Showing papers on "Ammonium hydroxide published in 2008"

Oxidation of Aniline: Polyaniline Granules, Nanotubes, and Oligoaniline Microspheres

Abstract: Aniline was oxidized with ammonium peroxydisulfate in solutions of strong acid (0.1 M sulfuric acid), weak acid (0.4 M acetic acid), or alkali (0.2 M ammonium hydroxide). The properties of the oxidation products and their morphology are controlled by the initial acidity of the medium and the acidity profile during the oxidation; the acidity increases because sulfuric acid is a byproduct. Conducting polyaniline nanogranules, nanotubes, or nonconducting oligoaniline microspheres were obtained, respectively. FTIR spectra suggest that the oligomers produced by the oxidation of neutral aniline molecules at the beginning of oxidation are similar, regardless of the acidity of the medium. Neutral aniline molecules, prevailing under alkaline conditions, are easily oxidized to aniline oligomers composed of ortho- and para-coupled aniline constitutional units. Ortho-coupled units are further converted by oxidative intramolecular cyclization to phenazines. It is proposed that, in acidic media, N-phenylphenazine units...

Aqueous Ammonia Soaking of Switchgrass Followed by Simultaneous Saccharification and Fermentation

Abstract: Simultaneous saccharification and fermentation (SSF) of switchgrass was performed following aqueous ammonia pretreatment. Switchgrass was soaked in aqueous ammonium hydroxide (30%) with different liquid–solid ratios (5 and 10 ml/g) for either 5 or 10 days. The pretreatment was carried out at atmospheric conditions without agitation. A 40–50% delignification (Klason lignin basis) was achieved, whereas cellulose content remained unchanged and hemicellulose content decreased by approximately 50%. The Sacccharomyces cerevisiae (D5A)-mediated SSF of ammonia-treated switchgrass was investigated at two glucan loadings (3 and 6%) and three enzyme loadings (26, 38.5, and 77 FPU/g cellulose), using Spezyme CP. The percentage of maximum theoretical ethanol yield achieved was 72. Liquid–solid ratio and steeping time affected lignin removal slightly, but did not cause a significant change in overall ethanol conversion yields at sufficiently high enzyme loadings. These results suggest that ammonia steeping may be an effective method of pretreatment for lignocellulosic feedstocks.

Decomposition pathways of an alkaline fuel cell membrane material component via evolved gas analysis

Abstract: The mechanism of the thermal decomposition of [NMe4][OH]·5H2O, tetramethyl ammonium hydroxide pentahydrate, was studied using DSC, TG and evolved gas analysis because of the importance of related ions in anion exchange membranes. The products of the reaction are trimethyl amine, methanol and dimethyl ether. The relative ratio of the products is determined by how much water remains in the sample as it is decomposing. Isotopic labeling experiments with D2O show that deprotonation of the tetramethyl ammonium ion by hydroxide establishes a rapid equilibrium between tetramethyl ammonium ion and the nitrogen ylide species and water that scrambles the deuterium with the proton in the methyl groups. The results of this work also suggest that tetraalkyl ammonium cations may be more stable in hydroxide conducting membranes than previously believed.

Production of Tetramethyl Ammonium Hydroxide Using Bipolar Membrane Electrodialysis

Abstract: To produce tetramethyl ammonium hydroxide (TMAH) at lower energy consumption and with less environmental pollution, a bipolar membrane electrodialysis (BMED) of A-BP configuration (A, anion exchange membrane; BP, bipolar membrane) was adopted to electro-alkalize tetramethyl ammonium chloride. The results for one-unit BMED stack indicate that current efficiency increases and energy consumption decreases as feed concentration increases or current density decreases. The highest current efficiency can reach 99.9%, and the lowest energy consumption is 1.43 kWh kg−1. On the basis of a 3-unit BMED, the process cost is estimated to be 0.33 $ kg−1 of TMAH. This method is not only environmentally friendly but also cost-effective.

