ash at the appropriate Si:TPAOH mole ratios, e.g., 25Si:9TPAOH and 30Si:9TPAOH, and synthesis conditions (80°C and 96 h). An increased ratio from 25Si:9TPAOH:0.16NaOH to 30Si:9TPAOH:0.16NaOH was suspected to increased gel viscosity. An increased NaOH content in the 30Si:9TPAOH:0.64NaOH increased the silicalite‐1 yield, possibly by reducing silica polymerization. Decreasing the TPAOH content increased silicalite‐1 yields, but provided unfavorable conditions for nanoparticles. Increasing the reaction time increased the silicalite‐1 yield, but the crystals tended to agglomerate. For the 25Si:7TPAOH, lower reaction temperature (70°C) gave a decreased silicalite‐1 yield and a smaller crystal size than the higher temperature (80°C). Adding silica residues and zeolite nuclei in the mother liquid recycling from the first synthesis batch increased the silicalite‐1 yield. For 25Si:9TPAOH, mother liquid recycling had less effect on the crystal size, which was attributed to there being a sufficient amount of TPAOH for synthesizing nanocrystal silicalite‐1. However, a considerable crystal size reduction was observed when using 25Si:5TPAOH with mother liquid recycling, due to more nuclei being added from the mother liquid. Therefore, a greener and more efficient synthesis for nano‐silicalite‐1 could be performed by using an alternative silica source from biomass fly ash and by recycling of the mother liquid. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 188–193, 2015