Influence of pH of the Impregnation Solution on the Catalytic Properties of Co/γ-Alumina for Fischer-Tropsch Synthesis

Abstract: The Co/{gamma}-Al{sub 2}O{sub 3} catalysts were prepared by the slurry impregnation of an aqueous solution of cobalt(II) nitrate precursor Nitric acid or ammonium hydroxide was added to the cobalt nitrate solution, during impregnation, to give an acidic or basic environment The changes in the particle size of cobalt species were estimated by X-ray diffraction (XRD) and hydrogen chemisorption The reduction degree of cobalt oxides was measured by temperature-programmed reduction (TPR) The catalysts prepared under acidic conditions showed a higher reduction degree compared to those prepared at higher pH because of the reduced salt-support interaction During the Fischer-Tropsch synthesis at 220{sup o}C, employing the catalysts prepared at a different pH (080, 494, 996, and 1112), a considerable difference in the initial activity was observed, depending upon the cobalt metal surface area However, after stabilization, all of the catalysts attained a similar level of conversion, possibly because of the active-site rearrangement, deactivation, and wax formation on the catalyst surface At a higher reaction temperature of 240{sup o}C, the catalysts prepared at lower solution pH exhibited higher conversion than those prepared at higher solution pH The cobalt species on the catalysts prepared under acidic conditions had a heterogeneous particle size distribution, showing highermore » steady-state activity, because of the reduced interaction with the support The product distribution revealed a higher selectivity to C{sub 1} and C{sub 8+} on the catalyst prepared with a higher solution pH 44 refs, 6 figs, 3 tabs« less

Investigation of dye-doped sol–gels for ammonia gas sensing

Abstract: Sol–gel films doped with fluorescein (FL) and phenol red (PR) dyes were evaluated for their responses to ammonia gas. In a steady state, the sensors respond to the gas-phase ammonia evolved from ammonium hydroxide solutions in the range of 5 × 10−6 to 0.05 M for FL-doped gels, and 10−4 to 1 M for PR-doped gels. The sensors have high selectivity for ammonia against larger amines and moderate selectivity against methyl and ethylamines. The FL-gel exhibits rapid and reproducible response to dry NH3 gas samples of 9–50 ppm, while PR-gel is insensitive to ammonia in this low concentration range. The life-times of the sensors are over a year.

Compounds derived from herbicidal carboxylic acids and tetraalkylammonium or (arylalkyl) trialkylammonium hydroxides

Abstract: Compounds formed by combining a carboxylic acid herbicide with N-((C1- C16) alkyl or arylalkyl) tri((C1-C16) alkyl)ammonium hydroxide have herbicidal activity on an acid equivalent basis at least as active as the commercially used carboxylic acid herbicide salts, but are less volatile.

Study of the effect of the base, the silica and the niobium sources on the [Nb]-MCM-41 synthesized at room temperature

Abstract: [Nb]-MCM-41 was synthesized at room temperature by varying the base (tetramethylammonium hydroxide or ammonium hydroxide), the silica source (tetraethyl orthosilicate or tetramethyl orthosilicate), the niobium source (ammonium niobium oxalate, NH 4 [NbO(C 2 O 4 ) 2 (H 2 O) 2 ] · 3H 2 O, or potassium niobate, K 8 Nb 6 O 19 ) and the order of addition of the niobium source (before or after the silica source) These variations were determinant in the amount of niobium incorporated into the framework and in the structural order of the [Nb]-MCM-41 obtained Only one method led to the formation of [Nb]-MCM-41 with the desired characteristics and active in the epoxidation of cis -cyclooctene with tert -butyl hydroperoxide leading to 19% conversion and 95% selectivity for cyclooctene oxide after 10 h

Compositions containing chromium, oxygen, and at least two modifier metals selected the group consisting of gold, silver, and palladium, their preparation, and their use as catalysts and catalyst precursors

Abstract: A catalyst composition is disclosed that includes chromium, oxygen, and at least two of gold, silver, and palladium as essential constituent elements. The amount of modifier metals (gold, silver, and/or palladium) in the composition is from about 0.05 atom % to about 10 atom % based on the total amount of chromium and modifier metals. Also disclosed is a process for changing the fluorine distribution (i.e., content and/or arrangement) in a hydrocarbon or halogenated hydrocarbon in the presence of the catalyst composition; and methods for preparing said catalyst composition. One preparation method involves (a) co-precipitating a solid by adding ammonium hydroxide (aqueous ammonia) to an aqueous solution of soluble salts of modifier metals and a soluble chromium salt that contains at least three moles of nitrate per mole of chromium in the solution and has a modifier metal content of from about 0.05 atom % to about 10 atom % of the total content of modifier metals and chromium in the solution to form an aqueous mixture containing co-precipitated solid; (b) drying the co-precipitated solid formed in (a); and (c) calcining the dried solid formed in (b) in an atmosphere containing at least 10% oxygen by volume. Another preparation method involves (a) impregnating solid chromium oxide with a solution of a soluble modifier metal salts; (b) drying the impregnated chromium oxide prepared in (a); and optionally; (c) calcining the dried solid. Yet another preparation method involves mixing multiple compositions, each comprising chromium, oxygen, and at least one modifier metal.

The Aerobic Oxidation of Alcohols with a Ruthenium Porphyrin Catalyst in Organic and Fluorinated Solvents

Abstract: Carbonylruthenium tetrakis(pentafluorophenyl)porphyrin Ru(TPFPP)(CO) was utilized for the aerobic oxidation of alcohols. The in situactivation of the catalyst with mCPBA provided a species capable of catalyzing the oxidation of alcohols with molecular oxygen. The choice of solvent and additive was crucial to obtaining high activity and selectivity. Secondary aromatic alcohols were oxidized in the presence of the ruthenium porphyrin and tetrabutyl ammonium hydroxide in the solvent bromotrichloromethane, enabling high yields to be achieved (up to 99%). Alternatively, alcohols could be oxidized in perfluoro(methyldecalin) with the ruthenium porphyrin at higher temperatures (140 °C) and elevated oxygen pressures (50 psi).

On the synthesis of LaCl3 catalysts for oxidative chlorination of methane

Abstract: LaCl3 is an active and selective catalyst for oxidative chlorination of methane to methyl chloride, generated in situ by chlorination from LaOCl The latter is prepared by precipitation of La(OH)2Cl and subsequent calcination The synthesis route was modified by using different bases in order to synthesize high surface area LaOCl catalyst precursors Ammonium hydroxide and the organic bases tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide are used as precipitating agents The marked increase of the specific surface area by using organic bases indicates also that they may act as templating agents After chlorination the specific surface areas of pure LaOCl samples decrease drastically, lanthanum carbonate, however, acts as structural promoter stabilizing the specific surface area during chlorination

Catalysts for production of biodiesel fuel and glycerol

Abstract: A method of producing biodiesel through the trans-esterification of a triglyceride, comprising mixing a triglyceride, an alcohol, and a catalyst to form a mixture, where said catalyst is non-metal quaternary ammonium hydroxide or non-metal quaternary phosphonium hydroxide, removing volatile components from said mixture, and allowing the remaining mixture to separate into a biodiesel-rich layer and a glycerol-rich layer

Dispersant for wet grinding of heavy calcium carbonate and preparation method thereof

Abstract: The invention provides a dispersant used for wet grinding of heavy calcium carbonate and the preparation method thereof. The dispersant is composed of Alpha and Beta-unsaturated carboxylic acid of 80 to 100 parts by weight, and other monomers of 0 to 20 parts by weight, which are polymerized together, and a neutralizing agent in the polymer is selected from one or two of inorganic base ammonium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, etc., or organic base diethylamine, triethylamine, mono ethanolamine, diethanolamine, triethanolamine, etc. The dispersant of the invention is used for grinding calcium carbonate pulp with high solid content, low viscosity and good time efficiency and stability.

Preparation method for pure silicon beta molecular sieve film

Abstract: The invention pertains to the preparation field of pure silicon beta molecule sieve membrane, which in particular relates a method for preparing highly-oriented beta molecule sieve membrane using dealuminized beta molecule sieve seeds on a plurality of carriers The seeded carriers are prepared on a pre-treated carrier with a mol ratio of NaOH to silica to tetraethyl ammonium hydroxide to NaAlO2 to H2O ranging from 2:10:2:02:100: to 6:50:15:2:500, and then the molecule sieve membrane is prepared on the seeded carriers with a mol ratio of tetraethyl ammonium hydroxide to teos to hydrofluoric acid to H2O ranging from 01:01:005:05 to 10:10:5:50 Suitable carriers include monocrystalline silicon wafer, glass flake, stainless steel coupons, stainless steel meshes and ceramic sheet The membrane is continuous and compact with better repeatability, and applicable to industrial scale-up

Polyaniline — A Conducting Polymer

Abstract: Polyaniline, a conducting polymer, is prepared by the oxidation of aniline hydrochloride with ammonium peroxodisulfate in aqueous medium. The polymer is obtained in nearly quantitative yield; its conductivity at 20°C is 4.4 Scm−1. Protonated polyaniline is converted to non-conducting polyaniline base by treatment with ammonium hydroxide solution.

High temperature stable anatase titanium dioxide

Abstract: This disclosure relates to a process for making titanium dioxide in an anatase crystalline form which is stable at temperatures above 1000°C, comprising: precipitating a halide salt and a hydrolyzed compound comprising titanium from a reaction mixture comprising a titanium starting material selected from the group consisting of titanium tetrachloride, titanium oxychloride, and mixtures thereof, a base selected from the group consisting of ammonium hydroxide, ammonium carbonate, ammonium bicarbonate, tetramethyl ammonium hydroxide or tetraethyl ammonium hydroxide or mixture thereof, a solvent selected from the group consisting of ethanol, n-propanol, i-propanol, dimethyl acetamide, alcoholic ammonium halide and aqueous ammonium halide and mixtures thereof, a source of aluminum and a source of silicon to form a precipitate; and removing the halide salt from the precipitate to recover a oxide of titanium in a predominantly anatase crystalline form. The disclosure additionally relates to anatase which is stable at temperatures above 1000°C.

An electrospray ionization tandem mass spectrometric study of p-tert-butylcalix[6]arene complexation with ammonium hydroxide, and ammonium and sodium ions.

Abstract: The formation of complexes involving p-tert-butylcalix[6]arene with neutral and charged species has been investigated by tandem mass spectrometry combined with electrospray ionization. Complexes of p-tert-butylcalix[6]arene with NH ions were observed in the ratios 1:1, 2:1, and 3:1, together with the complexes of p-tert-butylcalix[6]arene with NH4OH and Na+ ions in the ratios 1:1:1, 2:1:1, and 3:1:1. A single 1:1 complex of p-tert-butylcalix[6]arene with Na+ ions was observed. In addition, a doubly charged complex of p-tert-butylcalix[6]arene with NH4OH, Na+, and NH ions in the ratio 6:1:1:1 was observed. The identity of each complex was determined by mass analysis of product ions formed by the application of a declustering potential over the range 20–220 V and by observation of product ion mass spectra wherein the collision energy was varied from 5 to 50 eV. Fragmentation of the complexes is characterized by the facile loss of the ammonia molecule, sodium and ammonium ions, loss of neutral p-tert-butylcalix[6]arene, and successive neutral losses of C4H8 from the six tert-butyl groups in each p-tert-butylcalix[6]arene molecule. Copyright © 2008 John Wiley & Sons, Ltd.

Preparation of composition containing chromium, oxygen, and either silver or palladium, and their use as catalysts and catalyst precursors

Abstract: A method for preparing a catalyst composition suitable for increasing the fluorine content in a hydrocarbon or a halogenated hydrocarbon is disclosed. The method involves (a) co-precipitating a solid by adding ammonium hydroxide to an aqueous solution of a soluble trivalent chromium salt and a soluble salt of a modifier metal selected from silver and palladium, that contains at least three moles of nitrate (i.e., NO 3 − ) per mole of chromium (i.e., Cr +3 ) in the solution and has a modifier metal concentration of from about 0.05 atom % to about 10 atom % of the total concentration of modifier metal and chromium in the solution to form an aqueous mixture containing co-precipitated solid and dissolved ammonium nitrate; and after at least three moles of ammonium hydroxide per mole of chromium in the solution has been added to the solution, (b) drying said aqueous mixture formed in (a); and (c) calcining the dried solid formed in (b) in an atmosphere containing at least 10% oxygen by volume (e.g., air). Also disclosed is a catalyst composition comprising alpha-chromium oxide and a modifier metal selected from silver and palladium prepared by the above method. Also disclosed is a process for increasing the fluorine content in a hydrocarbon or halogenated hydrocarbon in the presence of a catalyst; and processes using a catalyst composition comprising chromium, oxygen and a modifier metal selected from siver and palladium as essential constituent elements (e.g., a catalyst composition prepared by the above process). An azeotropic composition involving CF 3 CCl═CF 2 and HF is also disclosed.

Compositions containing chromium, oxygen and gold, their preparation, and their use as catalysts and catalyst precursors

Abstract: A catalyst composition is disclosed that includes chromium, oxygen, and gold as essential constituent elements. The amount of gold in the composition is from about 0.05 atom % to about 10 atom % based on the total amount of chromium and gold. Also disclosed is a process for changing the fluorine distribution (i.e., content and/or arrangement) in a hydrocarbon or halogenated hydrocarbon in the presence of the catalyst composition; and methods for preparing said catalyst composition. One preparation method involves; (a) co-precipitating a solid by adding ammonium hydroxide (aqueous ammonia) to an aqueous solution of a soluble gold salt and a soluble chromium salt that contains at least three moles of nitrate per mole of chromium in the solution and has a gold content of from about 0.05 atom % to about 10 atom % of the total content of gold and chromium in the solution to form an aqueous mixture containing co-precipitated solid; (b) drying the co-precipitated solid formed in (a); and (c) calcining the dried solid formed in (b) in an atmosphere containing at least 10% oxygen by volume. Another preparation method involves (a) impregnating solid chromium oxide with a solution of a soluble gold salt, (b) drying the impregnated chromium oxide prepared in (a); and optionally, (c) calcining the dried solid. A third preparation method involves (a) evaporating an aqueous solution of chromium(VI) oxide and a soluble gold salt to form a solid; (b) drying the solid formed in (a); and (c) calcining the dried solid formed in (b) in an atmosphere containing at least 10% oxygen by volume.

Ammonia adsorption on nanostructured silica materials for hydrogen storage and other applications.

Abstract: Our focus in the present study is to apply high specific surface area silica nanostructured porous materials (about 2200 m2/g, as synthesized, and 600-700 m2/g, after stabilization) to adsorb ammonia (NH3) for hydrogen storage and other chemical and pollution abatement applications. We describe here the synthesis, and characterization of these silica materials, and the adsorption study of N2 and NH3. These materials were obtained with the help of a modification of the Stober-Fink-Bohn (SFB) method. The main change, made here to the SFB method, was the use of amines, i.e., triethylamine as catalysts instead of ammonium hydroxide. The silica materials have been characterized with the help of SEM and FTIR Spectrometry. The N2 adsorption study was carried out with the help of the Quantachrome-Autosorb-1 and the NH3 adsorption with the Quantachrome-Autosorb-l-C. The amount of hydrogen adsorbed in the form of NH3 in the studied silica samples at: P=760 [Torr] (1.01325 x 10(5) [Pa]), was 2 [wt.%] and the amount of hydrogen stored in the form of NH3 at about: P=7500 [Torr] (10.0 x 10(5) [Pa]), in the studied stabilized silica samples was 11 wt.%, a magnitude higher than the goal figure of 6.5 [wt.%] established by the United States of America, Department of Energy.

Solution for processing of metal replacement with metal aluminum or aluminum alloy and method for surface processing using such solution

Abstract: There is disclosed a processing solution for metal replacement for metal aluminum or an aluminum alloy. The processing solution is used for surface processing of an underlying aluminum material. The processing solution for metal replacement removes an oxide film on the underlying aluminum material and suppresses corrosive attack to it to allow a plating film having high smoothness and good plating appearance to be deposited on the underlying aluminum material. The processing solution for metal replacement at least includes a metal salt capable of being replaced with aluminum, and an alkaline compound. A quaternary ammonium hydroxide is contained in the processing solution for metal replacement as the alkaline compound.